On 27-09-2013 08:24, Nishanth Menon wrote:
> On 23:13-20130926, Eduardo Valentin wrote:
>> This patch changes the dtsi entry on omap4430 to contain
>> the thermal data. This data will enable the passive
>> cooling with CPUfreq cooling device at 100C and the
>> system will do a thermal shutdown at 125C.
>>
>> Cc: "Beno?t Cousson" <[email protected]>
>> Cc: Tony Lindgren <[email protected]>
>> Cc: Russell King <[email protected]>
>> Cc: [email protected]
>> Cc: [email protected]
>> Cc: [email protected]
>> Cc: [email protected]
>> Signed-off-by: Eduardo Valentin <[email protected]>
>> ---
>> arch/arm/boot/dts/omap443x.dtsi | 10 ++++++++--
>> 1 file changed, 8 insertions(+), 2 deletions(-)
>>
>> diff --git a/arch/arm/boot/dts/omap443x.dtsi b/arch/arm/boot/dts/omap443x.dtsi
>> index bcf455e..e9c97d6 100644
>> --- a/arch/arm/boot/dts/omap443x.dtsi
>> +++ b/arch/arm/boot/dts/omap443x.dtsi
>> @@ -12,7 +12,7 @@
>>
>> / {
>> cpus {
>> - cpu@0 {
>> + cpu0: cpu@0 {
>> /* OMAP443x variants OPP50-OPPNT */
>> operating-points = <
>> /* kHz uV */
>> @@ -25,9 +25,15 @@
>> };
>> };
>>
>> - bandgap {
>> + thermal-zones{
>> + #include "omap4-cpu-thermal.dtsi"
>> + };
>> +
>> + bandgap: bandgap {
>> reg = <0x4a002260 0x4
>> 0x4a00232C 0x4>;
>> compatible = "ti,omap4430-bandgap";
>> +
>> + #thermal-sensor-cells = <0>;
> 2 cents:
> we might want to move bandgap under ocp?
>

Yes, agreed. But I don't think this change is related to this patch or
to this series.

Tks Nishanth

>> };
>> };
>> --
>> 1.8.2.1.342.gfa7285d
>>
>>
>> _______________________________________________
>> linux-arm-kernel mailing list
>> [email protected]
>> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
>

--
You have got to be excited about what you are doing. (L. Lamport)

Eduardo Valentin

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2013-09-27 13:26:40

by Nishanth Menon

[permalink] [raw]

Subject: Re: [PATCHv4 11/18] arm: dts: add omap4430 thermal data

On Fri, Sep 27, 2013 at 8:20 AM, Eduardo Valentin
<[email protected]> wrote:
> On 27-09-2013 08:24, Nishanth Menon wrote:
>> On 23:13-20130926, Eduardo Valentin wrote:
>>> This patch changes the dtsi entry on omap4430 to contain
>>> the thermal data. This data will enable the passive
>>> cooling with CPUfreq cooling device at 100C and the
>>> system will do a thermal shutdown at 125C.
>>>
>>> Cc: "Beno?t Cousson" <[email protected]>
>>> Cc: Tony Lindgren <[email protected]>
>>> Cc: Russell King <[email protected]>
>>> Cc: [email protected]
>>> Cc: [email protected]
>>> Cc: [email protected]
>>> Cc: [email protected]
>>> Signed-off-by: Eduardo Valentin <[email protected]>
>>> ---
>>> arch/arm/boot/dts/omap443x.dtsi | 10 ++++++++--
>>> 1 file changed, 8 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/arch/arm/boot/dts/omap443x.dtsi b/arch/arm/boot/dts/omap443x.dtsi
>>> index bcf455e..e9c97d6 100644
>>> --- a/arch/arm/boot/dts/omap443x.dtsi
>>> +++ b/arch/arm/boot/dts/omap443x.dtsi
>>> @@ -12,7 +12,7 @@
>>>
>>> / {
>>> cpus {
>>> - cpu@0 {
>>> + cpu0: cpu@0 {
>>> /* OMAP443x variants OPP50-OPPNT */
>>> operating-points = <
>>> /* kHz uV */
>>> @@ -25,9 +25,15 @@
>>> };
>>> };
>>>
>>> - bandgap {
>>> + thermal-zones{
>>> + #include "omap4-cpu-thermal.dtsi"
>>> + };
>>> +
>>> + bandgap: bandgap {
>>> reg = <0x4a002260 0x4
>>> 0x4a00232C 0x4>;
>>> compatible = "ti,omap4430-bandgap";
>>> +
>>> + #thermal-sensor-cells = <0>;
>> 2 cents:
>> we might want to move bandgap under ocp?
>>
>
> Yes, agreed. But I don't think this change is related to this patch or
> to this series.

Correct - this comment is not related to the current patch, hence my 2
cents ;) - will be nice to have it cleaned up though..

Regards,
Nishanth Menon

2013-09-27 13:44:49

Hi Mark

Thanks for another good review round. I am following up your concerns
inline.

On 30-09-2013 11:36, Mark Rutland wrote:
> Hi Eduardo,
>
> On Fri, Sep 27, 2013 at 04:13:10AM +0100, Eduardo Valentin wrote:
>> This patch introduces a device tree bindings for
>> describing the hardware thermal behavior and limits.
>> Also a parser to read and interpret the data and feed
>> it in the thermal framework is presented.
>>
>> This patch introduces a thermal data parser for device
>> tree. The parsed data is used to build thermal zones
>> and thermal binding parameters. The output data
>> can then be used to deploy thermal policies.
>>
>> This patch adds also documentation regarding this
>> API and how to define tree nodes to use
>> this infrastructure.
>>
>> Note that, in order to be able to have control
>> on the sensor registration on the DT thermal zone,
>> it was required to allow changing the thermal zone
>> .get_temp callback. For this reason, this patch
>> also removes the 'const' modifier from the .ops
>> field of thermal zone devices.
>>
>> Cc: Zhang Rui <[email protected]>
>> Cc: [email protected]
>> Cc: [email protected]
>> Signed-off-by: Eduardo Valentin <[email protected]>
>> ---
>>
>> Hello folks,
>>
>> For those interested on this work, here is a short changelog from v6:
>> - Reviewed binding documentation and added type and size on all properties
>> - Described 'thermal-zones' node in binding documentation
>> - Using now cooling state terminology instead of cooling level
>> - Renamed milliCelsius to millicelsius
>> - Renamed cooling-attachments to 'cooling-maps'
>> - Renamed sensor to thermal sensor
>> - Renamed #sensor-cells to #thermal-sensor-cells
>> - #thermal-sensor-cells now is allowed to be 0
>> - Renamed 'sensors' property to 'thermal-sensors'
>> - Changed trip type property to be now string and documented possible values
>> - Described better the cooling properties
>> - Now parses 'contribution' instead of 'usage'
>> - Renamed cdev to cooling device
>> - Renamed 'passive-delay' property to 'polling-delay-passive'
>> - Fixed a couple of error messages to match the property name
>> - Fixed a binding issue while using cpufreq as module
>> - Reworked thermal_of_build_thermal_zone function so that it frees
>> requested memory if something goes wrong and checks for sub-nodes
>> with zero children.
>>
>> ---
>> .../devicetree/bindings/thermal/thermal.txt | 537 +++++++++++++
>> drivers/thermal/Kconfig | 13 +
>> drivers/thermal/Makefile | 1 +
>> drivers/thermal/of-thermal.c | 845 +++++++++++++++++++++
>> drivers/thermal/thermal_core.c | 9 +-
>> drivers/thermal/thermal_core.h | 9 +
>> include/dt-bindings/thermal/thermal.h | 27 +
>> include/linux/thermal.h | 28 +-
>> 8 files changed, 1466 insertions(+), 3 deletions(-)
>> create mode 100644 Documentation/devicetree/bindings/thermal/thermal.txt
>> create mode 100644 drivers/thermal/of-thermal.c
>> create mode 100644 include/dt-bindings/thermal/thermal.h
>>
>> diff --git a/Documentation/devicetree/bindings/thermal/thermal.txt b/Documentation/devicetree/bindings/thermal/thermal.txt
>> new file mode 100644
>> index 0000000..3dbc017
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/thermal/thermal.txt
>> @@ -0,0 +1,537 @@
>> +* Thermal Framework Device Tree descriptor
>> +
>> +Generic binding to provide a way of defining hardware thermal
>> +structure using device tree. A thermal structure includes thermal
>> +zones and their components, such as trip points, polling intervals,
>> +sensors and cooling devices binding descriptors.
>> +
>> +The target of device tree thermal descriptors is to describe only
>> +the hardware thermal aspects, not how the system must control or which
>> +algorithm or policy must be taken in place.
>> +
>> +There are five types of nodes involved to describe thermal bindings:
>> +- sensors: used to describe the device source of temperature sensing;
>> +- cooling devices: used to describe devices source of power dissipation control;
>> +- trip points: used to describe points in temperature domain defined to
>> +make the system aware of hardware limits;
>> +- cooling maps: used to describe links between trip points and
>> +cooling devices;
>> +- thermal zones: used to describe thermal data within the hardware;
>> +
>> +It follows a description of each type of these device tree nodes.
>> +
>> +Note: This binding is a working in progress.
>
> What does this mean? Is the binding expected to change in incompatible
> ways?

Well, no. The note was more to say we still don't have a final
agreement. But for merging this patch, once we have agreed to get it
merged, I believe this comment can be left out.

>
> I see we have similar wording at the top of the clock bindings, which
> should probably go -- it's ABI now...

OK.

>
>> +
>> +* Thermal sensor devices
>> +
>> +Thermal sensor devices are nodes providing temperature sensing capabilities on
>> +thermal zones. Typical devices are I2C ADC converters and bandgaps. Theses are
>> +nodes providing temperature data to thermal zones. Thermal sensor devices may
>> +control one or more internal sensors.
>> +
>> +Required property:
>> +- #thermal-sensor-cells: Used to provide sensor device specific information
>> + Type: unsigned while referring to it. Typically 0, on thermal sensor
>> + Size: one cell nodes with only one sensor, and at least 1 on nodes
>> + with several internal sensors, in order
>> + to identify uniquely the sensor instances within
>> + the IC. See thermal zone binding for more details
>> + on how consumers refer to sensor devices.
>> +
>> +* Cooling device nodes
>> +
>> +Cooling devices are nodes providing control on power dissipation. There
>> +are essentially two ways to provide control on power dissipation. First
>> +is by means of regulating device performance, which is known as passive
>> +cooling. A typical passive cooling is a CPU that has dynamic voltage and
>> +frequency scaling, and uses lower frequencies as cooling states.
>> +Second is by means of activating devices in order to remove
>> +the dissipated heat, which is known as active cooling, e.g. regulating
>> +fan speeds. In both cases, cooling devices shall have a way to determine
>> +the state of cooling in which the device is.
>> +
>> +Required property:
>> +- cooling-min-state: An integer indicating the smallest
>> + Type: unsigned cooling state accepted. Typically 0.
>> + Size: one cell
>> +
>> +- cooling-max-state: An integer indicating the largest
>> + Type: unsigned cooling state accepted.
>> + Size: one cell
>> +
>> +- #cooling-cells: Used to provide cooling device specific information
>> + Type: unsigned while referring to it. Must be at least 2, in order
>> + Size: one cell to specify minimum and maximum cooling state used
>> + in the reference. The first cell is the minimum
>> + cooling state requested and the second cell is
>> + the maximum cooling state requested in the reference.
>> + See Cooling device maps section below for more details
>> + on how consumers refer to cooling devices.
>> +
>> +* Trip points
>> +
>> +The trip node is a node to describe a point in the temperature domain
>> +in which the system takes an action. This node describes just the point,
>> +not the action.
>> +
>> +Required properties:
>> +- temperature: An integer indicating the trip temperature level,
>> + Type: signed in millicelsius.
>> + Size: one cell
>> +
>> +- hysteresis: a (low) hysteresis value on 'temperature'. This is a
>> + Type: unsigned relative value, in millicelsius.
>> + Size: one cell
>> +
>> +- type: a string containing the trip type. Supported values are:
>
> Odd spacing above.

Do you mean we should remove one \t? While in patch format it looks odd,
but in the ending file it will be aligned to the above descriptions
(from hysteresis and temperature).

>
>> + "active": A trip point to enable active cooling
>> + "passive": A trip point to enable passive cooling
>> + "hot": A trip point to notify emergency
>> + "critical": Hardware not reliable.
>> + Type: string
>> +
>> +There are also string constants defined at
>> +include/dt-bindings/thermal/thermal.h.
>> +
>> +* Cooling device maps
>> +
>> +The cooling device maps node is a node to describe how cooling devices
>> +get assigned to trip points of the zone. The cooling devices are expected
>> +to be loaded in the target system.
>> +
>> +Required properties:
>> +- cooling-device: A phandle of a cooling device with its specifier,
>> + Type: phandle referring to which cooling device is used in this
>
> More odd spacing. There's a fair amount later that would be nice to fix
> up too.

OK. It would be nice to have a suggestion of preferred spacing though.
At least to me, looks pretty good to read.

>
>> + binding. The required specifiers are: the minimum
>> + cooling state and the maximum cooling level used
>> + in this map.
>
> There seems to be some confusion as to the word "specifier". Typically,
> a specifier is all the cells after the phandle described by the #*-cells
> property for the node pointed to. So here there is one
> cooling-specifier, which describes the min and max values, and possibly
> some other values.

OK. So specifier is the set of values that describe the reference to a
phandle. I will rephrase the document accordingly.

>
>> +- trip: A phandle of a trip point node within the same thermal
>> + Type: phandle zone.
>> +
>> +Optional property:
>> +- contribution: The cooling contribution to the thermal zone of the
>> + Type: unsigned referred cooling device at the referred trip point.
>> + Size: one cell The contribution is a ratio of the sum
>> + of all cooling contributions within a thermal zone.
>> +
>> +Note: Using the THERMAL_NO_LIMIT (-1L) constant in the cooling-device phandle
>> +limit specifier means:
>> +(i) - minimum state allowed for minimum cooling level used in the reference.
>> +(ii) - maximum state allowed for maximum cooling level used in the reference.
>> +Refer to include/dt-bindings/thermal/thermal.h for definition of this constant.
>
> How does that work with an unsigned value? Does the code check for
> 0xffffffff, or compare against -1?

The code define is -1UL (pasting existing defines):
/* invalid cooling state */
#define THERMAL_CSTATE_INVALID -1UL

/* No upper/lower limit requirement */
#define THERMAL_NO_LIMIT THERMAL_CSTATE_INVALID

>
>> +
>> +* Thermal zone nodes
>> +
>> +The thermal zone node is the node containing all the required info
>> +for describing a thermal zone, including its cooling device bindings. The
>> +thermal zone node must contain, apart from its own properties, one node containing
>> +trip nodes and one node containing all the zone cooling maps.
>> +
>> +Required properties:
>> +- polling-delay-passive: The maximum number of milliseconds to wait
>> + Type: unsigned between polls when performing passive cooling.
>> + Size: one cell
>
> Is this when performing passive cooling, or any passive or above (i.e.
> any cooling whatsoever)?

No, just when performing passive cooling.

>
>> +
>> +- polling-delay: The maximum number of milliseconds to wait between polls
>> + Type: unsigned when checking this thermal zone.
>> + Size: one cell

While polling for this zone, in any other state other than when doing
passive cooling, the above polling value is used. Including for when
doing any other cooling whatsoever.

>> +
>> +- thermal-sensors: A list of sensor phandles and sensor specifier
>> + Type: list of phandles used while monitoring the thermal zone.
>
> The type and the description don't agree here. The type description can
> probably be omitted as the description describes the format of the
> property.

OK. I just wanted to follow one single format while describing any
property in this document.

>
>> +
>> +- trips: A sub-node which is a container of only trip point nodes
>> + Type: sub-node required to describe the thermal zone.
>> +
>> +- cooling-maps: A sub-node which is a container of only cooling device
>> + Type: sub-node map nodes, used to describe the relation between trips
>> + and cooling devices.
>> +
>> +Optional property:
>> +- thermal-sensors-names: List of thermal sensor name strings sorted
>> + Type: list of strings in the same order as the thermal-sensors
>> + property.
>
> Was there a reason for adding this?
>

The reason is to describe where (physically) the sensor is, or which
location it represents, when a thermal zone is composed by several sensors.

> There was some confusion over my request for cooling-specifier and
> thermal-sensor-specifier terminology last time [1]. I was simply asking
> for terminology, not -names properties.

I see. So, answering you question in [1], I believe comments are enough
to describe where each sensor is located, if needed while writing the
binding for a specific thermal zone. At runtime, what would really make
the difference is the usage of the 'coefficients' property below, as
there is no simple way to guess the sensor contribution in the linear
relation just based on the string names provided. Unless there is a
need to have this information, just for hardware description purposes.

>
>> +
>> +- coefficients: An array of integers (one signed cell) containing
>> + Type: array coefficients to compose a linear relation between
>> + Elem size: one cell the sensors described in the thermal-sensors property.
>> + Elem type: signed Coefficients defaults to 1, in case this property
>> + is not specified. A simple linear polynomial is used:
>> + Z = c0 * x0 + c1 + x1 + ... + c(n-1) * x(n-1) + cn.
>> +
>> + The coefficients are ordered and they match with sensors
>> + by means of sensor ID. Additional coefficients are
>> + interpreted as constant offsets.
>> +
>> +Note: The delay properties are bound to the maximum dT/dt (temperature
>> +derivative over time) in two situations for a thermal zone:
>> +(i) - when active cooling is activated (polling-delay-passive); and
>
> Ah, so any coolnig implies the passive polling delay. That makes teh
> naming confusing (active cooling means we're polling for the passive
> delay). Sorry for the poor suggestion.
>

No, that was a very mistake in my phrasing. The above sentence must be:
+(i) - when *passive* cooling is activated (polling-delay-passive); and

> How about having polling-delay-cooled instead. That better describes
> when it applies.
>
>> +(ii) - when the zone just needs to be monitored (polling-delay).
>> +The maximum dT/dt is highly bound to hardware power consumption and dissipation
>> +capability.
>
> It would be nice to have another line break here.

OK.

>
>> +The delays are chosen to account for said max dT/dt, such that a device
>
> s/are/should be/

indeed.

>
>> +does not cross several trip boundaries unexpectedly between polls. Choosing
>> +the right polling delays shall avoid having the device in temperature ranges
>> +that may damage the silicon structures and reduce silicon lifetime.
>> +
>> +* The thermal-zones node
>> +
>> +The "thermal-zones" node is a container for all thermal zone nodes. It shall
>> +contain only sub-nodes describing thermal zones as in the section
>> +"Thermal zone nodes".
>
> I assume thermal-zones appears under /, rather than under a subnode? It
> might be worth mentioning.

OK. I am adding this info.

>
>> +
>> +* Examples
>> +
>> +Below are several examples on how to use thermal data descriptors
>> +using device tree bindings:
>> +
>> +(a) - CPU thermal zone
>> +
>> +The CPU thermal zone example below describes how to setup one thermal zone
>> +using one single sensor as temperature source and many cooling devices and
>> +power dissipation control sources.
>> +
>> +#include <dt-bindings/thermal/thermal.h>
>> +
>> +cpus {
>> + cpu0: cpu@0 {
>> + ...
>> + cooling-min-state = <0>;
>> + cooling-max-state = <3>;
>> + #cooling-cells = <2>; /* min followed by max */
>> + };
>> + ...
>> +};
>
> If we're going to give an example of cpu nodes with cooling-cells, we
> should have a binding for cpu nodes explaining what the abstract cooling
> properties mean for them.
>
> What _specifically_ do each of the values 0,1,2,3 mean here? Are they
> indexes of OPPs to use (which aren't shown in the example)? Are they
> specific to a particular CPU (the compatible string for which is not
> shown in the example)? Are they generic and applicable to all CPUs
> somehow?

OK. They are indexes of OPPs, yes, but in reverse order. That is, in the
case the CPU has 4 OPPs, 0 means all for OPPs are allowed to be used, 1
means only 3 lower OPPs are allowed, 2 means only 2 lower OPPs are
allowed to be used and 1 means only the lowest is allowed. I will add a
more detailed example.

>
>> +
>> +&i2c1 {
>> + ...
>
> Having a comment inline describing this fictional sensor would be
> useful, something like:
>
> /*
> * A simple fan controlller. Supports 10 speeds of operation
> * (represented as 0-9).
> */
>
> I didn't notice the block below until already having tried to comprehend
> the example. Inline comments would help in that regard.
>

OK. I will add comments to describe them briefly.

>> + fan0: fan@0x48 {
>> + ...
>> + cooling-min-state = <0>;
>> + cooling-max-state = <9>;
>> + #cooling-cells = <2>; /* min followed by max */
>> + };
>> +};
>> +
>
> Similarly, it would be nice to have something here like:
>
> /*
> * A simple IC with a single bandgap temperature sensor.
> */
>
>> +bandgap0: bandgap@0x0000ED00 {
>> + ...
>> + #thermal-sensor-cells = <0>;
>> +};
>> +
>> +cpu-thermal: cpu-thermal {
>
> This should be under a thermal-zones node. Similarly for the other
> examples, they should have all relevant context.

OK. I agree to add the thermal-zones container.

>
>> + polling-delay-passive = <250>; /* milliseconds */
>> + polling-delay = <1000>; /* milliseconds */
>> +
>
> The comment below is no longer relevant.

Indeed.

>
>> + /* sensor ID */
>> + thermal-sensors = <&bandgap0>;
>> +
>> + trips {
>> + cpu-alert0: cpu-alert {
>> + temperature = <90000>; /* millicelsius */
>> + hysteresis = <2000>; /* millicelsius */
>> + type = THERMAL_TRIP_ACTIVE;
>
> This got changed to a string in the binding, but is a CPP value here.
> Similarly in many other places below.

I am not sure I follow you here. What do you mean it is a CPP value? It
is simply a macro to a string.

>
>> + };
>> + cpu-alert1: cpu-alert {
>> + temperature = <100000>; /* millicelsius */
>> + hysteresis = <2000>; /* millicelsius */
>> + type = THERMAL_TRIP_PASSIVE;
>> + };
>> + cpu-crit: cpu-crit {
>> + temperature = <125000>; /* millicelsius */
>> + hysteresis = <2000>; /* millicelsius */
>> + type = THERMAL_TRIP_CRITICAL;
>> + };
>> + };
>> +
>> + cooling-maps {
>> + map0 {
>> + trip = <&cpu-alert0>;
>> + cooling-device = <&fan0 THERMAL_NO_LIMITS 4>;
>> + };
>> + map1 {
>> + trip = <&cpu-alert1>;
>> + cooling-device = <&fan0 5 THERMAL_NO_LIMITS>;
>> + };
>> + map2 {
>> + trip = <&cpu-alert1>;
>> + cooling-device =
>> + <&cpu0 THERMAL_NO_LIMITS THERMAL_NO_LIMITS>;
>> + };
>> + };
>> +};
>> +
>> +In the example above, the ADC sensor at address 0x0000ED00 is used to monitor
>> +the zone 'cpu-thermal' using its the sensor 0. The fan0, a fan device controlled
>> +via I2C bus 1, at adress 0x48, which has ten different cooling states.
>
> This is a little difficult to understand. How about:
>
> In the example above, the ADC sensor (bandgap0) at address 0x0000ED00 is
> used to monitor the zone 'cpu-thermal' using its sole sensor. A fan
> device (fan0) is controlled via I2C bus 1, at address 0x48, and has ten
> different cooling states 0-9.

Yes, it is a better phrasing. Thanks.

>
>> +It is used to remove the heat out of the thermal zone 'cpu-thermal' using its
>> +cooling states from its minimum to 4, when it reaches trip point 'cpu-alert0'
>> +at 90C, as an example of active cooling. The same cooling device is used at
>> +'cpu-alert1', but from 5 to its maximum state. The cpu@0 device is also
>> +linked to the same thermal zone, 'cpu-thermal', as a passive cooling device,
>> +using all its cooling states at trip point 'cpu-alert1',
>> +which is a trip point at 100C.
>> +
>> +(b) - IC with several internal sensors
>> +
>> +The example below describes how to deploy several thermal zones based off a
>> +single sensor IC, assuming it has several internal sensors. This is a common
>> +case on SoC designs with several internal IPs that may need different thermal
>> +requirements, and thus may have their own sensor to monitor or detect internal
>> +hotspots in their silicon.
>> +
>> +#include <dt-bindings/thermal/thermal.h>
>> +
>> +bandgap0: bandgap@0x0000ED00 {
>> + ...
>> + #thermal-sensor-cells = <1>;
>> +};
>> +
>> +cpu-thermal: cpu-thermal {
>> + polling-delay-passive = <250>; /* milliseconds */
>> + polling-delay = <1000>; /* milliseconds */
>> +
>> + /* sensor ID */
>> + thermal-sensors = <&bandgap0 0>;
>> +
>> + trips {
>> + /* each zone within the SoC may have its own trips */
>> + cpu-alert: cpu-alert {
>> + temperature = <100000>; /* millicelsius */
>> + hysteresis = <2000>; /* millicelsius */
>> + type = THERMAL_TRIP_PASSIVE;
>> + };
>> + cpu-crit: cpu-crit {
>> + temperature = <125000>; /* millicelsius */
>> + hysteresis = <2000>; /* millicelsius */
>> + type = THERMAL_TRIP_CRITICAL;
>> + };
>> + };
>> +
>> + cooling-maps {
>> + /* each zone within the SoC may have its own cooling */
>> + ...
>> + };
>> +};
>> +
>> +gpu-thermal: gpu-thermal {
>> + polling-delay-passive = <120>; /* milliseconds */
>> + polling-delay = <1000>; /* milliseconds */
>> +
>> + /* sensor ID */
>> + thermal-sensors = <&bandgap0 1>;
>> +
>> + trips {
>> + /* each zone within the SoC may have its own trips */
>> + gpu-alert: gpu-alert {
>> + temperature = <90000>; /* millicelsius */
>> + hysteresis = <2000>; /* millicelsius */
>> + type = THERMAL_TRIP_PASSIVE;
>> + };
>> + gpu-crit: gpu-crit {
>> + temperature = <105000>; /* millicelsius */
>> + hysteresis = <2000>; /* millicelsius */
>> + type = THERMAL_TRIP_CRITICAL;
>> + };
>> + };
>> +
>> + cooling-maps {
>> + /* each zone within the SoC may have its own cooling */
>> + ...
>> + };
>> +};
>> +
>> +dsp-thermal: dsp-thermal {
>> + polling-delay-passive = <50>; /* milliseconds */
>> + polling-delay = <1000>; /* milliseconds */
>> +
>> + /* sensor ID */
>> + thermal-sensors = <&bandgap0 2>;
>> +
>> + trips {
>> + /* each zone within the SoC may have its own trips */
>> + dsp-alert: gpu-alert {
>> + temperature = <90000>; /* millicelsius */
>> + hysteresis = <2000>; /* millicelsius */
>> + type = THERMAL_TRIP_PASSIVE;
>> + };
>> + dsp-crit: gpu-crit {
>> + temperature = <135000>; /* millicelsius */
>> + hysteresis = <2000>; /* millicelsius */
>> + type = THERMAL_TRIP_CRITICAL;
>> + };
>> + };
>> +
>> + cooling-maps {
>> + /* each zone within the SoC may have its own cooling */
>> + ...
>> + };
>> +};
>> +
>> +In the example above there is one bandgap IC which has the capability to
>> +monitor three sensors. The hardware has been designed so that sensors are
>> +placed on different places in the DIE to monitor different temperature
>> +hotspots: one for CPU thermal zone, one for GPU thermal zone and the
>> +other to monitor a DSP thermal zone.
>> +
>> +Thus, there is a need to assign each sensor provided by the bandgap IC
>> +to different thermal zones. This is achieved by means of using the
>> +#thermal-sensor-cells property and using the first specifier as sensor ID.
>> +In the example, then, bandgap.sensor0 is used to monitor CPU thermal zone,
>
> The reference to bandgap.sensor0 is confusing. How about saying
> <&bandgap 0> instead? It makes it far easier to see correspondence
> between the text and the dt. Similarly for the other instances below.

Agreed.

>
>> +bandgap.sensor1 is used to monitor GPU thermal zone and bandgap.sensor2
>> +is used to monitor DSP thermal zone. Each zone may be uncorrelated,
>> +having its own dT/dt requirements, trips and cooling maps.
>> +
>> +
>> +(c) - Several sensors within one single thermal zone
>> +
>> +The example below illustrates how to use more than one sensor within
>> +one thermal zone.
>> +
>> +#include <dt-bindings/thermal/thermal.h>
>> +
>> +&i2c1 {
>> + ...
>> + adc: sensor@0x49 {
>> + ...
>> + #thermal-sensor-cells = <0>;
>> + };
>> +};
>> +
>> +bandgap0: bandgap@0x0000ED00 {
>> + ...
>> + #thermal-sensor-cells = <0>;
>> +};
>> +
>> +cpu-thermal: cpu-thermal {
>> + polling-delay-passive = <250>; /* milliseconds */
>> + polling-delay = <1000>; /* milliseconds */
>> +
>> + /* sensor ID */
>> + thermal-sensors = <&bandgap0>,
>> + <&adc>;
>> + thermal-sensors-names = "cpu", "pcb north";
>> +
>> + /* hotspot = 100 * bandgap - 120 * adc + 484 */
>> + coefficients = <100 -120 484>;
>> +
>> + trips {
>> + ...
>> + };
>> +
>> + cooling-maps {
>> + ...
>> + };
>> +};
>> +
>> +In some cases, there is a need to use more than one sensor to extrapolate
>> +a thermal hotspot in the silicon. The above example illustrate this situation.
>
> s/illustrate/illustrates/

OK.

>
>> +For instance, it may be the case that a sensor external to CPU IP may be place
>
> s/place/placed/

OK.

>
>> +close to CPU hotspot and together with internal CPU sensor, it is used
>> +to determine the hotspot. The hyppotetical extrapolation rule would be:
>
> s/hyppotetical/hypothetical/

OK.

>
> [...]
>
>> +static int of_thermal_set_trip_temp(struct thermal_zone_device *tz, int trip,
>> + unsigned long temp)
>> +{
>> + struct __thermal_zone *data = tz->devdata;
>> +
>> + if (trip >= data->ntrips || trip < 0)
>> + return -EDOM;
>> +
>> + /* thermal fw should take care of data->mask & (1 << trip) */
>
> I mentioned this last time, and it's tripped me up again while reading:
> It's rather too easy to read "fw" as "firmware" and get confused.
>
> s/fw/framework/ please. :)

OK.

>
>> + data->trips[trip].temperature = temp;
>> +
>> + return 0;
>> +}
>
> [...]
>
>> +struct thermal_zone_device *
>> +thermal_zone_of_sensor_register(struct device *dev, int sensor_id,
>> + void *data, int (*get_temp)(void *, long *),
>> + int (*get_trend)(void *, long *))
>> +{
>> + struct device_node *np, *child, *sensor_np;
>> +
>> + np = of_find_node_by_name(NULL, "thermal-zones");
>> + if (!np)
>> + return ERR_PTR(-ENODEV);
>> +
>> + if (!dev || !dev->of_node)
>> + return ERR_PTR(-EINVAL);
>> +
>> + sensor_np = dev->of_node;
>> +
>> + for_each_child_of_node(np, child) {
>> + struct of_phandle_args sensor_specs;
>> + int ret, id;
>> +
>> + /* For now, thermal framework supports only 1 sensor per zone */
>> + ret = of_parse_phandle_with_args(child, "thermal-sensors",
>> + "#thermal-sensor-cells",
>> + 0, &sensor_specs);
>> + if (ret)
>> + continue;
>> +
>> + if (sensor_specs.args_count < 1)
>> + id = 0;
>> + else
>> + id = sensor_specs.args[0];
>> +
>
> For the moment it might be worth printing a warning if args_count > 1,
> as thermal management might not function correctly.

Agreed. Adding this warning.

>
>> + if (sensor_specs.np == sensor_np && id == sensor_id) {
>> + of_node_put(np);
>> + return thermal_zone_of_add_sensor(child, sensor_np,
>> + data,
>> + get_temp,
>> + get_trend);
>> + }
>> + }
>> + of_node_put(np);
>> +
>> + return ERR_PTR(-ENODEV);
>> +}
>> +EXPORT_SYMBOL_GPL(thermal_zone_of_sensor_register);
>
> Cheers,
> Mark.
>
> [1] https://lkml.org/lkml/2013/9/24/501
>
>

--
You have got to be excited about what you are doing. (L. Lamport)

Eduardo Valentin

Attachments:

signature.asc (295.00 B)
OpenPGP digital signature

2013-10-01 02:40:47

by Eduardo Valentin

[permalink] [raw]

Subject: [PATCHv8 03/18] thermal: introduce device tree parser

This patch introduces a device tree bindings for
describing the hardware thermal behavior and limits.
Also a parser to read and interpret the data and feed
it in the thermal framework is presented.

This patch introduces a thermal data parser for device
tree. The parsed data is used to build thermal zones
and thermal binding parameters. The output data
can then be used to deploy thermal policies.

This patch adds also documentation regarding this
API and how to define tree nodes to use
this infrastructure.

Note that, in order to be able to have control
on the sensor registration on the DT thermal zone,
it was required to allow changing the thermal zone
.get_temp callback. For this reason, this patch
also removes the 'const' modifier from the .ops
field of thermal zone devices.

Cc: Zhang Rui <[email protected]>
Cc: [email protected]
Cc: [email protected]
Signed-off-by: Eduardo Valentin <[email protected]>
---
Hello Mark, folks,

So, here is v8. Pretty small changes. Most are better
English phrasing in the binding document. It follows changelog:
- Several rephrasing in the binding document, including
spelling, grammar and better phrasing.
- Removed WiP warning from binding document.
- Several spacing and formatting changes in the binding document
- Used the '-specifier' nomenclature properly in the binding doc
- Removed the optional property 'thermal-sensors-names', because
it does not provide useful runtime information
- Fixed description of 'polling-delay-passive'
- Improved examples by adding comments and better explanation
- s/fw/framework/g
- Added a WARN when sensors specifiers are greater and 1.

All best,

Eduardo

---
.../devicetree/bindings/thermal/thermal.txt | 587 ++++++++++++++
drivers/thermal/Kconfig | 13 +
drivers/thermal/Makefile | 1 +
drivers/thermal/of-thermal.c | 849 +++++++++++++++++++++
drivers/thermal/thermal_core.c | 9 +-
drivers/thermal/thermal_core.h | 9 +
include/dt-bindings/thermal/thermal.h | 27 +
include/linux/thermal.h | 28 +-
8 files changed, 1520 insertions(+), 3 deletions(-)
create mode 100644 Documentation/devicetree/bindings/thermal/thermal.txt
create mode 100644 drivers/thermal/of-thermal.c
create mode 100644 include/dt-bindings/thermal/thermal.h

diff --git a/Documentation/devicetree/bindings/thermal/thermal.txt b/Documentation/devicetree/bindings/thermal/thermal.txt
new file mode 100644
index 0000000..ad06a8d
--- /dev/null
+++ b/Documentation/devicetree/bindings/thermal/thermal.txt
@@ -0,0 +1,587 @@
+* Thermal Framework Device Tree descriptor
+
+This file describes a generic binding to provide a way of
+defining hardware thermal structure using device tree.
+A thermal structure includes thermal zones and their components,
+such as trip points, polling intervals, sensors and cooling devices
+binding descriptors.
+
+The target of device tree thermal descriptors is to describe only
+the hardware thermal aspects. The thermal device tree bindings are
+not about how the system must control or which algorithm or policy
+must be taken in place.
+
+There are five types of nodes involved to describe thermal bindings:
+- sensors: used to describe the device source of temperature sensing;
+- cooling devices: used to describe devices source of power dissipation control;
+- trip points: used to describe points in temperature domain defined to
+make the system aware of hardware limits;
+- cooling maps: used to describe links between trip points and cooling devices;
+- thermal zones: used to describe thermal data within the hardware;
+
+It follows a description of each type of these device tree nodes.
+
+* Thermal sensor devices
+
+Thermal sensor devices are nodes providing temperature sensing capabilities on
+thermal zones. Typical devices are I2C ADC converters and bandgaps. These are
+nodes providing temperature data to thermal zones. Thermal sensor devices may
+control one or more internal sensors.
+
+Required property:
+- #thermal-sensor-cells: Used to provide sensor device specific information
+ Type: unsigned while referring to it. Typically 0 on thermal sensor
+ Size: one cell nodes with only one sensor, and at least 1 on nodes
+ with several internal sensors, in order
+ to identify uniquely the sensor instances within
+ the IC. See thermal zone binding for more details
+ on how consumers refer to sensor devices.
+
+* Cooling device nodes
+
+Cooling devices are nodes providing control on power dissipation. There
+are essentially two ways to provide control on power dissipation. First
+is by means of regulating device performance, which is known as passive
+cooling. A typical passive cooling is a CPU that has dynamic voltage and
+frequency scaling (DVFS), and uses lower frequencies as cooling states.
+Second is by means of activating devices in order to remove
+the dissipated heat, which is known as active cooling, e.g. regulating
+fan speeds. In both cases, cooling devices shall have a way to determine
+the state of cooling in which the device is.
+
+Required properties:
+- cooling-min-state: An integer indicating the smallest
+ Type: unsigned cooling state accepted. Typically 0.
+ Size: one cell
+
+- cooling-max-state: An integer indicating the largest
+ Type: unsigned cooling state accepted.
+ Size: one cell
+
+- #cooling-cells: Used to provide cooling device specific information
+ Type: unsigned while referring to it. Must be at least 2, in order
+ Size: one cell to specify minimum and maximum cooling state used
+ in the reference. The first cell is the minimum
+ cooling state requested and the second cell is
+ the maximum cooling state requested in the reference.
+ See Cooling device maps section below for more details
+ on how consumers refer to cooling devices.
+
+* Trip points
+
+The trip node is a node to describe a point in the temperature domain
+in which the system takes an action. This node describes just the point,
+not the action.
+
+Required properties:
+- temperature: An integer indicating the trip temperature level,
+ Type: signed in millicelsius.
+ Size: one cell
+
+- hysteresis: a (low) hysteresis value on 'temperature'. This is a
+ Type: unsigned relative value, in millicelsius.
+ Size: one cell
+
+- type: a string containing the trip type. Supported values are:
+ "active": A trip point to enable active cooling
+ "passive": A trip point to enable passive cooling
+ "hot": A trip point to notify emergency
+ "critical": Hardware not reliable.
+ Type: string
+
+There are also string constants defined at
+include/dt-bindings/thermal/thermal.h.
+
+* Cooling device maps
+
+The cooling device maps node is a node to describe how cooling devices
+get assigned to trip points of the zone. The cooling devices are expected
+to be loaded in the target system.
+
+Required properties:
+- cooling-device: A phandle of a cooling device with its specifier,
+ Type: phandle of referring to which cooling device is used in this
+ cooling device binding. In the cooling specifier, the first cell
+ is the minimum cooling state and the second cell
+ is the maximum cooling state used in this map.
+- trip: A phandle of a trip point node within the same thermal
+ Type: phandle of zone.
+ trip point node
+
+Optional property:
+- contribution: The cooling contribution to the thermal zone of the
+ Type: unsigned referred cooling device at the referred trip point.
+ Size: one cell The contribution is a ratio of the sum
+ of all cooling contributions within a thermal zone.
+
+Note: Using the THERMAL_NO_LIMIT (-1UL) constant in the cooling-device phandle
+limit specifier means:
+(i) - minimum state allowed for minimum cooling state used in the reference.
+(ii) - maximum state allowed for maximum cooling state used in the reference.
+Refer to include/dt-bindings/thermal/thermal.h for definition of this constant.
+
+* Thermal zone nodes
+
+The thermal zone node is the node containing all the required info
+for describing a thermal zone, including its cooling device bindings. The
+thermal zone node must contain, apart from its own properties, one sub-node
+containing trip nodes and one sub-node containing all the zone cooling maps.
+
+Required properties:
+- polling-delay: The maximum number of milliseconds to wait between polls
+ Type: unsigned when checking this thermal zone.
+ Size: one cell
+
+- polling-delay-passive: The maximum number of milliseconds to wait
+ Type: unsigned between polls when performing passive cooling.
+ Size: one cell
+
+- thermal-sensors: A list of thermal sensor phandles and sensor specifier
+ Type: list of used while monitoring the thermal zone.
+ sensor phandles
+
+- trips: A sub-node which is a container of only trip point nodes
+ Type: sub-node required to describe the thermal zone.
+
+- cooling-maps: A sub-node which is a container of only cooling device
+ Type: sub-node map nodes, used to describe the relation between trips
+ and cooling devices.
+
+Optional property:
+- coefficients: An array of integers (one signed cell) containing
+ Type: array coefficients to compose a linear relation between
+ Elem size: one cell the sensors listed in the thermal-sensors property.
+ Elem type: signed Coefficients defaults to 1, in case this property
+ is not specified. A simple linear polynomial is used:
+ Z = c0 * x0 + c1 + x1 + ... + c(n-1) * x(n-1) + cn.
+
+ The coefficients are ordered and they match with sensors
+ by means of sensor ID. Additional coefficients are
+ interpreted as constant offset.
+
+Note: The delay properties are bound to the maximum dT/dt (temperature
+derivative over time) in two situations for a thermal zone:
+(i) - when passive cooling is activated (polling-delay-passive); and
+(ii) - when the zone just needs to be monitored (polling-delay) or
+when active cooling is activated.
+
+The maximum dT/dt is highly bound to hardware power consumption and dissipation
+capability. The delays should be chosen to account for said max dT/dt,
+such that a device does not cross several trip boundaries unexpectedly
+between polls. Choosing the right polling delays shall avoid having the
+device in temperature ranges that may damage the silicon structures and
+reduce silicon lifetime.
+
+* The thermal-zones node
+
+The "thermal-zones" node is a container for all thermal zone nodes. It shall
+contain only sub-nodes describing thermal zones as in the section
+"Thermal zone nodes". The "thermal-zones" node appears under "/".
+
+* Examples
+
+Below are several examples on how to use thermal data descriptors
+using device tree bindings:
+
+(a) - CPU thermal zone
+
+The CPU thermal zone example below describes how to setup one thermal zone
+using one single sensor as temperature source and many cooling devices and
+power dissipation control sources.
+
+#include <dt-bindings/thermal/thermal.h>
+
+cpus {
+ /*
+ * Here is an example of describing a cooling device for a DVFS
+ * capable CPU. The CPU node describes its four OPPs.
+ * The cooling states possible are 0..3, and they are
+ * used as OPP indexes. The minimum cooling state is 0, which means
+ * all four OPPs can be available to the system. The maximum
+ * cooling state is 3, which means only the lowest OPPs ([email protected])
+ * can be available in the system.
+ */
+ cpu0: cpu@0 {
+ ...
+ operating-points = <
+ /* kHz uV */
+ 970000 1200000
+ 792000 1100000
+ 396000 950000
+ 198000 850000
+ >;
+ cooling-min-state = <0>;
+ cooling-max-state = <3>;
+ #cooling-cells = <2>; /* min followed by max */
+ };
+ ...
+};
+
+&i2c1 {
+ ...
+ /*
+ * A simple fan controller which supports 10 speeds of operation
+ * (represented as 0-9).
+ */
+ fan0: fan@0x48 {
+ ...
+ cooling-min-state = <0>;
+ cooling-max-state = <9>;
+ #cooling-cells = <2>; /* min followed by max */
+ };
+};
+
+ocp {
+ ...
+ /*
+ * A simple IC with a single bandgap temperature sensor.
+ */
+ bandgap0: bandgap@0x0000ED00 {
+ ...
+ #thermal-sensor-cells = <0>;
+ };
+};
+
+thermal-zones {
+ cpu-thermal: cpu-thermal {
+ polling-delay-passive = <250>; /* milliseconds */
+ polling-delay = <1000>; /* milliseconds */
+
+ thermal-sensors = <&bandgap0>;
+
+ trips {
+ cpu-alert0: cpu-alert {
+ temperature = <90000>; /* millicelsius */
+ hysteresis = <2000>; /* millicelsius */
+ type = "active";
+ };
+ cpu-alert1: cpu-alert {
+ temperature = <100000>; /* millicelsius */
+ hysteresis = <2000>; /* millicelsius */
+ type = "passive";
+ };
+ cpu-crit: cpu-crit {
+ temperature = <125000>; /* millicelsius */
+ hysteresis = <2000>; /* millicelsius */
+ type = "critical";
+ };
+ };
+
+ cooling-maps {
+ map0 {
+ trip = <&cpu-alert0>;
+ cooling-device = <&fan0 THERMAL_NO_LIMITS 4>;
+ };
+ map1 {
+ trip = <&cpu-alert1>;
+ cooling-device = <&fan0 5 THERMAL_NO_LIMITS>;
+ };
+ map2 {
+ trip = <&cpu-alert1>;
+ cooling-device =
+ <&cpu0 THERMAL_NO_LIMITS THERMAL_NO_LIMITS>;
+ };
+ };
+ };
+};
+
+In the example above, the ADC sensor (bandgap0) at address 0x0000ED00 is
+used to monitor the zone 'cpu-thermal' using its sole sensor. A fan
+device (fan0) is controlled via I2C bus 1, at address 0x48, and has ten
+different cooling states 0-9. It is used to remove the heat out of
+the thermal zone 'cpu-thermal' using its cooling states
+from its minimum to 4, when it reaches trip point 'cpu-alert0'
+at 90C, as an example of active cooling. The same cooling device is used at
+'cpu-alert1', but from 5 to its maximum state. The cpu@0 device is also
+linked to the same thermal zone, 'cpu-thermal', as a passive cooling device,
+using all its cooling states at trip point 'cpu-alert1',
+which is a trip point at 100C. On the thermal zone 'cpu-thermal', at the
+temperature of 125C, represented by the trip point 'cpu-crit', the silicon
+is not reliable anymore.
+
+(b) - IC with several internal sensors
+
+The example below describes how to deploy several thermal zones based off a
+single sensor IC, assuming it has several internal sensors. This is a common
+case on SoC designs with several internal IPs that may need different thermal
+requirements, and thus may have their own sensor to monitor or detect internal
+hotspots in their silicon.
+
+#include <dt-bindings/thermal/thermal.h>
+
+ocp {
+ ...
+ /*
+ * A simple IC with several bandgap temperature sensors.
+ */
+ bandgap0: bandgap@0x0000ED00 {
+ ...
+ #thermal-sensor-cells = <1>;
+ };
+};
+
+thermal-zones {
+ cpu-thermal: cpu-thermal {
+ polling-delay-passive = <250>; /* milliseconds */
+ polling-delay = <1000>; /* milliseconds */
+
+ /* sensor ID */
+ thermal-sensors = <&bandgap0 0>;
+
+ trips {
+ /* each zone within the SoC may have its own trips */
+ cpu-alert: cpu-alert {
+ temperature = <100000>; /* millicelsius */
+ hysteresis = <2000>; /* millicelsius */
+ type = "passive";
+ };
+ cpu-crit: cpu-crit {
+ temperature = <125000>; /* millicelsius */
+ hysteresis = <2000>; /* millicelsius */
+ type = "critical";
+ };
+ };
+
+ cooling-maps {
+ /* each zone within the SoC may have its own cooling */
+ ...
+ };
+ };
+
+ gpu-thermal: gpu-thermal {
+ polling-delay-passive = <120>; /* milliseconds */
+ polling-delay = <1000>; /* milliseconds */
+
+ /* sensor ID */
+ thermal-sensors = <&bandgap0 1>;
+
+ trips {
+ /* each zone within the SoC may have its own trips */
+ gpu-alert: gpu-alert {
+ temperature = <90000>; /* millicelsius */
+ hysteresis = <2000>; /* millicelsius */
+ type = "passive";
+ };
+ gpu-crit: gpu-crit {
+ temperature = <105000>; /* millicelsius */
+ hysteresis = <2000>; /* millicelsius */
+ type = "critical";
+ };
+ };
+
+ cooling-maps {
+ /* each zone within the SoC may have its own cooling */
+ ...
+ };
+ };
+
+ dsp-thermal: dsp-thermal {
+ polling-delay-passive = <50>; /* milliseconds */
+ polling-delay = <1000>; /* milliseconds */
+
+ /* sensor ID */
+ thermal-sensors = <&bandgap0 2>;
+
+ trips {
+ /* each zone within the SoC may have its own trips */
+ dsp-alert: gpu-alert {
+ temperature = <90000>; /* millicelsius */
+ hysteresis = <2000>; /* millicelsius */
+ type = "passive";
+ };
+ dsp-crit: gpu-crit {
+ temperature = <135000>; /* millicelsius */
+ hysteresis = <2000>; /* millicelsius */
+ type = "critical";
+ };
+ };
+
+ cooling-maps {
+ /* each zone within the SoC may have its own cooling */
+ ...
+ };
+ };
+};
+
+In the example above, there is one bandgap IC which has the capability to
+monitor three sensors. The hardware has been designed so that sensors are
+placed on different places in the DIE to monitor different temperature
+hotspots: one for CPU thermal zone, one for GPU thermal zone and the
+other to monitor a DSP thermal zone.
+
+Thus, there is a need to assign each sensor provided by the bandgap IC
+to different thermal zones. This is achieved by means of using the
+#thermal-sensor-cells property and using the first cell of the sensor
+specifier as sensor ID. In the example, then, <bandgap 0> is used to
+monitor CPU thermal zone, <bandgap 1> is used to monitor GPU thermal
+zone and <bandgap 2> is used to monitor DSP thermal zone. Each zone
+may be uncorrelated, having its own dT/dt requirements, trips
+and cooling maps.
+
+
+(c) - Several sensors within one single thermal zone
+
+The example below illustrates how to use more than one sensor within
+one thermal zone.
+
+#include <dt-bindings/thermal/thermal.h>
+
+&i2c1 {
+ ...
+ /*
+ * A simple IC with a single temperature sensor.
+ */
+ adc: sensor@0x49 {
+ ...
+ #thermal-sensor-cells = <0>;
+ };
+};
+
+ocp {
+ ...
+ /*
+ * A simple IC with a single bandgap temperature sensor.
+ */
+ bandgap0: bandgap@0x0000ED00 {
+ ...
+ #thermal-sensor-cells = <0>;
+ };
+};
+
+thermal-zones {
+ cpu-thermal: cpu-thermal {
+ polling-delay-passive = <250>; /* milliseconds */
+ polling-delay = <1000>; /* milliseconds */
+
+ thermal-sensors = <&bandgap0>, /* cpu */
+ <&adc>; /* pcb north */
+
+ /* hotspot = 100 * bandgap - 120 * adc + 484 */
+ coefficients = <100 -120 484>;
+
+ trips {
+ ...
+ };
+
+ cooling-maps {
+ ...
+ };
+ };
+};
+
+In some cases, there is a need to use more than one sensor to extrapolate
+a thermal hotspot in the silicon. The above example illustrates this situation.
+For instance, it may be the case that a sensor external to CPU IP may be placed
+close to CPU hotspot and together with internal CPU sensor, it is used
+to determine the hotspot. Assuming this is the case for the above example,
+the hypothetical extrapolation rule would be:
+ hotspot = 100 * bandgap - 120 * adc + 484
+
+In other context, the same idea can be used to add fixed offset. For instance,
+consider the hotspot extrapolation rule below:
+ hotspot = 1 * adc + 6000
+
+In the above equation, the hotspot is always 6C higher than what is read
+from the ADC sensor. The binding would be then:
+ thermal-sensors = <&adc>;
+
+ /* hotspot = 1 * adc + 6000 */
+ coefficients = <1 6000>;
+
+(d) - Board thermal
+
+The board thermal example below illustrates how to setup one thermal zone
+with many sensors and many cooling devices.
+
+#include <dt-bindings/thermal/thermal.h>
+
+&i2c1 {
+ ...
+ /*
+ * An IC with several temperature sensor.
+ */
+ adc-dummy: sensor@0x50 {
+ ...
+ #thermal-sensor-cells = <1>; /* sensor internal ID */
+ };
+};
+
+thermal-zones {
+ batt-thermal {
+ polling-delay-passive = <500>; /* milliseconds */
+ polling-delay = <2500>; /* milliseconds */
+
+ /* sensor ID */
+ thermal-sensors = <&adc-dummy 4>;
+
+ trips {
+ ...
+ };
+
+ cooling-maps {
+ ...
+ };
+ };
+
+ board-thermal: board-thermal {
+ polling-delay-passive = <1000>; /* milliseconds */
+ polling-delay = <2500>; /* milliseconds */
+
+ /* sensor ID */
+ thermal-sensors = <&adc-dummy 0>, /* pcb top edge */
+ <&adc-dummy 1>, /* lcd */
+ <&adc-dymmy 2>; /* back cover */
+ /*
+ * An array of coefficients describing the sensor
+ * linear relation. E.g.:
+ * z = c1*x1 + c2*x2 + c3*x3
+ */
+ coefficients = <1200 -345 890>;
+
+ trips {
+ /* Trips are based on resulting linear equation */
+ cpu-trip: cpu-trip {
+ temperature = <60000>; /* millicelsius */
+ hysteresis = <2000>; /* millicelsius */
+ type = "passive";
+ };
+ gpu-trip: gpu-trip {
+ temperature = <55000>; /* millicelsius */
+ hysteresis = <2000>; /* millicelsius */
+ type = "passive";
+ }
+ lcd-trip: lcp-trip {
+ temperature = <53000>; /* millicelsius */
+ hysteresis = <2000>; /* millicelsius */
+ type = "passive";
+ };
+ crit-trip: crit-trip {
+ temperature = <68000>; /* millicelsius */
+ hysteresis = <2000>; /* millicelsius */
+ type = "critical";
+ };
+ };
+
+ cooling-maps {
+ map0 {
+ trip = <&cpu-trip>;
+ cooling-device = <&cpu0 0 2>;
+ contribution = <55>;
+ };
+ map1 {
+ trip = <&gpu-trip>;
+ cooling-device = <&gpu0 0 2>;
+ contribution = <20>;
+ };
+ map2 {
+ trip = <&lcd-trip>;
+ cooling-device = <&lcd0 5 10>;
+ contribution = <15>;
+ };
+ };
+ };
+};
+
+The above example is a mix of previous examples, a sensor IP with several internal
+sensors used to monitor different zones, one of them is composed by several sensors and
+with different cooling devices.
diff --git a/drivers/thermal/Kconfig b/drivers/thermal/Kconfig
index dbfc390..dd81eb8 100644
--- a/drivers/thermal/Kconfig
+++ b/drivers/thermal/Kconfig
@@ -29,6 +29,19 @@ config THERMAL_HWMON
Say 'Y' here if you want all thermal sensors to
have hwmon sysfs interface too.

+config THERMAL_OF
+ bool
+ prompt "APIs to parse thermal data out of device tree"
+ depends on OF
+ default y
+ help
+ This options provides helpers to add the support to
+ read and parse thermal data definitions out of the
+ device tree blob.
+
+ Say 'Y' here if you need to build thermal infrastructure
+ based on device tree.
+
choice
prompt "Default Thermal governor"
default THERMAL_DEFAULT_GOV_STEP_WISE
diff --git a/drivers/thermal/Makefile b/drivers/thermal/Makefile
index 584b363..4b03956 100644
--- a/drivers/thermal/Makefile
+++ b/drivers/thermal/Makefile
@@ -7,6 +7,7 @@ thermal_sys-y += thermal_core.o

# interface to/from other layers providing sensors
thermal_sys-$(CONFIG_THERMAL_HWMON) += thermal_hwmon.o
+thermal_sys-$(CONFIG_THERMAL_OF) += of-thermal.o

# governors
thermal_sys-$(CONFIG_THERMAL_GOV_FAIR_SHARE) += fair_share.o
diff --git a/drivers/thermal/of-thermal.c b/drivers/thermal/of-thermal.c
new file mode 100644
index 0000000..66f9eb2
--- /dev/null
+++ b/drivers/thermal/of-thermal.c
@@ -0,0 +1,849 @@
+/*
+ * of-thermal.c - Generic Thermal Management device tree support.
+ *
+ * Copyright (C) 2013 Texas Instruments
+ * Copyright (C) 2013 Eduardo Valentin <[email protected]>
+ *
+ *
+ * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
+ *
+ * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ */
+#include <linux/thermal.h>
+#include <linux/slab.h>
+#include <linux/types.h>
+#include <linux/of_device.h>
+#include <linux/of_platform.h>
+#include <linux/err.h>
+#include <linux/export.h>
+#include <linux/string.h>
+
+#include "thermal_core.h"
+
+/*** Private data structures to represent thermal device tree data ***/
+
+/**
+ * struct __thermal_trip - representation of a point in temperature domain
+ * @np: pointer to struct device_node that this trip point was created from
+ * @temperature: temperature value in miliCelsius
+ * @hysteresis: relative hysteresis in miliCelsius
+ * @type: trip point type
+ */
+
+struct __thermal_trip {
+ struct device_node *np;
+ unsigned long int temperature;
+ unsigned long int hysteresis;
+ enum thermal_trip_type type;
+};
+
+/**
+ * struct __thermal_bind_param - a match between trip and cooling device
+ * @cooling_device: a pointer to identify the referred cooling device
+ * @trip_id: the trip point index
+ * @usage: the percentage (from 0 to 100) of cooling contribution
+ * @min: minimum cooling state used at this trip point
+ * @max: maximum cooling state used at this trip point
+ */
+
+struct __thermal_bind_params {
+ struct device_node *cooling_device;
+ unsigned int trip_id;
+ unsigned int usage;
+ unsigned long min;
+ unsigned long max;
+};
+
+/**
+ * struct __thermal_zone - internal representation of a thermal zone
+ * @mode: current thermal zone device mode (enabled/disabled)
+ * @passive_delay: polling interval while passive cooling is activated
+ * @polling_delay: zone polling interval
+ * @ntrips: number of trip points
+ * @trips: an array of trip points (0..ntrips - 1)
+ * @num_tbps: number of thermal bind params
+ * @tbps: an array of thermal bind params (0..num_tbps - 1)
+ * @sensor_data: sensor private data used while reading temperature and trend
+ * @get_temp: sensor callback to read temperature
+ * @get_trend: sensor callback to read temperature trend
+ */
+
+struct __thermal_zone {
+ enum thermal_device_mode mode;
+ int passive_delay;
+ int polling_delay;
+
+ /* trip data */
+ int ntrips;
+ struct __thermal_trip *trips;
+
+ /* cooling binding data */
+ int num_tbps;
+ struct __thermal_bind_params *tbps;
+
+ /* sensor interface */
+ void *sensor_data;
+ int (*get_temp)(void *, long *);
+ int (*get_trend)(void *, long *);
+};
+
+/*** DT thermal zone device callbacks ***/
+
+static int of_thermal_get_temp(struct thermal_zone_device *tz,
+ unsigned long *temp)
+{
+ struct __thermal_zone *data = tz->devdata;
+
+ if (!data->get_temp)
+ return -EINVAL;
+
+ return data->get_temp(data->sensor_data, temp);
+}
+
+static int of_thermal_get_trend(struct thermal_zone_device *tz, int trip,
+ enum thermal_trend *trend)
+{
+ struct __thermal_zone *data = tz->devdata;
+ long dev_trend;
+ int r;
+
+ if (!data->get_trend)
+ return -EINVAL;
+
+ r = data->get_trend(data->sensor_data, &dev_trend);
+ if (r)
+ return r;
+
+ /* TODO: These intervals might have some thresholds, but in core code */
+ if (dev_trend > 0)
+ *trend = THERMAL_TREND_RAISING;
+ else if (dev_trend < 0)
+ *trend = THERMAL_TREND_DROPPING;
+ else
+ *trend = THERMAL_TREND_STABLE;
+
+ return 0;
+}
+
+static int of_thermal_bind(struct thermal_zone_device *thermal,
+ struct thermal_cooling_device *cdev)
+{
+ struct __thermal_zone *data = thermal->devdata;
+ int i;
+
+ if (!data || IS_ERR(data))
+ return -ENODEV;
+
+ /* find where to bind */
+ for (i = 0; i < data->num_tbps; i++) {
+ struct __thermal_bind_params *tbp = data->tbps + i;
+
+ if (tbp->cooling_device == cdev->np) {
+ int ret;
+
+ ret = thermal_zone_bind_cooling_device(thermal,
+ tbp->trip_id, cdev,
+ tbp->min,
+ tbp->max);
+ if (ret)
+ return ret;
+ }
+ }
+
+ return 0;
+}
+
+static int of_thermal_unbind(struct thermal_zone_device *thermal,
+ struct thermal_cooling_device *cdev)
+{
+ struct __thermal_zone *data = thermal->devdata;
+ int i;
+
+ if (!data || IS_ERR(data))
+ return -ENODEV;
+
+ /* find where to unbind */
+ for (i = 0; i < data->num_tbps; i++) {
+ struct __thermal_bind_params *tbp = data->tbps + i;
+
+ if (tbp->cooling_device == cdev->np) {
+ int ret;
+
+ ret = thermal_zone_unbind_cooling_device(thermal,
+ tbp->trip_id, cdev);
+ if (ret)
+ return ret;
+ }
+ }
+
+ return 0;
+}
+
+static int of_thermal_get_mode(struct thermal_zone_device *tz,
+ enum thermal_device_mode *mode)
+{
+ struct __thermal_zone *data = tz->devdata;
+
+ *mode = data->mode;
+
+ return 0;
+}
+
+static int of_thermal_set_mode(struct thermal_zone_device *tz,
+ enum thermal_device_mode mode)
+{
+ struct __thermal_zone *data = tz->devdata;
+
+ mutex_lock(&tz->lock);
+
+ if (mode == THERMAL_DEVICE_ENABLED)
+ tz->polling_delay = data->polling_delay;
+ else
+ tz->polling_delay = 0;
+
+ mutex_unlock(&tz->lock);
+
+ data->mode = mode;
+ thermal_zone_device_update(tz);
+
+ return 0;
+}
+
+static int of_thermal_get_trip_type(struct thermal_zone_device *tz, int trip,
+ enum thermal_trip_type *type)
+{
+ struct __thermal_zone *data = tz->devdata;
+
+ if (trip >= data->ntrips || trip < 0)
+ return -EDOM;
+
+ *type = data->trips[trip].type;
+
+ return 0;
+}
+
+static int of_thermal_get_trip_temp(struct thermal_zone_device *tz, int trip,
+ unsigned long *temp)
+{
+ struct __thermal_zone *data = tz->devdata;
+
+ if (trip >= data->ntrips || trip < 0)
+ return -EDOM;
+
+ *temp = data->trips[trip].temperature;
+
+ return 0;
+}
+
+static int of_thermal_set_trip_temp(struct thermal_zone_device *tz, int trip,
+ unsigned long temp)
+{
+ struct __thermal_zone *data = tz->devdata;
+
+ if (trip >= data->ntrips || trip < 0)
+ return -EDOM;
+
+ /* thermal framework should take care of data->mask & (1 << trip) */
+ data->trips[trip].temperature = temp;
+
+ return 0;
+}
+
+static int of_thermal_get_trip_hyst(struct thermal_zone_device *tz, int trip,
+ unsigned long *hyst)
+{
+ struct __thermal_zone *data = tz->devdata;
+
+ if (trip >= data->ntrips || trip < 0)
+ return -EDOM;
+
+ *hyst = data->trips[trip].hysteresis;
+
+ return 0;
+}
+
+static int of_thermal_set_trip_hyst(struct thermal_zone_device *tz, int trip,
+ unsigned long hyst)
+{
+ struct __thermal_zone *data = tz->devdata;
+
+ if (trip >= data->ntrips || trip < 0)
+ return -EDOM;
+
+ /* thermal framework should take care of data->mask & (1 << trip) */
+ data->trips[trip].hysteresis = hyst;
+
+ return 0;
+}
+
+static int of_thermal_get_crit_temp(struct thermal_zone_device *tz,
+ unsigned long *temp)
+{
+ struct __thermal_zone *data = tz->devdata;
+ int i;
+
+ for (i = 0; i < data->ntrips; i++)
+ if (data->trips[i].type == THERMAL_TRIP_CRITICAL) {
+ *temp = data->trips[i].temperature;
+ return 0;
+ }
+
+ return -EINVAL;
+}
+
+static struct thermal_zone_device_ops of_thermal_ops = {
+ .get_mode = of_thermal_get_mode,
+ .set_mode = of_thermal_set_mode,
+
+ .get_trip_type = of_thermal_get_trip_type,
+ .get_trip_temp = of_thermal_get_trip_temp,
+ .set_trip_temp = of_thermal_set_trip_temp,
+ .get_trip_hyst = of_thermal_get_trip_hyst,
+ .set_trip_hyst = of_thermal_set_trip_hyst,
+ .get_crit_temp = of_thermal_get_crit_temp,
+
+ .bind = of_thermal_bind,
+ .unbind = of_thermal_unbind,
+};
+
+/*** sensor API ***/
+
+static struct thermal_zone_device *
+thermal_zone_of_add_sensor(struct device_node *zone,
+ struct device_node *sensor, void *data,
+ int (*get_temp)(void *, long *),
+ int (*get_trend)(void *, long *))
+{
+ struct thermal_zone_device *tzd;
+ struct __thermal_zone *tz;
+
+ tzd = thermal_zone_get_zone_by_name(zone->name);
+ if (IS_ERR(tzd))
+ return ERR_PTR(-EPROBE_DEFER);
+
+ tz = tzd->devdata;
+
+ mutex_lock(&tzd->lock);
+ tz->get_temp = get_temp;
+ tz->get_trend = get_trend;
+ tz->sensor_data = data;
+
+ tzd->ops->get_temp = of_thermal_get_temp;
+ tzd->ops->get_trend = of_thermal_get_trend;
+ mutex_unlock(&tzd->lock);
+
+ return tzd;
+}
+
+/**
+ * thermal_zone_of_sensor_register - registers a sensor to a DT thermal zone
+ * @dev: a valid struct device pointer of a sensor device. Must contain
+ * a valid .of_node, for the sensor node.
+ * @sensor_id: a sensor identifier, in case the sensor IP has more
+ * than one sensors
+ * @data: a private pointer (owned by the caller) that will be passed
+ * back, when a temperature reading is needed.
+ * @get_temp: a pointer to a function that reads the sensor temperature.
+ * @get_trend: a pointer to a function that reads the sensor temperature trend.
+ *
+ * This function will search the list of thermal zones described in device
+ * tree and look for the zone that refer to the sensor device pointed by
+ * @dev->of_node as temperature providers. For the zone pointing to the
+ * sensor node, the sensor will be added to the DT thermal zone device.
+ *
+ * The thermal zone temperature is provided by the @get_temp function
+ * pointer. When called, it will have the private pointer @data back.
+ *
+ * The thermal zone temperature trend is provided by the @get_trend function
+ * pointer. When called, it will have the private pointer @data back.
+ *
+ * TODO:
+ * 01 - This function must enqueue the new sensor instead of using
+ * it as the only source of temperature values.
+ *
+ * 02 - There must be a way to match the sensor with all thermal zones
+ * that refer to it.
+ *
+ * Return: On success returns a valid struct thermal_zone_device,
+ * otherwise, it returns a corresponding ERR_PTR(). Caller must
+ * check the return value with help of IS_ERR() helper.
+ */
+struct thermal_zone_device *
+thermal_zone_of_sensor_register(struct device *dev, int sensor_id,
+ void *data, int (*get_temp)(void *, long *),
+ int (*get_trend)(void *, long *))
+{
+ struct device_node *np, *child, *sensor_np;
+
+ np = of_find_node_by_name(NULL, "thermal-zones");
+ if (!np)
+ return ERR_PTR(-ENODEV);
+
+ if (!dev || !dev->of_node)
+ return ERR_PTR(-EINVAL);
+
+ sensor_np = dev->of_node;
+
+ for_each_child_of_node(np, child) {
+ struct of_phandle_args sensor_specs;
+ int ret, id;
+
+ /* For now, thermal framework supports only 1 sensor per zone */
+ ret = of_parse_phandle_with_args(child, "thermal-sensors",
+ "#thermal-sensor-cells",
+ 0, &sensor_specs);
+ if (ret)
+ continue;
+
+ if (sensor_specs.args_count >= 1) {
+ id = sensor_specs.args[0];
+ WARN(sensor_specs.args_count > 1,
+ "%s: too many cells in sensor specifier %d\n",
+ sensor_specs.np->name, sensor_specs.args_count);
+ } else {
+ id = 0;
+ }
+
+ if (sensor_specs.np == sensor_np && id == sensor_id) {
+ of_node_put(np);
+ return thermal_zone_of_add_sensor(child, sensor_np,
+ data,
+ get_temp,
+ get_trend);
+ }
+ }
+ of_node_put(np);
+
+ return ERR_PTR(-ENODEV);
+}
+EXPORT_SYMBOL_GPL(thermal_zone_of_sensor_register);
+
+/**
+ * thermal_zone_of_sensor_unregister - unregisters a sensor from a DT thermal zone
+ * @dev: a valid struct device pointer of a sensor device. Must contain
+ * a valid .of_node, for the sensor node.
+ * @tzd: a pointer to struct thermal_zone_device where the sensor is registered.
+ *
+ * This function removes the sensor callbacks and private data from the
+ * thermal zone device registered with thermal_zone_of_sensor_register()
+ * API. It will also silent the zone by remove the .get_temp() and .get_trend()
+ * thermal zone device callbacks.
+ *
+ * TODO: When the support to several sensors per zone is added, this
+ * function must search the sensor list based on @dev parameter.
+ *
+ */
+void thermal_zone_of_sensor_unregister(struct device *dev,
+ struct thermal_zone_device *tzd)
+{
+ struct __thermal_zone *tz;
+
+ if (!dev || !tzd || !tzd->devdata)
+ return;
+
+ tz = tzd->devdata;
+
+ /* no __thermal_zone, nothing to be done */
+ if (!tz)
+ return;
+
+ mutex_lock(&tzd->lock);
+ tzd->ops->get_temp = NULL;
+ tzd->ops->get_trend = NULL;
+
+ tz->get_temp = NULL;
+ tz->get_trend = NULL;
+ tz->sensor_data = NULL;
+ mutex_unlock(&tzd->lock);
+}
+EXPORT_SYMBOL_GPL(thermal_zone_of_sensor_unregister);
+
+/*** functions parsing device tree nodes ***/
+
+/**
+ * thermal_of_populate_bind_params - parse and fill cooling map data
+ * @np: DT node containing a cooling-map node
+ * @__tbp: data structure to be filled with cooling map info
+ * @trips: array of thermal zone trip points
+ * @ntrips: number of trip points inside trips.
+ *
+ * This function parses a cooling-map type of node represented by
+ * @np parameter and fills the read data into @__tbp data structure.
+ * It needs the already parsed array of trip points of the thermal zone
+ * in consideration.
+ *
+ * Return: 0 on success, proper error code otherwise
+ */
+static int thermal_of_populate_bind_params(struct device_node *np,
+ struct __thermal_bind_params *__tbp,
+ struct __thermal_trip *trips,
+ int ntrips)
+{
+ struct of_phandle_args cooling_spec;
+ struct device_node *trip;
+ int ret, i;
+ u32 prop;
+
+ /* Default weight. Usage is optional */
+ __tbp->usage = 0;
+ ret = of_property_read_u32(np, "contribution", &prop);
+ if (ret == 0)
+ __tbp->usage = prop;
+
+ trip = of_parse_phandle(np, "trip", 0);
+ if (!trip) {
+ pr_err("missing trip property\n");
+ return -ENODEV;
+ }
+
+ /* match using device_node */
+ for (i = 0; i < ntrips; i++)
+ if (trip == trips[i].np) {
+ __tbp->trip_id = i;
+ break;
+ }
+
+ if (i == ntrips) {
+ ret = -ENODEV;
+ goto end;
+ }
+
+ ret = of_parse_phandle_with_args(np, "cooling-device", "#cooling-cells",
+ 0, &cooling_spec);
+ if (ret < 0) {
+ pr_err("missing cooling_device property\n");
+ goto end;
+ }
+ __tbp->cooling_device = cooling_spec.np;
+ if (cooling_spec.args_count >= 2) { /* at least min and max */
+ __tbp->min = cooling_spec.args[0];
+ __tbp->max = cooling_spec.args[1];
+ } else {
+ pr_err("wrong reference to cooling device, missing limits\n");
+ }
+
+end:
+ of_node_put(trip);
+
+ return ret;
+}
+
+/**
+ * It maps 'enum thermal_trip_type' found in include/linux/thermal.h
+ * into the device tree binding of 'trip', property type.
+ */
+static const char * const trip_types[] = {
+ [THERMAL_TRIP_ACTIVE] = "active",
+ [THERMAL_TRIP_PASSIVE] = "passive",
+ [THERMAL_TRIP_HOT] = "hot",
+ [THERMAL_TRIP_CRITICAL] = "critical",
+};
+
+/**
+ * thermal_of_get_trip_type - Get phy mode for given device_node
+ * @np: Pointer to the given device_node
+ * @type: Pointer to resulting trip type
+ *
+ * The function gets trip type string from property 'type',
+ * and store its index in trip_types table in @type,
+ *
+ * Return: 0 on success, or errno in error case.
+ */
+static int thermal_of_get_trip_type(struct device_node *np,
+ enum thermal_trip_type *type)
+{
+ const char *t;
+ int err, i;
+
+ err = of_property_read_string(np, "type", &t);
+ if (err < 0)
+ return err;
+
+ for (i = 0; i < ARRAY_SIZE(trip_types); i++)
+ if (!strcasecmp(t, trip_types[i])) {
+ *type = i;
+ return 0;
+ }
+
+ return -ENODEV;
+}
+
+/**
+ * thermal_of_populate_trip - parse and fill one trip point data
+ * @np: DT node containing a trip point node
+ * @trip: trip point data structure to be filled up
+ *
+ * This function parses a trip point type of node represented by
+ * @np parameter and fills the read data into @trip data structure.
+ *
+ * Return: 0 on success, proper error code otherwise
+ */
+static int thermal_of_populate_trip(struct device_node *np,
+ struct __thermal_trip *trip)
+{
+ int prop;
+ int ret;
+
+ ret = of_property_read_u32(np, "temperature", &prop);
+ if (ret < 0) {
+ pr_err("missing temperature property\n");
+ return ret;
+ }
+ trip->temperature = prop;
+
+ ret = of_property_read_u32(np, "hysteresis", &prop);
+ if (ret < 0) {
+ pr_err("missing hysteresis property\n");
+ return ret;
+ }
+ trip->hysteresis = prop;
+
+ ret = thermal_of_get_trip_type(np, &trip->type);
+ if (ret < 0) {
+ pr_err("wrong trip type property\n");
+ return ret;
+ }
+
+ /* Required for cooling map matching */
+ trip->np = np;
+
+ return 0;
+}
+
+/**
+ * thermal_of_build_thermal_zone - parse and fill one thermal zone data
+ * @np: DT node containing a thermal zone node
+ *
+ * This function parses a thermal zone type of node represented by
+ * @np parameter and fills the read data into a __thermal_zone data structure
+ * and return this pointer.
+ *
+ * TODO: Missing properties to parse: thermal-sensor-names and coefficients
+ *
+ * Return: On success returns a valid struct __thermal_zone,
+ * otherwise, it returns a corresponding ERR_PTR(). Caller must
+ * check the return value with help of IS_ERR() helper.
+ */
+static struct __thermal_zone *
+thermal_of_build_thermal_zone(struct device_node *np)
+{
+ struct device_node *child = NULL, *gchild;
+ struct __thermal_zone *tz;
+ int ret, i;
+ u32 prop;
+
+ if (!np) {
+ pr_err("no thermal zone np\n");
+ return ERR_PTR(-EINVAL);
+ }
+
+ tz = kzalloc(sizeof(*tz), GFP_KERNEL);
+ if (!tz)
+ return ERR_PTR(-ENOMEM);
+
+ ret = of_property_read_u32(np, "polling-delay-passive", &prop);
+ if (ret < 0) {
+ pr_err("missing polling-delay-passive property\n");
+ goto free_tz;
+ }
+ tz->passive_delay = prop;
+
+ ret = of_property_read_u32(np, "polling-delay", &prop);
+ if (ret < 0) {
+ pr_err("missing polling-delay property\n");
+ goto free_tz;
+ }
+ tz->polling_delay = prop;
+
+ /* trips */
+ child = of_get_child_by_name(np, "trips");
+
+ /* No trips provided */
+ if (!child)
+ goto finish;
+
+ tz->ntrips = of_get_child_count(child);
+ if (tz->ntrips == 0) /* must have at least one child */
+ goto finish;
+
+ tz->trips = kzalloc(tz->ntrips * sizeof(*tz->trips), GFP_KERNEL);
+ if (!tz->trips) {
+ ret = -ENOMEM;
+ goto free_tz;
+ }
+
+ i = 0;
+ for_each_child_of_node(child, gchild) {
+ ret = thermal_of_populate_trip(gchild, &tz->trips[i++]);
+ if (ret)
+ goto free_trips;
+ }
+
+ of_node_put(child);
+
+ /* cooling-maps */
+ child = of_get_child_by_name(np, "cooling-maps");
+
+ /* cooling-maps not provided */
+ if (!child)
+ goto finish;
+
+ tz->num_tbps = of_get_child_count(child);
+ if (tz->num_tbps == 0)
+ goto finish;
+
+ tz->tbps = kzalloc(tz->num_tbps * sizeof(*tz->tbps), GFP_KERNEL);
+ if (!tz->tbps) {
+ ret = -ENOMEM;
+ goto free_trips;
+ }
+
+ i = 0;
+ for_each_child_of_node(child, gchild)
+ ret = thermal_of_populate_bind_params(gchild, &tz->tbps[i++],
+ tz->trips, tz->ntrips);
+ if (ret)
+ goto free_tbps;
+
+finish:
+ of_node_put(child);
+ tz->mode = THERMAL_DEVICE_DISABLED;
+
+ return tz;
+
+free_tbps:
+ kfree(tz->tbps);
+free_trips:
+ kfree(tz->trips);
+free_tz:
+ kfree(tz);
+ of_node_put(child);
+
+ return ERR_PTR(ret);
+}
+
+static inline void of_thermal_free_zone(struct __thermal_zone *tz)
+{
+ kfree(tz->tbps);
+ kfree(tz->trips);
+ kfree(tz);
+}
+
+/**
+ * of_parse_thermal_zones - parse device tree thermal data
+ *
+ * Initialization function that can be called by machine initialization
+ * code to parse thermal data and populate the thermal framework
+ * with hardware thermal zones info. This function only parses thermal zones.
+ * Cooling devices and sensor devices nodes are supposed to be parsed
+ * by their respective drivers.
+ *
+ * Return: 0 on success, proper error code otherwise
+ *
+ */
+int __init of_parse_thermal_zones(void)
+{
+ struct device_node *np, *child;
+ struct __thermal_zone *tz;
+ struct thermal_zone_device_ops *ops;
+
+ np = of_find_node_by_name(NULL, "thermal-zones");
+ if (!np) {
+ pr_debug("unable to find thermal zones\n");
+ return 0; /* Run successfully on systems without thermal DT */
+ }
+
+ for_each_child_of_node(np, child) {
+ struct thermal_zone_device *zone;
+ struct thermal_zone_params *tzp;
+
+ tz = thermal_of_build_thermal_zone(child);
+ if (IS_ERR(tz)) {
+ pr_err("failed to build thermal zone %s: %ld\n",
+ child->name,
+ PTR_ERR(tz));
+ continue;
+ }
+
+ ops = kmemdup(&of_thermal_ops, sizeof(*ops), GFP_KERNEL);
+ if (!ops)
+ goto exit_free;
+
+ tzp = kzalloc(sizeof(*tzp), GFP_KERNEL);
+ if (!tzp) {
+ kfree(ops);
+ goto exit_free;
+ }
+
+ /* No hwmon because there might be hwmon drivers registering */
+ tzp->no_hwmon = true;
+
+ zone = thermal_zone_device_register(child->name, tz->ntrips,
+ 0, tz,
+ ops, tzp,
+ tz->passive_delay,
+ tz->polling_delay);
+ if (IS_ERR(zone)) {
+ pr_err("Failed to build %s zone %ld\n", child->name,
+ PTR_ERR(zone));
+ kfree(tzp);
+ kfree(ops);
+ of_thermal_free_zone(tz);
+ /* attempting to build remaining zones still */
+ }
+ }
+
+ return 0;
+
+exit_free:
+ of_thermal_free_zone(tz);
+
+ /* no memory available, so free what we have built */
+ of_thermal_destroy_zones();
+
+ return -ENOMEM;
+}
+
+/**
+ * of_thermal_destroy_zones - remove all zones parsed and allocated resources
+ *
+ * Finds all zones parsed and added to the thermal framework and remove them
+ * from the system, together with their resources.
+ *
+ */
+void __exit of_thermal_destroy_zones(void)
+{
+ struct device_node *np, *child;
+
+ np = of_find_node_by_name(NULL, "thermal-zones");
+ if (!np) {
+ pr_err("unable to find thermal zones\n");
+ return;
+ }
+
+ for_each_child_of_node(np, child) {
+ struct thermal_zone_device *zone;
+
+ zone = thermal_zone_get_zone_by_name(child->name);
+ if (IS_ERR(zone))
+ continue;
+
+ thermal_zone_device_unregister(zone);
+ kfree(zone->tzp);
+ kfree(zone->ops);
+ of_thermal_free_zone(zone->devdata);
+ }
+}
diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
index f7a9f4f..fec3351 100644
--- a/drivers/thermal/thermal_core.c
+++ b/drivers/thermal/thermal_core.c
@@ -1371,7 +1371,7 @@ static void remove_trip_attrs(struct thermal_zone_device *tz)
*/
struct thermal_zone_device *thermal_zone_device_register(const char *type,
int trips, int mask, void *devdata,
- const struct thermal_zone_device_ops *ops,
+ struct thermal_zone_device_ops *ops,
const struct thermal_zone_params *tzp,
int passive_delay, int polling_delay)
{
@@ -1751,8 +1751,14 @@ static int __init thermal_init(void)
if (result)
goto unregister_class;

+ result = of_parse_thermal_zones();
+ if (result)
+ goto exit_netlink;
+
return 0;

+exit_netlink:
+ genetlink_exit();
unregister_governors:
thermal_unregister_governors();
unregister_class:
@@ -1768,6 +1774,7 @@ error:

static void __exit thermal_exit(void)
{
+ of_thermal_destroy_zones();
genetlink_exit();
class_unregister(&thermal_class);
thermal_unregister_governors();
diff --git a/drivers/thermal/thermal_core.h b/drivers/thermal/thermal_core.h
index 7cf2f66..3db339f 100644
--- a/drivers/thermal/thermal_core.h
+++ b/drivers/thermal/thermal_core.h
@@ -77,4 +77,13 @@ static inline int thermal_gov_user_space_register(void) { return 0; }
static inline void thermal_gov_user_space_unregister(void) {}
#endif /* CONFIG_THERMAL_GOV_USER_SPACE */

+/* device tree support */
+#ifdef CONFIG_THERMAL_OF
+int of_parse_thermal_zones(void);
+void of_thermal_destroy_zones(void);
+#else
+static inline int of_parse_thermal_zones(void) { return 0; }
+static inline void of_thermal_destroy_zones(void) { }
+#endif
+
#endif /* __THERMAL_CORE_H__ */
diff --git a/include/dt-bindings/thermal/thermal.h b/include/dt-bindings/thermal/thermal.h
new file mode 100644
index 0000000..59c4581
--- /dev/null
+++ b/include/dt-bindings/thermal/thermal.h
@@ -0,0 +1,27 @@
+/*
+ * This header provides constants for most thermal bindings.
+ *
+ * Copyright (C) 2013 Texas Instruments
+ * Eduardo Valentin <[email protected]>
+ *
+ * GPLv2 only
+ */
+
+#ifndef _DT_BINDINGS_THERMAL_THERMAL_H
+#define _DT_BINDINGS_THERMAL_THERMAL_H
+
+/*
+ * Here are the thermal trip types. This must
+ * match with enum thermal_trip_type at
+ * include/linux/thermal.h
+ */
+#define THERMAL_TRIP_ACTIVE "active"
+#define THERMAL_TRIP_PASSIVE "passive"
+#define THERMAL_TRIP_HOT "hot"
+#define THERMAL_TRIP_CRITICAL "critical"
+
+/* On cooling devices upper and lower limits */
+#define THERMAL_NO_LIMIT (-1UL)
+
+#endif
+
diff --git a/include/linux/thermal.h b/include/linux/thermal.h
index b268d3c..b780c5b 100644
--- a/include/linux/thermal.h
+++ b/include/linux/thermal.h
@@ -143,6 +143,7 @@ struct thermal_cooling_device {
int id;
char type[THERMAL_NAME_LENGTH];
struct device device;
+ struct device_node *np;
void *devdata;
const struct thermal_cooling_device_ops *ops;
bool updated; /* true if the cooling device does not need update */
@@ -172,7 +173,7 @@ struct thermal_zone_device {
int emul_temperature;
int passive;
unsigned int forced_passive;
- const struct thermal_zone_device_ops *ops;
+ struct thermal_zone_device_ops *ops;
const struct thermal_zone_params *tzp;
struct thermal_governor *governor;
struct list_head thermal_instances;
@@ -242,8 +243,31 @@ struct thermal_genl_event {
};

/* Function declarations */
+#ifdef CONFIG_THERMAL_OF
+struct thermal_zone_device *
+thermal_zone_of_sensor_register(struct device *dev, int id,
+ void *data, int (*get_temp)(void *, long *),
+ int (*get_trend)(void *, long *));
+void thermal_zone_of_sensor_unregister(struct device *dev,
+ struct thermal_zone_device *tz);
+#else
+static inline struct thermal_zone_device *
+thermal_zone_of_sensor_register(struct device *dev, int id,
+ void *data, int (*get_temp)(void *, long *),
+ int (*get_trend)(void *, long *))
+{
+ return NULL;
+}
+
+static inline
+void thermal_zone_of_sensor_unregister(struct device *dev,
+ struct thermal_zone_device *tz)
+{
+}
+
+#endif
struct thermal_zone_device *thermal_zone_device_register(const char *, int, int,
- void *, const struct thermal_zone_device_ops *,
+ void *, struct thermal_zone_device_ops *,
const struct thermal_zone_params *, int, int);
void thermal_zone_device_unregister(struct thermal_zone_device *);

--
1.8.2.1.342.gfa7285d

2013-10-07 20:51:30

by Mark Rutland

[permalink] [raw]

Subject: Re: [PATCHv8 03/18] thermal: introduce device tree parser

Hi all,

Given that this is a complex new class of binding, I'd appreciate if at least
one other device tree maintainer could also take a look over this and voice any
concerns or suggestions. I've left the entire patch context for this.

Apologies for the munged whitespace -- my mail server appears to have helpfully
and irreparably replaced all tabs with spaces.

On Tue, Oct 01, 2013 at 03:39:26AM +0100, Eduardo Valentin wrote:
> This patch introduces a device tree bindings for
> describing the hardware thermal behavior and limits.
> Also a parser to read and interpret the data and feed
> it in the thermal framework is presented.
>
> This patch introduces a thermal data parser for device
> tree. The parsed data is used to build thermal zones
> and thermal binding parameters. The output data
> can then be used to deploy thermal policies.
>
> This patch adds also documentation regarding this
> API and how to define tree nodes to use
> this infrastructure.
>
> Note that, in order to be able to have control
> on the sensor registration on the DT thermal zone,
> it was required to allow changing the thermal zone
> .get_temp callback. For this reason, this patch
> also removes the 'const' modifier from the .ops
> field of thermal zone devices.
>
> Cc: Zhang Rui <[email protected]>
> Cc: [email protected]
> Cc: [email protected]
> Signed-off-by: Eduardo Valentin <[email protected]>
> ---
> Hello Mark, folks,
>
> So, here is v8. Pretty small changes. Most are better
> English phrasing in the binding document. It follows changelog:
> - Several rephrasing in the binding document, including
> spelling, grammar and better phrasing.
> - Removed WiP warning from binding document.
> - Several spacing and formatting changes in the binding document
> - Used the '-specifier' nomenclature properly in the binding doc
> - Removed the optional property 'thermal-sensors-names', because
> it does not provide useful runtime information
> - Fixed description of 'polling-delay-passive'
> - Improved examples by adding comments and better explanation
> - s/fw/framework/g
> - Added a WARN when sensors specifiers are greater and 1.
>
> All best,
>
> Eduardo
>
> ---
> .../devicetree/bindings/thermal/thermal.txt | 587 ++++++++++++++
> drivers/thermal/Kconfig | 13 +
> drivers/thermal/Makefile | 1 +
> drivers/thermal/of-thermal.c | 849 +++++++++++++++++++++
> drivers/thermal/thermal_core.c | 9 +-
> drivers/thermal/thermal_core.h | 9 +
> include/dt-bindings/thermal/thermal.h | 27 +
> include/linux/thermal.h | 28 +-
> 8 files changed, 1520 insertions(+), 3 deletions(-)
> create mode 100644 Documentation/devicetree/bindings/thermal/thermal.txt
> create mode 100644 drivers/thermal/of-thermal.c
> create mode 100644 include/dt-bindings/thermal/thermal.h
>
> diff --git a/Documentation/devicetree/bindings/thermal/thermal.txt b/Documentation/devicetree/bindings/thermal/thermal.txt
> new file mode 100644
> index 0000000..ad06a8d
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/thermal/thermal.txt
> @@ -0,0 +1,587 @@
> +* Thermal Framework Device Tree descriptor
> +
> +This file describes a generic binding to provide a way of
> +defining hardware thermal structure using device tree.

s/defining/describing/

> +A thermal structure includes thermal zones and their components,
> +such as trip points, polling intervals, sensors and cooling devices
> +binding descriptors.
> +
> +The target of device tree thermal descriptors is to describe only
> +the hardware thermal aspects. The thermal device tree bindings are
> +not about how the system must control or which algorithm or policy
> +must be taken in place.

I'm not quite sure what this is saying -- it seems to contradict the
design of the binding where trip points get linked to cooling device
configuration, and thus we're defining a policy along the lines of "when
sensor $W hits temperature $X, configure cooling device $Y with value
$Z". I don't see how that can't be considered policy.

At best, we can say that policy is being defined because describing the
physical properties of a device and dealing with this at runtime is not
feasible.

> +
> +There are five types of nodes involved to describe thermal bindings:
> +- sensors: used to describe the device source of temperature sensing;

- thermal sensors: devices which may be used to take temperature
measurements.

> +- cooling devices: used to describe devices source of power dissipation control;

- cooling devices: devices which may be used to dissipate heat.

> +- trip points: used to describe points in temperature domain defined to
> +make the system aware of hardware limits;

- trip points: describe key temperatures at which cooling is recommended. The
set of points should be chosen based on hardware limits.

> +- cooling maps: used to describe links between trip points and cooling devices;
> +- thermal zones: used to describe thermal data within the hardware;
> +
> +It follows a description of each type of these device tree nodes.

How about:

The following is a description of each of these node types.

> +
> +* Thermal sensor devices
> +
> +Thermal sensor devices are nodes providing temperature sensing capabilities on
> +thermal zones. Typical devices are I2C ADC converters and bandgaps. These are
> +nodes providing temperature data to thermal zones. Thermal sensor devices may
> +control one or more internal sensors.
> +
> +Required property:
> +- #thermal-sensor-cells: Used to provide sensor device specific information
> + Type: unsigned while referring to it. Typically 0 on thermal sensor
> + Size: one cell nodes with only one sensor, and at least 1 on nodes
> + with several internal sensors, in order
> + to identify uniquely the sensor instances within
> + the IC. See thermal zone binding for more details
> + on how consumers refer to sensor devices.
> +
> +* Cooling device nodes
> +
> +Cooling devices are nodes providing control on power dissipation. There
> +are essentially two ways to provide control on power dissipation. First
> +is by means of regulating device performance, which is known as passive
> +cooling. A typical passive cooling is a CPU that has dynamic voltage and
> +frequency scaling (DVFS), and uses lower frequencies as cooling states.
> +Second is by means of activating devices in order to remove
> +the dissipated heat, which is known as active cooling, e.g. regulating
> +fan speeds. In both cases, cooling devices shall have a way to determine
> +the state of cooling in which the device is.

I'd probably say "heat dissipation" rather than "power dissipation", unless
this is a technical term I am not aware of?

Why is the determination of the state of the cooling device important?

> +
> +Required properties:
> +- cooling-min-state: An integer indicating the smallest
> + Type: unsigned cooling state accepted. Typically 0.
> + Size: one cell
> +
> +- cooling-max-state: An integer indicating the largest
> + Type: unsigned cooling state accepted.
> + Size: one cell
> +
> +- #cooling-cells: Used to provide cooling device specific information
> + Type: unsigned while referring to it. Must be at least 2, in order
> + Size: one cell to specify minimum and maximum cooling state used
> + in the reference. The first cell is the minimum
> + cooling state requested and the second cell is
> + the maximum cooling state requested in the reference.
> + See Cooling device maps section below for more details
> + on how consumers refer to cooling devices.

Is it assumed that all the values between min and max are valid, or might this
be a sparse set of cooling values?

> +
> +* Trip points
> +
> +The trip node is a node to describe a point in the temperature domain
> +in which the system takes an action. This node describes just the point,
> +not the action.
> +
> +Required properties:
> +- temperature: An integer indicating the trip temperature level,
> + Type: signed in millicelsius.
> + Size: one cell
> +
> +- hysteresis: a (low) hysteresis value on 'temperature'. This is a
> + Type: unsigned relative value, in millicelsius.
> + Size: one cell

What is it relative to?

Why is 'temperature' in quotes?

> +
> +- type: a string containing the trip type. Supported values are:
> + "active": A trip point to enable active cooling
> + "passive": A trip point to enable passive cooling
> + "hot": A trip point to notify emergency
> + "critical": Hardware not reliable.
> + Type: string
> +
> +There are also string constants defined at
> +include/dt-bindings/thermal/thermal.h.

Why?

> +
> +* Cooling device maps
> +
> +The cooling device maps node is a node to describe how cooling devices
> +get assigned to trip points of the zone. The cooling devices are expected
> +to be loaded in the target system.
> +
> +Required properties:
> +- cooling-device: A phandle of a cooling device with its specifier,
> + Type: phandle of referring to which cooling device is used in this
> + cooling device binding. In the cooling specifier, the first cell
> + is the minimum cooling state and the second cell
> + is the maximum cooling state used in this map.

The type is wrong here -- it's a phandle + cooling-cells, not just a phandle.

> +- trip: A phandle of a trip point node within the same thermal
> + Type: phandle of zone.
> + trip point node
> +
> +Optional property:
> +- contribution: The cooling contribution to the thermal zone of the
> + Type: unsigned referred cooling device at the referred trip point.
> + Size: one cell The contribution is a ratio of the sum
> + of all cooling contributions within a thermal zone.
> +
> +Note: Using the THERMAL_NO_LIMIT (-1UL) constant in the cooling-device phandle
> +limit specifier means:
> +(i) - minimum state allowed for minimum cooling state used in the reference.
> +(ii) - maximum state allowed for maximum cooling state used in the reference.
> +Refer to include/dt-bindings/thermal/thermal.h for definition of this constant.
> +
> +* Thermal zone nodes
> +
> +The thermal zone node is the node containing all the required info
> +for describing a thermal zone, including its cooling device bindings. The
> +thermal zone node must contain, apart from its own properties, one sub-node
> +containing trip nodes and one sub-node containing all the zone cooling maps.
> +
> +Required properties:
> +- polling-delay: The maximum number of milliseconds to wait between polls
> + Type: unsigned when checking this thermal zone.
> + Size: one cell
> +
> +- polling-delay-passive: The maximum number of milliseconds to wait
> + Type: unsigned between polls when performing passive cooling.
> + Size: one cell
> +
> +- thermal-sensors: A list of thermal sensor phandles and sensor specifier
> + Type: list of used while monitoring the thermal zone.
> + sensor phandles

The type is wrong here. A list of phandle + sensor specifiers.

> +
> +- trips: A sub-node which is a container of only trip point nodes
> + Type: sub-node required to describe the thermal zone.
> +
> +- cooling-maps: A sub-node which is a container of only cooling device
> + Type: sub-node map nodes, used to describe the relation between trips
> + and cooling devices.
> +
> +Optional property:
> +- coefficients: An array of integers (one signed cell) containing
> + Type: array coefficients to compose a linear relation between
> + Elem size: one cell the sensors listed in the thermal-sensors property.
> + Elem type: signed Coefficients defaults to 1, in case this property
> + is not specified. A simple linear polynomial is used:
> + Z = c0 * x0 + c1 + x1 + ... + c(n-1) * x(n-1) + cn.
> +
> + The coefficients are ordered and they match with sensors
> + by means of sensor ID. Additional coefficients are
> + interpreted as constant offset.
> +
> +Note: The delay properties are bound to the maximum dT/dt (temperature
> +derivative over time) in two situations for a thermal zone:
> +(i) - when passive cooling is activated (polling-delay-passive); and
> +(ii) - when the zone just needs to be monitored (polling-delay) or
> +when active cooling is activated.
> +
> +The maximum dT/dt is highly bound to hardware power consumption and dissipation
> +capability. The delays should be chosen to account for said max dT/dt,
> +such that a device does not cross several trip boundaries unexpectedly
> +between polls. Choosing the right polling delays shall avoid having the
> +device in temperature ranges that may damage the silicon structures and
> +reduce silicon lifetime.
> +
> +* The thermal-zones node
> +
> +The "thermal-zones" node is a container for all thermal zone nodes. It shall
> +contain only sub-nodes describing thermal zones as in the section
> +"Thermal zone nodes". The "thermal-zones" node appears under "/".
> +
> +* Examples
> +
> +Below are several examples on how to use thermal data descriptors
> +using device tree bindings:
> +
> +(a) - CPU thermal zone
> +
> +The CPU thermal zone example below describes how to setup one thermal zone
> +using one single sensor as temperature source and many cooling devices and
> +power dissipation control sources.
> +
> +#include <dt-bindings/thermal/thermal.h>
> +
> +cpus {
> + /*
> + * Here is an example of describing a cooling device for a DVFS
> + * capable CPU. The CPU node describes its four OPPs.
> + * The cooling states possible are 0..3, and they are
> + * used as OPP indexes. The minimum cooling state is 0, which means
> + * all four OPPs can be available to the system. The maximum
> + * cooling state is 3, which means only the lowest OPPs ([email protected])
> + * can be available in the system.
> + */
> + cpu0: cpu@0 {
> + ...
> + operating-points = <
> + /* kHz uV */
> + 970000 1200000
> + 792000 1100000
> + 396000 950000
> + 198000 850000
> + >;
> + cooling-min-state = <0>;
> + cooling-max-state = <3>;
> + #cooling-cells = <2>; /* min followed by max */
> + };
> + ...
> +};
> +
> +&i2c1 {
> + ...
> + /*
> + * A simple fan controller which supports 10 speeds of operation
> + * (represented as 0-9).
> + */
> + fan0: fan@0x48 {
> + ...
> + cooling-min-state = <0>;
> + cooling-max-state = <9>;
> + #cooling-cells = <2>; /* min followed by max */
> + };
> +};
> +
> +ocp {
> + ...
> + /*
> + * A simple IC with a single bandgap temperature sensor.
> + */
> + bandgap0: bandgap@0x0000ED00 {
> + ...
> + #thermal-sensor-cells = <0>;
> + };
> +};
> +
> +thermal-zones {
> + cpu-thermal: cpu-thermal {
> + polling-delay-passive = <250>; /* milliseconds */
> + polling-delay = <1000>; /* milliseconds */
> +
> + thermal-sensors = <&bandgap0>;
> +
> + trips {
> + cpu-alert0: cpu-alert {
> + temperature = <90000>; /* millicelsius */
> + hysteresis = <2000>; /* millicelsius */
> + type = "active";
> + };
> + cpu-alert1: cpu-alert {
> + temperature = <100000>; /* millicelsius */
> + hysteresis = <2000>; /* millicelsius */
> + type = "passive";
> + };
> + cpu-crit: cpu-crit {
> + temperature = <125000>; /* millicelsius */
> + hysteresis = <2000>; /* millicelsius */
> + type = "critical";
> + };
> + };
> +
> + cooling-maps {
> + map0 {
> + trip = <&cpu-alert0>;
> + cooling-device = <&fan0 THERMAL_NO_LIMITS 4>;
> + };
> + map1 {
> + trip = <&cpu-alert1>;
> + cooling-device = <&fan0 5 THERMAL_NO_LIMITS>;
> + };
> + map2 {
> + trip = <&cpu-alert1>;
> + cooling-device =
> + <&cpu0 THERMAL_NO_LIMITS THERMAL_NO_LIMITS>;
> + };
> + };
> + };
> +};
> +
> +In the example above, the ADC sensor (bandgap0) at address 0x0000ED00 is
> +used to monitor the zone 'cpu-thermal' using its sole sensor. A fan
> +device (fan0) is controlled via I2C bus 1, at address 0x48, and has ten
> +different cooling states 0-9. It is used to remove the heat out of
> +the thermal zone 'cpu-thermal' using its cooling states
> +from its minimum to 4, when it reaches trip point 'cpu-alert0'
> +at 90C, as an example of active cooling. The same cooling device is used at
> +'cpu-alert1', but from 5 to its maximum state. The cpu@0 device is also
> +linked to the same thermal zone, 'cpu-thermal', as a passive cooling device,
> +using all its cooling states at trip point 'cpu-alert1',
> +which is a trip point at 100C. On the thermal zone 'cpu-thermal', at the
> +temperature of 125C, represented by the trip point 'cpu-crit', the silicon
> +is not reliable anymore.
> +
> +(b) - IC with several internal sensors
> +
> +The example below describes how to deploy several thermal zones based off a
> +single sensor IC, assuming it has several internal sensors. This is a common
> +case on SoC designs with several internal IPs that may need different thermal
> +requirements, and thus may have their own sensor to monitor or detect internal
> +hotspots in their silicon.
> +
> +#include <dt-bindings/thermal/thermal.h>
> +
> +ocp {
> + ...
> + /*
> + * A simple IC with several bandgap temperature sensors.
> + */
> + bandgap0: bandgap@0x0000ED00 {
> + ...
> + #thermal-sensor-cells = <1>;
> + };
> +};
> +
> +thermal-zones {
> + cpu-thermal: cpu-thermal {
> + polling-delay-passive = <250>; /* milliseconds */
> + polling-delay = <1000>; /* milliseconds */
> +
> + /* sensor ID */
> + thermal-sensors = <&bandgap0 0>;
> +
> + trips {
> + /* each zone within the SoC may have its own trips */
> + cpu-alert: cpu-alert {
> + temperature = <100000>; /* millicelsius */
> + hysteresis = <2000>; /* millicelsius */
> + type = "passive";
> + };
> + cpu-crit: cpu-crit {
> + temperature = <125000>; /* millicelsius */
> + hysteresis = <2000>; /* millicelsius */
> + type = "critical";
> + };
> + };
> +
> + cooling-maps {
> + /* each zone within the SoC may have its own cooling */
> + ...
> + };
> + };
> +
> + gpu-thermal: gpu-thermal {
> + polling-delay-passive = <120>; /* milliseconds */
> + polling-delay = <1000>; /* milliseconds */
> +
> + /* sensor ID */
> + thermal-sensors = <&bandgap0 1>;
> +
> + trips {
> + /* each zone within the SoC may have its own trips */
> + gpu-alert: gpu-alert {
> + temperature = <90000>; /* millicelsius */
> + hysteresis = <2000>; /* millicelsius */
> + type = "passive";
> + };
> + gpu-crit: gpu-crit {
> + temperature = <105000>; /* millicelsius */
> + hysteresis = <2000>; /* millicelsius */
> + type = "critical";
> + };
> + };
> +
> + cooling-maps {
> + /* each zone within the SoC may have its own cooling */
> + ...
> + };
> + };
> +
> + dsp-thermal: dsp-thermal {
> + polling-delay-passive = <50>; /* milliseconds */
> + polling-delay = <1000>; /* milliseconds */
> +
> + /* sensor ID */
> + thermal-sensors = <&bandgap0 2>;
> +
> + trips {
> + /* each zone within the SoC may have its own trips */
> + dsp-alert: gpu-alert {
> + temperature = <90000>; /* millicelsius */
> + hysteresis = <2000>; /* millicelsius */
> + type = "passive";
> + };
> + dsp-crit: gpu-crit {
> + temperature = <135000>; /* millicelsius */
> + hysteresis = <2000>; /* millicelsius */
> + type = "critical";
> + };
> + };
> +
> + cooling-maps {
> + /* each zone within the SoC may have its own cooling */
> + ...
> + };
> + };
> +};
> +
> +In the example above, there is one bandgap IC which has the capability to
> +monitor three sensors. The hardware has been designed so that sensors are
> +placed on different places in the DIE to monitor different temperature
> +hotspots: one for CPU thermal zone, one for GPU thermal zone and the
> +other to monitor a DSP thermal zone.
> +
> +Thus, there is a need to assign each sensor provided by the bandgap IC
> +to different thermal zones. This is achieved by means of using the
> +#thermal-sensor-cells property and using the first cell of the sensor
> +specifier as sensor ID. In the example, then, <bandgap 0> is used to
> +monitor CPU thermal zone, <bandgap 1> is used to monitor GPU thermal
> +zone and <bandgap 2> is used to monitor DSP thermal zone. Each zone
> +may be uncorrelated, having its own dT/dt requirements, trips
> +and cooling maps.
> +
> +
> +(c) - Several sensors within one single thermal zone
> +
> +The example below illustrates how to use more than one sensor within
> +one thermal zone.
> +
> +#include <dt-bindings/thermal/thermal.h>
> +
> +&i2c1 {
> + ...
> + /*
> + * A simple IC with a single temperature sensor.
> + */
> + adc: sensor@0x49 {
> + ...
> + #thermal-sensor-cells = <0>;
> + };
> +};
> +
> +ocp {
> + ...
> + /*
> + * A simple IC with a single bandgap temperature sensor.
> + */
> + bandgap0: bandgap@0x0000ED00 {
> + ...
> + #thermal-sensor-cells = <0>;
> + };
> +};
> +
> +thermal-zones {
> + cpu-thermal: cpu-thermal {
> + polling-delay-passive = <250>; /* milliseconds */
> + polling-delay = <1000>; /* milliseconds */
> +
> + thermal-sensors = <&bandgap0>, /* cpu */
> + <&adc>; /* pcb north */
> +
> + /* hotspot = 100 * bandgap - 120 * adc + 484 */
> + coefficients = <100 -120 484>;
> +
> + trips {
> + ...
> + };
> +
> + cooling-maps {
> + ...
> + };
> + };
> +};
> +
> +In some cases, there is a need to use more than one sensor to extrapolate
> +a thermal hotspot in the silicon. The above example illustrates this situation.
> +For instance, it may be the case that a sensor external to CPU IP may be placed
> +close to CPU hotspot and together with internal CPU sensor, it is used
> +to determine the hotspot. Assuming this is the case for the above example,
> +the hypothetical extrapolation rule would be:
> + hotspot = 100 * bandgap - 120 * adc + 484
> +
> +In other context, the same idea can be used to add fixed offset. For instance,
> +consider the hotspot extrapolation rule below:
> + hotspot = 1 * adc + 6000
> +
> +In the above equation, the hotspot is always 6C higher than what is read
> +from the ADC sensor. The binding would be then:
> + thermal-sensors = <&adc>;
> +
> + /* hotspot = 1 * adc + 6000 */
> + coefficients = <1 6000>;
> +
> +(d) - Board thermal
> +
> +The board thermal example below illustrates how to setup one thermal zone
> +with many sensors and many cooling devices.
> +
> +#include <dt-bindings/thermal/thermal.h>
> +
> +&i2c1 {
> + ...
> + /*
> + * An IC with several temperature sensor.
> + */
> + adc-dummy: sensor@0x50 {
> + ...
> + #thermal-sensor-cells = <1>; /* sensor internal ID */
> + };
> +};
> +
> +thermal-zones {
> + batt-thermal {
> + polling-delay-passive = <500>; /* milliseconds */
> + polling-delay = <2500>; /* milliseconds */
> +
> + /* sensor ID */
> + thermal-sensors = <&adc-dummy 4>;
> +
> + trips {
> + ...
> + };
> +
> + cooling-maps {
> + ...
> + };
> + };
> +
> + board-thermal: board-thermal {
> + polling-delay-passive = <1000>; /* milliseconds */
> + polling-delay = <2500>; /* milliseconds */
> +
> + /* sensor ID */
> + thermal-sensors = <&adc-dummy 0>, /* pcb top edge */
> + <&adc-dummy 1>, /* lcd */
> + <&adc-dymmy 2>; /* back cover */
> + /*
> + * An array of coefficients describing the sensor
> + * linear relation. E.g.:
> + * z = c1*x1 + c2*x2 + c3*x3
> + */
> + coefficients = <1200 -345 890>;
> +
> + trips {
> + /* Trips are based on resulting linear equation */
> + cpu-trip: cpu-trip {
> + temperature = <60000>; /* millicelsius */
> + hysteresis = <2000>; /* millicelsius */
> + type = "passive";
> + };
> + gpu-trip: gpu-trip {
> + temperature = <55000>; /* millicelsius */
> + hysteresis = <2000>; /* millicelsius */
> + type = "passive";
> + }
> + lcd-trip: lcp-trip {
> + temperature = <53000>; /* millicelsius */
> + hysteresis = <2000>; /* millicelsius */
> + type = "passive";
> + };
> + crit-trip: crit-trip {
> + temperature = <68000>; /* millicelsius */
> + hysteresis = <2000>; /* millicelsius */
> + type = "critical";
> + };
> + };
> +
> + cooling-maps {
> + map0 {
> + trip = <&cpu-trip>;
> + cooling-device = <&cpu0 0 2>;
> + contribution = <55>;
> + };
> + map1 {
> + trip = <&gpu-trip>;
> + cooling-device = <&gpu0 0 2>;
> + contribution = <20>;
> + };
> + map2 {
> + trip = <&lcd-trip>;
> + cooling-device = <&lcd0 5 10>;
> + contribution = <15>;
> + };
> + };
> + };
> +};
> +
> +The above example is a mix of previous examples, a sensor IP with several internal
> +sensors used to monitor different zones, one of them is composed by several sensors and
> +with different cooling devices.
> diff --git a/drivers/thermal/Kconfig b/drivers/thermal/Kconfig
> index dbfc390..dd81eb8 100644
> --- a/drivers/thermal/Kconfig
> +++ b/drivers/thermal/Kconfig
> @@ -29,6 +29,19 @@ config THERMAL_HWMON
> Say 'Y' here if you want all thermal sensors to
> have hwmon sysfs interface too.
>
> +config THERMAL_OF
> + bool
> + prompt "APIs to parse thermal data out of device tree"
> + depends on OF
> + default y
> + help
> + This options provides helpers to add the support to
> + read and parse thermal data definitions out of the
> + device tree blob.
> +
> + Say 'Y' here if you need to build thermal infrastructure
> + based on device tree.
> +
> choice
> prompt "Default Thermal governor"
> default THERMAL_DEFAULT_GOV_STEP_WISE
> diff --git a/drivers/thermal/Makefile b/drivers/thermal/Makefile
> index 584b363..4b03956 100644
> --- a/drivers/thermal/Makefile
> +++ b/drivers/thermal/Makefile
> @@ -7,6 +7,7 @@ thermal_sys-y += thermal_core.o
>
> # interface to/from other layers providing sensors
> thermal_sys-$(CONFIG_THERMAL_HWMON) += thermal_hwmon.o
> +thermal_sys-$(CONFIG_THERMAL_OF) += of-thermal.o
>
> # governors
> thermal_sys-$(CONFIG_THERMAL_GOV_FAIR_SHARE) += fair_share.o
> diff --git a/drivers/thermal/of-thermal.c b/drivers/thermal/of-thermal.c
> new file mode 100644
> index 0000000..66f9eb2
> --- /dev/null
> +++ b/drivers/thermal/of-thermal.c
> @@ -0,0 +1,849 @@
> +/*
> + * of-thermal.c - Generic Thermal Management device tree support.
> + *
> + * Copyright (C) 2013 Texas Instruments
> + * Copyright (C) 2013 Eduardo Valentin <[email protected]>
> + *
> + *
> + * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; version 2 of the License.
> + *
> + * This program is distributed in the hope that it will be useful, but
> + * WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
> + * General Public License for more details.
> + *
> + * You should have received a copy of the GNU General Public License along
> + * with this program; if not, write to the Free Software Foundation, Inc.,
> + * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
> + *
> + * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> + */
> +#include <linux/thermal.h>
> +#include <linux/slab.h>
> +#include <linux/types.h>
> +#include <linux/of_device.h>
> +#include <linux/of_platform.h>
> +#include <linux/err.h>
> +#include <linux/export.h>
> +#include <linux/string.h>
> +
> +#include "thermal_core.h"
> +
> +/*** Private data structures to represent thermal device tree data ***/
> +
> +/**
> + * struct __thermal_trip - representation of a point in temperature domain
> + * @np: pointer to struct device_node that this trip point was created from
> + * @temperature: temperature value in miliCelsius
> + * @hysteresis: relative hysteresis in miliCelsius
> + * @type: trip point type
> + */
> +
> +struct __thermal_trip {
> + struct device_node *np;
> + unsigned long int temperature;
> + unsigned long int hysteresis;
> + enum thermal_trip_type type;
> +};
> +
> +/**
> + * struct __thermal_bind_param - a match between trip and cooling device
> + * @cooling_device: a pointer to identify the referred cooling device
> + * @trip_id: the trip point index
> + * @usage: the percentage (from 0 to 100) of cooling contribution
> + * @min: minimum cooling state used at this trip point
> + * @max: maximum cooling state used at this trip point
> + */
> +
> +struct __thermal_bind_params {
> + struct device_node *cooling_device;
> + unsigned int trip_id;
> + unsigned int usage;
> + unsigned long min;
> + unsigned long max;
> +};
> +
> +/**
> + * struct __thermal_zone - internal representation of a thermal zone
> + * @mode: current thermal zone device mode (enabled/disabled)
> + * @passive_delay: polling interval while passive cooling is activated
> + * @polling_delay: zone polling interval
> + * @ntrips: number of trip points
> + * @trips: an array of trip points (0..ntrips - 1)
> + * @num_tbps: number of thermal bind params
> + * @tbps: an array of thermal bind params (0..num_tbps - 1)
> + * @sensor_data: sensor private data used while reading temperature and trend
> + * @get_temp: sensor callback to read temperature
> + * @get_trend: sensor callback to read temperature trend
> + */
> +
> +struct __thermal_zone {
> + enum thermal_device_mode mode;
> + int passive_delay;
> + int polling_delay;
> +
> + /* trip data */
> + int ntrips;
> + struct __thermal_trip *trips;
> +
> + /* cooling binding data */
> + int num_tbps;
> + struct __thermal_bind_params *tbps;
> +
> + /* sensor interface */
> + void *sensor_data;
> + int (*get_temp)(void *, long *);
> + int (*get_trend)(void *, long *);
> +};
> +
> +/*** DT thermal zone device callbacks ***/
> +
> +static int of_thermal_get_temp(struct thermal_zone_device *tz,
> + unsigned long *temp)
> +{
> + struct __thermal_zone *data = tz->devdata;
> +
> + if (!data->get_temp)
> + return -EINVAL;
> +
> + return data->get_temp(data->sensor_data, temp);
> +}
> +
> +static int of_thermal_get_trend(struct thermal_zone_device *tz, int trip,
> + enum thermal_trend *trend)
> +{
> + struct __thermal_zone *data = tz->devdata;
> + long dev_trend;
> + int r;
> +
> + if (!data->get_trend)
> + return -EINVAL;
> +
> + r = data->get_trend(data->sensor_data, &dev_trend);
> + if (r)
> + return r;
> +
> + /* TODO: These intervals might have some thresholds, but in core code */
> + if (dev_trend > 0)
> + *trend = THERMAL_TREND_RAISING;
> + else if (dev_trend < 0)
> + *trend = THERMAL_TREND_DROPPING;
> + else
> + *trend = THERMAL_TREND_STABLE;
> +
> + return 0;
> +}
> +
> +static int of_thermal_bind(struct thermal_zone_device *thermal,
> + struct thermal_cooling_device *cdev)
> +{
> + struct __thermal_zone *data = thermal->devdata;
> + int i;
> +
> + if (!data || IS_ERR(data))
> + return -ENODEV;
> +
> + /* find where to bind */
> + for (i = 0; i < data->num_tbps; i++) {
> + struct __thermal_bind_params *tbp = data->tbps + i;
> +
> + if (tbp->cooling_device == cdev->np) {
> + int ret;
> +
> + ret = thermal_zone_bind_cooling_device(thermal,
> + tbp->trip_id, cdev,
> + tbp->min,
> + tbp->max);
> + if (ret)
> + return ret;
> + }
> + }
> +
> + return 0;
> +}
> +
> +static int of_thermal_unbind(struct thermal_zone_device *thermal,
> + struct thermal_cooling_device *cdev)
> +{
> + struct __thermal_zone *data = thermal->devdata;
> + int i;
> +
> + if (!data || IS_ERR(data))
> + return -ENODEV;
> +
> + /* find where to unbind */
> + for (i = 0; i < data->num_tbps; i++) {
> + struct __thermal_bind_params *tbp = data->tbps + i;
> +
> + if (tbp->cooling_device == cdev->np) {
> + int ret;
> +
> + ret = thermal_zone_unbind_cooling_device(thermal,
> + tbp->trip_id, cdev);
> + if (ret)
> + return ret;
> + }
> + }
> +
> + return 0;
> +}
> +
> +static int of_thermal_get_mode(struct thermal_zone_device *tz,
> + enum thermal_device_mode *mode)
> +{
> + struct __thermal_zone *data = tz->devdata;
> +
> + *mode = data->mode;
> +
> + return 0;
> +}
> +
> +static int of_thermal_set_mode(struct thermal_zone_device *tz,
> + enum thermal_device_mode mode)
> +{
> + struct __thermal_zone *data = tz->devdata;
> +
> + mutex_lock(&tz->lock);
> +
> + if (mode == THERMAL_DEVICE_ENABLED)
> + tz->polling_delay = data->polling_delay;
> + else
> + tz->polling_delay = 0;
> +
> + mutex_unlock(&tz->lock);
> +
> + data->mode = mode;
> + thermal_zone_device_update(tz);
> +
> + return 0;
> +}
> +
> +static int of_thermal_get_trip_type(struct thermal_zone_device *tz, int trip,
> + enum thermal_trip_type *type)
> +{
> + struct __thermal_zone *data = tz->devdata;
> +
> + if (trip >= data->ntrips || trip < 0)
> + return -EDOM;
> +
> + *type = data->trips[trip].type;
> +
> + return 0;
> +}
> +
> +static int of_thermal_get_trip_temp(struct thermal_zone_device *tz, int trip,
> + unsigned long *temp)
> +{
> + struct __thermal_zone *data = tz->devdata;
> +
> + if (trip >= data->ntrips || trip < 0)
> + return -EDOM;
> +
> + *temp = data->trips[trip].temperature;
> +
> + return 0;
> +}
> +
> +static int of_thermal_set_trip_temp(struct thermal_zone_device *tz, int trip,
> + unsigned long temp)
> +{
> + struct __thermal_zone *data = tz->devdata;
> +
> + if (trip >= data->ntrips || trip < 0)
> + return -EDOM;
> +
> + /* thermal framework should take care of data->mask & (1 << trip) */
> + data->trips[trip].temperature = temp;
> +
> + return 0;
> +}
> +
> +static int of_thermal_get_trip_hyst(struct thermal_zone_device *tz, int trip,
> + unsigned long *hyst)
> +{
> + struct __thermal_zone *data = tz->devdata;
> +
> + if (trip >= data->ntrips || trip < 0)
> + return -EDOM;
> +
> + *hyst = data->trips[trip].hysteresis;
> +
> + return 0;
> +}
> +
> +static int of_thermal_set_trip_hyst(struct thermal_zone_device *tz, int trip,
> + unsigned long hyst)
> +{
> + struct __thermal_zone *data = tz->devdata;
> +
> + if (trip >= data->ntrips || trip < 0)
> + return -EDOM;
> +
> + /* thermal framework should take care of data->mask & (1 << trip) */
> + data->trips[trip].hysteresis = hyst;
> +
> + return 0;
> +}
> +
> +static int of_thermal_get_crit_temp(struct thermal_zone_device *tz,
> + unsigned long *temp)
> +{
> + struct __thermal_zone *data = tz->devdata;
> + int i;
> +
> + for (i = 0; i < data->ntrips; i++)
> + if (data->trips[i].type == THERMAL_TRIP_CRITICAL) {
> + *temp = data->trips[i].temperature;
> + return 0;
> + }
> +
> + return -EINVAL;
> +}
> +
> +static struct thermal_zone_device_ops of_thermal_ops = {
> + .get_mode = of_thermal_get_mode,
> + .set_mode = of_thermal_set_mode,
> +
> + .get_trip_type = of_thermal_get_trip_type,
> + .get_trip_temp = of_thermal_get_trip_temp,
> + .set_trip_temp = of_thermal_set_trip_temp,
> + .get_trip_hyst = of_thermal_get_trip_hyst,
> + .set_trip_hyst = of_thermal_set_trip_hyst,
> + .get_crit_temp = of_thermal_get_crit_temp,
> +
> + .bind = of_thermal_bind,
> + .unbind = of_thermal_unbind,
> +};
> +
> +/*** sensor API ***/
> +
> +static struct thermal_zone_device *
> +thermal_zone_of_add_sensor(struct device_node *zone,
> + struct device_node *sensor, void *data,
> + int (*get_temp)(void *, long *),
> + int (*get_trend)(void *, long *))
> +{
> + struct thermal_zone_device *tzd;
> + struct __thermal_zone *tz;
> +
> + tzd = thermal_zone_get_zone_by_name(zone->name);
> + if (IS_ERR(tzd))
> + return ERR_PTR(-EPROBE_DEFER);
> +
> + tz = tzd->devdata;
> +
> + mutex_lock(&tzd->lock);
> + tz->get_temp = get_temp;
> + tz->get_trend = get_trend;
> + tz->sensor_data = data;
> +
> + tzd->ops->get_temp = of_thermal_get_temp;
> + tzd->ops->get_trend = of_thermal_get_trend;
> + mutex_unlock(&tzd->lock);
> +
> + return tzd;
> +}
> +
> +/**
> + * thermal_zone_of_sensor_register - registers a sensor to a DT thermal zone
> + * @dev: a valid struct device pointer of a sensor device. Must contain
> + * a valid .of_node, for the sensor node.
> + * @sensor_id: a sensor identifier, in case the sensor IP has more
> + * than one sensors
> + * @data: a private pointer (owned by the caller) that will be passed
> + * back, when a temperature reading is needed.
> + * @get_temp: a pointer to a function that reads the sensor temperature.
> + * @get_trend: a pointer to a function that reads the sensor temperature trend.
> + *
> + * This function will search the list of thermal zones described in device
> + * tree and look for the zone that refer to the sensor device pointed by
> + * @dev->of_node as temperature providers. For the zone pointing to the
> + * sensor node, the sensor will be added to the DT thermal zone device.
> + *
> + * The thermal zone temperature is provided by the @get_temp function
> + * pointer. When called, it will have the private pointer @data back.
> + *
> + * The thermal zone temperature trend is provided by the @get_trend function
> + * pointer. When called, it will have the private pointer @data back.
> + *
> + * TODO:
> + * 01 - This function must enqueue the new sensor instead of using
> + * it as the only source of temperature values.
> + *
> + * 02 - There must be a way to match the sensor with all thermal zones
> + * that refer to it.
> + *
> + * Return: On success returns a valid struct thermal_zone_device,
> + * otherwise, it returns a corresponding ERR_PTR(). Caller must
> + * check the return value with help of IS_ERR() helper.
> + */
> +struct thermal_zone_device *
> +thermal_zone_of_sensor_register(struct device *dev, int sensor_id,
> + void *data, int (*get_temp)(void *, long *),
> + int (*get_trend)(void *, long *))
> +{
> + struct device_node *np, *child, *sensor_np;
> +
> + np = of_find_node_by_name(NULL, "thermal-zones");
> + if (!np)
> + return ERR_PTR(-ENODEV);
> +
> + if (!dev || !dev->of_node)
> + return ERR_PTR(-EINVAL);
> +
> + sensor_np = dev->of_node;
> +
> + for_each_child_of_node(np, child) {
> + struct of_phandle_args sensor_specs;
> + int ret, id;
> +
> + /* For now, thermal framework supports only 1 sensor per zone */
> + ret = of_parse_phandle_with_args(child, "thermal-sensors",
> + "#thermal-sensor-cells",
> + 0, &sensor_specs);
> + if (ret)
> + continue;
> +
> + if (sensor_specs.args_count >= 1) {
> + id = sensor_specs.args[0];
> + WARN(sensor_specs.args_count > 1,
> + "%s: too many cells in sensor specifier %d\n",
> + sensor_specs.np->name, sensor_specs.args_count);
> + } else {
> + id = 0;
> + }
> +
> + if (sensor_specs.np == sensor_np && id == sensor_id) {
> + of_node_put(np);
> + return thermal_zone_of_add_sensor(child, sensor_np,
> + data,
> + get_temp,
> + get_trend);
> + }
> + }
> + of_node_put(np);
> +
> + return ERR_PTR(-ENODEV);
> +}
> +EXPORT_SYMBOL_GPL(thermal_zone_of_sensor_register);
> +
> +/**
> + * thermal_zone_of_sensor_unregister - unregisters a sensor from a DT thermal zone
> + * @dev: a valid struct device pointer of a sensor device. Must contain
> + * a valid .of_node, for the sensor node.
> + * @tzd: a pointer to struct thermal_zone_device where the sensor is registered.
> + *
> + * This function removes the sensor callbacks and private data from the
> + * thermal zone device registered with thermal_zone_of_sensor_register()
> + * API. It will also silent the zone by remove the .get_temp() and .get_trend()
> + * thermal zone device callbacks.
> + *
> + * TODO: When the support to several sensors per zone is added, this
> + * function must search the sensor list based on @dev parameter.
> + *
> + */
> +void thermal_zone_of_sensor_unregister(struct device *dev,
> + struct thermal_zone_device *tzd)
> +{
> + struct __thermal_zone *tz;
> +
> + if (!dev || !tzd || !tzd->devdata)
> + return;
> +
> + tz = tzd->devdata;
> +
> + /* no __thermal_zone, nothing to be done */
> + if (!tz)
> + return;
> +
> + mutex_lock(&tzd->lock);
> + tzd->ops->get_temp = NULL;
> + tzd->ops->get_trend = NULL;
> +
> + tz->get_temp = NULL;
> + tz->get_trend = NULL;
> + tz->sensor_data = NULL;
> + mutex_unlock(&tzd->lock);
> +}
> +EXPORT_SYMBOL_GPL(thermal_zone_of_sensor_unregister);
> +
> +/*** functions parsing device tree nodes ***/
> +
> +/**
> + * thermal_of_populate_bind_params - parse and fill cooling map data
> + * @np: DT node containing a cooling-map node
> + * @__tbp: data structure to be filled with cooling map info
> + * @trips: array of thermal zone trip points
> + * @ntrips: number of trip points inside trips.
> + *
> + * This function parses a cooling-map type of node represented by
> + * @np parameter and fills the read data into @__tbp data structure.
> + * It needs the already parsed array of trip points of the thermal zone
> + * in consideration.
> + *
> + * Return: 0 on success, proper error code otherwise
> + */
> +static int thermal_of_populate_bind_params(struct device_node *np,
> + struct __thermal_bind_params *__tbp,
> + struct __thermal_trip *trips,
> + int ntrips)
> +{
> + struct of_phandle_args cooling_spec;
> + struct device_node *trip;
> + int ret, i;
> + u32 prop;
> +
> + /* Default weight. Usage is optional */
> + __tbp->usage = 0;
> + ret = of_property_read_u32(np, "contribution", &prop);
> + if (ret == 0)
> + __tbp->usage = prop;
> +
> + trip = of_parse_phandle(np, "trip", 0);
> + if (!trip) {
> + pr_err("missing trip property\n");
> + return -ENODEV;
> + }
> +
> + /* match using device_node */
> + for (i = 0; i < ntrips; i++)
> + if (trip == trips[i].np) {
> + __tbp->trip_id = i;
> + break;
> + }
> +
> + if (i == ntrips) {
> + ret = -ENODEV;
> + goto end;
> + }
> +
> + ret = of_parse_phandle_with_args(np, "cooling-device", "#cooling-cells",
> + 0, &cooling_spec);
> + if (ret < 0) {
> + pr_err("missing cooling_device property\n");
> + goto end;
> + }
> + __tbp->cooling_device = cooling_spec.np;
> + if (cooling_spec.args_count >= 2) { /* at least min and max */
> + __tbp->min = cooling_spec.args[0];
> + __tbp->max = cooling_spec.args[1];
> + } else {
> + pr_err("wrong reference to cooling device, missing limits\n");
> + }
> +
> +end:
> + of_node_put(trip);
> +
> + return ret;
> +}
> +
> +/**
> + * It maps 'enum thermal_trip_type' found in include/linux/thermal.h
> + * into the device tree binding of 'trip', property type.
> + */
> +static const char * const trip_types[] = {
> + [THERMAL_TRIP_ACTIVE] = "active",
> + [THERMAL_TRIP_PASSIVE] = "passive",
> + [THERMAL_TRIP_HOT] = "hot",
> + [THERMAL_TRIP_CRITICAL] = "critical",
> +};
> +
> +/**
> + * thermal_of_get_trip_type - Get phy mode for given device_node
> + * @np: Pointer to the given device_node
> + * @type: Pointer to resulting trip type
> + *
> + * The function gets trip type string from property 'type',
> + * and store its index in trip_types table in @type,
> + *
> + * Return: 0 on success, or errno in error case.
> + */
> +static int thermal_of_get_trip_type(struct device_node *np,
> + enum thermal_trip_type *type)
> +{
> + const char *t;
> + int err, i;
> +
> + err = of_property_read_string(np, "type", &t);
> + if (err < 0)
> + return err;
> +
> + for (i = 0; i < ARRAY_SIZE(trip_types); i++)
> + if (!strcasecmp(t, trip_types[i])) {
> + *type = i;
> + return 0;
> + }
> +
> + return -ENODEV;
> +}
> +
> +/**
> + * thermal_of_populate_trip - parse and fill one trip point data
> + * @np: DT node containing a trip point node
> + * @trip: trip point data structure to be filled up
> + *
> + * This function parses a trip point type of node represented by
> + * @np parameter and fills the read data into @trip data structure.
> + *
> + * Return: 0 on success, proper error code otherwise
> + */
> +static int thermal_of_populate_trip(struct device_node *np,
> + struct __thermal_trip *trip)
> +{
> + int prop;
> + int ret;
> +
> + ret = of_property_read_u32(np, "temperature", &prop);
> + if (ret < 0) {
> + pr_err("missing temperature property\n");
> + return ret;
> + }
> + trip->temperature = prop;
> +
> + ret = of_property_read_u32(np, "hysteresis", &prop);
> + if (ret < 0) {
> + pr_err("missing hysteresis property\n");
> + return ret;
> + }
> + trip->hysteresis = prop;
> +
> + ret = thermal_of_get_trip_type(np, &trip->type);
> + if (ret < 0) {
> + pr_err("wrong trip type property\n");
> + return ret;
> + }
> +
> + /* Required for cooling map matching */
> + trip->np = np;
> +
> + return 0;
> +}
> +
> +/**
> + * thermal_of_build_thermal_zone - parse and fill one thermal zone data
> + * @np: DT node containing a thermal zone node
> + *
> + * This function parses a thermal zone type of node represented by
> + * @np parameter and fills the read data into a __thermal_zone data structure
> + * and return this pointer.
> + *
> + * TODO: Missing properties to parse: thermal-sensor-names and coefficients
> + *
> + * Return: On success returns a valid struct __thermal_zone,
> + * otherwise, it returns a corresponding ERR_PTR(). Caller must
> + * check the return value with help of IS_ERR() helper.
> + */
> +static struct __thermal_zone *
> +thermal_of_build_thermal_zone(struct device_node *np)
> +{
> + struct device_node *child = NULL, *gchild;
> + struct __thermal_zone *tz;
> + int ret, i;
> + u32 prop;
> +
> + if (!np) {
> + pr_err("no thermal zone np\n");
> + return ERR_PTR(-EINVAL);
> + }
> +
> + tz = kzalloc(sizeof(*tz), GFP_KERNEL);
> + if (!tz)
> + return ERR_PTR(-ENOMEM);
> +
> + ret = of_property_read_u32(np, "polling-delay-passive", &prop);
> + if (ret < 0) {
> + pr_err("missing polling-delay-passive property\n");
> + goto free_tz;
> + }
> + tz->passive_delay = prop;
> +
> + ret = of_property_read_u32(np, "polling-delay", &prop);
> + if (ret < 0) {
> + pr_err("missing polling-delay property\n");
> + goto free_tz;
> + }
> + tz->polling_delay = prop;
> +
> + /* trips */
> + child = of_get_child_by_name(np, "trips");
> +
> + /* No trips provided */
> + if (!child)
> + goto finish;
> +
> + tz->ntrips = of_get_child_count(child);
> + if (tz->ntrips == 0) /* must have at least one child */
> + goto finish;
> +
> + tz->trips = kzalloc(tz->ntrips * sizeof(*tz->trips), GFP_KERNEL);
> + if (!tz->trips) {
> + ret = -ENOMEM;
> + goto free_tz;
> + }
> +
> + i = 0;
> + for_each_child_of_node(child, gchild) {
> + ret = thermal_of_populate_trip(gchild, &tz->trips[i++]);
> + if (ret)
> + goto free_trips;
> + }
> +
> + of_node_put(child);
> +
> + /* cooling-maps */
> + child = of_get_child_by_name(np, "cooling-maps");
> +
> + /* cooling-maps not provided */
> + if (!child)
> + goto finish;
> +
> + tz->num_tbps = of_get_child_count(child);
> + if (tz->num_tbps == 0)
> + goto finish;
> +
> + tz->tbps = kzalloc(tz->num_tbps * sizeof(*tz->tbps), GFP_KERNEL);
> + if (!tz->tbps) {
> + ret = -ENOMEM;
> + goto free_trips;
> + }
> +
> + i = 0;
> + for_each_child_of_node(child, gchild)
> + ret = thermal_of_populate_bind_params(gchild, &tz->tbps[i++],
> + tz->trips, tz->ntrips);
> + if (ret)
> + goto free_tbps;
> +
> +finish:
> + of_node_put(child);
> + tz->mode = THERMAL_DEVICE_DISABLED;
> +
> + return tz;
> +
> +free_tbps:
> + kfree(tz->tbps);
> +free_trips:
> + kfree(tz->trips);
> +free_tz:
> + kfree(tz);
> + of_node_put(child);
> +
> + return ERR_PTR(ret);
> +}
> +
> +static inline void of_thermal_free_zone(struct __thermal_zone *tz)
> +{
> + kfree(tz->tbps);
> + kfree(tz->trips);
> + kfree(tz);
> +}
> +
> +/**
> + * of_parse_thermal_zones - parse device tree thermal data
> + *
> + * Initialization function that can be called by machine initialization
> + * code to parse thermal data and populate the thermal framework
> + * with hardware thermal zones info. This function only parses thermal zones.
> + * Cooling devices and sensor devices nodes are supposed to be parsed
> + * by their respective drivers.
> + *
> + * Return: 0 on success, proper error code otherwise
> + *
> + */
> +int __init of_parse_thermal_zones(void)
> +{
> + struct device_node *np, *child;
> + struct __thermal_zone *tz;
> + struct thermal_zone_device_ops *ops;
> +
> + np = of_find_node_by_name(NULL, "thermal-zones");
> + if (!np) {
> + pr_debug("unable to find thermal zones\n");
> + return 0; /* Run successfully on systems without thermal DT */
> + }
> +
> + for_each_child_of_node(np, child) {
> + struct thermal_zone_device *zone;
> + struct thermal_zone_params *tzp;
> +
> + tz = thermal_of_build_thermal_zone(child);
> + if (IS_ERR(tz)) {
> + pr_err("failed to build thermal zone %s: %ld\n",
> + child->name,
> + PTR_ERR(tz));
> + continue;
> + }
> +
> + ops = kmemdup(&of_thermal_ops, sizeof(*ops), GFP_KERNEL);
> + if (!ops)
> + goto exit_free;
> +
> + tzp = kzalloc(sizeof(*tzp), GFP_KERNEL);
> + if (!tzp) {
> + kfree(ops);
> + goto exit_free;
> + }
> +
> + /* No hwmon because there might be hwmon drivers registering */
> + tzp->no_hwmon = true;
> +
> + zone = thermal_zone_device_register(child->name, tz->ntrips,
> + 0, tz,
> + ops, tzp,
> + tz->passive_delay,
> + tz->polling_delay);
> + if (IS_ERR(zone)) {
> + pr_err("Failed to build %s zone %ld\n", child->name,
> + PTR_ERR(zone));
> + kfree(tzp);
> + kfree(ops);
> + of_thermal_free_zone(tz);
> + /* attempting to build remaining zones still */
> + }
> + }
> +
> + return 0;
> +
> +exit_free:
> + of_thermal_free_zone(tz);
> +
> + /* no memory available, so free what we have built */
> + of_thermal_destroy_zones();
> +
> + return -ENOMEM;
> +}
> +
> +/**
> + * of_thermal_destroy_zones - remove all zones parsed and allocated resources
> + *
> + * Finds all zones parsed and added to the thermal framework and remove them
> + * from the system, together with their resources.
> + *
> + */
> +void __exit of_thermal_destroy_zones(void)
> +{
> + struct device_node *np, *child;
> +
> + np = of_find_node_by_name(NULL, "thermal-zones");
> + if (!np) {
> + pr_err("unable to find thermal zones\n");
> + return;
> + }
> +
> + for_each_child_of_node(np, child) {
> + struct thermal_zone_device *zone;
> +
> + zone = thermal_zone_get_zone_by_name(child->name);
> + if (IS_ERR(zone))
> + continue;
> +
> + thermal_zone_device_unregister(zone);
> + kfree(zone->tzp);
> + kfree(zone->ops);
> + of_thermal_free_zone(zone->devdata);
> + }
> +}
> diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
> index f7a9f4f..fec3351 100644
> --- a/drivers/thermal/thermal_core.c
> +++ b/drivers/thermal/thermal_core.c
> @@ -1371,7 +1371,7 @@ static void remove_trip_attrs(struct thermal_zone_device *tz)
> */
> struct thermal_zone_device *thermal_zone_device_register(const char *type,
> int trips, int mask, void *devdata,
> - const struct thermal_zone_device_ops *ops,
> + struct thermal_zone_device_ops *ops,
> const struct thermal_zone_params *tzp,
> int passive_delay, int polling_delay)
> {
> @@ -1751,8 +1751,14 @@ static int __init thermal_init(void)
> if (result)
> goto unregister_class;
>
> + result = of_parse_thermal_zones();
> + if (result)
> + goto exit_netlink;
> +
> return 0;
>
> +exit_netlink:
> + genetlink_exit();
> unregister_governors:
> thermal_unregister_governors();
> unregister_class:
> @@ -1768,6 +1774,7 @@ error:
>
> static void __exit thermal_exit(void)
> {
> + of_thermal_destroy_zones();
> genetlink_exit();
> class_unregister(&thermal_class);
> thermal_unregister_governors();
> diff --git a/drivers/thermal/thermal_core.h b/drivers/thermal/thermal_core.h
> index 7cf2f66..3db339f 100644
> --- a/drivers/thermal/thermal_core.h
> +++ b/drivers/thermal/thermal_core.h
> @@ -77,4 +77,13 @@ static inline int thermal_gov_user_space_register(void) { return 0; }
> static inline void thermal_gov_user_space_unregister(void) {}
> #endif /* CONFIG_THERMAL_GOV_USER_SPACE */
>
> +/* device tree support */
> +#ifdef CONFIG_THERMAL_OF
> +int of_parse_thermal_zones(void);
> +void of_thermal_destroy_zones(void);
> +#else
> +static inline int of_parse_thermal_zones(void) { return 0; }
> +static inline void of_thermal_destroy_zones(void) { }
> +#endif
> +
> #endif /* __THERMAL_CORE_H__ */
> diff --git a/include/dt-bindings/thermal/thermal.h b/include/dt-bindings/thermal/thermal.h
> new file mode 100644
> index 0000000..59c4581
> --- /dev/null
> +++ b/include/dt-bindings/thermal/thermal.h
> @@ -0,0 +1,27 @@
> +/*
> + * This header provides constants for most thermal bindings.
> + *
> + * Copyright (C) 2013 Texas Instruments
> + * Eduardo Valentin <[email protected]>
> + *
> + * GPLv2 only
> + */
> +
> +#ifndef _DT_BINDINGS_THERMAL_THERMAL_H
> +#define _DT_BINDINGS_THERMAL_THERMAL_H
> +
> +/*
> + * Here are the thermal trip types. This must
> + * match with enum thermal_trip_type at
> + * include/linux/thermal.h
> + */
> +#define THERMAL_TRIP_ACTIVE "active"
> +#define THERMAL_TRIP_PASSIVE "passive"
> +#define THERMAL_TRIP_HOT "hot"
> +#define THERMAL_TRIP_CRITICAL "critical"

I don't like this. If someone wants to include this in a C file they can't do so
at the same time as include/linux/thermal.h. The defined names are longer than
the actual string values, and the comment makes it sound like these could be
modified rather than being a fixed ABI.

I do not see the point of these constants.

Thanks,
Mark.

> +
> +/* On cooling devices upper and lower limits */
> +#define THERMAL_NO_LIMIT (-1UL)
> +
> +#endif
> +
> diff --git a/include/linux/thermal.h b/include/linux/thermal.h
> index b268d3c..b780c5b 100644
> --- a/include/linux/thermal.h
> +++ b/include/linux/thermal.h
> @@ -143,6 +143,7 @@ struct thermal_cooling_device {
> int id;
> char type[THERMAL_NAME_LENGTH];
> struct device device;
> + struct device_node *np;
> void *devdata;
> const struct thermal_cooling_device_ops *ops;
> bool updated; /* true if the cooling device does not need update */
> @@ -172,7 +173,7 @@ struct thermal_zone_device {
> int emul_temperature;
> int passive;
> unsigned int forced_passive;
> - const struct thermal_zone_device_ops *ops;
> + struct thermal_zone_device_ops *ops;
> const struct thermal_zone_params *tzp;
> struct thermal_governor *governor;
> struct list_head thermal_instances;
> @@ -242,8 +243,31 @@ struct thermal_genl_event {
> };
>
> /* Function declarations */
> +#ifdef CONFIG_THERMAL_OF
> +struct thermal_zone_device *
> +thermal_zone_of_sensor_register(struct device *dev, int id,
> + void *data, int (*get_temp)(void *, long *),
> + int (*get_trend)(void *, long *));
> +void thermal_zone_of_sensor_unregister(struct device *dev,
> + struct thermal_zone_device *tz);
> +#else
> +static inline struct thermal_zone_device *
> +thermal_zone_of_sensor_register(struct device *dev, int id,
> + void *data, int (*get_temp)(void *, long *),
> + int (*get_trend)(void *, long *))
> +{
> + return NULL;
> +}
> +
> +static inline
> +void thermal_zone_of_sensor_unregister(struct device *dev,
> + struct thermal_zone_device *tz)
> +{
> +}
> +
> +#endif
> struct thermal_zone_device *thermal_zone_device_register(const char *, int, int,
> - void *, const struct thermal_zone_device_ops *,
> + void *, struct thermal_zone_device_ops *,
> const struct thermal_zone_params *, int, int);
> void thermal_zone_device_unregister(struct thermal_zone_device *);
>
> --
> 1.8.2.1.342.gfa7285d
>
>

2013-10-08 15:01:19

by Eduardo Valentin

[permalink] [raw]

Subject: Re: [PATCHv8 03/18] thermal: introduce device tree parser

On 07-10-2013 16:51, Mark Rutland wrote:
> Hi all,
>
> Given that this is a complex new class of binding, I'd appreciate if at least
> one other device tree maintainer could also take a look over this and voice any
> concerns or suggestions. I've left the entire patch context for this.
>

I agree with you. Did I miss someone in my To/Cc list? I got a couple of
review iterations by Stephen and Pawel (so, they are Copied) in the very
early stages of this work.

> Apologies for the munged whitespace -- my mail server appears to have helpfully
> and irreparably replaced all tabs with spaces.

I

>
> On Tue, Oct 01, 2013 at 03:39:26AM +0100, Eduardo Valentin wrote:
>> This patch introduces a device tree bindings for
>> describing the hardware thermal behavior and limits.
>> Also a parser to read and interpret the data and feed
>> it in the thermal framework is presented.
>>
>> This patch introduces a thermal data parser for device
>> tree. The parsed data is used to build thermal zones
>> and thermal binding parameters. The output data
>> can then be used to deploy thermal policies.
>>
>> This patch adds also documentation regarding this
>> API and how to define tree nodes to use
>> this infrastructure.
>>
>> Note that, in order to be able to have control
>> on the sensor registration on the DT thermal zone,
>> it was required to allow changing the thermal zone
>> .get_temp callback. For this reason, this patch
>> also removes the 'const' modifier from the .ops
>> field of thermal zone devices.
>>
>> Cc: Zhang Rui <[email protected]>
>> Cc: [email protected]
>> Cc: [email protected]
>> Signed-off-by: Eduardo Valentin <[email protected]>
>> ---
>> Hello Mark, folks,
>>
>> So, here is v8. Pretty small changes. Most are better
>> English phrasing in the binding document. It follows changelog:
>> - Several rephrasing in the binding document, including
>> spelling, grammar and better phrasing.
>> - Removed WiP warning from binding document.
>> - Several spacing and formatting changes in the binding document
>> - Used the '-specifier' nomenclature properly in the binding doc
>> - Removed the optional property 'thermal-sensors-names', because
>> it does not provide useful runtime information
>> - Fixed description of 'polling-delay-passive'
>> - Improved examples by adding comments and better explanation
>> - s/fw/framework/g
>> - Added a WARN when sensors specifiers are greater and 1.
>>
>> All best,
>>
>> Eduardo
>>
>> ---
>> .../devicetree/bindings/thermal/thermal.txt | 587 ++++++++++++++
>> drivers/thermal/Kconfig | 13 +
>> drivers/thermal/Makefile | 1 +
>> drivers/thermal/of-thermal.c | 849 +++++++++++++++++++++
>> drivers/thermal/thermal_core.c | 9 +-
>> drivers/thermal/thermal_core.h | 9 +
>> include/dt-bindings/thermal/thermal.h | 27 +
>> include/linux/thermal.h | 28 +-
>> 8 files changed, 1520 insertions(+), 3 deletions(-)
>> create mode 100644 Documentation/devicetree/bindings/thermal/thermal.txt
>> create mode 100644 drivers/thermal/of-thermal.c
>> create mode 100644 include/dt-bindings/thermal/thermal.h
>>
>> diff --git a/Documentation/devicetree/bindings/thermal/thermal.txt b/Documentation/devicetree/bindings/thermal/thermal.txt
>> new file mode 100644
>> index 0000000..ad06a8d
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/thermal/thermal.txt
>> @@ -0,0 +1,587 @@
>> +* Thermal Framework Device Tree descriptor
>> +
>> +This file describes a generic binding to provide a way of
>> +defining hardware thermal structure using device tree.
>
> s/defining/describing/

Well, I just want to avoid being prolix, and I dont really think we
loose context or meaning by using defining here.

>
>> +A thermal structure includes thermal zones and their components,
>> +such as trip points, polling intervals, sensors and cooling devices
>> +binding descriptors.
>> +
>> +The target of device tree thermal descriptors is to describe only
>> +the hardware thermal aspects. The thermal device tree bindings are
>> +not about how the system must control or which algorithm or policy
>> +must be taken in place.
>
> I'm not quite sure what this is saying -- it seems to contradict the
> design of the binding where trip points get linked to cooling device
> configuration, and thus we're defining a policy along the lines of "when
> sensor $W hits temperature $X, configure cooling device $Y with value
> $Z". I don't see how that can't be considered policy.

It is saying that describing these entities does not necessarily means
we are imposing policies, but that we are only describing the hardware
proprieties and knobs so that policies may be built on top of them.
There are plenty of algorithm to implement a control system, with
thermal is not different. We are not describing algorithms / policies,
but only focusing on hardware information and limits that we can extract
and use them to control the system.

For instance, there is no obligation to implement a closed loop
proportional-integral-derivative controller. Nor there is a strong
implication to implement a simple stepping control algorithm. But with
the hardware description flexibility we are providing with this binding,
for sure it is possible to choose one of the referred policies. We are
describing data points, so that the logic to use them can be picked out
of OS design decision.

I don't thing that matching cooling devices with trip points of sensors
on a thermal zone is defining thermal policy. This matching, to me at
least, it is a direct outcome of describing your hardware and its
limits. There are a couple of steps ahead of it to have a finalized
thermal policy.

>
> At best, we can say that policy is being defined because describing the
> physical properties of a device and dealing with this at runtime is not
> feasible.

OK. I see it slightly different, as I mentioned above. We are describing
physical properties and letting OSes to deal with them the way they choose.

>
>> +
>> +There are five types of nodes involved to describe thermal bindings:
>> +- sensors: used to describe the device source of temperature sensing;
>
> - thermal sensors: devices which may be used to take temperature
> measurements.
>
>> +- cooling devices: used to describe devices source of power dissipation control;
>
> - cooling devices: devices which may be used to dissipate heat.
>
>> +- trip points: used to describe points in temperature domain defined to
>> +make the system aware of hardware limits;
>
> - trip points: describe key temperatures at which cooling is recommended. The
> set of points should be chosen based on hardware limits.
>
>> +- cooling maps: used to describe links between trip points and cooling devices;
>> +- thermal zones: used to describe thermal data within the hardware;
>> +
>> +It follows a description of each type of these device tree nodes.
>
> How about:
>
> The following is a description of each of these node types.

OK, for the above suggestions.

>
>> +
>> +* Thermal sensor devices
>> +
>> +Thermal sensor devices are nodes providing temperature sensing capabilities on
>> +thermal zones. Typical devices are I2C ADC converters and bandgaps. These are
>> +nodes providing temperature data to thermal zones. Thermal sensor devices may
>> +control one or more internal sensors.
>> +
>> +Required property:
>> +- #thermal-sensor-cells: Used to provide sensor device specific information
>> + Type: unsigned while referring to it. Typically 0 on thermal sensor
>> + Size: one cell nodes with only one sensor, and at least 1 on nodes
>> + with several internal sensors, in order
>> + to identify uniquely the sensor instances within
>> + the IC. See thermal zone binding for more details
>> + on how consumers refer to sensor devices.
>> +
>> +* Cooling device nodes
>> +
>> +Cooling devices are nodes providing control on power dissipation. There
>> +are essentially two ways to provide control on power dissipation. First
>> +is by means of regulating device performance, which is known as passive
>> +cooling. A typical passive cooling is a CPU that has dynamic voltage and
>> +frequency scaling (DVFS), and uses lower frequencies as cooling states.
>> +Second is by means of activating devices in order to remove
>> +the dissipated heat, which is known as active cooling, e.g. regulating
>> +fan speeds. In both cases, cooling devices shall have a way to determine
>> +the state of cooling in which the device is.
>
> I'd probably say "heat dissipation" rather than "power dissipation", unless
> this is a technical term I am not aware of?
>
> Why is the determination of the state of the cooling device important?
>
>> +
>> +Required properties:
>> +- cooling-min-state: An integer indicating the smallest
>> + Type: unsigned cooling state accepted. Typically 0.
>> + Size: one cell
>> +
>> +- cooling-max-state: An integer indicating the largest
>> + Type: unsigned cooling state accepted.
>> + Size: one cell
>> +
>> +- #cooling-cells: Used to provide cooling device specific information
>> + Type: unsigned while referring to it. Must be at least 2, in order
>> + Size: one cell to specify minimum and maximum cooling state used
>> + in the reference. The first cell is the minimum
>> + cooling state requested and the second cell is
>> + the maximum cooling state requested in the reference.
>> + See Cooling device maps section below for more details
>> + on how consumers refer to cooling devices.
>
> Is it assumed that all the values between min and max are valid, or might this
> be a sparse set of cooling values?

I am assuming they are valid states.

>
>> +
>> +* Trip points
>> +
>> +The trip node is a node to describe a point in the temperature domain
>> +in which the system takes an action. This node describes just the point,
>> +not the action.
>> +
>> +Required properties:
>> +- temperature: An integer indicating the trip temperature level,
>> + Type: signed in millicelsius.
>> + Size: one cell
>> +
>> +- hysteresis: a (low) hysteresis value on 'temperature'. This is a
>> + Type: unsigned relative value, in millicelsius.
>> + Size: one cell
>
> What is it relative to?
>
> Why is 'temperature' in quotes?

They relative to the temperature property, describe above. I am
rephrasing this to avoid misunderstanding.

a (low) hysteresis value on temperature property (above).

>
>> +
>> +- type: a string containing the trip type. Supported values are:
>> + "active": A trip point to enable active cooling
>> + "passive": A trip point to enable passive cooling
>> + "hot": A trip point to notify emergency
>> + "critical": Hardware not reliable.
>> + Type: string
>> +
>> +There are also string constants defined at
>> +include/dt-bindings/thermal/thermal.h.
>
> Why?

That was originally suggested by swarren, but I was using integer
constants. I kept the his suggestion though, despite the type.

>
>> +
>> +* Cooling device maps
>> +
>> +The cooling device maps node is a node to describe how cooling devices
>> +get assigned to trip points of the zone. The cooling devices are expected
>> +to be loaded in the target system.
>> +
>> +Required properties:
>> +- cooling-device: A phandle of a cooling device with its specifier,
>> + Type: phandle of referring to which cooling device is used in this
>> + cooling device binding. In the cooling specifier, the first cell
>> + is the minimum cooling state and the second cell
>> + is the maximum cooling state used in this map.
>
> The type is wrong here -- it's a phandle + cooling-cells, not just a phandle.

I suppose you meant phandle + cooling specifier.

And yes, I am fixing that.

>
>> +- trip: A phandle of a trip point node within the same thermal
>> + Type: phandle of zone.
>> + trip point node
>> +
>> +Optional property:
>> +- contribution: The cooling contribution to the thermal zone of the
>> + Type: unsigned referred cooling device at the referred trip point.
>> + Size: one cell The contribution is a ratio of the sum
>> + of all cooling contributions within a thermal zone.
>> +
>> +Note: Using the THERMAL_NO_LIMIT (-1UL) constant in the cooling-device phandle
>> +limit specifier means:
>> +(i) - minimum state allowed for minimum cooling state used in the reference.
>> +(ii) - maximum state allowed for maximum cooling state used in the reference.
>> +Refer to include/dt-bindings/thermal/thermal.h for definition of this constant.
>> +
>> +* Thermal zone nodes
>> +
>> +The thermal zone node is the node containing all the required info
>> +for describing a thermal zone, including its cooling device bindings. The
>> +thermal zone node must contain, apart from its own properties, one sub-node
>> +containing trip nodes and one sub-node containing all the zone cooling maps.
>> +
>> +Required properties:
>> +- polling-delay: The maximum number of milliseconds to wait between polls
>> + Type: unsigned when checking this thermal zone.
>> + Size: one cell
>> +
>> +- polling-delay-passive: The maximum number of milliseconds to wait
>> + Type: unsigned between polls when performing passive cooling.
>> + Size: one cell
>> +
>> +- thermal-sensors: A list of thermal sensor phandles and sensor specifier
>> + Type: list of used while monitoring the thermal zone.
>> + sensor phandles
>
> The type is wrong here. A list of phandle + sensor specifiers.

OK.

>
>> +
>> +- trips: A sub-node which is a container of only trip point nodes
>> + Type: sub-node required to describe the thermal zone.
>> +
>> +- cooling-maps: A sub-node which is a container of only cooling device
>> + Type: sub-node map nodes, used to describe the relation between trips
>> + and cooling devices.
>> +
>> +Optional property:
>> +- coefficients: An array of integers (one signed cell) containing
>> + Type: array coefficients to compose a linear relation between
>> + Elem size: one cell the sensors listed in the thermal-sensors property.
>> + Elem type: signed Coefficients defaults to 1, in case this property
>> + is not specified. A simple linear polynomial is used:
>> + Z = c0 * x0 + c1 + x1 + ... + c(n-1) * x(n-1) + cn.
>> +
>> + The coefficients are ordered and they match with sensors
>> + by means of sensor ID. Additional coefficients are
>> + interpreted as constant offset.
>> +
>> +Note: The delay properties are bound to the maximum dT/dt (temperature
>> +derivative over time) in two situations for a thermal zone:
>> +(i) - when passive cooling is activated (polling-delay-passive); and
>> +(ii) - when the zone just needs to be monitored (polling-delay) or
>> +when active cooling is activated.
>> +
>> +The maximum dT/dt is highly bound to hardware power consumption and dissipation
>> +capability. The delays should be chosen to account for said max dT/dt,
>> +such that a device does not cross several trip boundaries unexpectedly
>> +between polls. Choosing the right polling delays shall avoid having the
>> +device in temperature ranges that may damage the silicon structures and
>> +reduce silicon lifetime.
>> +
>> +* The thermal-zones node
>> +
>> +The "thermal-zones" node is a container for all thermal zone nodes. It shall
>> +contain only sub-nodes describing thermal zones as in the section
>> +"Thermal zone nodes". The "thermal-zones" node appears under "/".
>> +
>> +* Examples
>> +
>> +Below are several examples on how to use thermal data descriptors
>> +using device tree bindings:
>> +
>> +(a) - CPU thermal zone
>> +
>> +The CPU thermal zone example below describes how to setup one thermal zone
>> +using one single sensor as temperature source and many cooling devices and
>> +power dissipation control sources.
>> +
>> +#include <dt-bindings/thermal/thermal.h>
>> +
>> +cpus {
>> + /*
>> + * Here is an example of describing a cooling device for a DVFS
>> + * capable CPU. The CPU node describes its four OPPs.
>> + * The cooling states possible are 0..3, and they are
>> + * used as OPP indexes. The minimum cooling state is 0, which means
>> + * all four OPPs can be available to the system. The maximum
>> + * cooling state is 3, which means only the lowest OPPs ([email protected])
>> + * can be available in the system.
>> + */
>> + cpu0: cpu@0 {
>> + ...
>> + operating-points = <
>> + /* kHz uV */
>> + 970000 1200000
>> + 792000 1100000
>> + 396000 950000
>> + 198000 850000
>> + >;
>> + cooling-min-state = <0>;
>> + cooling-max-state = <3>;
>> + #cooling-cells = <2>; /* min followed by max */
>> + };
>> + ...
>> +};
>> +
>> +&i2c1 {
>> + ...
>> + /*
>> + * A simple fan controller which supports 10 speeds of operation
>> + * (represented as 0-9).
>> + */
>> + fan0: fan@0x48 {
>> + ...
>> + cooling-min-state = <0>;
>> + cooling-max-state = <9>;
>> + #cooling-cells = <2>; /* min followed by max */
>> + };
>> +};
>> +
>> +ocp {
>> + ...
>> + /*
>> + * A simple IC with a single bandgap temperature sensor.
>> + */
>> + bandgap0: bandgap@0x0000ED00 {
>> + ...
>> + #thermal-sensor-cells = <0>;
>> + };
>> +};
>> +
>> +thermal-zones {
>> + cpu-thermal: cpu-thermal {
>> + polling-delay-passive = <250>; /* milliseconds */
>> + polling-delay = <1000>; /* milliseconds */
>> +
>> + thermal-sensors = <&bandgap0>;
>> +
>> + trips {
>> + cpu-alert0: cpu-alert {
>> + temperature = <90000>; /* millicelsius */
>> + hysteresis = <2000>; /* millicelsius */
>> + type = "active";
>> + };
>> + cpu-alert1: cpu-alert {
>> + temperature = <100000>; /* millicelsius */
>> + hysteresis = <2000>; /* millicelsius */
>> + type = "passive";
>> + };
>> + cpu-crit: cpu-crit {
>> + temperature = <125000>; /* millicelsius */
>> + hysteresis = <2000>; /* millicelsius */
>> + type = "critical";
>> + };
>> + };
>> +
>> + cooling-maps {
>> + map0 {
>> + trip = <&cpu-alert0>;
>> + cooling-device = <&fan0 THERMAL_NO_LIMITS 4>;
>> + };
>> + map1 {
>> + trip = <&cpu-alert1>;
>> + cooling-device = <&fan0 5 THERMAL_NO_LIMITS>;
>> + };
>> + map2 {
>> + trip = <&cpu-alert1>;
>> + cooling-device =
>> + <&cpu0 THERMAL_NO_LIMITS THERMAL_NO_LIMITS>;
>> + };
>> + };
>> + };
>> +};
>> +
>> +In the example above, the ADC sensor (bandgap0) at address 0x0000ED00 is
>> +used to monitor the zone 'cpu-thermal' using its sole sensor. A fan
>> +device (fan0) is controlled via I2C bus 1, at address 0x48, and has ten
>> +different cooling states 0-9. It is used to remove the heat out of
>> +the thermal zone 'cpu-thermal' using its cooling states
>> +from its minimum to 4, when it reaches trip point 'cpu-alert0'
>> +at 90C, as an example of active cooling. The same cooling device is used at
>> +'cpu-alert1', but from 5 to its maximum state. The cpu@0 device is also
>> +linked to the same thermal zone, 'cpu-thermal', as a passive cooling device,
>> +using all its cooling states at trip point 'cpu-alert1',
>> +which is a trip point at 100C. On the thermal zone 'cpu-thermal', at the
>> +temperature of 125C, represented by the trip point 'cpu-crit', the silicon
>> +is not reliable anymore.
>> +
>> +(b) - IC with several internal sensors
>> +
>> +The example below describes how to deploy several thermal zones based off a
>> +single sensor IC, assuming it has several internal sensors. This is a common
>> +case on SoC designs with several internal IPs that may need different thermal
>> +requirements, and thus may have their own sensor to monitor or detect internal
>> +hotspots in their silicon.
>> +
>> +#include <dt-bindings/thermal/thermal.h>
>> +
>> +ocp {
>> + ...
>> + /*
>> + * A simple IC with several bandgap temperature sensors.
>> + */
>> + bandgap0: bandgap@0x0000ED00 {
>> + ...
>> + #thermal-sensor-cells = <1>;
>> + };
>> +};
>> +
>> +thermal-zones {
>> + cpu-thermal: cpu-thermal {
>> + polling-delay-passive = <250>; /* milliseconds */
>> + polling-delay = <1000>; /* milliseconds */
>> +
>> + /* sensor ID */
>> + thermal-sensors = <&bandgap0 0>;
>> +
>> + trips {
>> + /* each zone within the SoC may have its own trips */
>> + cpu-alert: cpu-alert {
>> + temperature = <100000>; /* millicelsius */
>> + hysteresis = <2000>; /* millicelsius */
>> + type = "passive";
>> + };
>> + cpu-crit: cpu-crit {
>> + temperature = <125000>; /* millicelsius */
>> + hysteresis = <2000>; /* millicelsius */
>> + type = "critical";
>> + };
>> + };
>> +
>> + cooling-maps {
>> + /* each zone within the SoC may have its own cooling */
>> + ...
>> + };
>> + };
>> +
>> + gpu-thermal: gpu-thermal {
>> + polling-delay-passive = <120>; /* milliseconds */
>> + polling-delay = <1000>; /* milliseconds */
>> +
>> + /* sensor ID */
>> + thermal-sensors = <&bandgap0 1>;
>> +
>> + trips {
>> + /* each zone within the SoC may have its own trips */
>> + gpu-alert: gpu-alert {
>> + temperature = <90000>; /* millicelsius */
>> + hysteresis = <2000>; /* millicelsius */
>> + type = "passive";
>> + };
>> + gpu-crit: gpu-crit {
>> + temperature = <105000>; /* millicelsius */
>> + hysteresis = <2000>; /* millicelsius */
>> + type = "critical";
>> + };
>> + };
>> +
>> + cooling-maps {
>> + /* each zone within the SoC may have its own cooling */
>> + ...
>> + };
>> + };
>> +
>> + dsp-thermal: dsp-thermal {
>> + polling-delay-passive = <50>; /* milliseconds */
>> + polling-delay = <1000>; /* milliseconds */
>> +
>> + /* sensor ID */
>> + thermal-sensors = <&bandgap0 2>;
>> +
>> + trips {
>> + /* each zone within the SoC may have its own trips */
>> + dsp-alert: gpu-alert {
>> + temperature = <90000>; /* millicelsius */
>> + hysteresis = <2000>; /* millicelsius */
>> + type = "passive";
>> + };
>> + dsp-crit: gpu-crit {
>> + temperature = <135000>; /* millicelsius */
>> + hysteresis = <2000>; /* millicelsius */
>> + type = "critical";
>> + };
>> + };
>> +
>> + cooling-maps {
>> + /* each zone within the SoC may have its own cooling */
>> + ...
>> + };
>> + };
>> +};
>> +
>> +In the example above, there is one bandgap IC which has the capability to
>> +monitor three sensors. The hardware has been designed so that sensors are
>> +placed on different places in the DIE to monitor different temperature
>> +hotspots: one for CPU thermal zone, one for GPU thermal zone and the
>> +other to monitor a DSP thermal zone.
>> +
>> +Thus, there is a need to assign each sensor provided by the bandgap IC
>> +to different thermal zones. This is achieved by means of using the
>> +#thermal-sensor-cells property and using the first cell of the sensor
>> +specifier as sensor ID. In the example, then, <bandgap 0> is used to
>> +monitor CPU thermal zone, <bandgap 1> is used to monitor GPU thermal
>> +zone and <bandgap 2> is used to monitor DSP thermal zone. Each zone
>> +may be uncorrelated, having its own dT/dt requirements, trips
>> +and cooling maps.
>> +
>> +
>> +(c) - Several sensors within one single thermal zone
>> +
>> +The example below illustrates how to use more than one sensor within
>> +one thermal zone.
>> +
>> +#include <dt-bindings/thermal/thermal.h>
>> +
>> +&i2c1 {
>> + ...
>> + /*
>> + * A simple IC with a single temperature sensor.
>> + */
>> + adc: sensor@0x49 {
>> + ...
>> + #thermal-sensor-cells = <0>;
>> + };
>> +};
>> +
>> +ocp {
>> + ...
>> + /*
>> + * A simple IC with a single bandgap temperature sensor.
>> + */
>> + bandgap0: bandgap@0x0000ED00 {
>> + ...
>> + #thermal-sensor-cells = <0>;
>> + };
>> +};
>> +
>> +thermal-zones {
>> + cpu-thermal: cpu-thermal {
>> + polling-delay-passive = <250>; /* milliseconds */
>> + polling-delay = <1000>; /* milliseconds */
>> +
>> + thermal-sensors = <&bandgap0>, /* cpu */
>> + <&adc>; /* pcb north */
>> +
>> + /* hotspot = 100 * bandgap - 120 * adc + 484 */
>> + coefficients = <100 -120 484>;
>> +
>> + trips {
>> + ...
>> + };
>> +
>> + cooling-maps {
>> + ...
>> + };
>> + };
>> +};
>> +
>> +In some cases, there is a need to use more than one sensor to extrapolate
>> +a thermal hotspot in the silicon. The above example illustrates this situation.
>> +For instance, it may be the case that a sensor external to CPU IP may be placed
>> +close to CPU hotspot and together with internal CPU sensor, it is used
>> +to determine the hotspot. Assuming this is the case for the above example,
>> +the hypothetical extrapolation rule would be:
>> + hotspot = 100 * bandgap - 120 * adc + 484
>> +
>> +In other context, the same idea can be used to add fixed offset. For instance,
>> +consider the hotspot extrapolation rule below:
>> + hotspot = 1 * adc + 6000
>> +
>> +In the above equation, the hotspot is always 6C higher than what is read
>> +from the ADC sensor. The binding would be then:
>> + thermal-sensors = <&adc>;
>> +
>> + /* hotspot = 1 * adc + 6000 */
>> + coefficients = <1 6000>;
>> +
>> +(d) - Board thermal
>> +
>> +The board thermal example below illustrates how to setup one thermal zone
>> +with many sensors and many cooling devices.
>> +
>> +#include <dt-bindings/thermal/thermal.h>
>> +
>> +&i2c1 {
>> + ...
>> + /*
>> + * An IC with several temperature sensor.
>> + */
>> + adc-dummy: sensor@0x50 {
>> + ...
>> + #thermal-sensor-cells = <1>; /* sensor internal ID */
>> + };
>> +};
>> +
>> +thermal-zones {
>> + batt-thermal {
>> + polling-delay-passive = <500>; /* milliseconds */
>> + polling-delay = <2500>; /* milliseconds */
>> +
>> + /* sensor ID */
>> + thermal-sensors = <&adc-dummy 4>;
>> +
>> + trips {
>> + ...
>> + };
>> +
>> + cooling-maps {
>> + ...
>> + };
>> + };
>> +
>> + board-thermal: board-thermal {
>> + polling-delay-passive = <1000>; /* milliseconds */
>> + polling-delay = <2500>; /* milliseconds */
>> +
>> + /* sensor ID */
>> + thermal-sensors = <&adc-dummy 0>, /* pcb top edge */
>> + <&adc-dummy 1>, /* lcd */
>> + <&adc-dymmy 2>; /* back cover */
>> + /*
>> + * An array of coefficients describing the sensor
>> + * linear relation. E.g.:
>> + * z = c1*x1 + c2*x2 + c3*x3
>> + */
>> + coefficients = <1200 -345 890>;
>> +
>> + trips {
>> + /* Trips are based on resulting linear equation */
>> + cpu-trip: cpu-trip {
>> + temperature = <60000>; /* millicelsius */
>> + hysteresis = <2000>; /* millicelsius */
>> + type = "passive";
>> + };
>> + gpu-trip: gpu-trip {
>> + temperature = <55000>; /* millicelsius */
>> + hysteresis = <2000>; /* millicelsius */
>> + type = "passive";
>> + }
>> + lcd-trip: lcp-trip {
>> + temperature = <53000>; /* millicelsius */
>> + hysteresis = <2000>; /* millicelsius */
>> + type = "passive";
>> + };
>> + crit-trip: crit-trip {
>> + temperature = <68000>; /* millicelsius */
>> + hysteresis = <2000>; /* millicelsius */
>> + type = "critical";
>> + };
>> + };
>> +
>> + cooling-maps {
>> + map0 {
>> + trip = <&cpu-trip>;
>> + cooling-device = <&cpu0 0 2>;
>> + contribution = <55>;
>> + };
>> + map1 {
>> + trip = <&gpu-trip>;
>> + cooling-device = <&gpu0 0 2>;
>> + contribution = <20>;
>> + };
>> + map2 {
>> + trip = <&lcd-trip>;
>> + cooling-device = <&lcd0 5 10>;
>> + contribution = <15>;
>> + };
>> + };
>> + };
>> +};
>> +
>> +The above example is a mix of previous examples, a sensor IP with several internal
>> +sensors used to monitor different zones, one of them is composed by several sensors and
>> +with different cooling devices.
>> diff --git a/drivers/thermal/Kconfig b/drivers/thermal/Kconfig
>> index dbfc390..dd81eb8 100644
>> --- a/drivers/thermal/Kconfig
>> +++ b/drivers/thermal/Kconfig
>> @@ -29,6 +29,19 @@ config THERMAL_HWMON
>> Say 'Y' here if you want all thermal sensors to
>> have hwmon sysfs interface too.
>>
>> +config THERMAL_OF
>> + bool
>> + prompt "APIs to parse thermal data out of device tree"
>> + depends on OF
>> + default y
>> + help
>> + This options provides helpers to add the support to
>> + read and parse thermal data definitions out of the
>> + device tree blob.
>> +
>> + Say 'Y' here if you need to build thermal infrastructure
>> + based on device tree.
>> +
>> choice
>> prompt "Default Thermal governor"
>> default THERMAL_DEFAULT_GOV_STEP_WISE
>> diff --git a/drivers/thermal/Makefile b/drivers/thermal/Makefile
>> index 584b363..4b03956 100644
>> --- a/drivers/thermal/Makefile
>> +++ b/drivers/thermal/Makefile
>> @@ -7,6 +7,7 @@ thermal_sys-y += thermal_core.o
>>
>> # interface to/from other layers providing sensors
>> thermal_sys-$(CONFIG_THERMAL_HWMON) += thermal_hwmon.o
>> +thermal_sys-$(CONFIG_THERMAL_OF) += of-thermal.o
>>
>> # governors
>> thermal_sys-$(CONFIG_THERMAL_GOV_FAIR_SHARE) += fair_share.o
>> diff --git a/drivers/thermal/of-thermal.c b/drivers/thermal/of-thermal.c
>> new file mode 100644
>> index 0000000..66f9eb2
>> --- /dev/null
>> +++ b/drivers/thermal/of-thermal.c
>> @@ -0,0 +1,849 @@
>> +/*
>> + * of-thermal.c - Generic Thermal Management device tree support.
>> + *
>> + * Copyright (C) 2013 Texas Instruments
>> + * Copyright (C) 2013 Eduardo Valentin <[email protected]>
>> + *
>> + *
>> + * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> + *
>> + * This program is free software; you can redistribute it and/or modify
>> + * it under the terms of the GNU General Public License as published by
>> + * the Free Software Foundation; version 2 of the License.
>> + *
>> + * This program is distributed in the hope that it will be useful, but
>> + * WITHOUT ANY WARRANTY; without even the implied warranty of
>> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
>> + * General Public License for more details.
>> + *
>> + * You should have received a copy of the GNU General Public License along
>> + * with this program; if not, write to the Free Software Foundation, Inc.,
>> + * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
>> + *
>> + * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> + */
>> +#include <linux/thermal.h>
>> +#include <linux/slab.h>
>> +#include <linux/types.h>
>> +#include <linux/of_device.h>
>> +#include <linux/of_platform.h>
>> +#include <linux/err.h>
>> +#include <linux/export.h>
>> +#include <linux/string.h>
>> +
>> +#include "thermal_core.h"
>> +
>> +/*** Private data structures to represent thermal device tree data ***/
>> +
>> +/**
>> + * struct __thermal_trip - representation of a point in temperature domain
>> + * @np: pointer to struct device_node that this trip point was created from
>> + * @temperature: temperature value in miliCelsius
>> + * @hysteresis: relative hysteresis in miliCelsius
>> + * @type: trip point type
>> + */
>> +
>> +struct __thermal_trip {
>> + struct device_node *np;
>> + unsigned long int temperature;
>> + unsigned long int hysteresis;
>> + enum thermal_trip_type type;
>> +};
>> +
>> +/**
>> + * struct __thermal_bind_param - a match between trip and cooling device
>> + * @cooling_device: a pointer to identify the referred cooling device
>> + * @trip_id: the trip point index
>> + * @usage: the percentage (from 0 to 100) of cooling contribution
>> + * @min: minimum cooling state used at this trip point
>> + * @max: maximum cooling state used at this trip point
>> + */
>> +
>> +struct __thermal_bind_params {
>> + struct device_node *cooling_device;
>> + unsigned int trip_id;
>> + unsigned int usage;
>> + unsigned long min;
>> + unsigned long max;
>> +};
>> +
>> +/**
>> + * struct __thermal_zone - internal representation of a thermal zone
>> + * @mode: current thermal zone device mode (enabled/disabled)
>> + * @passive_delay: polling interval while passive cooling is activated
>> + * @polling_delay: zone polling interval
>> + * @ntrips: number of trip points
>> + * @trips: an array of trip points (0..ntrips - 1)
>> + * @num_tbps: number of thermal bind params
>> + * @tbps: an array of thermal bind params (0..num_tbps - 1)
>> + * @sensor_data: sensor private data used while reading temperature and trend
>> + * @get_temp: sensor callback to read temperature
>> + * @get_trend: sensor callback to read temperature trend
>> + */
>> +
>> +struct __thermal_zone {
>> + enum thermal_device_mode mode;
>> + int passive_delay;
>> + int polling_delay;
>> +
>> + /* trip data */
>> + int ntrips;
>> + struct __thermal_trip *trips;
>> +
>> + /* cooling binding data */
>> + int num_tbps;
>> + struct __thermal_bind_params *tbps;
>> +
>> + /* sensor interface */
>> + void *sensor_data;
>> + int (*get_temp)(void *, long *);
>> + int (*get_trend)(void *, long *);
>> +};
>> +
>> +/*** DT thermal zone device callbacks ***/
>> +
>> +static int of_thermal_get_temp(struct thermal_zone_device *tz,
>> + unsigned long *temp)
>> +{
>> + struct __thermal_zone *data = tz->devdata;
>> +
>> + if (!data->get_temp)
>> + return -EINVAL;
>> +
>> + return data->get_temp(data->sensor_data, temp);
>> +}
>> +
>> +static int of_thermal_get_trend(struct thermal_zone_device *tz, int trip,
>> + enum thermal_trend *trend)
>> +{
>> + struct __thermal_zone *data = tz->devdata;
>> + long dev_trend;
>> + int r;
>> +
>> + if (!data->get_trend)
>> + return -EINVAL;
>> +
>> + r = data->get_trend(data->sensor_data, &dev_trend);
>> + if (r)
>> + return r;
>> +
>> + /* TODO: These intervals might have some thresholds, but in core code */
>> + if (dev_trend > 0)
>> + *trend = THERMAL_TREND_RAISING;
>> + else if (dev_trend < 0)
>> + *trend = THERMAL_TREND_DROPPING;
>> + else
>> + *trend = THERMAL_TREND_STABLE;
>> +
>> + return 0;
>> +}
>> +
>> +static int of_thermal_bind(struct thermal_zone_device *thermal,
>> + struct thermal_cooling_device *cdev)
>> +{
>> + struct __thermal_zone *data = thermal->devdata;
>> + int i;
>> +
>> + if (!data || IS_ERR(data))
>> + return -ENODEV;
>> +
>> + /* find where to bind */
>> + for (i = 0; i < data->num_tbps; i++) {
>> + struct __thermal_bind_params *tbp = data->tbps + i;
>> +
>> + if (tbp->cooling_device == cdev->np) {
>> + int ret;
>> +
>> + ret = thermal_zone_bind_cooling_device(thermal,
>> + tbp->trip_id, cdev,
>> + tbp->min,
>> + tbp->max);
>> + if (ret)
>> + return ret;
>> + }
>> + }
>> +
>> + return 0;
>> +}
>> +
>> +static int of_thermal_unbind(struct thermal_zone_device *thermal,
>> + struct thermal_cooling_device *cdev)
>> +{
>> + struct __thermal_zone *data = thermal->devdata;
>> + int i;
>> +
>> + if (!data || IS_ERR(data))
>> + return -ENODEV;
>> +
>> + /* find where to unbind */
>> + for (i = 0; i < data->num_tbps; i++) {
>> + struct __thermal_bind_params *tbp = data->tbps + i;
>> +
>> + if (tbp->cooling_device == cdev->np) {
>> + int ret;
>> +
>> + ret = thermal_zone_unbind_cooling_device(thermal,
>> + tbp->trip_id, cdev);
>> + if (ret)
>> + return ret;
>> + }
>> + }
>> +
>> + return 0;
>> +}
>> +
>> +static int of_thermal_get_mode(struct thermal_zone_device *tz,
>> + enum thermal_device_mode *mode)
>> +{
>> + struct __thermal_zone *data = tz->devdata;
>> +
>> + *mode = data->mode;
>> +
>> + return 0;
>> +}
>> +
>> +static int of_thermal_set_mode(struct thermal_zone_device *tz,
>> + enum thermal_device_mode mode)
>> +{
>> + struct __thermal_zone *data = tz->devdata;
>> +
>> + mutex_lock(&tz->lock);
>> +
>> + if (mode == THERMAL_DEVICE_ENABLED)
>> + tz->polling_delay = data->polling_delay;
>> + else
>> + tz->polling_delay = 0;
>> +
>> + mutex_unlock(&tz->lock);
>> +
>> + data->mode = mode;
>> + thermal_zone_device_update(tz);
>> +
>> + return 0;
>> +}
>> +
>> +static int of_thermal_get_trip_type(struct thermal_zone_device *tz, int trip,
>> + enum thermal_trip_type *type)
>> +{
>> + struct __thermal_zone *data = tz->devdata;
>> +
>> + if (trip >= data->ntrips || trip < 0)
>> + return -EDOM;
>> +
>> + *type = data->trips[trip].type;
>> +
>> + return 0;
>> +}
>> +
>> +static int of_thermal_get_trip_temp(struct thermal_zone_device *tz, int trip,
>> + unsigned long *temp)
>> +{
>> + struct __thermal_zone *data = tz->devdata;
>> +
>> + if (trip >= data->ntrips || trip < 0)
>> + return -EDOM;
>> +
>> + *temp = data->trips[trip].temperature;
>> +
>> + return 0;
>> +}
>> +
>> +static int of_thermal_set_trip_temp(struct thermal_zone_device *tz, int trip,
>> + unsigned long temp)
>> +{
>> + struct __thermal_zone *data = tz->devdata;
>> +
>> + if (trip >= data->ntrips || trip < 0)
>> + return -EDOM;
>> +
>> + /* thermal framework should take care of data->mask & (1 << trip) */
>> + data->trips[trip].temperature = temp;
>> +
>> + return 0;
>> +}
>> +
>> +static int of_thermal_get_trip_hyst(struct thermal_zone_device *tz, int trip,
>> + unsigned long *hyst)
>> +{
>> + struct __thermal_zone *data = tz->devdata;
>> +
>> + if (trip >= data->ntrips || trip < 0)
>> + return -EDOM;
>> +
>> + *hyst = data->trips[trip].hysteresis;
>> +
>> + return 0;
>> +}
>> +
>> +static int of_thermal_set_trip_hyst(struct thermal_zone_device *tz, int trip,
>> + unsigned long hyst)
>> +{
>> + struct __thermal_zone *data = tz->devdata;
>> +
>> + if (trip >= data->ntrips || trip < 0)
>> + return -EDOM;
>> +
>> + /* thermal framework should take care of data->mask & (1 << trip) */
>> + data->trips[trip].hysteresis = hyst;
>> +
>> + return 0;
>> +}
>> +
>> +static int of_thermal_get_crit_temp(struct thermal_zone_device *tz,
>> + unsigned long *temp)
>> +{
>> + struct __thermal_zone *data = tz->devdata;
>> + int i;
>> +
>> + for (i = 0; i < data->ntrips; i++)
>> + if (data->trips[i].type == THERMAL_TRIP_CRITICAL) {
>> + *temp = data->trips[i].temperature;
>> + return 0;
>> + }
>> +
>> + return -EINVAL;
>> +}
>> +
>> +static struct thermal_zone_device_ops of_thermal_ops = {
>> + .get_mode = of_thermal_get_mode,
>> + .set_mode = of_thermal_set_mode,
>> +
>> + .get_trip_type = of_thermal_get_trip_type,
>> + .get_trip_temp = of_thermal_get_trip_temp,
>> + .set_trip_temp = of_thermal_set_trip_temp,
>> + .get_trip_hyst = of_thermal_get_trip_hyst,
>> + .set_trip_hyst = of_thermal_set_trip_hyst,
>> + .get_crit_temp = of_thermal_get_crit_temp,
>> +
>> + .bind = of_thermal_bind,
>> + .unbind = of_thermal_unbind,
>> +};
>> +
>> +/*** sensor API ***/
>> +
>> +static struct thermal_zone_device *
>> +thermal_zone_of_add_sensor(struct device_node *zone,
>> + struct device_node *sensor, void *data,
>> + int (*get_temp)(void *, long *),
>> + int (*get_trend)(void *, long *))
>> +{
>> + struct thermal_zone_device *tzd;
>> + struct __thermal_zone *tz;
>> +
>> + tzd = thermal_zone_get_zone_by_name(zone->name);
>> + if (IS_ERR(tzd))
>> + return ERR_PTR(-EPROBE_DEFER);
>> +
>> + tz = tzd->devdata;
>> +
>> + mutex_lock(&tzd->lock);
>> + tz->get_temp = get_temp;
>> + tz->get_trend = get_trend;
>> + tz->sensor_data = data;
>> +
>> + tzd->ops->get_temp = of_thermal_get_temp;
>> + tzd->ops->get_trend = of_thermal_get_trend;
>> + mutex_unlock(&tzd->lock);
>> +
>> + return tzd;
>> +}
>> +
>> +/**
>> + * thermal_zone_of_sensor_register - registers a sensor to a DT thermal zone
>> + * @dev: a valid struct device pointer of a sensor device. Must contain
>> + * a valid .of_node, for the sensor node.
>> + * @sensor_id: a sensor identifier, in case the sensor IP has more
>> + * than one sensors
>> + * @data: a private pointer (owned by the caller) that will be passed
>> + * back, when a temperature reading is needed.
>> + * @get_temp: a pointer to a function that reads the sensor temperature.
>> + * @get_trend: a pointer to a function that reads the sensor temperature trend.
>> + *
>> + * This function will search the list of thermal zones described in device
>> + * tree and look for the zone that refer to the sensor device pointed by
>> + * @dev->of_node as temperature providers. For the zone pointing to the
>> + * sensor node, the sensor will be added to the DT thermal zone device.
>> + *
>> + * The thermal zone temperature is provided by the @get_temp function
>> + * pointer. When called, it will have the private pointer @data back.
>> + *
>> + * The thermal zone temperature trend is provided by the @get_trend function
>> + * pointer. When called, it will have the private pointer @data back.
>> + *
>> + * TODO:
>> + * 01 - This function must enqueue the new sensor instead of using
>> + * it as the only source of temperature values.
>> + *
>> + * 02 - There must be a way to match the sensor with all thermal zones
>> + * that refer to it.
>> + *
>> + * Return: On success returns a valid struct thermal_zone_device,
>> + * otherwise, it returns a corresponding ERR_PTR(). Caller must
>> + * check the return value with help of IS_ERR() helper.
>> + */
>> +struct thermal_zone_device *
>> +thermal_zone_of_sensor_register(struct device *dev, int sensor_id,
>> + void *data, int (*get_temp)(void *, long *),
>> + int (*get_trend)(void *, long *))
>> +{
>> + struct device_node *np, *child, *sensor_np;
>> +
>> + np = of_find_node_by_name(NULL, "thermal-zones");
>> + if (!np)
>> + return ERR_PTR(-ENODEV);
>> +
>> + if (!dev || !dev->of_node)
>> + return ERR_PTR(-EINVAL);
>> +
>> + sensor_np = dev->of_node;
>> +
>> + for_each_child_of_node(np, child) {
>> + struct of_phandle_args sensor_specs;
>> + int ret, id;
>> +
>> + /* For now, thermal framework supports only 1 sensor per zone */
>> + ret = of_parse_phandle_with_args(child, "thermal-sensors",
>> + "#thermal-sensor-cells",
>> + 0, &sensor_specs);
>> + if (ret)
>> + continue;
>> +
>> + if (sensor_specs.args_count >= 1) {
>> + id = sensor_specs.args[0];
>> + WARN(sensor_specs.args_count > 1,
>> + "%s: too many cells in sensor specifier %d\n",
>> + sensor_specs.np->name, sensor_specs.args_count);
>> + } else {
>> + id = 0;
>> + }
>> +
>> + if (sensor_specs.np == sensor_np && id == sensor_id) {
>> + of_node_put(np);
>> + return thermal_zone_of_add_sensor(child, sensor_np,
>> + data,
>> + get_temp,
>> + get_trend);
>> + }
>> + }
>> + of_node_put(np);
>> +
>> + return ERR_PTR(-ENODEV);
>> +}
>> +EXPORT_SYMBOL_GPL(thermal_zone_of_sensor_register);
>> +
>> +/**
>> + * thermal_zone_of_sensor_unregister - unregisters a sensor from a DT thermal zone
>> + * @dev: a valid struct device pointer of a sensor device. Must contain
>> + * a valid .of_node, for the sensor node.
>> + * @tzd: a pointer to struct thermal_zone_device where the sensor is registered.
>> + *
>> + * This function removes the sensor callbacks and private data from the
>> + * thermal zone device registered with thermal_zone_of_sensor_register()
>> + * API. It will also silent the zone by remove the .get_temp() and .get_trend()
>> + * thermal zone device callbacks.
>> + *
>> + * TODO: When the support to several sensors per zone is added, this
>> + * function must search the sensor list based on @dev parameter.
>> + *
>> + */
>> +void thermal_zone_of_sensor_unregister(struct device *dev,
>> + struct thermal_zone_device *tzd)
>> +{
>> + struct __thermal_zone *tz;
>> +
>> + if (!dev || !tzd || !tzd->devdata)
>> + return;
>> +
>> + tz = tzd->devdata;
>> +
>> + /* no __thermal_zone, nothing to be done */
>> + if (!tz)
>> + return;
>> +
>> + mutex_lock(&tzd->lock);
>> + tzd->ops->get_temp = NULL;
>> + tzd->ops->get_trend = NULL;
>> +
>> + tz->get_temp = NULL;
>> + tz->get_trend = NULL;
>> + tz->sensor_data = NULL;
>> + mutex_unlock(&tzd->lock);
>> +}
>> +EXPORT_SYMBOL_GPL(thermal_zone_of_sensor_unregister);
>> +
>> +/*** functions parsing device tree nodes ***/
>> +
>> +/**
>> + * thermal_of_populate_bind_params - parse and fill cooling map data
>> + * @np: DT node containing a cooling-map node
>> + * @__tbp: data structure to be filled with cooling map info
>> + * @trips: array of thermal zone trip points
>> + * @ntrips: number of trip points inside trips.
>> + *
>> + * This function parses a cooling-map type of node represented by
>> + * @np parameter and fills the read data into @__tbp data structure.
>> + * It needs the already parsed array of trip points of the thermal zone
>> + * in consideration.
>> + *
>> + * Return: 0 on success, proper error code otherwise
>> + */
>> +static int thermal_of_populate_bind_params(struct device_node *np,
>> + struct __thermal_bind_params *__tbp,
>> + struct __thermal_trip *trips,
>> + int ntrips)
>> +{
>> + struct of_phandle_args cooling_spec;
>> + struct device_node *trip;
>> + int ret, i;
>> + u32 prop;
>> +
>> + /* Default weight. Usage is optional */
>> + __tbp->usage = 0;
>> + ret = of_property_read_u32(np, "contribution", &prop);
>> + if (ret == 0)
>> + __tbp->usage = prop;
>> +
>> + trip = of_parse_phandle(np, "trip", 0);
>> + if (!trip) {
>> + pr_err("missing trip property\n");
>> + return -ENODEV;
>> + }
>> +
>> + /* match using device_node */
>> + for (i = 0; i < ntrips; i++)
>> + if (trip == trips[i].np) {
>> + __tbp->trip_id = i;
>> + break;
>> + }
>> +
>> + if (i == ntrips) {
>> + ret = -ENODEV;
>> + goto end;
>> + }
>> +
>> + ret = of_parse_phandle_with_args(np, "cooling-device", "#cooling-cells",
>> + 0, &cooling_spec);
>> + if (ret < 0) {
>> + pr_err("missing cooling_device property\n");
>> + goto end;
>> + }
>> + __tbp->cooling_device = cooling_spec.np;
>> + if (cooling_spec.args_count >= 2) { /* at least min and max */
>> + __tbp->min = cooling_spec.args[0];
>> + __tbp->max = cooling_spec.args[1];
>> + } else {
>> + pr_err("wrong reference to cooling device, missing limits\n");
>> + }
>> +
>> +end:
>> + of_node_put(trip);
>> +
>> + return ret;
>> +}
>> +
>> +/**
>> + * It maps 'enum thermal_trip_type' found in include/linux/thermal.h
>> + * into the device tree binding of 'trip', property type.
>> + */
>> +static const char * const trip_types[] = {
>> + [THERMAL_TRIP_ACTIVE] = "active",
>> + [THERMAL_TRIP_PASSIVE] = "passive",
>> + [THERMAL_TRIP_HOT] = "hot",
>> + [THERMAL_TRIP_CRITICAL] = "critical",
>> +};
>> +
>> +/**
>> + * thermal_of_get_trip_type - Get phy mode for given device_node
>> + * @np: Pointer to the given device_node
>> + * @type: Pointer to resulting trip type
>> + *
>> + * The function gets trip type string from property 'type',
>> + * and store its index in trip_types table in @type,
>> + *
>> + * Return: 0 on success, or errno in error case.
>> + */
>> +static int thermal_of_get_trip_type(struct device_node *np,
>> + enum thermal_trip_type *type)
>> +{
>> + const char *t;
>> + int err, i;
>> +
>> + err = of_property_read_string(np, "type", &t);
>> + if (err < 0)
>> + return err;
>> +
>> + for (i = 0; i < ARRAY_SIZE(trip_types); i++)
>> + if (!strcasecmp(t, trip_types[i])) {
>> + *type = i;
>> + return 0;
>> + }
>> +
>> + return -ENODEV;
>> +}
>> +
>> +/**
>> + * thermal_of_populate_trip - parse and fill one trip point data
>> + * @np: DT node containing a trip point node
>> + * @trip: trip point data structure to be filled up
>> + *
>> + * This function parses a trip point type of node represented by
>> + * @np parameter and fills the read data into @trip data structure.
>> + *
>> + * Return: 0 on success, proper error code otherwise
>> + */
>> +static int thermal_of_populate_trip(struct device_node *np,
>> + struct __thermal_trip *trip)
>> +{
>> + int prop;
>> + int ret;
>> +
>> + ret = of_property_read_u32(np, "temperature", &prop);
>> + if (ret < 0) {
>> + pr_err("missing temperature property\n");
>> + return ret;
>> + }
>> + trip->temperature = prop;
>> +
>> + ret = of_property_read_u32(np, "hysteresis", &prop);
>> + if (ret < 0) {
>> + pr_err("missing hysteresis property\n");
>> + return ret;
>> + }
>> + trip->hysteresis = prop;
>> +
>> + ret = thermal_of_get_trip_type(np, &trip->type);
>> + if (ret < 0) {
>> + pr_err("wrong trip type property\n");
>> + return ret;
>> + }
>> +
>> + /* Required for cooling map matching */
>> + trip->np = np;
>> +
>> + return 0;
>> +}
>> +
>> +/**
>> + * thermal_of_build_thermal_zone - parse and fill one thermal zone data
>> + * @np: DT node containing a thermal zone node
>> + *
>> + * This function parses a thermal zone type of node represented by
>> + * @np parameter and fills the read data into a __thermal_zone data structure
>> + * and return this pointer.
>> + *
>> + * TODO: Missing properties to parse: thermal-sensor-names and coefficients
>> + *
>> + * Return: On success returns a valid struct __thermal_zone,
>> + * otherwise, it returns a corresponding ERR_PTR(). Caller must
>> + * check the return value with help of IS_ERR() helper.
>> + */
>> +static struct __thermal_zone *
>> +thermal_of_build_thermal_zone(struct device_node *np)
>> +{
>> + struct device_node *child = NULL, *gchild;
>> + struct __thermal_zone *tz;
>> + int ret, i;
>> + u32 prop;
>> +
>> + if (!np) {
>> + pr_err("no thermal zone np\n");
>> + return ERR_PTR(-EINVAL);
>> + }
>> +
>> + tz = kzalloc(sizeof(*tz), GFP_KERNEL);
>> + if (!tz)
>> + return ERR_PTR(-ENOMEM);
>> +
>> + ret = of_property_read_u32(np, "polling-delay-passive", &prop);
>> + if (ret < 0) {
>> + pr_err("missing polling-delay-passive property\n");
>> + goto free_tz;
>> + }
>> + tz->passive_delay = prop;
>> +
>> + ret = of_property_read_u32(np, "polling-delay", &prop);
>> + if (ret < 0) {
>> + pr_err("missing polling-delay property\n");
>> + goto free_tz;
>> + }
>> + tz->polling_delay = prop;
>> +
>> + /* trips */
>> + child = of_get_child_by_name(np, "trips");
>> +
>> + /* No trips provided */
>> + if (!child)
>> + goto finish;
>> +
>> + tz->ntrips = of_get_child_count(child);
>> + if (tz->ntrips == 0) /* must have at least one child */
>> + goto finish;
>> +
>> + tz->trips = kzalloc(tz->ntrips * sizeof(*tz->trips), GFP_KERNEL);
>> + if (!tz->trips) {
>> + ret = -ENOMEM;
>> + goto free_tz;
>> + }
>> +
>> + i = 0;
>> + for_each_child_of_node(child, gchild) {
>> + ret = thermal_of_populate_trip(gchild, &tz->trips[i++]);
>> + if (ret)
>> + goto free_trips;
>> + }
>> +
>> + of_node_put(child);
>> +
>> + /* cooling-maps */
>> + child = of_get_child_by_name(np, "cooling-maps");
>> +
>> + /* cooling-maps not provided */
>> + if (!child)
>> + goto finish;
>> +
>> + tz->num_tbps = of_get_child_count(child);
>> + if (tz->num_tbps == 0)
>> + goto finish;
>> +
>> + tz->tbps = kzalloc(tz->num_tbps * sizeof(*tz->tbps), GFP_KERNEL);
>> + if (!tz->tbps) {
>> + ret = -ENOMEM;
>> + goto free_trips;
>> + }
>> +
>> + i = 0;
>> + for_each_child_of_node(child, gchild)
>> + ret = thermal_of_populate_bind_params(gchild, &tz->tbps[i++],
>> + tz->trips, tz->ntrips);
>> + if (ret)
>> + goto free_tbps;
>> +
>> +finish:
>> + of_node_put(child);
>> + tz->mode = THERMAL_DEVICE_DISABLED;
>> +
>> + return tz;
>> +
>> +free_tbps:
>> + kfree(tz->tbps);
>> +free_trips:
>> + kfree(tz->trips);
>> +free_tz:
>> + kfree(tz);
>> + of_node_put(child);
>> +
>> + return ERR_PTR(ret);
>> +}
>> +
>> +static inline void of_thermal_free_zone(struct __thermal_zone *tz)
>> +{
>> + kfree(tz->tbps);
>> + kfree(tz->trips);
>> + kfree(tz);
>> +}
>> +
>> +/**
>> + * of_parse_thermal_zones - parse device tree thermal data
>> + *
>> + * Initialization function that can be called by machine initialization
>> + * code to parse thermal data and populate the thermal framework
>> + * with hardware thermal zones info. This function only parses thermal zones.
>> + * Cooling devices and sensor devices nodes are supposed to be parsed
>> + * by their respective drivers.
>> + *
>> + * Return: 0 on success, proper error code otherwise
>> + *
>> + */
>> +int __init of_parse_thermal_zones(void)
>> +{
>> + struct device_node *np, *child;
>> + struct __thermal_zone *tz;
>> + struct thermal_zone_device_ops *ops;
>> +
>> + np = of_find_node_by_name(NULL, "thermal-zones");
>> + if (!np) {
>> + pr_debug("unable to find thermal zones\n");
>> + return 0; /* Run successfully on systems without thermal DT */
>> + }
>> +
>> + for_each_child_of_node(np, child) {
>> + struct thermal_zone_device *zone;
>> + struct thermal_zone_params *tzp;
>> +
>> + tz = thermal_of_build_thermal_zone(child);
>> + if (IS_ERR(tz)) {
>> + pr_err("failed to build thermal zone %s: %ld\n",
>> + child->name,
>> + PTR_ERR(tz));
>> + continue;
>> + }
>> +
>> + ops = kmemdup(&of_thermal_ops, sizeof(*ops), GFP_KERNEL);
>> + if (!ops)
>> + goto exit_free;
>> +
>> + tzp = kzalloc(sizeof(*tzp), GFP_KERNEL);
>> + if (!tzp) {
>> + kfree(ops);
>> + goto exit_free;
>> + }
>> +
>> + /* No hwmon because there might be hwmon drivers registering */
>> + tzp->no_hwmon = true;
>> +
>> + zone = thermal_zone_device_register(child->name, tz->ntrips,
>> + 0, tz,
>> + ops, tzp,
>> + tz->passive_delay,
>> + tz->polling_delay);
>> + if (IS_ERR(zone)) {
>> + pr_err("Failed to build %s zone %ld\n", child->name,
>> + PTR_ERR(zone));
>> + kfree(tzp);
>> + kfree(ops);
>> + of_thermal_free_zone(tz);
>> + /* attempting to build remaining zones still */
>> + }
>> + }
>> +
>> + return 0;
>> +
>> +exit_free:
>> + of_thermal_free_zone(tz);
>> +
>> + /* no memory available, so free what we have built */
>> + of_thermal_destroy_zones();
>> +
>> + return -ENOMEM;
>> +}
>> +
>> +/**
>> + * of_thermal_destroy_zones - remove all zones parsed and allocated resources
>> + *
>> + * Finds all zones parsed and added to the thermal framework and remove them
>> + * from the system, together with their resources.
>> + *
>> + */
>> +void __exit of_thermal_destroy_zones(void)
>> +{
>> + struct device_node *np, *child;
>> +
>> + np = of_find_node_by_name(NULL, "thermal-zones");
>> + if (!np) {
>> + pr_err("unable to find thermal zones\n");
>> + return;
>> + }
>> +
>> + for_each_child_of_node(np, child) {
>> + struct thermal_zone_device *zone;
>> +
>> + zone = thermal_zone_get_zone_by_name(child->name);
>> + if (IS_ERR(zone))
>> + continue;
>> +
>> + thermal_zone_device_unregister(zone);
>> + kfree(zone->tzp);
>> + kfree(zone->ops);
>> + of_thermal_free_zone(zone->devdata);
>> + }
>> +}
>> diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
>> index f7a9f4f..fec3351 100644
>> --- a/drivers/thermal/thermal_core.c
>> +++ b/drivers/thermal/thermal_core.c
>> @@ -1371,7 +1371,7 @@ static void remove_trip_attrs(struct thermal_zone_device *tz)
>> */
>> struct thermal_zone_device *thermal_zone_device_register(const char *type,
>> int trips, int mask, void *devdata,
>> - const struct thermal_zone_device_ops *ops,
>> + struct thermal_zone_device_ops *ops,
>> const struct thermal_zone_params *tzp,
>> int passive_delay, int polling_delay)
>> {
>> @@ -1751,8 +1751,14 @@ static int __init thermal_init(void)
>> if (result)
>> goto unregister_class;
>>
>> + result = of_parse_thermal_zones();
>> + if (result)
>> + goto exit_netlink;
>> +
>> return 0;
>>
>> +exit_netlink:
>> + genetlink_exit();
>> unregister_governors:
>> thermal_unregister_governors();
>> unregister_class:
>> @@ -1768,6 +1774,7 @@ error:
>>
>> static void __exit thermal_exit(void)
>> {
>> + of_thermal_destroy_zones();
>> genetlink_exit();
>> class_unregister(&thermal_class);
>> thermal_unregister_governors();
>> diff --git a/drivers/thermal/thermal_core.h b/drivers/thermal/thermal_core.h
>> index 7cf2f66..3db339f 100644
>> --- a/drivers/thermal/thermal_core.h
>> +++ b/drivers/thermal/thermal_core.h
>> @@ -77,4 +77,13 @@ static inline int thermal_gov_user_space_register(void) { return 0; }
>> static inline void thermal_gov_user_space_unregister(void) {}
>> #endif /* CONFIG_THERMAL_GOV_USER_SPACE */
>>
>> +/* device tree support */
>> +#ifdef CONFIG_THERMAL_OF
>> +int of_parse_thermal_zones(void);
>> +void of_thermal_destroy_zones(void);
>> +#else
>> +static inline int of_parse_thermal_zones(void) { return 0; }
>> +static inline void of_thermal_destroy_zones(void) { }
>> +#endif
>> +
>> #endif /* __THERMAL_CORE_H__ */
>> diff --git a/include/dt-bindings/thermal/thermal.h b/include/dt-bindings/thermal/thermal.h
>> new file mode 100644
>> index 0000000..59c4581
>> --- /dev/null
>> +++ b/include/dt-bindings/thermal/thermal.h
>> @@ -0,0 +1,27 @@
>> +/*
>> + * This header provides constants for most thermal bindings.
>> + *
>> + * Copyright (C) 2013 Texas Instruments
>> + * Eduardo Valentin <[email protected]>
>> + *
>> + * GPLv2 only
>> + */
>> +
>> +#ifndef _DT_BINDINGS_THERMAL_THERMAL_H
>> +#define _DT_BINDINGS_THERMAL_THERMAL_H
>> +
>> +/*
>> + * Here are the thermal trip types. This must
>> + * match with enum thermal_trip_type at
>> + * include/linux/thermal.h
>> + */
>> +#define THERMAL_TRIP_ACTIVE "active"
>> +#define THERMAL_TRIP_PASSIVE "passive"
>> +#define THERMAL_TRIP_HOT "hot"
>> +#define THERMAL_TRIP_CRITICAL "critical"
>
> I don't like this. If someone wants to include this in a C file they can't do so
> at the same time as include/linux/thermal.h. The defined names are longer than
> the actual string values, and the comment makes it sound like these could be
> modified rather than being a fixed ABI.
>
> I do not see the point of these constants.
>
> Thanks,
> Mark.
>
>> +
>> +/* On cooling devices upper and lower limits */
>> +#define THERMAL_NO_LIMIT (-1UL)
>> +
>> +#endif
>> +
>> diff --git a/include/linux/thermal.h b/include/linux/thermal.h
>> index b268d3c..b780c5b 100644
>> --- a/include/linux/thermal.h
>> +++ b/include/linux/thermal.h
>> @@ -143,6 +143,7 @@ struct thermal_cooling_device {
>> int id;
>> char type[THERMAL_NAME_LENGTH];
>> struct device device;
>> + struct device_node *np;
>> void *devdata;
>> const struct thermal_cooling_device_ops *ops;
>> bool updated; /* true if the cooling device does not need update */
>> @@ -172,7 +173,7 @@ struct thermal_zone_device {
>> int emul_temperature;
>> int passive;
>> unsigned int forced_passive;
>> - const struct thermal_zone_device_ops *ops;
>> + struct thermal_zone_device_ops *ops;
>> const struct thermal_zone_params *tzp;
>> struct thermal_governor *governor;
>> struct list_head thermal_instances;
>> @@ -242,8 +243,31 @@ struct thermal_genl_event {
>> };
>>
>> /* Function declarations */
>> +#ifdef CONFIG_THERMAL_OF
>> +struct thermal_zone_device *
>> +thermal_zone_of_sensor_register(struct device *dev, int id,
>> + void *data, int (*get_temp)(void *, long *),
>> + int (*get_trend)(void *, long *));
>> +void thermal_zone_of_sensor_unregister(struct device *dev,
>> + struct thermal_zone_device *tz);
>> +#else
>> +static inline struct thermal_zone_device *
>> +thermal_zone_of_sensor_register(struct device *dev, int id,
>> + void *data, int (*get_temp)(void *, long *),
>> + int (*get_trend)(void *, long *))
>> +{
>> + return NULL;
>> +}
>> +
>> +static inline
>> +void thermal_zone_of_sensor_unregister(struct device *dev,
>> + struct thermal_zone_device *tz)
>> +{
>> +}
>> +
>> +#endif
>> struct thermal_zone_device *thermal_zone_device_register(const char *, int, int,
>> - void *, const struct thermal_zone_device_ops *,
>> + void *, struct thermal_zone_device_ops *,
>> const struct thermal_zone_params *, int, int);
>> void thermal_zone_device_unregister(struct thermal_zone_device *);
>>
>> --
>> 1.8.2.1.342.gfa7285d
>>
>>
>
>

--
You have got to be excited about what you are doing. (L. Lamport)

Eduardo Valentin

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