This series introduces the generic thermal MMIO driver that will use
memory mapped reads to get the temperature. Any HW/System that
allows temperature reading by a single memory-mapped reading, be it
register or shared memory, is a potential candidate to work with this
driver.
This driver is most suitable for cases such as the following:
- The entire thermal HW setup is done by another SW entity (e.g.
bootloader) and all that is left is to read the current temperature from
a register.
- The thermal HW setup is done via an external CPU (e.g. micro-controller)
and that CPU has is using shared memory that can be memory-mapped to this
driver.
- The thermal HW setup and reading is done via CPLD, which exports the
current temperature to the system via a register.
- The thermal HW is working out-of-the-box and only reports temperature via
a single register access.
Talel Shenhar (2):
dt-bindings: thermal: thermal_mmio: Add binding documentation
thermal: Introduce thermal MMIO
.../devicetree/bindings/thermal/thermal_mmio.txt | 173 +++++++++++++++++
drivers/thermal/Kconfig | 11 ++
drivers/thermal/Makefile | 3 +
drivers/thermal/thermal_mmio.c | 214 +++++++++++++++++++++
4 files changed, 401 insertions(+)
create mode 100644 Documentation/devicetree/bindings/thermal/thermal_mmio.txt
create mode 100644 drivers/thermal/thermal_mmio.c
--
2.7.4
Add thermal binding documentation for thermal MMIO driver.
Signed-off-by: Talel Shenhar <[email protected]>
---
.../devicetree/bindings/thermal/thermal_mmio.txt | 173 +++++++++++++++++++++
1 file changed, 173 insertions(+)
create mode 100644 Documentation/devicetree/bindings/thermal/thermal_mmio.txt
diff --git a/Documentation/devicetree/bindings/thermal/thermal_mmio.txt b/Documentation/devicetree/bindings/thermal/thermal_mmio.txt
new file mode 100644
index 0000000..1f4d738
--- /dev/null
+++ b/Documentation/devicetree/bindings/thermal/thermal_mmio.txt
@@ -0,0 +1,173 @@
+Generic Thermal MMIO Driver
+
+The generic thermal driver enables easy connectivity between "simple"
+thermal HW devices to the thermal subsystem. "simple" - thermal HW that
+doesn't need any configuration (such as power reset or clock enable) by a
+driver and only exports the temperature via simple MMIO access, or,
+alternatively, all the configuration is done by other entity (e.g.
+bootloader).
+
+Any system that allows temperature reading via a single memory map read, be
+it register or shared memory, is a potential candidate to work with this
+driver.
+This driver allows manipulations on the read value in order to allow some
+flexibility for the various thermal HW, e.g. sensor-factor which will be
+multiplied by the read value.
+
+This driver is most suitable for cases such as the following:
+- The entire thermal HW setup (e.g. configure the thermal HW to work in
+ continuous mode) is done by another SW entity (e.g. bootloader) and all
+ that is left is to read the current temperature from a register
+- The thermal reading is done by an external CPU (e.g. micro-controller)
+ and that CPU is exporting the reading via a shared memory
+- The thermal HW setup and reading is done via CPLD, which exports the
+ current temperature to the system via a register
+- The thermal HW is working out-of-the-box and only reports temperature via
+ a single register access
+
+Some examples for cases that this driver is not suitable for:
+- Your HW need clock enabling to be done by thermal driver
+- Your HW need some registers configurations in order to start reporting
+ temperatures and it is not doable by other entities (e.g. bootloader)
+- Your HW allows reading of temperatures only between ADCs (or any other
+ timing constrains)
+- In case your HW was configured by a bootloader and it lose the
+ configuration as part of low-power-state and need to be reconfigured.
+ (bootloader configuration typically is not sustained across low power
+ states)
+- In case the reading from the MMIO require any type of locking
+
+So the only operation this driver will do is MMIO read for the temperature.
+In case you are using HW that require some configurations this driver is
+not suitable (you can decide to move all the configuration logic into your
+bootloader and only leave the temperature reading to this driver but this
+is up to you).
+
+An example of a system that uses this driver is the Amazon Nitro SoC in
+which there is the main CPU and micro-controller:
+(1) The micro-controller accesses an SBUS controller to read the thermal
+ sensor from an SBUS slave called Avago Technologies digital
+ Temperature/Voltage Sensor (ip16_SENS_thermvolt25_0)
+(2) Once the micro-controller gathers the temperature it relays it to the
+ main CPU via a Shared Integrated RAM which is MMIO accessible by the CPU
+(3) The thermal_mmio driver that runs on the main CPU will read the
+ temperature via an MMIO access to the Shared RAM
+
++------------------+ +----------------+
+| | (3) | |
+| Main CPU +----->+ Integrated RAM |
+| | | |
++------------------+ +---------^------+
+ |(2)
++-----------------+ +------------------+
+| | (1) | |
+| SBUS controller <-------+ micro-controller |
+| | | |
++--------+--------+ +------------------+
+ |
++--------v---------------------+
+| |
+| Avago Technologies digital |
+| Temperature/Voltage Sensor |
+| (ip16_SENS_thermvolt25_0) |
+| |
++------------------------------+
+
+Required properties:
+- compatible: "thermal-mmio".
+- reg: The physical base address and length of the sensor's registers.
+- #thermal-sensor-cells: Must be 1. See ./thermal.txt for a description.
+
+Optional properties:
+- sensor-width: Width (in bytes) of each consecutive sensor.
+ Supported: 1, 2, 4.
+ (Default = 4)
+- sensor-mask: Mask to be applied on the raw read value before any
+ calculation.
+ (Default = 0xFFFFFFFF)
+- sensor-factor: Scale value by which to multiple the masked read value
+ This is a signed 32 bit value.
+ (Default = 1)
+- sensor-bias: Bias value to be added to the scaled value.
+ This is a signed 32 bit value.
+ (Default = 0)
+- sensor-divider: Dividing value by which to divide the calculated value.
+ Diving will be Integer Division.
+ This is a unsigned 32 bit value.
+ (Default = 1)
+
+Conversion formula from HW MMIO read value to millidegrees (Celsius):
+T_millidegrees = (bias + (T_raw & mask)*factor)/divider
+
+Example 1, two thermal devices with one thermal sensor each, that uses only
+the required properties (uses default):
+
+ thermal_d1: thermal_d1 {
+ compatible = "thermal-mmio";
+ reg = <0x0 0x05002860 0x0 0x4>;
+ #thermal-sensor-cells = <0x1>;
+ };
+
+ thermal_d2: thermal_d2 {
+ compatible = "thermal-mmio";
+ reg = <0x0 0x05000730 0x0 0x4>;
+ #thermal-sensor-cells = <0x1>;
+ };
+
+ thermal-zones {
+ thermal_d1_z0 {
+ polling-delay-passive = <250>;
+ polling-delay = <1000>;
+ thermal-sensors = <&thermal_d1 0>;
+ trips {
+ thermal_d1_z0_crit {
+ temperature = <105000>;
+ hysteresis = <2000>;
+ type = "critical";
+ };
+ };
+
+ };
+
+ thermal_d2_z0 {
+ polling-delay-passive = <250>;
+ polling-delay = <1000>;
+ thermal-sensors = <&thermal_d2 0>;
+ trips {
+ thermal_d2_z0_crit {
+ temperature = <105000>;
+ hysteresis = <2000>;
+ type = "critical";
+ };
+ };
+ };
+ };
+
+Example 2, one thermal device with two sensors of 6 bits each each, that
+has a factor of -5, bias of 23 and dividing of 2:
+
+ thermal_d3: thermal_d3 {
+ compatible = "thermal-mmio";
+ reg = <0x0 0x05005700 0x0 0x2>;
+ #thermal-sensor-cells = <0x1>;
+ sensor-width = <1>;
+ sensor-mask = <0x3F>;
+ sensor-factor = <(-5)>;
+ sensor-bias = <23>;
+ sensor-divider = <2>;
+ };
+
+ thermal-zones {
+ thermal_d3 {
+ polling-delay-passive = <250>;
+ polling-delay = <1000>;
+ thermal-sensors = <&thermal_d3 0>;
+ trips {
+ thermal_d3_z0_crit {
+ temperature = <105000>;
+ hysteresis = <2000>;
+ type = "critical";
+ };
+ };
+ };
+ };
--
2.7.4
This patch introduces a generic thermal driver, which enables easy
connectivity between "simple" thermal HW devices and the thermal
subsystem.
"simple" may be any system that allows temperature reading via a single
memory-mapped read, be it register or shared memory, and that doesn't
require any HW configuration to be done by the driver.
Such "simple" HW is a candidate to work with this driver.
Signed-off-by: Talel Shenhar <[email protected]>
---
drivers/thermal/Kconfig | 11 +++
drivers/thermal/Makefile | 3 +
drivers/thermal/thermal_mmio.c | 214 +++++++++++++++++++++++++++++++++++++++++
3 files changed, 228 insertions(+)
create mode 100644 drivers/thermal/thermal_mmio.c
diff --git a/drivers/thermal/Kconfig b/drivers/thermal/Kconfig
index 1775d44..0033ba2 100644
--- a/drivers/thermal/Kconfig
+++ b/drivers/thermal/Kconfig
@@ -199,6 +199,17 @@ config THERMAL_EMULATION
because userland can easily disable the thermal policy by simply
flooding this sysfs node with low temperature values.
+config THERMAL_MMIO
+ bool
+ depends on OF || COMPILE_TEST
+ prompt "mmio thermal driver"
+ help
+ This option enables the generic thermal MMIO driver that will use
+ memory-mapped reads to get the temperature. Any HW/System that
+ allows temperature reading by a single memory-mapped reading, be it
+ register or shared memory, is a potential candidate to work with this
+ driver.
+
config HISI_THERMAL
tristate "Hisilicon thermal driver"
depends on ARCH_HISI || COMPILE_TEST
diff --git a/drivers/thermal/Makefile b/drivers/thermal/Makefile
index 82bb50d..beec616 100644
--- a/drivers/thermal/Makefile
+++ b/drivers/thermal/Makefile
@@ -27,6 +27,9 @@ thermal_sys-$(CONFIG_CLOCK_THERMAL) += clock_cooling.o
# devfreq cooling
thermal_sys-$(CONFIG_DEVFREQ_THERMAL) += devfreq_cooling.o
+# generic memory mapped thermal driver
+thermal_sys-$(CONFIG_THERMAL_MMIO) += thermal_mmio.o
+
# platform thermal drivers
obj-y += broadcom/
obj-$(CONFIG_QCOM_SPMI_TEMP_ALARM) += qcom-spmi-temp-alarm.o
diff --git a/drivers/thermal/thermal_mmio.c b/drivers/thermal/thermal_mmio.c
new file mode 100644
index 0000000..1119e71
--- /dev/null
+++ b/drivers/thermal/thermal_mmio.c
@@ -0,0 +1,214 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright 2018 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ */
+
+#include <linux/module.h>
+#include <linux/of_address.h>
+#include <linux/platform_device.h>
+#include <linux/thermal.h>
+
+#define THERMAL_MMIO_DEFAULT_SENSOR_WIDTH sizeof(u32)
+#define THERMAL_MMIO_DEFAULT_SENSOR_FACTOR 1
+#define THERMAL_MMIO_DEFAULT_SENSOR_BIAS 0
+#define THERMAL_MMIO_DEFAULT_SENSOR_DIVIDER 1
+
+struct thermal_mmio {
+ void __iomem *mmio_base;
+ u32 (*read_mmio)(void __iomem *mmio_base);
+ int width;
+ u32 mask;
+ int factor;
+ int bias;
+ int divider;
+};
+
+static u32 thermal_mmio_readb(void __iomem *mmio_base)
+{
+ return readb(mmio_base);
+}
+
+static u32 thermal_mmio_readw(void __iomem *mmio_base)
+{
+ return readw(mmio_base);
+}
+
+static u32 thermal_mmio_readl(void __iomem *mmio_base)
+{
+ return readl(mmio_base);
+}
+
+static int thermal_mmio_get_temperature(void *private, int *temp)
+{
+ int t;
+ struct thermal_mmio *sensor =
+ (struct thermal_mmio *)private;
+
+ t = sensor->read_mmio(sensor->mmio_base) & sensor->mask;
+ t *= sensor->factor;
+ t += sensor->bias;
+ t /= sensor->divider;
+
+ *temp = t;
+
+ return 0;
+}
+
+static struct thermal_zone_of_device_ops thermal_mmio_ops = {
+ .get_temp = thermal_mmio_get_temperature,
+};
+
+static int thermal_mmio_parse_dt(struct platform_device *pdev,
+ struct thermal_mmio *sensor)
+{
+ struct resource *resource;
+ int ret;
+
+ resource = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ if (IS_ERR(resource)) {
+ dev_err(&pdev->dev,
+ "fail to get platform memory resource (%ld)\n",
+ PTR_ERR(resource));
+ return PTR_ERR(resource);
+ }
+
+ sensor->mmio_base = devm_ioremap_resource(&pdev->dev, resource);
+ if (IS_ERR(sensor->mmio_base)) {
+ dev_err(&pdev->dev, "failed to ioremap memory (%ld)\n",
+ PTR_ERR(sensor->mmio_base));
+ return PTR_ERR(sensor->mmio_base);
+ }
+
+ ret = of_property_read_u32(pdev->dev.of_node, "sensor-width",
+ &sensor->width);
+ if (ret < 0) {
+ sensor->width = THERMAL_MMIO_DEFAULT_SENSOR_WIDTH;
+ dev_dbg(&pdev->dev,
+ "sensor-width undefined (%d) - using default: %d\n",
+ ret, sensor->width);
+ }
+
+ ret = of_property_read_u32(pdev->dev.of_node, "sensor-mask",
+ &sensor->mask);
+ if (ret < 0) {
+ sensor->mask = GENMASK(sizeof(u32) * BITS_PER_BYTE - 1, 0);
+ dev_dbg(&pdev->dev,
+ "sensor-mask undefined (%d) - using default: 0x%x\n",
+ ret, sensor->mask);
+ }
+
+ ret = of_property_read_s32(pdev->dev.of_node, "sensor-factor",
+ &sensor->factor);
+ if (ret < 0) {
+ sensor->factor = THERMAL_MMIO_DEFAULT_SENSOR_FACTOR;
+ dev_dbg(&pdev->dev,
+ "sensor-factor undefined (%d) - using default: %d\n",
+ ret, sensor->factor);
+ }
+
+ ret = of_property_read_s32(pdev->dev.of_node, "sensor-bias",
+ &sensor->bias);
+ if (ret < 0) {
+ sensor->bias = THERMAL_MMIO_DEFAULT_SENSOR_BIAS;
+ dev_dbg(&pdev->dev,
+ "sensor-bias undefined (%d) - using default: %d\n",
+ ret, sensor->bias);
+ }
+
+ ret = of_property_read_u32(pdev->dev.of_node, "sensor-divider",
+ &sensor->divider);
+ if (ret < 0) {
+ sensor->divider = THERMAL_MMIO_DEFAULT_SENSOR_DIVIDER;
+ dev_dbg(&pdev->dev,
+ "sensor-divider undefined (%d) - using default: %d\n",
+ ret, sensor->divider);
+ }
+
+ /* configuration value sanity */
+ if (sensor->width > resource_size(resource)) {
+ dev_err(&pdev->dev,
+ "too small MMIO size, expected (%d) < supplied (%d)\n",
+ sensor->width, (int)resource_size(resource));
+ return -EINVAL;
+ }
+
+ dev_dbg(&pdev->dev,
+ "width=%d, mask=0x%x factor=%d bias=%d divider=%d\n",
+ sensor->width, sensor->mask, sensor->factor, sensor->bias,
+ sensor->divider);
+
+ return 0;
+}
+
+static int thermal_mmio_probe(struct platform_device *pdev)
+{
+ struct thermal_mmio *sensor;
+ struct thermal_zone_device *thermal_zone;
+ int ret;
+ int temperature;
+
+ sensor = devm_kzalloc(&pdev->dev, sizeof(*sensor), GFP_KERNEL);
+ if (!sensor)
+ return -ENOMEM;
+
+ ret = thermal_mmio_parse_dt(pdev, sensor);
+ if (ret) {
+ dev_err(&pdev->dev, "fail to parse dt\n");
+ return ret;
+ }
+
+ switch (sensor->width) {
+ case sizeof(u8):
+ sensor->read_mmio = thermal_mmio_readb;
+ break;
+ case sizeof(u16):
+ sensor->read_mmio = thermal_mmio_readw;
+ break;
+ case sizeof(u32):
+ sensor->read_mmio = thermal_mmio_readl;
+ break;
+ default:
+ dev_err(&pdev->dev, "bad sensor-width property supplied: %d\n",
+ sensor->width);
+ return -EINVAL;
+ }
+
+ thermal_zone = devm_thermal_zone_of_sensor_register(&pdev->dev,
+ 0,
+ sensor,
+ &thermal_mmio_ops);
+ if (IS_ERR(thermal_zone)) {
+ dev_err(&pdev->dev,
+ "failed to register sensor (%ld)\n",
+ PTR_ERR(thermal_zone));
+ return PTR_ERR(thermal_zone);
+ }
+
+ thermal_mmio_get_temperature(sensor, &temperature);
+ dev_info(&pdev->dev,
+ "thermal mmio sensor %s registered, current temperature: %d\n",
+ pdev->name, temperature);
+
+ return 0;
+}
+
+static const struct of_device_id thermal_mmio_id_table[] = {
+ { .compatible = "thermal-mmio" },
+ {}
+};
+MODULE_DEVICE_TABLE(of, thermal_mmio_id_table);
+
+static struct platform_driver thermal_mmio_driver = {
+ .probe = thermal_mmio_probe,
+ .driver = {
+ .name = "thermal-mmio",
+ .owner = THIS_MODULE,
+ .of_match_table = of_match_ptr(thermal_mmio_id_table),
+ },
+};
+
+module_platform_driver(thermal_mmio_driver);
+
+MODULE_AUTHOR("Talel Shenhar <[email protected]>");
+MODULE_DESCRIPTION("Thermal MMIO Driver");
+MODULE_LICENSE("GPL v2");
--
2.7.4
On Sun, Mar 03, 2019 at 10:49:25AM +0200, Talel Shenhar wrote:
> Add thermal binding documentation for thermal MMIO driver.
>
> Signed-off-by: Talel Shenhar <[email protected]>
> ---
> .../devicetree/bindings/thermal/thermal_mmio.txt | 173 +++++++++++++++++++++
> 1 file changed, 173 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/thermal/thermal_mmio.txt
>
> diff --git a/Documentation/devicetree/bindings/thermal/thermal_mmio.txt b/Documentation/devicetree/bindings/thermal/thermal_mmio.txt
> new file mode 100644
> index 0000000..1f4d738
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/thermal/thermal_mmio.txt
> @@ -0,0 +1,173 @@
> +Generic Thermal MMIO Driver
Bindings aren't for drivers.
Do h/w specific bindings and map those to a generic driver if you like.
We simply don't do single register level bindings because that doesn't
scale and things never turn out to be so generic.
> +
> +The generic thermal driver enables easy connectivity between "simple"
> +thermal HW devices to the thermal subsystem. "simple" - thermal HW that
> +doesn't need any configuration (such as power reset or clock enable) by a
> +driver and only exports the temperature via simple MMIO access, or,
> +alternatively, all the configuration is done by other entity (e.g.
> +bootloader).
> +
> +Any system that allows temperature reading via a single memory map read, be
> +it register or shared memory, is a potential candidate to work with this
> +driver.
> +This driver allows manipulations on the read value in order to allow some
> +flexibility for the various thermal HW, e.g. sensor-factor which will be
> +multiplied by the read value.
> +
> +This driver is most suitable for cases such as the following:
> +- The entire thermal HW setup (e.g. configure the thermal HW to work in
> + continuous mode) is done by another SW entity (e.g. bootloader) and all
> + that is left is to read the current temperature from a register
> +- The thermal reading is done by an external CPU (e.g. micro-controller)
> + and that CPU is exporting the reading via a shared memory
> +- The thermal HW setup and reading is done via CPLD, which exports the
> + current temperature to the system via a register
> +- The thermal HW is working out-of-the-box and only reports temperature via
> + a single register access
> +
> +Some examples for cases that this driver is not suitable for:
> +- Your HW need clock enabling to be done by thermal driver
...or avoiding disabling of a clock, regulator, etc.
> +- Your HW need some registers configurations in order to start reporting
> + temperatures and it is not doable by other entities (e.g. bootloader)
> +- Your HW allows reading of temperatures only between ADCs (or any other
> + timing constrains)
> +- In case your HW was configured by a bootloader and it lose the
> + configuration as part of low-power-state and need to be reconfigured.
> + (bootloader configuration typically is not sustained across low power
> + states)
> +- In case the reading from the MMIO require any type of locking
Or filtering/averaging of values.
> +
> +So the only operation this driver will do is MMIO read for the temperature.
> +In case you are using HW that require some configurations this driver is
> +not suitable (you can decide to move all the configuration logic into your
> +bootloader and only leave the temperature reading to this driver but this
> +is up to you).
> +
> +An example of a system that uses this driver is the Amazon Nitro SoC in
> +which there is the main CPU and micro-controller:
> +(1) The micro-controller accesses an SBUS controller to read the thermal
> + sensor from an SBUS slave called Avago Technologies digital
> + Temperature/Voltage Sensor (ip16_SENS_thermvolt25_0)
> +(2) Once the micro-controller gathers the temperature it relays it to the
> + main CPU via a Shared Integrated RAM which is MMIO accessible by the CPU
> +(3) The thermal_mmio driver that runs on the main CPU will read the
> + temperature via an MMIO access to the Shared RAM
> +
> ++------------------+ +----------------+
> +| | (3) | |
> +| Main CPU +----->+ Integrated RAM |
> +| | | |
> ++------------------+ +---------^------+
> + |(2)
> ++-----------------+ +------------------+
> +| | (1) | |
> +| SBUS controller <-------+ micro-controller |
> +| | | |
> ++--------+--------+ +------------------+
> + |
> ++--------v---------------------+
> +| |
> +| Avago Technologies digital |
> +| Temperature/Voltage Sensor |
> +| (ip16_SENS_thermvolt25_0) |
> +| |
> ++------------------------------+
Very specific information for a 'generic' binding.
> +
> +Required properties:
> +- compatible: "thermal-mmio".
> +- reg: The physical base address and length of the sensor's registers.
> +- #thermal-sensor-cells: Must be 1. See ./thermal.txt for a description.
> +
> +Optional properties:> +- sensor-width: Width (in bytes) of each consecutive sensor.
> + Supported: 1, 2, 4.
> + (Default = 4)
> +- sensor-mask: Mask to be applied on the raw read value before any
> + calculation.
> + (Default = 0xFFFFFFFF)
> +- sensor-factor: Scale value by which to multiple the masked read value
> + This is a signed 32 bit value.
> + (Default = 1)
> +- sensor-bias: Bias value to be added to the scaled value.
> + This is a signed 32 bit value.
> + (Default = 0)
> +- sensor-divider: Dividing value by which to divide the calculated value.
> + Diving will be Integer Division.
> + This is a unsigned 32 bit value.
> + (Default = 1)
If you are going to abstract all the h/w access, then get rid of all of
this and just put Celsius values into the "register".
> +
> +Conversion formula from HW MMIO read value to millidegrees (Celsius):
> +T_millidegrees = (bias + (T_raw & mask)*factor)/divider
> +
> +Example 1, two thermal devices with one thermal sensor each, that uses only
> +the required properties (uses default):
> +
> + thermal_d1: thermal_d1 {
> + compatible = "thermal-mmio";
> + reg = <0x0 0x05002860 0x0 0x4>;
> + #thermal-sensor-cells = <0x1>;
> + };
> +
> + thermal_d2: thermal_d2 {
> + compatible = "thermal-mmio";
> + reg = <0x0 0x05000730 0x0 0x4>;
> + #thermal-sensor-cells = <0x1>;
> + };
> +
> + thermal-zones {
> + thermal_d1_z0 {
> + polling-delay-passive = <250>;
> + polling-delay = <1000>;
> + thermal-sensors = <&thermal_d1 0>;
> + trips {
> + thermal_d1_z0_crit {
> + temperature = <105000>;
> + hysteresis = <2000>;
> + type = "critical";
> + };
> + };
> +
> + };
> +
> + thermal_d2_z0 {
> + polling-delay-passive = <250>;
> + polling-delay = <1000>;
> + thermal-sensors = <&thermal_d2 0>;
> + trips {
> + thermal_d2_z0_crit {
> + temperature = <105000>;
> + hysteresis = <2000>;
> + type = "critical";
> + };
> + };
> + };
> + };
> +
> +Example 2, one thermal device with two sensors of 6 bits each each, that
> +has a factor of -5, bias of 23 and dividing of 2:
> +
> + thermal_d3: thermal_d3 {
> + compatible = "thermal-mmio";
> + reg = <0x0 0x05005700 0x0 0x2>;
> + #thermal-sensor-cells = <0x1>;
> + sensor-width = <1>;
> + sensor-mask = <0x3F>;
> + sensor-factor = <(-5)>;
> + sensor-bias = <23>;
> + sensor-divider = <2>;
> + };
> +
> + thermal-zones {
> + thermal_d3 {
> + polling-delay-passive = <250>;
> + polling-delay = <1000>;
> + thermal-sensors = <&thermal_d3 0>;
> + trips {
> + thermal_d3_z0_crit {
> + temperature = <105000>;
> + hysteresis = <2000>;
> + type = "critical";
> + };
> + };
> + };
> + };
> --
> 2.7.4
>