I have a system that has very over spec'd fans so the amount of noise when they
run at 100% duty cycle is considerable. We have userspace monitoring tools that
will configure appropriate fan control parameters but there is a bit of a delay
between the kernel loading the driver and the userland tools catching up to
configure the fan control. This series adds device properties that allow the
PWM duty cycle to be specified via device properties so the PWM duty cycle can
be reduced as soon as possible.
This series attempts to setup the adt7475 as a pwm provider so that we can
specify these properties. The devicetree support was reasonably straight
forward (example usage is in the binding patch). I struggled to get the ACPI
version working well and in the end the code had to distinguish between the
of_node and other case. The ASL I've ended up with is
Device (ADT0)
{
Name (_HID, "PRP0001")
Name (_CRS, ResourceTemplate () {
I2cSerialBusV2 (0x2E, ControllerInitiated,
100000, AddressingMode7Bit,
"^^CH00", 0x00,
ResourceConsumer, , Exclusive, )
})
Name (_DSD, Package () {
ToUUID (UUID_DEVICE_PROPERTIES),
Package () {
Package () { "compatible", "adi,adt7476" },
Package () { "#pwm-cells", 4 },
},
})
Device (FAN0)
{
Name (_ADR, 0)
Name (_DSD, Package () {
ToUUID (UUID_DEVICE_PROPERTIES),
Package () {
Package () { "pwms", Package () { 0, 22500, 1, 50 } },
}
})
}
Device (FAN1)
{
Name (_ADR, 0)
Name (_DSD, Package () {
ToUUID (UUID_DEVICE_PROPERTIES),
Package () {
Package () { "pwms", Package () { 2, 22500, 1, 50 } },
}
})
}
}
If had to introduce a code path that parses that because try as I might I could
not convince fwnode_property_get_reference_args() to fetch the information out
of the ACPI data. If I've missed something obvious please let me know.
Chris Packham (3):
dt-bindings: hwmon: Add adt7475 fan/pwm properties
dt-bindings: hwmon: adt7475: Deprecate adi,pwm-active-state
hwmon: (adt7475) Add support for configuring initial PWM state
.../devicetree/bindings/hwmon/adt7475.yaml | 27 ++++-
drivers/hwmon/adt7475.c | 112 ++++++++++++++++++
2 files changed, 137 insertions(+), 2 deletions(-)
--
2.45.1
By default the PWM duty cycle in hardware is 100%. On some systems this
can cause unwanted fan noise. Add the ability to specify the fan
connections and initial state of the PWMs via device properties.
Signed-off-by: Chris Packham <[email protected]>
---
Notes:
Changes in v4:
- Support DT and ACPI fwnodes
- Put PWM into manual mode
Changes in v3:
- Use the pwm provider/consumer bindings
Changes in v2:
- Use correct device property string for frequency
- Allow -EINVAL and only warn on error
- Use a frequency of 0 to indicate that the hardware should be left as-is
drivers/hwmon/adt7475.c | 112 ++++++++++++++++++++++++++++++++++++++++
1 file changed, 112 insertions(+)
diff --git a/drivers/hwmon/adt7475.c b/drivers/hwmon/adt7475.c
index 4224ffb30483..b5c58e3cda03 100644
--- a/drivers/hwmon/adt7475.c
+++ b/drivers/hwmon/adt7475.c
@@ -21,6 +21,8 @@
#include <linux/of.h>
#include <linux/util_macros.h>
+#include <dt-bindings/pwm/pwm.h>
+
/* Indexes for the sysfs hooks */
#define INPUT 0
@@ -1662,6 +1664,112 @@ static int adt7475_set_pwm_polarity(struct i2c_client *client)
return 0;
}
+struct adt7475_pwm_config {
+ int index;
+ int freq;
+ int flags;
+ int duty;
+};
+
+static int adt7475_pwm_properties_parse_reference_args(struct fwnode_handle *fwnode,
+ struct adt7475_pwm_config *cfg)
+{
+ int ret;
+ struct fwnode_reference_args args = {};
+
+ ret = fwnode_property_get_reference_args(fwnode, "pwms", "#pwm-cells", 0, 0, &args);
+ if (ret)
+ return ret;
+
+ if (args.nargs != 4) {
+ fwnode_handle_put(args.fwnode);
+ return -EINVAL;
+ }
+
+ cfg->index = args.args[0];
+ cfg->freq = find_closest(args.args[1], pwmfreq_table, ARRAY_SIZE(pwmfreq_table));
+ cfg->flags = args.args[2];
+ cfg->duty = clamp_val(args.args[3], 0, 0xFF);
+
+ fwnode_handle_put(args.fwnode);
+
+ return 0;
+}
+
+static int adt7475_pwm_properties_parse_args(struct fwnode_handle *fwnode,
+ struct adt7475_pwm_config *cfg)
+{
+ int ret;
+ u32 args[4] = {};
+
+ ret = fwnode_property_read_u32_array(fwnode, "pwms", args, ARRAY_SIZE(args));
+ if (ret)
+ return ret;
+
+ cfg->index = args[0];
+ cfg->freq = find_closest(args[1], pwmfreq_table, ARRAY_SIZE(pwmfreq_table));
+ cfg->flags = args[2];
+ cfg->duty = clamp_val(args[3], 0, 0xFF);
+
+ return 0;
+}
+
+static int adt7475_fan_pwm_config(struct i2c_client *client)
+{
+ struct adt7475_data *data = i2c_get_clientdata(client);
+ struct fwnode_handle *child;
+ struct adt7475_pwm_config cfg = {};
+ int ret;
+
+ device_for_each_child_node(&client->dev, child) {
+ if (!fwnode_property_present(child, "pwms"))
+ continue;
+
+ if (is_of_node(child))
+ ret = adt7475_pwm_properties_parse_reference_args(child, &cfg);
+ else
+ ret = adt7475_pwm_properties_parse_args(child, &cfg);
+
+ if (cfg.index >= ADT7475_PWM_COUNT)
+ return -EINVAL;
+
+ ret = adt7475_read(PWM_CONFIG_REG(cfg.index));
+ if (ret < 0)
+ return ret;
+ data->pwm[CONTROL][cfg.index] = ret;
+ if (cfg.flags & PWM_POLARITY_INVERTED)
+ data->pwm[CONTROL][cfg.index] |= BIT(4);
+ else
+ data->pwm[CONTROL][cfg.index] &= ~BIT(4);
+
+ /* Force to manual mode so PWM values take effect */
+ data->pwm[CONTROL][cfg.index] &= ~0xE0;
+ data->pwm[CONTROL][cfg.index] |= 0x07 << 5;
+
+ ret = i2c_smbus_write_byte_data(client, PWM_CONFIG_REG(cfg.index),
+ data->pwm[CONTROL][cfg.index]);
+ if (ret)
+ return ret;
+
+ data->pwm[INPUT][cfg.index] = cfg.duty;
+ ret = i2c_smbus_write_byte_data(client, PWM_REG(cfg.index),
+ data->pwm[INPUT][cfg.index]);
+ if (ret)
+ return ret;
+
+ data->range[cfg.index] = adt7475_read(TEMP_TRANGE_REG(cfg.index));
+ data->range[cfg.index] &= ~0xf;
+ data->range[cfg.index] |= cfg.freq;
+
+ ret = i2c_smbus_write_byte_data(client, TEMP_TRANGE_REG(cfg.index),
+ data->range[cfg.index]);
+ if (ret)
+ return ret;
+ }
+
+ return 0;
+}
+
static int adt7475_probe(struct i2c_client *client)
{
enum chips chip;
@@ -1778,6 +1886,10 @@ static int adt7475_probe(struct i2c_client *client)
if (ret && ret != -EINVAL)
dev_warn(&client->dev, "Error configuring pwm polarity\n");
+ ret = adt7475_fan_pwm_config(client);
+ if (ret)
+ dev_warn(&client->dev, "Error %d configuring fan/pwm\n", ret);
+
/* Start monitoring */
switch (chip) {
case adt7475:
--
2.45.1
Add fan child nodes that allow describing the connections for the
ADT7475 to the fans it controls. This also allows setting some
initial values for the pwm duty cycle and frequency.
Signed-off-by: Chris Packham <[email protected]>
---
Notes:
I realise there is still some discussion about how to express the
frequency and duty cycle. I have a personal preference for using hertz
for the frequency and 0-255 for the duty cycle but if the consensus is
to express these things some other way I'm fine with doing some math.
Changes in v4:
- 0 is not a valid frequency value
Changes in v3:
- Use the pwm provider/consumer bindings
Changes in v2:
- Document 0 as a valid value (leaves hardware as-is)
.../devicetree/bindings/hwmon/adt7475.yaml | 25 ++++++++++++++++++-
1 file changed, 24 insertions(+), 1 deletion(-)
diff --git a/Documentation/devicetree/bindings/hwmon/adt7475.yaml b/Documentation/devicetree/bindings/hwmon/adt7475.yaml
index 051c976ab711..bfef4c803bf7 100644
--- a/Documentation/devicetree/bindings/hwmon/adt7475.yaml
+++ b/Documentation/devicetree/bindings/hwmon/adt7475.yaml
@@ -51,6 +51,15 @@ properties:
enum: [0, 1]
default: 1
+ "#pwm-cells":
+ const: 4
+ description: |
+ Number of cells in a PWM specifier.
+ - 0: The pwm channel
+ - 1: The pwm frequency in hertz - 11, 14, 22, 29, 35, 44, 58, 88, 22500
+ - 2: PWM flags 0 or PWM_POLARITY_INVERTED
+ - 3: The default pwm duty cycle - 0-255
+
patternProperties:
"^adi,bypass-attenuator-in[0-4]$":
description: |
@@ -81,6 +90,10 @@ patternProperties:
- smbalert#
- gpio
+ "^fan-[0-9]+$":
+ $ref: fan-common.yaml#
+ unevaluatedProperties: false
+
required:
- compatible
- reg
@@ -89,11 +102,12 @@ additionalProperties: false
examples:
- |
+ #include <dt-bindings/pwm/pwm.h>
i2c {
#address-cells = <1>;
#size-cells = <0>;
- hwmon@2e {
+ pwm: hwmon@2e {
compatible = "adi,adt7476";
reg = <0x2e>;
adi,bypass-attenuator-in0 = <1>;
@@ -101,5 +115,14 @@ examples:
adi,pwm-active-state = <1 0 1>;
adi,pin10-function = "smbalert#";
adi,pin14-function = "tach4";
+ #pwm-cells = <4>;
+
+ fan-0 {
+ pwms = <&pwm 0 22500 PWM_POLARITY_INVERTED 255>;
+ };
+
+ fan-1 {
+ pwms = <&pwm 2 22500 PWM_POLARITY_INVERTED 255>;
+ };
};
};
--
2.45.1
Now that we have fan child nodes that can specify flags for the PWM
outputs we no longer need the adi,pwm-active-state property.
Signed-off-by: Chris Packham <[email protected]>
---
Notes:
Changes in v3:
- New
Documentation/devicetree/bindings/hwmon/adt7475.yaml | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/Documentation/devicetree/bindings/hwmon/adt7475.yaml b/Documentation/devicetree/bindings/hwmon/adt7475.yaml
index bfef4c803bf7..ed18984c2529 100644
--- a/Documentation/devicetree/bindings/hwmon/adt7475.yaml
+++ b/Documentation/devicetree/bindings/hwmon/adt7475.yaml
@@ -45,6 +45,7 @@ properties:
the pwm uses a logic low output for 100% duty cycle. If set to 1 the pwm
uses a logic high output for 100% duty cycle.
$ref: /schemas/types.yaml#/definitions/uint32-array
+ deprecated: true
minItems: 3
maxItems: 3
items:
@@ -112,7 +113,6 @@ examples:
reg = <0x2e>;
adi,bypass-attenuator-in0 = <1>;
adi,bypass-attenuator-in1 = <0>;
- adi,pwm-active-state = <1 0 1>;
adi,pin10-function = "smbalert#";
adi,pin14-function = "tach4";
#pwm-cells = <4>;
--
2.45.1
On Wed, 29 May 2024 10:56:37 +1200, Chris Packham wrote:
> Now that we have fan child nodes that can specify flags for the PWM
> outputs we no longer need the adi,pwm-active-state property.
>
> Signed-off-by: Chris Packham <[email protected]>
> ---
>
> Notes:
> Changes in v3:
> - New
>
> Documentation/devicetree/bindings/hwmon/adt7475.yaml | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
Acked-by: Rob Herring (Arm) <[email protected]>