[PATCH V2 0/2] hwmon: pwm-fan: Add optional regulator support

[PATCH V2 0/2] hwmon: pwm-fan: Add optional regulator support

[Stefan Wahren]

This small series implements the optional regulator support for the
pwm-fan driver.

Changes in V2:
- address Guenter's comments:
  - handle error case first
  - drop ENOSYS handling
  - implement more consistent bail out handling
- enable regulator before setup PWM
- make sure we disable regulator if probe fails

Stefan Wahren (2):
  dt-bindings: hwmon: Add optional regulator support to pwm-fan
  hwmon: pwm-fan: Add optional regulator support

 .../devicetree/bindings/hwmon/pwm-fan.txt          |  3 ++
 drivers/hwmon/pwm-fan.c                            | 39 +++++++++++++++++++++-
 2 files changed, 41 insertions(+), 1 deletion(-)

-- 
2.7.4

[PATCH V2 1/2] dt-bindings: hwmon: Add optional regulator support to pwm-fan

[Stefan Wahren]

This adds an optional regulator support (e.g. switchable supply) to the
pwm fan binding.

Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>
---
 Documentation/devicetree/bindings/hwmon/pwm-fan.txt | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/Documentation/devicetree/bindings/hwmon/pwm-fan.txt b/Documentation/devicetree/bindings/hwmon/pwm-fan.txt
index c6d5332..49ca5d8 100644
--- a/Documentation/devicetree/bindings/hwmon/pwm-fan.txt
+++ b/Documentation/devicetree/bindings/hwmon/pwm-fan.txt
@@ -6,6 +6,9 @@ Required properties:
 - cooling-levels      : PWM duty cycle values in a range from 0 to 255
 			which correspond to thermal cooling states
 
+Optional properties:
+- fan-supply    : phandle to the regulator that provides power to the fan
+
 Example:
 	fan0: pwm-fan {
 		compatible = "pwm-fan";
-- 
2.7.4

Re: [PATCH V2 1/2] dt-bindings: hwmon: Add optional regulator support to pwm-fan

[Rob Herring]

On Thu,  7 Feb 2019 17:37:59 +0100, Stefan Wahren wrote:
> This adds an optional regulator support (e.g. switchable supply) to the
> pwm fan binding.
> 
> Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>
> ---
>  Documentation/devicetree/bindings/hwmon/pwm-fan.txt | 3 +++
>  1 file changed, 3 insertions(+)
> 

Reviewed-by: Rob Herring <robh@kernel.org>

[PATCH V2 2/2] hwmon: pwm-fan: Add optional regulator support

[Stefan Wahren]

This adds optional regulator support to the pwm-fan driver. This is
necessary for pwm fans which are powered by a switchable supply.

Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>
---
 drivers/hwmon/pwm-fan.c | 39 ++++++++++++++++++++++++++++++++++++++-
 1 file changed, 38 insertions(+), 1 deletion(-)

diff --git a/drivers/hwmon/pwm-fan.c b/drivers/hwmon/pwm-fan.c
index 2c94482..344915c 100644
--- a/drivers/hwmon/pwm-fan.c
+++ b/drivers/hwmon/pwm-fan.c
@@ -23,6 +23,7 @@
 #include <linux/of.h>
 #include <linux/platform_device.h>
 #include <linux/pwm.h>
+#include <linux/regulator/consumer.h>
 #include <linux/sysfs.h>
 #include <linux/thermal.h>
 
@@ -31,6 +32,7 @@
 struct pwm_fan_ctx {
 	struct mutex lock;
 	struct pwm_device *pwm;
+	struct regulator *reg_en;
 	unsigned int pwm_value;
 	unsigned int pwm_fan_state;
 	unsigned int pwm_fan_max_state;
@@ -231,6 +233,21 @@ static int pwm_fan_probe(struct platform_device *pdev)
 
 	platform_set_drvdata(pdev, ctx);
 
+	ctx->reg_en = devm_regulator_get_optional(&pdev->dev, "fan");
+	if (IS_ERR(ctx->reg_en)) {
+		if (PTR_ERR(ctx->reg_en) == -ENODEV)
+			ctx->reg_en = NULL;
+		else
+			return PTR_ERR(ctx->reg_en);
+	} else {
+		ret = regulator_enable(ctx->reg_en);
+		if (ret) {
+			dev_err(&pdev->dev,
+				"Failed to enable fan supply: %d\n", ret);
+			return ret;
+		}
+	}
+
 	ctx->pwm_value = MAX_PWM;
 
 	/* Set duty cycle to maximum allowed and enable PWM output */
@@ -241,7 +258,7 @@ static int pwm_fan_probe(struct platform_device *pdev)
 	ret = pwm_apply_state(ctx->pwm, &state);
 	if (ret) {
 		dev_err(&pdev->dev, "Failed to configure PWM\n");
-		return ret;
+		goto err_reg_disable;
 	}
 
 	hwmon = devm_hwmon_device_register_with_groups(&pdev->dev, "pwmfan",
@@ -277,6 +294,10 @@ static int pwm_fan_probe(struct platform_device *pdev)
 	state.enabled = false;
 	pwm_apply_state(ctx->pwm, &state);
 
+err_reg_disable:
+	if (ctx->reg_en)
+		regulator_disable(ctx->reg_en);
+
 	return ret;
 }
 
@@ -287,6 +308,10 @@ static int pwm_fan_remove(struct platform_device *pdev)
 	thermal_cooling_device_unregister(ctx->cdev);
 	if (ctx->pwm_value)
 		pwm_disable(ctx->pwm);
+
+	if (ctx->reg_en)
+		regulator_disable(ctx->reg_en);
+
 	return 0;
 }
 
@@ -299,6 +324,12 @@ static int pwm_fan_suspend(struct device *dev)
 
 	pwm_get_args(ctx->pwm, &args);
 
+	if (ctx->reg_en) {
+		ret = regulator_disable(ctx->reg_en);
+		if (ret)
+			dev_err(dev, "Failed to disable fan supply: %d\n", ret);
+	}
+
 	if (ctx->pwm_value) {
 		ret = pwm_config(ctx->pwm, 0, args.period);
 		if (ret < 0)
@@ -317,6 +348,12 @@ static int pwm_fan_resume(struct device *dev)
 	unsigned long duty;
 	int ret;
 
+	if (ctx->reg_en) {
+		ret = regulator_enable(ctx->reg_en);
+		if (ret)
+			dev_err(dev, "Failed to enable fan supply: %d\n", ret);
+	}
+
 	if (ctx->pwm_value == 0)
 		return 0;
 
-- 
2.7.4

Re: [PATCH V2 2/2] hwmon: pwm-fan: Add optional regulator support

[Guenter Roeck]

On Thu, Feb 07, 2019 at 05:38:00PM +0100, Stefan Wahren wrote:
> This adds optional regulator support to the pwm-fan driver. This is
> necessary for pwm fans which are powered by a switchable supply.
> 
> Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>
> ---
>  drivers/hwmon/pwm-fan.c | 39 ++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 38 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/hwmon/pwm-fan.c b/drivers/hwmon/pwm-fan.c
> index 2c94482..344915c 100644
> --- a/drivers/hwmon/pwm-fan.c
> +++ b/drivers/hwmon/pwm-fan.c
> @@ -23,6 +23,7 @@
>  #include <linux/of.h>
>  #include <linux/platform_device.h>
>  #include <linux/pwm.h>
> +#include <linux/regulator/consumer.h>
>  #include <linux/sysfs.h>
>  #include <linux/thermal.h>
>  
> @@ -31,6 +32,7 @@
>  struct pwm_fan_ctx {
>  	struct mutex lock;
>  	struct pwm_device *pwm;
> +	struct regulator *reg_en;
>  	unsigned int pwm_value;
>  	unsigned int pwm_fan_state;
>  	unsigned int pwm_fan_max_state;
> @@ -231,6 +233,21 @@ static int pwm_fan_probe(struct platform_device *pdev)
>  
>  	platform_set_drvdata(pdev, ctx);
>  
> +	ctx->reg_en = devm_regulator_get_optional(&pdev->dev, "fan");
> +	if (IS_ERR(ctx->reg_en)) {
> +		if (PTR_ERR(ctx->reg_en) == -ENODEV)
> +			ctx->reg_en = NULL;
> +		else
> +			return PTR_ERR(ctx->reg_en);

		if PTR_ERR(ctx->reg_en) != -ENODEV)
			return PTR_ERR(ctx->reg_en);
		ctx->reg_en = NULL;

would be a bit easier to read and avoid an else.

> +	} else {
> +		ret = regulator_enable(ctx->reg_en);
> +		if (ret) {
> +			dev_err(&pdev->dev,
> +				"Failed to enable fan supply: %d\n", ret);
> +			return ret;
> +		}
> +	}
> +
>  	ctx->pwm_value = MAX_PWM;
>  
>  	/* Set duty cycle to maximum allowed and enable PWM output */
> @@ -241,7 +258,7 @@ static int pwm_fan_probe(struct platform_device *pdev)
>  	ret = pwm_apply_state(ctx->pwm, &state);
>  	if (ret) {
>  		dev_err(&pdev->dev, "Failed to configure PWM\n");
> -		return ret;
> +		goto err_reg_disable;
>  	}
>  
>  	hwmon = devm_hwmon_device_register_with_groups(&pdev->dev, "pwmfan",
> @@ -277,6 +294,10 @@ static int pwm_fan_probe(struct platform_device *pdev)
>  	state.enabled = false;
>  	pwm_apply_state(ctx->pwm, &state);
>  
> +err_reg_disable:
> +	if (ctx->reg_en)
> +		regulator_disable(ctx->reg_en);
> +
>  	return ret;
>  }
>  
> @@ -287,6 +308,10 @@ static int pwm_fan_remove(struct platform_device *pdev)
>  	thermal_cooling_device_unregister(ctx->cdev);
>  	if (ctx->pwm_value)
>  		pwm_disable(ctx->pwm);
> +
> +	if (ctx->reg_en)
> +		regulator_disable(ctx->reg_en);
> +
>  	return 0;
>  }
>  
> @@ -299,6 +324,12 @@ static int pwm_fan_suspend(struct device *dev)
>  
>  	pwm_get_args(ctx->pwm, &args);
>  
> +	if (ctx->reg_en) {
> +		ret = regulator_disable(ctx->reg_en);
> +		if (ret)
> +			dev_err(dev, "Failed to disable fan supply: %d\n", ret);

This is a bit weird. The error is returned to the caller, but only if
ctx->pwm_value is 0. Otherwise it is ignored. This warrants an explanation
(and some selling) if it is on purpose.

> +	}
> +
>  	if (ctx->pwm_value) {
>  		ret = pwm_config(ctx->pwm, 0, args.period);
>  		if (ret < 0)
> @@ -317,6 +348,12 @@ static int pwm_fan_resume(struct device *dev)
>  	unsigned long duty;
>  	int ret;
>  
> +	if (ctx->reg_en) {
> +		ret = regulator_enable(ctx->reg_en);
> +		if (ret)
> +			dev_err(dev, "Failed to enable fan supply: %d\n", ret);

Does it really make sense here to ignore this error ? After all,
the fan will likely not work if that error really happens. Doesn't
that count as resume failure ?

> +	}
> +
>  	if (ctx->pwm_value == 0)
>  		return 0;
>  
> -- 
> 2.7.4
>