[PATCH v2 0/2] pwm-fan: Refactor and convert to recommended API

[PATCH v2 0/2] pwm-fan: Refactor and convert to recommended API

[Paul Barker]

This series includes the first patch from my previous series adding support
for multiple fan tachometers [1] which Guenter has already reviewed, plus a
second patch to convert the driver to use the hwmon_device_register_with_info
API as requested.

These patches have been tested on a SanCloud BeagleBone Enhanced using an
oscilloscope to check the PWM output and a signal generator to simulate
the fan tachometer signals. I've tested both with and without a fan
tachometer input defined in the device tree.

There shouldn't be any functional change to the driver after these patches,
it just puts us in a much better place for further development.

These changes can also be pulled from:

  https://gitlab.com/pbarker.dev/staging/linux.git
  tag: for-hwmon/pwm-fan-refactor-v2_2020-11-28

Changes from v1:

  * Addressed review comment from Guenter: Simplify pwm_fan_write, return
    -ENOTSUPP from pwm_fan_read if the wrong type is given, use devm_kcalloc
    instead of devm_kzalloc to ensure multiplication is safe.

Paul Barker (2):
  hwmon: pwm-fan: Refactor pwm_fan_probe
  hwmon: pwm-fan: Convert to hwmon_device_register_with_info API

 drivers/hwmon/pwm-fan.c | 164 +++++++++++++++++++++++++---------------
 1 file changed, 104 insertions(+), 60 deletions(-)


base-commit: e6e2c18f63c62df778ce484945fccad088594533
-- 
2.26.2

[PATCH v2 1/2] hwmon: pwm-fan: Refactor pwm_fan_probe

[Paul Barker]

Use platform_irq_count to determine the number of fan tachometer inputs
configured in the device tree. At this stage we support either 0 or 1
inputs.

Once we have this information we only need to read the
pulses-per-revolution value if a fan tachometer is actually configured
via an IRQ value.

Also add a debug print of the IRQ number and the pulses-per-revolution
value to aid in investigating issues.

Signed-off-by: Paul Barker <pbarker@konsulko.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
---
 drivers/hwmon/pwm-fan.c | 50 +++++++++++++++++++++++++++--------------
 1 file changed, 33 insertions(+), 17 deletions(-)

diff --git a/drivers/hwmon/pwm-fan.c b/drivers/hwmon/pwm-fan.c
index 1f63807c0399..efe2764f42d3 100644
--- a/drivers/hwmon/pwm-fan.c
+++ b/drivers/hwmon/pwm-fan.c
@@ -286,7 +286,7 @@ static int pwm_fan_probe(struct platform_device *pdev)
 	struct device *hwmon;
 	int ret;
 	struct pwm_state state = { };
-	u32 ppr = 2;
+	int tach_count;
 
 	ctx = devm_kzalloc(dev, sizeof(*ctx), GFP_KERNEL);
 	if (!ctx)
@@ -300,10 +300,6 @@ static int pwm_fan_probe(struct platform_device *pdev)
 
 	platform_set_drvdata(pdev, ctx);
 
-	ctx->irq = platform_get_irq_optional(pdev, 0);
-	if (ctx->irq == -EPROBE_DEFER)
-		return ctx->irq;
-
 	ctx->reg_en = devm_regulator_get_optional(dev, "fan");
 	if (IS_ERR(ctx->reg_en)) {
 		if (PTR_ERR(ctx->reg_en) != -ENODEV)
@@ -339,20 +335,40 @@ static int pwm_fan_probe(struct platform_device *pdev)
 	if (ret)
 		return ret;
 
-	of_property_read_u32(dev->of_node, "pulses-per-revolution", &ppr);
-	ctx->pulses_per_revolution = ppr;
-	if (!ctx->pulses_per_revolution) {
-		dev_err(dev, "pulses-per-revolution can't be zero.\n");
-		return -EINVAL;
-	}
+	tach_count = platform_irq_count(pdev);
+	if (tach_count < 0)
+		return dev_err_probe(dev, tach_count,
+				     "Could not get number of fan tachometer inputs\n");
+
+	if (tach_count > 0) {
+		u32 ppr = 2;
+
+		ctx->irq = platform_get_irq(pdev, 0);
+		if (ctx->irq == -EPROBE_DEFER)
+			return ctx->irq;
+		if (ctx->irq > 0) {
+			ret = devm_request_irq(dev, ctx->irq, pulse_handler, 0,
+					       pdev->name, ctx);
+			if (ret) {
+				dev_err(dev,
+					"Failed to request interrupt: %d\n",
+					ret);
+				return ret;
+			}
+		}
 
-	if (ctx->irq > 0) {
-		ret = devm_request_irq(dev, ctx->irq, pulse_handler, 0,
-				       pdev->name, ctx);
-		if (ret) {
-			dev_err(dev, "Failed to request interrupt: %d\n", ret);
-			return ret;
+		of_property_read_u32(dev->of_node,
+				     "pulses-per-revolution",
+				     &ppr);
+		ctx->pulses_per_revolution = ppr;
+		if (!ctx->pulses_per_revolution) {
+			dev_err(dev, "pulses-per-revolution can't be zero.\n");
+			return -EINVAL;
 		}
+
+		dev_dbg(dev, "tach: irq=%d, pulses_per_revolution=%d\n",
+			ctx->irq, ctx->pulses_per_revolution);
+
 		ctx->sample_start = ktime_get();
 		mod_timer(&ctx->rpm_timer, jiffies + HZ);
 	}
-- 
2.26.2

Re: [PATCH v2 1/2] hwmon: pwm-fan: Refactor pwm_fan_probe

[Guenter Roeck]

On Sat, Nov 28, 2020 at 05:49:08PM +0000, Paul Barker wrote:
> Use platform_irq_count to determine the number of fan tachometer inputs
> configured in the device tree. At this stage we support either 0 or 1
> inputs.
> 
> Once we have this information we only need to read the
> pulses-per-revolution value if a fan tachometer is actually configured
> via an IRQ value.
> 
> Also add a debug print of the IRQ number and the pulses-per-revolution
> value to aid in investigating issues.
> 
> Signed-off-by: Paul Barker <pbarker@konsulko.com>
> Reviewed-by: Guenter Roeck <linux@roeck-us.net>

Applied.

Thanks,
Guenter

> ---
>  drivers/hwmon/pwm-fan.c | 50 +++++++++++++++++++++++++++--------------
>  1 file changed, 33 insertions(+), 17 deletions(-)
> 
> diff --git a/drivers/hwmon/pwm-fan.c b/drivers/hwmon/pwm-fan.c
> index 1f63807c0399..efe2764f42d3 100644
> --- a/drivers/hwmon/pwm-fan.c
> +++ b/drivers/hwmon/pwm-fan.c
> @@ -286,7 +286,7 @@ static int pwm_fan_probe(struct platform_device *pdev)
>  	struct device *hwmon;
>  	int ret;
>  	struct pwm_state state = { };
> -	u32 ppr = 2;
> +	int tach_count;
>  
>  	ctx = devm_kzalloc(dev, sizeof(*ctx), GFP_KERNEL);
>  	if (!ctx)
> @@ -300,10 +300,6 @@ static int pwm_fan_probe(struct platform_device *pdev)
>  
>  	platform_set_drvdata(pdev, ctx);
>  
> -	ctx->irq = platform_get_irq_optional(pdev, 0);
> -	if (ctx->irq == -EPROBE_DEFER)
> -		return ctx->irq;
> -
>  	ctx->reg_en = devm_regulator_get_optional(dev, "fan");
>  	if (IS_ERR(ctx->reg_en)) {
>  		if (PTR_ERR(ctx->reg_en) != -ENODEV)
> @@ -339,20 +335,40 @@ static int pwm_fan_probe(struct platform_device *pdev)
>  	if (ret)
>  		return ret;
>  
> -	of_property_read_u32(dev->of_node, "pulses-per-revolution", &ppr);
> -	ctx->pulses_per_revolution = ppr;
> -	if (!ctx->pulses_per_revolution) {
> -		dev_err(dev, "pulses-per-revolution can't be zero.\n");
> -		return -EINVAL;
> -	}
> +	tach_count = platform_irq_count(pdev);
> +	if (tach_count < 0)
> +		return dev_err_probe(dev, tach_count,
> +				     "Could not get number of fan tachometer inputs\n");
> +
> +	if (tach_count > 0) {
> +		u32 ppr = 2;
> +
> +		ctx->irq = platform_get_irq(pdev, 0);
> +		if (ctx->irq == -EPROBE_DEFER)
> +			return ctx->irq;
> +		if (ctx->irq > 0) {
> +			ret = devm_request_irq(dev, ctx->irq, pulse_handler, 0,
> +					       pdev->name, ctx);
> +			if (ret) {
> +				dev_err(dev,
> +					"Failed to request interrupt: %d\n",
> +					ret);
> +				return ret;
> +			}
> +		}
>  
> -	if (ctx->irq > 0) {
> -		ret = devm_request_irq(dev, ctx->irq, pulse_handler, 0,
> -				       pdev->name, ctx);
> -		if (ret) {
> -			dev_err(dev, "Failed to request interrupt: %d\n", ret);
> -			return ret;
> +		of_property_read_u32(dev->of_node,
> +				     "pulses-per-revolution",
> +				     &ppr);
> +		ctx->pulses_per_revolution = ppr;
> +		if (!ctx->pulses_per_revolution) {
> +			dev_err(dev, "pulses-per-revolution can't be zero.\n");
> +			return -EINVAL;
>  		}
> +
> +		dev_dbg(dev, "tach: irq=%d, pulses_per_revolution=%d\n",
> +			ctx->irq, ctx->pulses_per_revolution);
> +
>  		ctx->sample_start = ktime_get();
>  		mod_timer(&ctx->rpm_timer, jiffies + HZ);
>  	}
> -- 
> 2.26.2
> 

[PATCH v2 2/2] hwmon: pwm-fan: Convert to hwmon_device_register_with_info API

[Paul Barker]

The pwm-fan driver is updated to use the recommended API.

Signed-off-by: Paul Barker <pbarker@konsulko.com>
---
 drivers/hwmon/pwm-fan.c | 114 +++++++++++++++++++++++++---------------
 1 file changed, 71 insertions(+), 43 deletions(-)

diff --git a/drivers/hwmon/pwm-fan.c b/drivers/hwmon/pwm-fan.c
index efe2764f42d3..57b574837b58 100644
--- a/drivers/hwmon/pwm-fan.c
+++ b/drivers/hwmon/pwm-fan.c
@@ -8,7 +8,6 @@
  */
 
 #include <linux/hwmon.h>
-#include <linux/hwmon-sysfs.h>
 #include <linux/interrupt.h>
 #include <linux/module.h>
 #include <linux/mutex.h>
@@ -39,6 +38,28 @@ struct pwm_fan_ctx {
 	unsigned int pwm_fan_max_state;
 	unsigned int *pwm_fan_cooling_levels;
 	struct thermal_cooling_device *cdev;
+
+	struct hwmon_chip_info info;
+};
+
+static const u32 pwm_fan_channel_config_pwm[] = {
+	HWMON_PWM_INPUT,
+	0
+};
+
+static const struct hwmon_channel_info pwm_fan_channel_pwm = {
+	.type = hwmon_pwm,
+	.config = pwm_fan_channel_config_pwm,
+};
+
+static const u32 pwm_fan_channel_config_fan[] = {
+	HWMON_F_INPUT,
+	0
+};
+
+static const struct hwmon_channel_info pwm_fan_channel_fan = {
+	.type = hwmon_fan,
+	.config = pwm_fan_channel_config_fan,
 };
 
 /* This handler assumes self resetting edge triggered interrupt. */
@@ -103,70 +124,64 @@ static void pwm_fan_update_state(struct pwm_fan_ctx *ctx, unsigned long pwm)
 	ctx->pwm_fan_state = i;
 }
 
-static ssize_t pwm_store(struct device *dev, struct device_attribute *attr,
-			 const char *buf, size_t count)
+static int pwm_fan_write(struct device *dev, enum hwmon_sensor_types type,
+			 u32 attr, int channel, long val)
 {
 	struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
-	unsigned long pwm;
 	int ret;
 
-	if (kstrtoul(buf, 10, &pwm) || pwm > MAX_PWM)
+	if (val < 0 || val > MAX_PWM)
 		return -EINVAL;
 
-	ret = __set_pwm(ctx, pwm);
+	ret = __set_pwm(ctx, val);
 	if (ret)
 		return ret;
 
-	pwm_fan_update_state(ctx, pwm);
-	return count;
+	pwm_fan_update_state(ctx, val);
+	return 0;
 }
 
-static ssize_t pwm_show(struct device *dev, struct device_attribute *attr,
-			char *buf)
+static int pwm_fan_read(struct device *dev, enum hwmon_sensor_types type,
+			u32 attr, int channel, long *val)
 {
 	struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
 
-	return sprintf(buf, "%u\n", ctx->pwm_value);
-}
+	switch (type) {
+	case hwmon_pwm:
+		*val = ctx->pwm_value;
+		return 0;
 
-static ssize_t rpm_show(struct device *dev,
-			struct device_attribute *attr, char *buf)
-{
-	struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
+	case hwmon_fan:
+		*val = ctx->rpm;
+		return 0;
 
-	return sprintf(buf, "%u\n", ctx->rpm);
+	default:
+		return -ENOTSUPP;
+	}
 }
 
-static SENSOR_DEVICE_ATTR_RW(pwm1, pwm, 0);
-static SENSOR_DEVICE_ATTR_RO(fan1_input, rpm, 0);
+static umode_t pwm_fan_is_visible(const void *data,
+				  enum hwmon_sensor_types type,
+				  u32 attr, int channel)
+{
+	struct pwm_fan_ctx *ctx = (struct pwm_fan_ctx *)data;
 
-static struct attribute *pwm_fan_attrs[] = {
-	&sensor_dev_attr_pwm1.dev_attr.attr,
-	&sensor_dev_attr_fan1_input.dev_attr.attr,
-	NULL,
-};
+	switch (type) {
+	case hwmon_pwm:
+		return 0644;
 
-static umode_t pwm_fan_attrs_visible(struct kobject *kobj, struct attribute *a,
-				     int n)
-{
-	struct device *dev = container_of(kobj, struct device, kobj);
-	struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
+	case hwmon_fan:
+		return 0444;
 
-	/* Hide fan_input in case no interrupt is available  */
-	if (n == 1 && ctx->irq <= 0)
+	default:
 		return 0;
-
-	return a->mode;
+	}
 }
 
-static const struct attribute_group pwm_fan_group = {
-	.attrs = pwm_fan_attrs,
-	.is_visible = pwm_fan_attrs_visible,
-};
-
-static const struct attribute_group *pwm_fan_groups[] = {
-	&pwm_fan_group,
-	NULL,
+static const struct hwmon_ops pwm_fan_hwmon_ops = {
+	.is_visible = pwm_fan_is_visible,
+	.read = pwm_fan_read,
+	.write = pwm_fan_write,
 };
 
 /* thermal cooling device callbacks */
@@ -287,6 +302,7 @@ static int pwm_fan_probe(struct platform_device *pdev)
 	int ret;
 	struct pwm_state state = { };
 	int tach_count;
+	const struct hwmon_channel_info **channels;
 
 	ctx = devm_kzalloc(dev, sizeof(*ctx), GFP_KERNEL);
 	if (!ctx)
@@ -340,6 +356,13 @@ static int pwm_fan_probe(struct platform_device *pdev)
 		return dev_err_probe(dev, tach_count,
 				     "Could not get number of fan tachometer inputs\n");
 
+	channels = devm_kcalloc(dev, tach_count + 2,
+				sizeof(struct hwmon_channel_info *), GFP_KERNEL);
+	if (!channels)
+		return -ENOMEM;
+
+	channels[0] = &pwm_fan_channel_pwm;
+
 	if (tach_count > 0) {
 		u32 ppr = 2;
 
@@ -371,10 +394,15 @@ static int pwm_fan_probe(struct platform_device *pdev)
 
 		ctx->sample_start = ktime_get();
 		mod_timer(&ctx->rpm_timer, jiffies + HZ);
+
+		channels[1] = &pwm_fan_channel_fan;
 	}
 
-	hwmon = devm_hwmon_device_register_with_groups(dev, "pwmfan",
-						       ctx, pwm_fan_groups);
+	ctx->info.ops = &pwm_fan_hwmon_ops;
+	ctx->info.info = channels;
+
+	hwmon = devm_hwmon_device_register_with_info(dev, "pwmfan",
+						     ctx, &ctx->info, NULL);
 	if (IS_ERR(hwmon)) {
 		dev_err(dev, "Failed to register hwmon device\n");
 		return PTR_ERR(hwmon);
-- 
2.26.2

Re: [PATCH v2 2/2] hwmon: pwm-fan: Convert to hwmon_device_register_with_info API

[Guenter Roeck]

On Sat, Nov 28, 2020 at 05:49:09PM +0000, Paul Barker wrote:
> The pwm-fan driver is updated to use the recommended API.
> 
> Signed-off-by: Paul Barker <pbarker@konsulko.com>

Applied.

Thanks,
Guenter

> ---
>  drivers/hwmon/pwm-fan.c | 114 +++++++++++++++++++++++++---------------
>  1 file changed, 71 insertions(+), 43 deletions(-)
> 
> diff --git a/drivers/hwmon/pwm-fan.c b/drivers/hwmon/pwm-fan.c
> index efe2764f42d3..57b574837b58 100644
> --- a/drivers/hwmon/pwm-fan.c
> +++ b/drivers/hwmon/pwm-fan.c
> @@ -8,7 +8,6 @@
>   */
>  
>  #include <linux/hwmon.h>
> -#include <linux/hwmon-sysfs.h>
>  #include <linux/interrupt.h>
>  #include <linux/module.h>
>  #include <linux/mutex.h>
> @@ -39,6 +38,28 @@ struct pwm_fan_ctx {
>  	unsigned int pwm_fan_max_state;
>  	unsigned int *pwm_fan_cooling_levels;
>  	struct thermal_cooling_device *cdev;
> +
> +	struct hwmon_chip_info info;
> +};
> +
> +static const u32 pwm_fan_channel_config_pwm[] = {
> +	HWMON_PWM_INPUT,
> +	0
> +};
> +
> +static const struct hwmon_channel_info pwm_fan_channel_pwm = {
> +	.type = hwmon_pwm,
> +	.config = pwm_fan_channel_config_pwm,
> +};
> +
> +static const u32 pwm_fan_channel_config_fan[] = {
> +	HWMON_F_INPUT,
> +	0
> +};
> +
> +static const struct hwmon_channel_info pwm_fan_channel_fan = {
> +	.type = hwmon_fan,
> +	.config = pwm_fan_channel_config_fan,
>  };
>  
>  /* This handler assumes self resetting edge triggered interrupt. */
> @@ -103,70 +124,64 @@ static void pwm_fan_update_state(struct pwm_fan_ctx *ctx, unsigned long pwm)
>  	ctx->pwm_fan_state = i;
>  }
>  
> -static ssize_t pwm_store(struct device *dev, struct device_attribute *attr,
> -			 const char *buf, size_t count)
> +static int pwm_fan_write(struct device *dev, enum hwmon_sensor_types type,
> +			 u32 attr, int channel, long val)
>  {
>  	struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
> -	unsigned long pwm;
>  	int ret;
>  
> -	if (kstrtoul(buf, 10, &pwm) || pwm > MAX_PWM)
> +	if (val < 0 || val > MAX_PWM)
>  		return -EINVAL;
>  
> -	ret = __set_pwm(ctx, pwm);
> +	ret = __set_pwm(ctx, val);
>  	if (ret)
>  		return ret;
>  
> -	pwm_fan_update_state(ctx, pwm);
> -	return count;
> +	pwm_fan_update_state(ctx, val);
> +	return 0;
>  }
>  
> -static ssize_t pwm_show(struct device *dev, struct device_attribute *attr,
> -			char *buf)
> +static int pwm_fan_read(struct device *dev, enum hwmon_sensor_types type,
> +			u32 attr, int channel, long *val)
>  {
>  	struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
>  
> -	return sprintf(buf, "%u\n", ctx->pwm_value);
> -}
> +	switch (type) {
> +	case hwmon_pwm:
> +		*val = ctx->pwm_value;
> +		return 0;
>  
> -static ssize_t rpm_show(struct device *dev,
> -			struct device_attribute *attr, char *buf)
> -{
> -	struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
> +	case hwmon_fan:
> +		*val = ctx->rpm;
> +		return 0;
>  
> -	return sprintf(buf, "%u\n", ctx->rpm);
> +	default:
> +		return -ENOTSUPP;
> +	}
>  }
>  
> -static SENSOR_DEVICE_ATTR_RW(pwm1, pwm, 0);
> -static SENSOR_DEVICE_ATTR_RO(fan1_input, rpm, 0);
> +static umode_t pwm_fan_is_visible(const void *data,
> +				  enum hwmon_sensor_types type,
> +				  u32 attr, int channel)
> +{
> +	struct pwm_fan_ctx *ctx = (struct pwm_fan_ctx *)data;
>  
> -static struct attribute *pwm_fan_attrs[] = {
> -	&sensor_dev_attr_pwm1.dev_attr.attr,
> -	&sensor_dev_attr_fan1_input.dev_attr.attr,
> -	NULL,
> -};
> +	switch (type) {
> +	case hwmon_pwm:
> +		return 0644;
>  
> -static umode_t pwm_fan_attrs_visible(struct kobject *kobj, struct attribute *a,
> -				     int n)
> -{
> -	struct device *dev = container_of(kobj, struct device, kobj);
> -	struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
> +	case hwmon_fan:
> +		return 0444;
>  
> -	/* Hide fan_input in case no interrupt is available  */
> -	if (n == 1 && ctx->irq <= 0)
> +	default:
>  		return 0;
> -
> -	return a->mode;
> +	}
>  }
>  
> -static const struct attribute_group pwm_fan_group = {
> -	.attrs = pwm_fan_attrs,
> -	.is_visible = pwm_fan_attrs_visible,
> -};
> -
> -static const struct attribute_group *pwm_fan_groups[] = {
> -	&pwm_fan_group,
> -	NULL,
> +static const struct hwmon_ops pwm_fan_hwmon_ops = {
> +	.is_visible = pwm_fan_is_visible,
> +	.read = pwm_fan_read,
> +	.write = pwm_fan_write,
>  };
>  
>  /* thermal cooling device callbacks */
> @@ -287,6 +302,7 @@ static int pwm_fan_probe(struct platform_device *pdev)
>  	int ret;
>  	struct pwm_state state = { };
>  	int tach_count;
> +	const struct hwmon_channel_info **channels;
>  
>  	ctx = devm_kzalloc(dev, sizeof(*ctx), GFP_KERNEL);
>  	if (!ctx)
> @@ -340,6 +356,13 @@ static int pwm_fan_probe(struct platform_device *pdev)
>  		return dev_err_probe(dev, tach_count,
>  				     "Could not get number of fan tachometer inputs\n");
>  
> +	channels = devm_kcalloc(dev, tach_count + 2,
> +				sizeof(struct hwmon_channel_info *), GFP_KERNEL);
> +	if (!channels)
> +		return -ENOMEM;
> +
> +	channels[0] = &pwm_fan_channel_pwm;
> +
>  	if (tach_count > 0) {
>  		u32 ppr = 2;
>  
> @@ -371,10 +394,15 @@ static int pwm_fan_probe(struct platform_device *pdev)
>  
>  		ctx->sample_start = ktime_get();
>  		mod_timer(&ctx->rpm_timer, jiffies + HZ);
> +
> +		channels[1] = &pwm_fan_channel_fan;
>  	}
>  
> -	hwmon = devm_hwmon_device_register_with_groups(dev, "pwmfan",
> -						       ctx, pwm_fan_groups);
> +	ctx->info.ops = &pwm_fan_hwmon_ops;
> +	ctx->info.info = channels;
> +
> +	hwmon = devm_hwmon_device_register_with_info(dev, "pwmfan",
> +						     ctx, &ctx->info, NULL);
>  	if (IS_ERR(hwmon)) {
>  		dev_err(dev, "Failed to register hwmon device\n");
>  		return PTR_ERR(hwmon);
> -- 
> 2.26.2
>