[PATCH V5 0/3] hwmon: pwm-fan: Add RPM support

[PATCH V5 0/3] hwmon: pwm-fan: Add RPM support

[Stefan Wahren]

Contrary to the gpio-fan the pwm-fan driver isn't easy to setup
with pwmconfig/fancontrol because of the missing hwmon sysfs entry
for actual revolutions per minute. This series adds this feature.

Changes in V5:
- address Guenter's and Robin's comments:
  - use of_property_read_u32 to get pulses-per-revolution
  - call platform_get_irq ealier to avoid glitches on the regulator
  - simplify pwm_fan_attrs_visible

Changes in V4:
- remove copy & paste artifact in dt-binding example
- switch to u64 for rpm calculation
- drop overflow handling and init atomic
- handle 0 not as valid irq
- reduce range of pulses_per_revolution
- handle probe defer of platform_get_irq
- delete timer properly in bail-out path

Changes in V3:
- rename property interrupt-ratio to pulses-per-revolution
  to avoid confusion with interrupt binding
- handle error case pulses-per-revolution = 0
- bail out properly in case we are unable to request the irq

Changes in V2:
- address Guenter's comments:
  - improve description of interrupts
  - use atomic_t to avoid races of the pulse counter
  - measure sample time to make rpm more reliable under load
  - make sysfs entry fan1_input conditional
- add dt-property to define interrupts per fan revolution
- example for fan with RPM support

Stefan Wahren (3):
  dt-bindings: hwmon: Add tachometer interrupt to pwm-fan
  Documentation: pwm-fan: Add description for RPM support
  hwmon: pwm-fan: Add RPM support via external interrupt

 .../devicetree/bindings/hwmon/pwm-fan.txt          |  21 +++-
 Documentation/hwmon/pwm-fan                        |   3 +
 drivers/hwmon/pwm-fan.c                            | 107 ++++++++++++++++++++-
 3 files changed, 126 insertions(+), 5 deletions(-)

-- 
2.7.4

[PATCH V5 1/3] dt-bindings: hwmon: Add tachometer interrupt to pwm-fan

[Stefan Wahren]

This adds the tachometer interrupt to the pwm-fan binding, which is
necessary for RPM support.

Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>
Reviewed-by: Rob Herring <robh@kernel.org>
---
 Documentation/devicetree/bindings/hwmon/pwm-fan.txt | 21 ++++++++++++++++++++-
 1 file changed, 20 insertions(+), 1 deletion(-)

diff --git a/Documentation/devicetree/bindings/hwmon/pwm-fan.txt b/Documentation/devicetree/bindings/hwmon/pwm-fan.txt
index 49ca5d8..6ced829b 100644
--- a/Documentation/devicetree/bindings/hwmon/pwm-fan.txt
+++ b/Documentation/devicetree/bindings/hwmon/pwm-fan.txt
@@ -7,7 +7,16 @@ Required properties:
 			which correspond to thermal cooling states
 
 Optional properties:
-- fan-supply    : phandle to the regulator that provides power to the fan
+- fan-supply		: phandle to the regulator that provides power to the fan
+- interrupts		: This contains a single interrupt specifier which
+			  describes the tachometer output of the fan as an
+			  interrupt source. The output signal must generate a
+			  defined number of interrupts per fan revolution, which
+			  require that it must be self resetting edge interrupts.
+			  See interrupt-controller/interrupts.txt for the format.
+- pulses-per-revolution : define the tachometer pulses per fan revolution as
+			  an integer (default is 2 interrupts per revolution).
+			  The value must be greater than zero.
 
 Example:
 	fan0: pwm-fan {
@@ -38,3 +47,13 @@ Example:
 					};
 			     };
 		};
+
+Example 2:
+	fan0: pwm-fan {
+		compatible = "pwm-fan";
+		pwms = <&pwm 0 40000 0>;
+		fan-supply = <&reg_fan>;
+		interrupt-parent = <&gpio5>;
+		interrupts = <1 IRQ_TYPE_EDGE_FALLING>;
+		pulses-per-revolution = <2>;
+	};
-- 
2.7.4

[PATCH V5 2/3] Documentation: pwm-fan: Add description for RPM support

[Stefan Wahren]

This adds a short description for the new RPM support of the pwm-fan
driver.

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

diff --git a/Documentation/hwmon/pwm-fan b/Documentation/hwmon/pwm-fan
index 18529d2..82fe967 100644
--- a/Documentation/hwmon/pwm-fan
+++ b/Documentation/hwmon/pwm-fan
@@ -15,3 +15,6 @@ The driver implements a simple interface for driving a fan connected to
 a PWM output. It uses the generic PWM interface, thus it can be used with
 a range of SoCs. The driver exposes the fan to the user space through
 the hwmon's sysfs interface.
+
+The fan rotation speed returned via the optional 'fan1_input' is extrapolated
+from the sampled interrupts from the tachometer signal within 1 second.
-- 
2.7.4

[PATCH V5 3/3] hwmon: pwm-fan: Add RPM support via external interrupt

[Stefan Wahren]

This adds RPM support to the pwm-fan driver in order to use with
fancontrol/pwmconfig. This feature is intended for fans with a tachometer
output signal, which generate a defined number of pulses per revolution.

Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>
---
 drivers/hwmon/pwm-fan.c | 107 ++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 103 insertions(+), 4 deletions(-)

diff --git a/drivers/hwmon/pwm-fan.c b/drivers/hwmon/pwm-fan.c
index e4c5197..8c4c5ee 100644
--- a/drivers/hwmon/pwm-fan.c
+++ b/drivers/hwmon/pwm-fan.c
@@ -18,6 +18,7 @@
 
 #include <linux/hwmon.h>
 #include <linux/hwmon-sysfs.h>
+#include <linux/interrupt.h>
 #include <linux/module.h>
 #include <linux/mutex.h>
 #include <linux/of.h>
@@ -26,6 +27,7 @@
 #include <linux/regulator/consumer.h>
 #include <linux/sysfs.h>
 #include <linux/thermal.h>
+#include <linux/timer.h>
 
 #define MAX_PWM 255
 
@@ -33,6 +35,14 @@ struct pwm_fan_ctx {
 	struct mutex lock;
 	struct pwm_device *pwm;
 	struct regulator *reg_en;
+
+	int irq;
+	atomic_t pulses;
+	unsigned int rpm;
+	u8 pulses_per_revolution;
+	ktime_t sample_start;
+	struct timer_list rpm_timer;
+
 	unsigned int pwm_value;
 	unsigned int pwm_fan_state;
 	unsigned int pwm_fan_max_state;
@@ -40,6 +50,32 @@ struct pwm_fan_ctx {
 	struct thermal_cooling_device *cdev;
 };
 
+/* This handler assumes self resetting edge triggered interrupt. */
+static irqreturn_t pulse_handler(int irq, void *dev_id)
+{
+	struct pwm_fan_ctx *ctx = dev_id;
+
+	atomic_inc(&ctx->pulses);
+
+	return IRQ_HANDLED;
+}
+
+static void sample_timer(struct timer_list *t)
+{
+	struct pwm_fan_ctx *ctx = from_timer(ctx, t, rpm_timer);
+	int pulses;
+	u64 tmp;
+
+	pulses = atomic_read(&ctx->pulses);
+	atomic_sub(pulses, &ctx->pulses);
+	tmp = (u64)pulses * ktime_ms_delta(ktime_get(), ctx->sample_start) * 60;
+	do_div(tmp, ctx->pulses_per_revolution * 1000);
+	ctx->rpm = tmp;
+
+	ctx->sample_start = ktime_get();
+	mod_timer(&ctx->rpm_timer, jiffies + HZ);
+}
+
 static int  __set_pwm(struct pwm_fan_ctx *ctx, unsigned long pwm)
 {
 	unsigned long period;
@@ -100,15 +136,47 @@ static ssize_t pwm_show(struct device *dev, struct device_attribute *attr,
 	return sprintf(buf, "%u\n", ctx->pwm_value);
 }
 
+static ssize_t rpm_show(struct device *dev,
+			struct device_attribute *attr, char *buf)
+{
+	struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
+
+	return sprintf(buf, "%u\n", ctx->rpm);
+}
 
 static SENSOR_DEVICE_ATTR_RW(pwm1, pwm, 0);
+static SENSOR_DEVICE_ATTR_RO(fan1_input, rpm, 0);
 
 static struct attribute *pwm_fan_attrs[] = {
 	&sensor_dev_attr_pwm1.dev_attr.attr,
+	&sensor_dev_attr_fan1_input.dev_attr.attr,
 	NULL,
 };
 
-ATTRIBUTE_GROUPS(pwm_fan);
+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);
+	struct device_attribute *devattr;
+
+	/* Hide fan_input in case no interrupt is available  */
+	devattr = container_of(a, struct device_attribute, attr);
+	if (n == 1 && ctx->irq <= 0)
+		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,
+};
 
 /* thermal cooling device callbacks */
 static int pwm_fan_get_max_state(struct thermal_cooling_device *cdev,
@@ -214,6 +282,7 @@ static int pwm_fan_probe(struct platform_device *pdev)
 	struct device *hwmon;
 	int ret;
 	struct pwm_state state = { };
+	u32 ppr = 2;
 
 	ctx = devm_kzalloc(&pdev->dev, sizeof(*ctx), GFP_KERNEL);
 	if (!ctx)
@@ -233,6 +302,10 @@ static int pwm_fan_probe(struct platform_device *pdev)
 
 	platform_set_drvdata(pdev, ctx);
 
+	ctx->irq = platform_get_irq(pdev, 0);
+	if (ctx->irq == -EPROBE_DEFER)
+		return ctx->irq;
+
 	ctx->reg_en = devm_regulator_get_optional(&pdev->dev, "fan");
 	if (IS_ERR(ctx->reg_en)) {
 		if (PTR_ERR(ctx->reg_en) != -ENODEV)
@@ -261,17 +334,38 @@ static int pwm_fan_probe(struct platform_device *pdev)
 		goto err_reg_disable;
 	}
 
+	timer_setup(&ctx->rpm_timer, sample_timer, 0);
+
+	of_property_read_u32(pdev->dev.of_node, "pulses-per-revolution", &ppr);
+	ctx->pulses_per_revolution = ppr;
+	if (!ctx->pulses_per_revolution) {
+		dev_err(&pdev->dev, "pulses-per-revolution can't be zero.\n");
+		ret = -EINVAL;
+		goto err_pwm_disable;
+	}
+
+	if (ctx->irq > 0) {
+		ret = devm_request_irq(&pdev->dev, ctx->irq, pulse_handler, 0,
+				       pdev->name, ctx);
+		if (ret) {
+			dev_err(&pdev->dev, "Can't get interrupt working.\n");
+			goto err_pwm_disable;
+		}
+		ctx->sample_start = ktime_get();
+		mod_timer(&ctx->rpm_timer, jiffies + HZ);
+	}
+
 	hwmon = devm_hwmon_device_register_with_groups(&pdev->dev, "pwmfan",
 						       ctx, pwm_fan_groups);
 	if (IS_ERR(hwmon)) {
 		dev_err(&pdev->dev, "Failed to register hwmon device\n");
 		ret = PTR_ERR(hwmon);
-		goto err_pwm_disable;
+		goto err_del_timer;
 	}
 
 	ret = pwm_fan_of_get_cooling_data(&pdev->dev, ctx);
 	if (ret)
-		goto err_pwm_disable;
+		goto err_del_timer;
 
 	ctx->pwm_fan_state = ctx->pwm_fan_max_state;
 	if (IS_ENABLED(CONFIG_THERMAL)) {
@@ -282,7 +376,7 @@ static int pwm_fan_probe(struct platform_device *pdev)
 			dev_err(&pdev->dev,
 				"Failed to register pwm-fan as cooling device");
 			ret = PTR_ERR(cdev);
-			goto err_pwm_disable;
+			goto err_del_timer;
 		}
 		ctx->cdev = cdev;
 		thermal_cdev_update(cdev);
@@ -290,6 +384,9 @@ static int pwm_fan_probe(struct platform_device *pdev)
 
 	return 0;
 
+err_del_timer:
+	del_timer_sync(&ctx->rpm_timer);
+
 err_pwm_disable:
 	state.enabled = false;
 	pwm_apply_state(ctx->pwm, &state);
@@ -306,6 +403,8 @@ static int pwm_fan_remove(struct platform_device *pdev)
 	struct pwm_fan_ctx *ctx = platform_get_drvdata(pdev);
 
 	thermal_cooling_device_unregister(ctx->cdev);
+	del_timer_sync(&ctx->rpm_timer);
+
 	if (ctx->pwm_value)
 		pwm_disable(ctx->pwm);
 
-- 
2.7.4

Re: [PATCH V5 3/3] hwmon: pwm-fan: Add RPM support via external interrupt

[Guenter Roeck]

On Thu, Apr 11, 2019 at 03:30:11PM +0200, Stefan Wahren wrote:
> This adds RPM support to the pwm-fan driver in order to use with
> fancontrol/pwmconfig. This feature is intended for fans with a tachometer
> output signal, which generate a defined number of pulses per revolution.
> 
> Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>
> ---
>  drivers/hwmon/pwm-fan.c | 107 ++++++++++++++++++++++++++++++++++++++++++++++--
>  1 file changed, 103 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/hwmon/pwm-fan.c b/drivers/hwmon/pwm-fan.c
> index e4c5197..8c4c5ee 100644
> --- a/drivers/hwmon/pwm-fan.c
> +++ b/drivers/hwmon/pwm-fan.c
> @@ -18,6 +18,7 @@
>  
>  #include <linux/hwmon.h>
>  #include <linux/hwmon-sysfs.h>
> +#include <linux/interrupt.h>
>  #include <linux/module.h>
>  #include <linux/mutex.h>
>  #include <linux/of.h>
> @@ -26,6 +27,7 @@
>  #include <linux/regulator/consumer.h>
>  #include <linux/sysfs.h>
>  #include <linux/thermal.h>
> +#include <linux/timer.h>
>  
>  #define MAX_PWM 255
>  
> @@ -33,6 +35,14 @@ struct pwm_fan_ctx {
>  	struct mutex lock;
>  	struct pwm_device *pwm;
>  	struct regulator *reg_en;
> +
> +	int irq;
> +	atomic_t pulses;
> +	unsigned int rpm;
> +	u8 pulses_per_revolution;
> +	ktime_t sample_start;
> +	struct timer_list rpm_timer;
> +
>  	unsigned int pwm_value;
>  	unsigned int pwm_fan_state;
>  	unsigned int pwm_fan_max_state;
> @@ -40,6 +50,32 @@ struct pwm_fan_ctx {
>  	struct thermal_cooling_device *cdev;
>  };
>  
> +/* This handler assumes self resetting edge triggered interrupt. */
> +static irqreturn_t pulse_handler(int irq, void *dev_id)
> +{
> +	struct pwm_fan_ctx *ctx = dev_id;
> +
> +	atomic_inc(&ctx->pulses);
> +
> +	return IRQ_HANDLED;
> +}
> +
> +static void sample_timer(struct timer_list *t)
> +{
> +	struct pwm_fan_ctx *ctx = from_timer(ctx, t, rpm_timer);
> +	int pulses;
> +	u64 tmp;
> +
> +	pulses = atomic_read(&ctx->pulses);
> +	atomic_sub(pulses, &ctx->pulses);
> +	tmp = (u64)pulses * ktime_ms_delta(ktime_get(), ctx->sample_start) * 60;
> +	do_div(tmp, ctx->pulses_per_revolution * 1000);
> +	ctx->rpm = tmp;
> +
> +	ctx->sample_start = ktime_get();
> +	mod_timer(&ctx->rpm_timer, jiffies + HZ);
> +}
> +
>  static int  __set_pwm(struct pwm_fan_ctx *ctx, unsigned long pwm)
>  {
>  	unsigned long period;
> @@ -100,15 +136,47 @@ static ssize_t pwm_show(struct device *dev, struct device_attribute *attr,
>  	return sprintf(buf, "%u\n", ctx->pwm_value);
>  }
>  
> +static ssize_t rpm_show(struct device *dev,
> +			struct device_attribute *attr, char *buf)
> +{
> +	struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
> +
> +	return sprintf(buf, "%u\n", ctx->rpm);
> +}
>  
>  static SENSOR_DEVICE_ATTR_RW(pwm1, pwm, 0);
> +static SENSOR_DEVICE_ATTR_RO(fan1_input, rpm, 0);
>  
>  static struct attribute *pwm_fan_attrs[] = {
>  	&sensor_dev_attr_pwm1.dev_attr.attr,
> +	&sensor_dev_attr_fan1_input.dev_attr.attr,
>  	NULL,
>  };
>  
> -ATTRIBUTE_GROUPS(pwm_fan);
> +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);
> +	struct device_attribute *devattr;
> +
> +	/* Hide fan_input in case no interrupt is available  */
> +	devattr = container_of(a, struct device_attribute, attr);

Field day for static analyzers - devattr is no longer used.
No need to resend. I'll let the series rest for a couple of days
and then apply to hwmon-next (after removing devattr) unless there are
additional comments.

> +	if (n == 1 && ctx->irq <= 0)
> +		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,
> +};
>  
>  /* thermal cooling device callbacks */
>  static int pwm_fan_get_max_state(struct thermal_cooling_device *cdev,
> @@ -214,6 +282,7 @@ static int pwm_fan_probe(struct platform_device *pdev)
>  	struct device *hwmon;
>  	int ret;
>  	struct pwm_state state = { };
> +	u32 ppr = 2;
>  
>  	ctx = devm_kzalloc(&pdev->dev, sizeof(*ctx), GFP_KERNEL);
>  	if (!ctx)
> @@ -233,6 +302,10 @@ static int pwm_fan_probe(struct platform_device *pdev)
>  
>  	platform_set_drvdata(pdev, ctx);
>  
> +	ctx->irq = platform_get_irq(pdev, 0);
> +	if (ctx->irq == -EPROBE_DEFER)
> +		return ctx->irq;
> +
>  	ctx->reg_en = devm_regulator_get_optional(&pdev->dev, "fan");
>  	if (IS_ERR(ctx->reg_en)) {
>  		if (PTR_ERR(ctx->reg_en) != -ENODEV)
> @@ -261,17 +334,38 @@ static int pwm_fan_probe(struct platform_device *pdev)
>  		goto err_reg_disable;
>  	}
>  
> +	timer_setup(&ctx->rpm_timer, sample_timer, 0);
> +
> +	of_property_read_u32(pdev->dev.of_node, "pulses-per-revolution", &ppr);
> +	ctx->pulses_per_revolution = ppr;
> +	if (!ctx->pulses_per_revolution) {
> +		dev_err(&pdev->dev, "pulses-per-revolution can't be zero.\n");
> +		ret = -EINVAL;
> +		goto err_pwm_disable;
> +	}
> +
> +	if (ctx->irq > 0) {
> +		ret = devm_request_irq(&pdev->dev, ctx->irq, pulse_handler, 0,
> +				       pdev->name, ctx);
> +		if (ret) {
> +			dev_err(&pdev->dev, "Can't get interrupt working.\n");
> +			goto err_pwm_disable;
> +		}
> +		ctx->sample_start = ktime_get();
> +		mod_timer(&ctx->rpm_timer, jiffies + HZ);
> +	}
> +
>  	hwmon = devm_hwmon_device_register_with_groups(&pdev->dev, "pwmfan",
>  						       ctx, pwm_fan_groups);
>  	if (IS_ERR(hwmon)) {
>  		dev_err(&pdev->dev, "Failed to register hwmon device\n");
>  		ret = PTR_ERR(hwmon);
> -		goto err_pwm_disable;
> +		goto err_del_timer;
>  	}
>  
>  	ret = pwm_fan_of_get_cooling_data(&pdev->dev, ctx);
>  	if (ret)
> -		goto err_pwm_disable;
> +		goto err_del_timer;
>  
>  	ctx->pwm_fan_state = ctx->pwm_fan_max_state;
>  	if (IS_ENABLED(CONFIG_THERMAL)) {
> @@ -282,7 +376,7 @@ static int pwm_fan_probe(struct platform_device *pdev)
>  			dev_err(&pdev->dev,
>  				"Failed to register pwm-fan as cooling device");
>  			ret = PTR_ERR(cdev);
> -			goto err_pwm_disable;
> +			goto err_del_timer;
>  		}
>  		ctx->cdev = cdev;
>  		thermal_cdev_update(cdev);
> @@ -290,6 +384,9 @@ static int pwm_fan_probe(struct platform_device *pdev)
>  
>  	return 0;
>  
> +err_del_timer:
> +	del_timer_sync(&ctx->rpm_timer);
> +
>  err_pwm_disable:
>  	state.enabled = false;
>  	pwm_apply_state(ctx->pwm, &state);
> @@ -306,6 +403,8 @@ static int pwm_fan_remove(struct platform_device *pdev)
>  	struct pwm_fan_ctx *ctx = platform_get_drvdata(pdev);
>  
>  	thermal_cooling_device_unregister(ctx->cdev);
> +	del_timer_sync(&ctx->rpm_timer);
> +
>  	if (ctx->pwm_value)
>  		pwm_disable(ctx->pwm);
>  
> -- 
> 2.7.4
> 

Re: [PATCH V5 3/3] hwmon: pwm-fan: Add RPM support via external interrupt

[Stefan Wahren]

On 11.04.19 18:57, Guenter Roeck wrote:
> On Thu, Apr 11, 2019 at 03:30:11PM +0200, Stefan Wahren wrote:
>>  
>> -ATTRIBUTE_GROUPS(pwm_fan);
>> +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);
>> +	struct device_attribute *devattr;
>> +
>> +	/* Hide fan_input in case no interrupt is available  */
>> +	devattr = container_of(a, struct device_attribute, attr);
> Field day for static analyzers - devattr is no longer used.
> No need to resend. I'll let the series rest for a couple of days
> and then apply to hwmon-next (after removing devattr) unless there are
> additional comments.
>
Thank you

Stefan

Re: [PATCH V5 3/3] hwmon: pwm-fan: Add RPM support via external interrupt

[Robin Murphy]

On 12/04/2019 12:07, Stefan Wahren wrote:
> On 11.04.19 18:57, Guenter Roeck wrote:
>> On Thu, Apr 11, 2019 at 03:30:11PM +0200, Stefan Wahren wrote:
>>>   
>>> -ATTRIBUTE_GROUPS(pwm_fan);
>>> +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);
>>> +	struct device_attribute *devattr;
>>> +
>>> +	/* Hide fan_input in case no interrupt is available  */
>>> +	devattr = container_of(a, struct device_attribute, attr);
>> Field day for static analyzers - devattr is no longer used.
>> No need to resend. I'll let the series rest for a couple of days
>> and then apply to hwmon-next (after removing devattr) unless there are
>> additional comments.
>>
> Thank you

FWIW you can have a

Reviewed-by: Robin Murphy <robin.murphy@arm.com>

for the whole series. The only minor comment that springs to mind
isn't actually specific to this patch, so is probably best made as
the follow-up below.

Robin.

----->8-----
From: Robin Murphy <robin.murphy@arm.com>
Subject: [PATCH] hwmon: pwm-fan: Report probe errors consistently

Printing the error code for a failure provides a head-start for
debugging, since it's often sufficient to pinpoint the origin of the
failure. We already do this for some probe-failure messages, so let's
make the rest of them consistent.

Signed-off-by: Robin Murphy <robin.murphy@arm.com>
---
 drivers/hwmon/pwm-fan.c | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/drivers/hwmon/pwm-fan.c b/drivers/hwmon/pwm-fan.c
index 8c4c5eefd4ca..556db4bef743 100644
--- a/drivers/hwmon/pwm-fan.c
+++ b/drivers/hwmon/pwm-fan.c
@@ -330,7 +330,7 @@ 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");
+		dev_err(&pdev->dev, "Failed to configure PWM: %d\n", ret);
 		goto err_reg_disable;
 	}

@@ -348,7 +348,8 @@ static int pwm_fan_probe(struct platform_device *pdev)
 		ret = devm_request_irq(&pdev->dev, ctx->irq, pulse_handler, 0,
 				       pdev->name, ctx);
 		if (ret) {
-			dev_err(&pdev->dev, "Can't get interrupt working.\n");
+			dev_err(&pdev->dev,
+				"Failed to request interrupt: %d\n", ret);
 			goto err_pwm_disable;
 		}
 		ctx->sample_start = ktime_get();
@@ -358,8 +359,9 @@ static int pwm_fan_probe(struct platform_device *pdev)
 	hwmon = devm_hwmon_device_register_with_groups(&pdev->dev, "pwmfan",
 						       ctx, pwm_fan_groups);
 	if (IS_ERR(hwmon)) {
-		dev_err(&pdev->dev, "Failed to register hwmon device\n");
 		ret = PTR_ERR(hwmon);
+		dev_err(&pdev->dev,
+			"Failed to register hwmon device: %d\n", ret);
 		goto err_del_timer;
 	}

@@ -373,9 +375,10 @@ static int pwm_fan_probe(struct platform_device *pdev)
 							  "pwm-fan", ctx,
 							  &pwm_fan_cooling_ops);
 		if (IS_ERR(cdev)) {
-			dev_err(&pdev->dev,
-				"Failed to register pwm-fan as cooling device");
 			ret = PTR_ERR(cdev);
+			dev_err(&pdev->dev,
+				"Failed to register pwm-fan as cooling device: %d\n",
+				ret);
 			goto err_del_timer;
 		}
 		ctx->cdev = cdev;

Re: [PATCH V5 3/3] hwmon: pwm-fan: Add RPM support via external interrupt

[Enrico Weigelt, metux IT consult]

On 11.04.19 15:30, Stefan Wahren wrote:
> This adds RPM support to the pwm-fan driver in order to use with
> fancontrol/pwmconfig. This feature is intended for fans with a tachometer
> output signal, which generate a defined number of pulses per revolution.

Wouldn't it be better to have a CONFIG_* flag for keeping the kernel
image size smaller when this feature isn't needed ?


--mtx

-- 
Enrico Weigelt, metux IT consult
Free software and Linux embedded engineering
info@metux.net -- +49-151-27565287

Re: [PATCH V5 3/3] hwmon: pwm-fan: Add RPM support via external interrupt

[Stefan Wahren]

Hi Enrico,

On 12.04.19 15:15, Enrico Weigelt, metux IT consult wrote:
> On 11.04.19 15:30, Stefan Wahren wrote:
>> This adds RPM support to the pwm-fan driver in order to use with
>> fancontrol/pwmconfig. This feature is intended for fans with a tachometer
>> output signal, which generate a defined number of pulses per revolution.
> Wouldn't it be better to have a CONFIG_* flag for keeping the kernel
> image size smaller when this feature isn't needed ?

i compared the kernel module size in linux-next for ARM without and with
this patch:
without patch: 12088 bytes
with patch: 14292 bytes

I don't think it is worth the trouble.

Stefan

>
>
> --mtx
>

Re: [PATCH V5 3/3] hwmon: pwm-fan: Add RPM support via external interrupt

[Guenter Roeck]

On 4/12/19 6:35 AM, Stefan Wahren wrote:
> Hi Enrico,
> 
> On 12.04.19 15:15, Enrico Weigelt, metux IT consult wrote:
>> On 11.04.19 15:30, Stefan Wahren wrote:
>>> This adds RPM support to the pwm-fan driver in order to use with
>>> fancontrol/pwmconfig. This feature is intended for fans with a tachometer
>>> output signal, which generate a defined number of pulses per revolution.
>> Wouldn't it be better to have a CONFIG_* flag for keeping the kernel
>> image size smaller when this feature isn't needed ?
> 
> i compared the kernel module size in linux-next for ARM without and with
> this patch:
> without patch: 12088 bytes
> with patch: 14292 bytes
> 
> I don't think it is worth the trouble.
> 

Agreed. This would end up being a mess, with lots of configuration options
in various drivers. Please don't start it.

Guenter

Re: [PATCH V5 3/3] hwmon: pwm-fan: Add RPM support via external interrupt

[Guenter Roeck]

On 4/12/19 4:50 AM, Robin Murphy wrote:
> On 12/04/2019 12:07, Stefan Wahren wrote:
>> On 11.04.19 18:57, Guenter Roeck wrote:
>>> On Thu, Apr 11, 2019 at 03:30:11PM +0200, Stefan Wahren wrote:
>>>>    
>>>> -ATTRIBUTE_GROUPS(pwm_fan);
>>>> +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);
>>>> +	struct device_attribute *devattr;
>>>> +
>>>> +	/* Hide fan_input in case no interrupt is available  */
>>>> +	devattr = container_of(a, struct device_attribute, attr);
>>> Field day for static analyzers - devattr is no longer used.
>>> No need to resend. I'll let the series rest for a couple of days
>>> and then apply to hwmon-next (after removing devattr) unless there are
>>> additional comments.
>>>
>> Thank you
> 
> FWIW you can have a
> 
> Reviewed-by: Robin Murphy <robin.murphy@arm.com>
> 
> for the whole series. The only minor comment that springs to mind
> isn't actually specific to this patch, so is probably best made as
> the follow-up below.
> 
> Robin.
> 

Any chance you can send the patch below as separate patch ? I track patches
using patchwork, and attachments don't show up there.

Thanks,
Guenter

> ----->8-----
> From: Robin Murphy <robin.murphy@arm.com>
> Subject: [PATCH] hwmon: pwm-fan: Report probe errors consistently
> 
> Printing the error code for a failure provides a head-start for
> debugging, since it's often sufficient to pinpoint the origin of the
> failure. We already do this for some probe-failure messages, so let's
> make the rest of them consistent.
> 
> Signed-off-by: Robin Murphy <robin.murphy@arm.com>
> ---
>   drivers/hwmon/pwm-fan.c | 13 ++++++++-----
>   1 file changed, 8 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/hwmon/pwm-fan.c b/drivers/hwmon/pwm-fan.c
> index 8c4c5eefd4ca..556db4bef743 100644
> --- a/drivers/hwmon/pwm-fan.c
> +++ b/drivers/hwmon/pwm-fan.c
> @@ -330,7 +330,7 @@ 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");
> +		dev_err(&pdev->dev, "Failed to configure PWM: %d\n", ret);
>   		goto err_reg_disable;
>   	}
> 
> @@ -348,7 +348,8 @@ static int pwm_fan_probe(struct platform_device *pdev)
>   		ret = devm_request_irq(&pdev->dev, ctx->irq, pulse_handler, 0,
>   				       pdev->name, ctx);
>   		if (ret) {
> -			dev_err(&pdev->dev, "Can't get interrupt working.\n");
> +			dev_err(&pdev->dev,
> +				"Failed to request interrupt: %d\n", ret);
>   			goto err_pwm_disable;
>   		}
>   		ctx->sample_start = ktime_get();
> @@ -358,8 +359,9 @@ static int pwm_fan_probe(struct platform_device *pdev)
>   	hwmon = devm_hwmon_device_register_with_groups(&pdev->dev, "pwmfan",
>   						       ctx, pwm_fan_groups);
>   	if (IS_ERR(hwmon)) {
> -		dev_err(&pdev->dev, "Failed to register hwmon device\n");
>   		ret = PTR_ERR(hwmon);
> +		dev_err(&pdev->dev,
> +			"Failed to register hwmon device: %d\n", ret);
>   		goto err_del_timer;
>   	}
> 
> @@ -373,9 +375,10 @@ static int pwm_fan_probe(struct platform_device *pdev)
>   							  "pwm-fan", ctx,
>   							  &pwm_fan_cooling_ops);
>   		if (IS_ERR(cdev)) {
> -			dev_err(&pdev->dev,
> -				"Failed to register pwm-fan as cooling device");
>   			ret = PTR_ERR(cdev);
> +			dev_err(&pdev->dev,
> +				"Failed to register pwm-fan as cooling device: %d\n",
> +				ret);
>   			goto err_del_timer;
>   		}
>   		ctx->cdev = cdev;
> 

Re: [PATCH V5 3/3] hwmon: pwm-fan: Add RPM support via external interrupt

[Robin Murphy]

On 12/04/2019 14:50, Guenter Roeck wrote:
> On 4/12/19 4:50 AM, Robin Murphy wrote:
>> On 12/04/2019 12:07, Stefan Wahren wrote:
>>> On 11.04.19 18:57, Guenter Roeck wrote:
>>>> On Thu, Apr 11, 2019 at 03:30:11PM +0200, Stefan Wahren wrote:
>>>>> -ATTRIBUTE_GROUPS(pwm_fan);
>>>>> +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);
>>>>> +    struct device_attribute *devattr;
>>>>> +
>>>>> +    /* Hide fan_input in case no interrupt is available  */
>>>>> +    devattr = container_of(a, struct device_attribute, attr);
>>>> Field day for static analyzers - devattr is no longer used.
>>>> No need to resend. I'll let the series rest for a couple of days
>>>> and then apply to hwmon-next (after removing devattr) unless there are
>>>> additional comments.
>>>>
>>> Thank you
>>
>> FWIW you can have a
>>
>> Reviewed-by: Robin Murphy <robin.murphy@arm.com>
>>
>> for the whole series. The only minor comment that springs to mind
>> isn't actually specific to this patch, so is probably best made as
>> the follow-up below.
>>
>> Robin.
>>
> 
> Any chance you can send the patch below as separate patch ? I track patches
> using patchwork, and attachments don't show up there.

Sure, can do - would you like an explicit R-b on #1 and #2 here for 
patchwork to pick up as well?

Robin.

> 
> Thanks,
> Guenter
> 
>> ----->8-----
>> From: Robin Murphy <robin.murphy@arm.com>
>> Subject: [PATCH] hwmon: pwm-fan: Report probe errors consistently
>>
>> Printing the error code for a failure provides a head-start for
>> debugging, since it's often sufficient to pinpoint the origin of the
>> failure. We already do this for some probe-failure messages, so let's
>> make the rest of them consistent.
>>
>> Signed-off-by: Robin Murphy <robin.murphy@arm.com>
>> ---
>>   drivers/hwmon/pwm-fan.c | 13 ++++++++-----
>>   1 file changed, 8 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/hwmon/pwm-fan.c b/drivers/hwmon/pwm-fan.c
>> index 8c4c5eefd4ca..556db4bef743 100644
>> --- a/drivers/hwmon/pwm-fan.c
>> +++ b/drivers/hwmon/pwm-fan.c
>> @@ -330,7 +330,7 @@ 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");
>> +        dev_err(&pdev->dev, "Failed to configure PWM: %d\n", ret);
>>           goto err_reg_disable;
>>       }
>>
>> @@ -348,7 +348,8 @@ static int pwm_fan_probe(struct platform_device 
>> *pdev)
>>           ret = devm_request_irq(&pdev->dev, ctx->irq, pulse_handler, 0,
>>                          pdev->name, ctx);
>>           if (ret) {
>> -            dev_err(&pdev->dev, "Can't get interrupt working.\n");
>> +            dev_err(&pdev->dev,
>> +                "Failed to request interrupt: %d\n", ret);
>>               goto err_pwm_disable;
>>           }
>>           ctx->sample_start = ktime_get();
>> @@ -358,8 +359,9 @@ static int pwm_fan_probe(struct platform_device 
>> *pdev)
>>       hwmon = devm_hwmon_device_register_with_groups(&pdev->dev, 
>> "pwmfan",
>>                                  ctx, pwm_fan_groups);
>>       if (IS_ERR(hwmon)) {
>> -        dev_err(&pdev->dev, "Failed to register hwmon device\n");
>>           ret = PTR_ERR(hwmon);
>> +        dev_err(&pdev->dev,
>> +            "Failed to register hwmon device: %d\n", ret);
>>           goto err_del_timer;
>>       }
>>
>> @@ -373,9 +375,10 @@ static int pwm_fan_probe(struct platform_device 
>> *pdev)
>>                                 "pwm-fan", ctx,
>>                                 &pwm_fan_cooling_ops);
>>           if (IS_ERR(cdev)) {
>> -            dev_err(&pdev->dev,
>> -                "Failed to register pwm-fan as cooling device");
>>               ret = PTR_ERR(cdev);
>> +            dev_err(&pdev->dev,
>> +                "Failed to register pwm-fan as cooling device: %d\n",
>> +                ret);
>>               goto err_del_timer;
>>           }
>>           ctx->cdev = cdev;
>>
> 

Re: [PATCH V5 3/3] hwmon: pwm-fan: Add RPM support via external interrupt

[Guenter Roeck]

On 4/12/19 6:54 AM, Robin Murphy wrote:
> On 12/04/2019 14:50, Guenter Roeck wrote:
>> On 4/12/19 4:50 AM, Robin Murphy wrote:
>>> On 12/04/2019 12:07, Stefan Wahren wrote:
>>>> On 11.04.19 18:57, Guenter Roeck wrote:
>>>>> On Thu, Apr 11, 2019 at 03:30:11PM +0200, Stefan Wahren wrote:
>>>>>> -ATTRIBUTE_GROUPS(pwm_fan);
>>>>>> +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);
>>>>>> +    struct device_attribute *devattr;
>>>>>> +
>>>>>> +    /* Hide fan_input in case no interrupt is available  */
>>>>>> +    devattr = container_of(a, struct device_attribute, attr);
>>>>> Field day for static analyzers - devattr is no longer used.
>>>>> No need to resend. I'll let the series rest for a couple of days
>>>>> and then apply to hwmon-next (after removing devattr) unless there are
>>>>> additional comments.
>>>>>
>>>> Thank you
>>>
>>> FWIW you can have a
>>>
>>> Reviewed-by: Robin Murphy <robin.murphy@arm.com>
>>>
>>> for the whole series. The only minor comment that springs to mind
>>> isn't actually specific to this patch, so is probably best made as
>>> the follow-up below.
>>>
>>> Robin.
>>>
>>
>> Any chance you can send the patch below as separate patch ? I track patches
>> using patchwork, and attachments don't show up there.
> 
> Sure, can do - would you like an explicit R-b on #1 and #2 here for patchwork to pick up as well?
> That would simplify my life a bit, but I can add that part myself to the patches.
I primarily like to have the patches in patchwork to make sure they don't get lost
and that I can pick them up again later if needed.

Thanks,
Guenter

> Robin.
> 
>>
>> Thanks,
>> Guenter
>>
>>> ----->8-----
>>> From: Robin Murphy <robin.murphy@arm.com>
>>> Subject: [PATCH] hwmon: pwm-fan: Report probe errors consistently
>>>
>>> Printing the error code for a failure provides a head-start for
>>> debugging, since it's often sufficient to pinpoint the origin of the
>>> failure. We already do this for some probe-failure messages, so let's
>>> make the rest of them consistent.
>>>
>>> Signed-off-by: Robin Murphy <robin.murphy@arm.com>
>>> ---
>>>   drivers/hwmon/pwm-fan.c | 13 ++++++++-----
>>>   1 file changed, 8 insertions(+), 5 deletions(-)
>>>
>>> diff --git a/drivers/hwmon/pwm-fan.c b/drivers/hwmon/pwm-fan.c
>>> index 8c4c5eefd4ca..556db4bef743 100644
>>> --- a/drivers/hwmon/pwm-fan.c
>>> +++ b/drivers/hwmon/pwm-fan.c
>>> @@ -330,7 +330,7 @@ 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");
>>> +        dev_err(&pdev->dev, "Failed to configure PWM: %d\n", ret);
>>>           goto err_reg_disable;
>>>       }
>>>
>>> @@ -348,7 +348,8 @@ static int pwm_fan_probe(struct platform_device *pdev)
>>>           ret = devm_request_irq(&pdev->dev, ctx->irq, pulse_handler, 0,
>>>                          pdev->name, ctx);
>>>           if (ret) {
>>> -            dev_err(&pdev->dev, "Can't get interrupt working.\n");
>>> +            dev_err(&pdev->dev,
>>> +                "Failed to request interrupt: %d\n", ret);
>>>               goto err_pwm_disable;
>>>           }
>>>           ctx->sample_start = ktime_get();
>>> @@ -358,8 +359,9 @@ static int pwm_fan_probe(struct platform_device *pdev)
>>>       hwmon = devm_hwmon_device_register_with_groups(&pdev->dev, "pwmfan",
>>>                                  ctx, pwm_fan_groups);
>>>       if (IS_ERR(hwmon)) {
>>> -        dev_err(&pdev->dev, "Failed to register hwmon device\n");
>>>           ret = PTR_ERR(hwmon);
>>> +        dev_err(&pdev->dev,
>>> +            "Failed to register hwmon device: %d\n", ret);
>>>           goto err_del_timer;
>>>       }
>>>
>>> @@ -373,9 +375,10 @@ static int pwm_fan_probe(struct platform_device *pdev)
>>>                                 "pwm-fan", ctx,
>>>                                 &pwm_fan_cooling_ops);
>>>           if (IS_ERR(cdev)) {
>>> -            dev_err(&pdev->dev,
>>> -                "Failed to register pwm-fan as cooling device");
>>>               ret = PTR_ERR(cdev);
>>> +            dev_err(&pdev->dev,
>>> +                "Failed to register pwm-fan as cooling device: %d\n",
>>> +                ret);
>>>               goto err_del_timer;
>>>           }
>>>           ctx->cdev = cdev;
>>>
>>
> 

Re: [PATCH V5 0/3] hwmon: pwm-fan: Add RPM support

[Guenter Roeck]

On 4/11/19 6:30 AM, Stefan Wahren wrote:
> Contrary to the gpio-fan the pwm-fan driver isn't easy to setup
> with pwmconfig/fancontrol because of the missing hwmon sysfs entry
> for actual revolutions per minute. This series adds this feature.
> 

Series applied to hwmon-next.

Thanks,
Guenter

> Changes in V5:
> - address Guenter's and Robin's comments:
>    - use of_property_read_u32 to get pulses-per-revolution
>    - call platform_get_irq ealier to avoid glitches on the regulator
>    - simplify pwm_fan_attrs_visible
> 
> Changes in V4:
> - remove copy & paste artifact in dt-binding example
> - switch to u64 for rpm calculation
> - drop overflow handling and init atomic
> - handle 0 not as valid irq
> - reduce range of pulses_per_revolution
> - handle probe defer of platform_get_irq
> - delete timer properly in bail-out path
> 
> Changes in V3:
> - rename property interrupt-ratio to pulses-per-revolution
>    to avoid confusion with interrupt binding
> - handle error case pulses-per-revolution = 0
> - bail out properly in case we are unable to request the irq
> 
> Changes in V2:
> - address Guenter's comments:
>    - improve description of interrupts
>    - use atomic_t to avoid races of the pulse counter
>    - measure sample time to make rpm more reliable under load
>    - make sysfs entry fan1_input conditional
> - add dt-property to define interrupts per fan revolution
> - example for fan with RPM support
> 
> Stefan Wahren (3):
>    dt-bindings: hwmon: Add tachometer interrupt to pwm-fan
>    Documentation: pwm-fan: Add description for RPM support
>    hwmon: pwm-fan: Add RPM support via external interrupt
> 
>   .../devicetree/bindings/hwmon/pwm-fan.txt          |  21 +++-
>   Documentation/hwmon/pwm-fan                        |   3 +
>   drivers/hwmon/pwm-fan.c                            | 107 ++++++++++++++++++++-
>   3 files changed, 126 insertions(+), 5 deletions(-)
>