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Commit 6b1ec478 authored by Stefan Wahren's avatar Stefan Wahren Committed by Guenter Roeck
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hwmon: (pwm-fan) Add RPM support via external interrupt 



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: default avatarStefan Wahren <stefan.wahren@i2se.com>
Reviewed-by: default avatarRobin Murphy <robin.murphy@arm.com>
Signed-off-by: default avatarRobin Murphy <robin.murphy@arm.com>
[groeck: Drop unused 'devattr' variable]
Signed-off-by: default avatarGuenter Roeck <linux@roeck-us.net>
parent 285d7483

drivers/hwmon/pwm-fan.c

+101 −4
Original line number Diff line number Diff line
@@ -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 +136,45 @@ 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);



	/* Hide fan_input in case no interrupt is available  */

	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 +280,7 @@ 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 +300,10 @@ 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 +332,38 @@ 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 +374,7 @@ 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 +382,9 @@ 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 +401,8 @@ 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);