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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: Stefan Wahren <stefan.wahren@i2se.com>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
[groeck: Drop unused 'devattr' variable]
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
This commit is contained in:
Stefan Wahren 2019-04-11 15:30:11 +02:00 committed by Guenter Roeck
parent 285d7483aa
commit 6b1ec4789f
1 changed files with 101 additions and 4 deletions
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105
drivers/hwmon/pwm-fan.c
View File

@ -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);