pwm-fan.c
// SPDX-License-Identifier: GPL-2.0-or-later
/*
* pwm-fan.c - Hwmon driver for fans connected to PWM lines.
*
* Copyright (c) 2014 Samsung Electronics Co., Ltd.
*
* Author: Kamil Debski <k.debski@samsung.com>
*/
#include <linux/hwmon.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/mutex.h>
#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>
#include <linux/timer.h>
#define MAX_PWM 255
struct pwm_fan_tach {
int irq;
atomic_t pulses;
unsigned int rpm;
u8 pulses_per_revolution;
};
struct pwm_fan_ctx {
struct mutex lock;
struct pwm_device *pwm;
struct pwm_state pwm_state;
struct regulator *reg_en;
int tach_count;
struct pwm_fan_tach *tachs;
ktime_t sample_start;
struct timer_list rpm_timer;
unsigned int pwm_value;
unsigned int pwm_fan_state;
unsigned int pwm_fan_max_state;
unsigned int *pwm_fan_cooling_levels;
struct thermal_cooling_device *cdev;
struct hwmon_chip_info info;
struct hwmon_channel_info fan_channel;
};
/* This handler assumes self resetting edge triggered interrupt. */
static irqreturn_t pulse_handler(int irq, void *dev_id)
{
struct pwm_fan_tach *tach = dev_id;
atomic_inc(&tach->pulses);
return IRQ_HANDLED;
}
static void sample_timer(struct timer_list *t)
{
struct pwm_fan_ctx *ctx = from_timer(ctx, t, rpm_timer);
unsigned int delta = ktime_ms_delta(ktime_get(), ctx->sample_start);
int i;
if (delta) {
for (i = 0; i < ctx->tach_count; i++) {
struct pwm_fan_tach *tach = &ctx->tachs[i];
int pulses;
pulses = atomic_read(&tach->pulses);
atomic_sub(pulses, &tach->pulses);
tach->rpm = (unsigned int)(pulses * 1000 * 60) /
(tach->pulses_per_revolution * delta);
}
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;
int ret = 0;
struct pwm_state *state = &ctx->pwm_state;
mutex_lock(&ctx->lock);
if (ctx->pwm_value == pwm)
goto exit_set_pwm_err;
period = state->period;
state->duty_cycle = DIV_ROUND_UP(pwm * (period - 1), MAX_PWM);
state->enabled = pwm ? true : false;
ret = pwm_apply_state(ctx->pwm, state);
if (!ret)
ctx->pwm_value = pwm;
exit_set_pwm_err:
mutex_unlock(&ctx->lock);
return ret;
}
static void pwm_fan_update_state(struct pwm_fan_ctx *ctx, unsigned long pwm)
{
int i;
for (i = 0; i < ctx->pwm_fan_max_state; ++i)
if (pwm < ctx->pwm_fan_cooling_levels[i + 1])
break;
ctx->pwm_fan_state = i;
}
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);
int ret;
if (val < 0 || val > MAX_PWM)
return -EINVAL;
ret = __set_pwm(ctx, val);
if (ret)
return ret;
pwm_fan_update_state(ctx, val);
return 0;
}
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);
switch (type) {
case hwmon_pwm:
*val = ctx->pwm_value;
return 0;
case hwmon_fan:
*val = ctx->tachs[channel].rpm;
return 0;
default:
return -ENOTSUPP;
}
}
static umode_t pwm_fan_is_visible(const void *data,
enum hwmon_sensor_types type,
u32 attr, int channel)
{
switch (type) {
case hwmon_pwm:
return 0644;
case hwmon_fan:
return 0444;
default:
return 0;
}
}
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 */
static int pwm_fan_get_max_state(struct thermal_cooling_device *cdev,
unsigned long *state)
{
struct pwm_fan_ctx *ctx = cdev->devdata;
if (!ctx)
return -EINVAL;
*state = ctx->pwm_fan_max_state;
return 0;
}
static int pwm_fan_get_cur_state(struct thermal_cooling_device *cdev,
unsigned long *state)
{
struct pwm_fan_ctx *ctx = cdev->devdata;
if (!ctx)
return -EINVAL;
*state = ctx->pwm_fan_state;
return 0;
}
static int
pwm_fan_set_cur_state(struct thermal_cooling_device *cdev, unsigned long state)
{
struct pwm_fan_ctx *ctx = cdev->devdata;
int ret;
if (!ctx || (state > ctx->pwm_fan_max_state))
return -EINVAL;
if (state == ctx->pwm_fan_state)
return 0;
ret = __set_pwm(ctx, ctx->pwm_fan_cooling_levels[state]);
if (ret) {
dev_err(&cdev->device, "Cannot set pwm!\n");
return ret;
}
ctx->pwm_fan_state = state;
return ret;
}
static const struct thermal_cooling_device_ops pwm_fan_cooling_ops = {
.get_max_state = pwm_fan_get_max_state,
.get_cur_state = pwm_fan_get_cur_state,
.set_cur_state = pwm_fan_set_cur_state,
};
static int pwm_fan_of_get_cooling_data(struct device *dev,
struct pwm_fan_ctx *ctx)
{
struct device_node *np = dev->of_node;
int num, i, ret;
if (!of_find_property(np, "cooling-levels", NULL))
return 0;
ret = of_property_count_u32_elems(np, "cooling-levels");
if (ret <= 0) {
dev_err(dev, "Wrong data!\n");
return ret ? : -EINVAL;
}
num = ret;
ctx->pwm_fan_cooling_levels = devm_kcalloc(dev, num, sizeof(u32),
GFP_KERNEL);
if (!ctx->pwm_fan_cooling_levels)
return -ENOMEM;
ret = of_property_read_u32_array(np, "cooling-levels",
ctx->pwm_fan_cooling_levels, num);
if (ret) {
dev_err(dev, "Property 'cooling-levels' cannot be read!\n");
return ret;
}
for (i = 0; i < num; i++) {
if (ctx->pwm_fan_cooling_levels[i] > MAX_PWM) {
dev_err(dev, "PWM fan state[%d]:%d > %d\n", i,
ctx->pwm_fan_cooling_levels[i], MAX_PWM);
return -EINVAL;
}
}
ctx->pwm_fan_max_state = num - 1;
return 0;
}
static void pwm_fan_regulator_disable(void *data)
{
regulator_disable(data);
}
static void pwm_fan_pwm_disable(void *__ctx)
{
struct pwm_fan_ctx *ctx = __ctx;
ctx->pwm_state.enabled = false;
pwm_apply_state(ctx->pwm, &ctx->pwm_state);
del_timer_sync(&ctx->rpm_timer);
}
static int pwm_fan_probe(struct platform_device *pdev)
{
struct thermal_cooling_device *cdev;
struct device *dev = &pdev->dev;
struct pwm_fan_ctx *ctx;
struct device *hwmon;
int ret;
const struct hwmon_channel_info **channels;
u32 *fan_channel_config;
int channel_count = 1; /* We always have a PWM channel. */
int i;
ctx = devm_kzalloc(dev, sizeof(*ctx), GFP_KERNEL);
if (!ctx)
return -ENOMEM;
mutex_init(&ctx->lock);
ctx->pwm = devm_of_pwm_get(dev, dev->of_node, NULL);
if (IS_ERR(ctx->pwm))
return dev_err_probe(dev, PTR_ERR(ctx->pwm), "Could not get PWM\n");
platform_set_drvdata(pdev, ctx);
ctx->reg_en = devm_regulator_get_optional(dev, "fan");
if (IS_ERR(ctx->reg_en)) {
if (PTR_ERR(ctx->reg_en) != -ENODEV)
return PTR_ERR(ctx->reg_en);
ctx->reg_en = NULL;
} else {
ret = regulator_enable(ctx->reg_en);
if (ret) {
dev_err(dev, "Failed to enable fan supply: %d\n", ret);
return ret;
}
ret = devm_add_action_or_reset(dev, pwm_fan_regulator_disable,
ctx->reg_en);
if (ret)
return ret;
}
pwm_init_state(ctx->pwm, &ctx->pwm_state);
/*
* __set_pwm assumes that MAX_PWM * (period - 1) fits into an unsigned
* long. Check this here to prevent the fan running at a too low
* frequency.
*/
if (ctx->pwm_state.period > ULONG_MAX / MAX_PWM + 1) {
dev_err(dev, "Configured period too big\n");
return -EINVAL;
}
/* Set duty cycle to maximum allowed and enable PWM output */
ret = __set_pwm(ctx, MAX_PWM);
if (ret) {
dev_err(dev, "Failed to configure PWM: %d\n", ret);
return ret;
}
timer_setup(&ctx->rpm_timer, sample_timer, 0);
ret = devm_add_action_or_reset(dev, pwm_fan_pwm_disable, ctx);
if (ret)
return ret;
ctx->tach_count = platform_irq_count(pdev);
if (ctx->tach_count < 0)
return dev_err_probe(dev, ctx->tach_count,
"Could not get number of fan tachometer inputs\n");
dev_dbg(dev, "%d fan tachometer inputs\n", ctx->tach_count);
if (ctx->tach_count) {
channel_count++; /* We also have a FAN channel. */
ctx->tachs = devm_kcalloc(dev, ctx->tach_count,
sizeof(struct pwm_fan_tach),
GFP_KERNEL);
if (!ctx->tachs)
return -ENOMEM;
ctx->fan_channel.type = hwmon_fan;
fan_channel_config = devm_kcalloc(dev, ctx->tach_count + 1,
sizeof(u32), GFP_KERNEL);
if (!fan_channel_config)
return -ENOMEM;
ctx->fan_channel.config = fan_channel_config;
}
channels = devm_kcalloc(dev, channel_count + 1,
sizeof(struct hwmon_channel_info *), GFP_KERNEL);
if (!channels)
return -ENOMEM;
channels[0] = HWMON_CHANNEL_INFO(pwm, HWMON_PWM_INPUT);
for (i = 0; i < ctx->tach_count; i++) {
struct pwm_fan_tach *tach = &ctx->tachs[i];
u32 ppr = 2;
tach->irq = platform_get_irq(pdev, i);
if (tach->irq == -EPROBE_DEFER)
return tach->irq;
if (tach->irq > 0) {
ret = devm_request_irq(dev, tach->irq, pulse_handler, 0,
pdev->name, tach);
if (ret) {
dev_err(dev,
"Failed to request interrupt: %d\n",
ret);
return ret;
}
}
of_property_read_u32_index(dev->of_node,
"pulses-per-revolution",
i,
&ppr);
tach->pulses_per_revolution = ppr;
if (!tach->pulses_per_revolution) {
dev_err(dev, "pulses-per-revolution can't be zero.\n");
return -EINVAL;
}
fan_channel_config[i] = HWMON_F_INPUT;
dev_dbg(dev, "tach%d: irq=%d, pulses_per_revolution=%d\n",
i, tach->irq, tach->pulses_per_revolution);
}
if (ctx->tach_count > 0) {
ctx->sample_start = ktime_get();
mod_timer(&ctx->rpm_timer, jiffies + HZ);
channels[1] = &ctx->fan_channel;
}
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);
}
ret = pwm_fan_of_get_cooling_data(dev, ctx);
if (ret)
return ret;
ctx->pwm_fan_state = ctx->pwm_fan_max_state;
if (IS_ENABLED(CONFIG_THERMAL)) {
cdev = devm_thermal_of_cooling_device_register(dev,
dev->of_node, "pwm-fan", ctx, &pwm_fan_cooling_ops);
if (IS_ERR(cdev)) {
ret = PTR_ERR(cdev);
dev_err(dev,
"Failed to register pwm-fan as cooling device: %d\n",
ret);
return ret;
}
ctx->cdev = cdev;
}
return 0;
}
static int pwm_fan_disable(struct device *dev)
{
struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
int ret;
if (ctx->pwm_value) {
/* keep ctx->pwm_state unmodified for pwm_fan_resume() */
struct pwm_state state = ctx->pwm_state;
state.duty_cycle = 0;
state.enabled = false;
ret = pwm_apply_state(ctx->pwm, &state);
if (ret < 0)
return ret;
}
if (ctx->reg_en) {
ret = regulator_disable(ctx->reg_en);
if (ret) {
dev_err(dev, "Failed to disable fan supply: %d\n", ret);
return ret;
}
}
return 0;
}
static void pwm_fan_shutdown(struct platform_device *pdev)
{
pwm_fan_disable(&pdev->dev);
}
#ifdef CONFIG_PM_SLEEP
static int pwm_fan_suspend(struct device *dev)
{
return pwm_fan_disable(dev);
}
static int pwm_fan_resume(struct device *dev)
{
struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
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);
return ret;
}
}
if (ctx->pwm_value == 0)
return 0;
return pwm_apply_state(ctx->pwm, &ctx->pwm_state);
}
#endif
static SIMPLE_DEV_PM_OPS(pwm_fan_pm, pwm_fan_suspend, pwm_fan_resume);
static const struct of_device_id of_pwm_fan_match[] = {
{ .compatible = "pwm-fan", },
{},
};
MODULE_DEVICE_TABLE(of, of_pwm_fan_match);
static struct platform_driver pwm_fan_driver = {
.probe = pwm_fan_probe,
.shutdown = pwm_fan_shutdown,
.driver = {
.name = "pwm-fan",
.pm = &pwm_fan_pm,
.of_match_table = of_pwm_fan_match,
},
};
module_platform_driver(pwm_fan_driver);
MODULE_AUTHOR("Kamil Debski <k.debski@samsung.com>");
MODULE_ALIAS("platform:pwm-fan");
MODULE_DESCRIPTION("PWM FAN driver");
MODULE_LICENSE("GPL");