https://github.com/torvalds/linux
Tip revision: f74c2bb98776e2de508f4d607cd519873065118e authored by Linus Torvalds on 08 September 2019, 20:33:15 UTC
Linux 5.3-rc8
Linux 5.3-rc8
Tip revision: f74c2bb
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/hwmon-sysfs.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_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;
unsigned int *pwm_fan_cooling_levels;
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;
int ret = 0;
struct pwm_state state = { };
mutex_lock(&ctx->lock);
if (ctx->pwm_value == pwm)
goto exit_set_pwm_err;
pwm_init_state(ctx->pwm, &state);
period = ctx->pwm->args.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 ssize_t pwm_store(struct device *dev, struct device_attribute *attr,
const char *buf, size_t count)
{
struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
unsigned long pwm;
int ret;
if (kstrtoul(buf, 10, &pwm) || pwm > MAX_PWM)
return -EINVAL;
ret = __set_pwm(ctx, pwm);
if (ret)
return ret;
pwm_fan_update_state(ctx, pwm);
return count;
}
static ssize_t pwm_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->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,
};
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,
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;
pwm_disable(ctx->pwm);
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;
struct pwm_state state = { };
u32 ppr = 2;
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)) {
ret = PTR_ERR(ctx->pwm);
if (ret != -EPROBE_DEFER)
dev_err(dev, "Could not get PWM: %d\n", ret);
return ret;
}
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(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;
}
ctx->pwm_value = MAX_PWM;
/* Set duty cycle to maximum allowed and enable PWM output */
pwm_init_state(ctx->pwm, &state);
state.duty_cycle = ctx->pwm->args.period - 1;
state.enabled = true;
ret = pwm_apply_state(ctx->pwm, &state);
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;
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;
}
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;
}
ctx->sample_start = ktime_get();
mod_timer(&ctx->rpm_timer, jiffies + HZ);
}
hwmon = devm_hwmon_device_register_with_groups(dev, "pwmfan",
ctx, pwm_fan_groups);
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;
thermal_cdev_update(cdev);
}
return 0;
}
#ifdef CONFIG_PM_SLEEP
static int pwm_fan_suspend(struct device *dev)
{
struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
struct pwm_args args;
int ret;
pwm_get_args(ctx->pwm, &args);
if (ctx->pwm_value) {
ret = pwm_config(ctx->pwm, 0, args.period);
if (ret < 0)
return ret;
pwm_disable(ctx->pwm);
}
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 int pwm_fan_resume(struct device *dev)
{
struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
struct pwm_args pargs;
unsigned long duty;
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;
pwm_get_args(ctx->pwm, &pargs);
duty = DIV_ROUND_UP(ctx->pwm_value * (pargs.period - 1), MAX_PWM);
ret = pwm_config(ctx->pwm, duty, pargs.period);
if (ret)
return ret;
return pwm_enable(ctx->pwm);
}
#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,
.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");