mirror of
https://github.com/torvalds/linux.git
synced 2024-12-05 10:32:35 +00:00
48b9d5b4f4
The state of a PWM output is not clearly defined after resume. Some PWM drivers do not restore the duty cycle upon resume, thus it is necessary to manually restore the correct value. Signed-off-by: Kamil Debski <k.debski@samsung.com> Signed-off-by: Guenter Roeck <linux@roeck-us.net>
201 lines
4.5 KiB
C
201 lines
4.5 KiB
C
/*
|
|
* 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>
|
|
*
|
|
* This program is free software; you can redistribute it and/or modify
|
|
* it under the terms of the GNU General Public License as published by
|
|
* the Free Software Foundation; either version 2 of the License, or
|
|
* (at your option) any later version.
|
|
*
|
|
* This program is distributed in the hope that it will be useful,
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
* GNU General Public License for more details.
|
|
*/
|
|
|
|
#include <linux/hwmon.h>
|
|
#include <linux/hwmon-sysfs.h>
|
|
#include <linux/module.h>
|
|
#include <linux/mutex.h>
|
|
#include <linux/of.h>
|
|
#include <linux/platform_device.h>
|
|
#include <linux/pwm.h>
|
|
#include <linux/sysfs.h>
|
|
|
|
#define MAX_PWM 255
|
|
|
|
struct pwm_fan_ctx {
|
|
struct mutex lock;
|
|
struct pwm_device *pwm;
|
|
unsigned char pwm_value;
|
|
};
|
|
|
|
static ssize_t set_pwm(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, duty;
|
|
ssize_t ret;
|
|
|
|
if (kstrtoul(buf, 10, &pwm) || pwm > MAX_PWM)
|
|
return -EINVAL;
|
|
|
|
mutex_lock(&ctx->lock);
|
|
|
|
if (ctx->pwm_value == pwm)
|
|
goto exit_set_pwm_no_change;
|
|
|
|
if (pwm == 0) {
|
|
pwm_disable(ctx->pwm);
|
|
goto exit_set_pwm;
|
|
}
|
|
|
|
duty = DIV_ROUND_UP(pwm * (ctx->pwm->period - 1), MAX_PWM);
|
|
ret = pwm_config(ctx->pwm, duty, ctx->pwm->period);
|
|
if (ret)
|
|
goto exit_set_pwm_err;
|
|
|
|
if (ctx->pwm_value == 0) {
|
|
ret = pwm_enable(ctx->pwm);
|
|
if (ret)
|
|
goto exit_set_pwm_err;
|
|
}
|
|
|
|
exit_set_pwm:
|
|
ctx->pwm_value = pwm;
|
|
exit_set_pwm_no_change:
|
|
ret = count;
|
|
exit_set_pwm_err:
|
|
mutex_unlock(&ctx->lock);
|
|
return ret;
|
|
}
|
|
|
|
static ssize_t show_pwm(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 SENSOR_DEVICE_ATTR(pwm1, S_IRUGO | S_IWUSR, show_pwm, set_pwm, 0);
|
|
|
|
static struct attribute *pwm_fan_attrs[] = {
|
|
&sensor_dev_attr_pwm1.dev_attr.attr,
|
|
NULL,
|
|
};
|
|
|
|
ATTRIBUTE_GROUPS(pwm_fan);
|
|
|
|
static int pwm_fan_probe(struct platform_device *pdev)
|
|
{
|
|
struct device *hwmon;
|
|
struct pwm_fan_ctx *ctx;
|
|
int duty_cycle;
|
|
int ret;
|
|
|
|
ctx = devm_kzalloc(&pdev->dev, sizeof(*ctx), GFP_KERNEL);
|
|
if (!ctx)
|
|
return -ENOMEM;
|
|
|
|
mutex_init(&ctx->lock);
|
|
|
|
ctx->pwm = devm_of_pwm_get(&pdev->dev, pdev->dev.of_node, NULL);
|
|
if (IS_ERR(ctx->pwm)) {
|
|
dev_err(&pdev->dev, "Could not get PWM\n");
|
|
return PTR_ERR(ctx->pwm);
|
|
}
|
|
|
|
platform_set_drvdata(pdev, ctx);
|
|
|
|
/* Set duty cycle to maximum allowed */
|
|
duty_cycle = ctx->pwm->period - 1;
|
|
ctx->pwm_value = MAX_PWM;
|
|
|
|
ret = pwm_config(ctx->pwm, duty_cycle, ctx->pwm->period);
|
|
if (ret) {
|
|
dev_err(&pdev->dev, "Failed to configure PWM\n");
|
|
return ret;
|
|
}
|
|
|
|
/* Enbale PWM output */
|
|
ret = pwm_enable(ctx->pwm);
|
|
if (ret) {
|
|
dev_err(&pdev->dev, "Failed to enable PWM\n");
|
|
return ret;
|
|
}
|
|
|
|
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");
|
|
pwm_disable(ctx->pwm);
|
|
return PTR_ERR(hwmon);
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
static int pwm_fan_remove(struct platform_device *pdev)
|
|
{
|
|
struct pwm_fan_ctx *ctx = platform_get_drvdata(pdev);
|
|
|
|
if (ctx->pwm_value)
|
|
pwm_disable(ctx->pwm);
|
|
return 0;
|
|
}
|
|
|
|
#ifdef CONFIG_PM_SLEEP
|
|
static int pwm_fan_suspend(struct device *dev)
|
|
{
|
|
struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
|
|
|
|
if (ctx->pwm_value)
|
|
pwm_disable(ctx->pwm);
|
|
return 0;
|
|
}
|
|
|
|
static int pwm_fan_resume(struct device *dev)
|
|
{
|
|
struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
|
|
unsigned long duty;
|
|
int ret;
|
|
|
|
if (ctx->pwm_value == 0)
|
|
return 0;
|
|
|
|
duty = DIV_ROUND_UP(ctx->pwm_value * (ctx->pwm->period - 1), MAX_PWM);
|
|
ret = pwm_config(ctx->pwm, duty, ctx->pwm->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 struct of_device_id of_pwm_fan_match[] = {
|
|
{ .compatible = "pwm-fan", },
|
|
{},
|
|
};
|
|
|
|
static struct platform_driver pwm_fan_driver = {
|
|
.probe = pwm_fan_probe,
|
|
.remove = pwm_fan_remove,
|
|
.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");
|