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/*
* 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");
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