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/*
* Generic pwmlib implementation
*
* Copyright (C) 2011 Sascha Hauer <s.hauer@pengutronix.de>
*
* 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, 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.
*
* You should have received a copy of the GNU General Public License
* along with this program; see the file COPYING. If not, write to
* the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include <linux/module.h>
#include <linux/pwm.h>
#include <linux/list.h>
#include <linux/mutex.h>
#include <linux/err.h>
#include <linux/slab.h>
#include <linux/device.h>
struct pwm_device {
struct pwm_chip *chip;
const char *label;
unsigned long flags;
#define FLAG_REQUESTED 0
#define FLAG_ENABLED 1
struct list_head node;
};
static LIST_HEAD(pwm_list);
static DEFINE_MUTEX(pwm_lock);
static struct pwm_device *_find_pwm(int pwm_id)
{
struct pwm_device *pwm;
list_for_each_entry(pwm, &pwm_list, node) {
if (pwm->chip->pwm_id == pwm_id)
return pwm;
}
return NULL;
}
/**
* pwmchip_add() - register a new PWM chip
* @chip: the PWM chip to add
*/
int pwmchip_add(struct pwm_chip *chip)
{
struct pwm_device *pwm;
int ret = 0;
pwm = kzalloc(sizeof(*pwm), GFP_KERNEL);
if (!pwm)
return -ENOMEM;
pwm->chip = chip;
mutex_lock(&pwm_lock);
if (chip->pwm_id >= 0 && _find_pwm(chip->pwm_id)) {
ret = -EBUSY;
goto out;
}
list_add_tail(&pwm->node, &pwm_list);
out:
mutex_unlock(&pwm_lock);
if (ret)
kfree(pwm);
return ret;
}
EXPORT_SYMBOL_GPL(pwmchip_add);
/**
* pwmchip_remove() - remove a PWM chip
* @chip: the PWM chip to remove
*
* Removes a PWM chip. This function may return busy if the PWM chip provides
* a PWM device that is still requested.
*/
int pwmchip_remove(struct pwm_chip *chip)
{
struct pwm_device *pwm;
int ret = 0;
mutex_lock(&pwm_lock);
pwm = _find_pwm(chip->pwm_id);
if (!pwm) {
ret = -ENOENT;
goto out;
}
if (test_bit(FLAG_REQUESTED, &pwm->flags)) {
ret = -EBUSY;
goto out;
}
list_del(&pwm->node);
kfree(pwm);
out:
mutex_unlock(&pwm_lock);
return ret;
}
EXPORT_SYMBOL_GPL(pwmchip_remove);
/**
* pwm_request() - request a PWM device
* @pwm_id: global PWM device index
* @label: PWM device label
*/
struct pwm_device *pwm_request(int pwm_id, const char *label)
{
struct pwm_device *pwm;
int ret;
mutex_lock(&pwm_lock);
pwm = _find_pwm(pwm_id);
if (!pwm) {
pwm = ERR_PTR(-ENOENT);
goto out;
}
if (test_bit(FLAG_REQUESTED, &pwm->flags)) {
pwm = ERR_PTR(-EBUSY);
goto out;
}
if (!try_module_get(pwm->chip->ops->owner)) {
pwm = ERR_PTR(-ENODEV);
goto out;
}
if (pwm->chip->ops->request) {
ret = pwm->chip->ops->request(pwm->chip);
if (ret) {
pwm = ERR_PTR(ret);
goto out_put;
}
}
pwm->label = label;
set_bit(FLAG_REQUESTED, &pwm->flags);
goto out;
out_put:
module_put(pwm->chip->ops->owner);
out:
mutex_unlock(&pwm_lock);
return pwm;
}
EXPORT_SYMBOL_GPL(pwm_request);
/**
* pwm_free() - free a PWM device
* @pwm: PWM device
*/
void pwm_free(struct pwm_device *pwm)
{
mutex_lock(&pwm_lock);
if (!test_and_clear_bit(FLAG_REQUESTED, &pwm->flags)) {
pr_warning("PWM device already freed\n");
goto out;
}
pwm->label = NULL;
module_put(pwm->chip->ops->owner);
out:
mutex_unlock(&pwm_lock);
}
EXPORT_SYMBOL_GPL(pwm_free);
/**
* pwm_config() - change a PWM device configuration
* @pwm: PWM device
* @duty_ns: "on" time (in nanoseconds)
* @period_ns: duration (in nanoseconds) of one cycle
*/
int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns)
{
return pwm->chip->ops->config(pwm->chip, duty_ns, period_ns);
}
EXPORT_SYMBOL_GPL(pwm_config);
/**
* pwm_enable() - start a PWM output toggling
* @pwm: PWM device
*/
int pwm_enable(struct pwm_device *pwm)
{
if (!test_and_set_bit(FLAG_ENABLED, &pwm->flags))
return pwm->chip->ops->enable(pwm->chip);
return 0;
}
EXPORT_SYMBOL_GPL(pwm_enable);
/**
* pwm_disable() - stop a PWM output toggling
* @pwm: PWM device
*/
void pwm_disable(struct pwm_device *pwm)
{
if (test_and_clear_bit(FLAG_ENABLED, &pwm->flags))
pwm->chip->ops->disable(pwm->chip);
}
EXPORT_SYMBOL_GPL(pwm_disable);
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