164 lines
3.4 KiB
C
164 lines
3.4 KiB
C
/*
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* Generic pwmlib implementation
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*
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* Copyright (C) 2011 Sascha Hauer <s.hauer@pengutronix.de>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2, or (at your option)
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* any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; see the file COPYING. If not, write to
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* the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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#include <common.h>
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#include <errno.h>
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#include <malloc.h>
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#include <pwm.h>
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#include <linux/list.h>
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struct pwm_device {
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struct pwm_chip *chip;
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unsigned long flags;
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#define FLAG_REQUESTED 0
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#define FLAG_ENABLED 1
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struct list_head node;
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};
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static LIST_HEAD(pwm_list);
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static struct pwm_device *_find_pwm(const char *devname)
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{
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struct pwm_device *pwm;
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list_for_each_entry(pwm, &pwm_list, node) {
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if (!strcmp(pwm->chip->devname, devname))
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return pwm;
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}
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return NULL;
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}
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/**
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* pwmchip_add() - register a new pwm
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* @chip: the pwm
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*
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* register a new pwm. pwm->devname must be initialized, usually
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* from dev_name(dev) from the hardware driver.
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*/
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int pwmchip_add(struct pwm_chip *chip)
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{
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struct pwm_device *pwm;
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int ret = 0;
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if (_find_pwm(chip->devname))
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return -EBUSY;
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pwm = xzalloc(sizeof(*pwm));
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pwm->chip = chip;
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list_add_tail(&pwm->node, &pwm_list);
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return ret;
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}
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EXPORT_SYMBOL_GPL(pwmchip_add);
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/**
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* pwmchip_remove() - remove a pwm
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* @chip: the pwm
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*
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* remove a pwm. This function may return busy if the pwm is still requested.
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*/
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int pwmchip_remove(struct pwm_chip *chip)
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{
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struct pwm_device *pwm;
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pwm = _find_pwm(chip->devname);
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if (!pwm)
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return -ENOENT;
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if (test_bit(FLAG_REQUESTED, &pwm->flags))
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return -EBUSY;
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list_del(&pwm->node);
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kfree(pwm);
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return 0;
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}
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EXPORT_SYMBOL_GPL(pwmchip_remove);
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/*
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* pwm_request - request a PWM device
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*/
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struct pwm_device *pwm_request(const char *devname)
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{
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struct pwm_device *pwm;
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int ret;
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pwm = _find_pwm(devname);
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if (!pwm)
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return NULL;
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if (test_bit(FLAG_REQUESTED, &pwm->flags))
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return NULL;
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if (pwm->chip->ops->request) {
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ret = pwm->chip->ops->request(pwm->chip);
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if (ret)
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return NULL;
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}
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set_bit(FLAG_REQUESTED, &pwm->flags);
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return pwm;
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}
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EXPORT_SYMBOL_GPL(pwm_request);
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/*
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* pwm_free - free a PWM device
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*/
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void pwm_free(struct pwm_device *pwm)
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{
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if (!test_and_clear_bit(FLAG_REQUESTED, &pwm->flags))
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return;
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}
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EXPORT_SYMBOL_GPL(pwm_free);
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/*
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* pwm_config - change a PWM device configuration
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*/
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int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns)
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{
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return pwm->chip->ops->config(pwm->chip, duty_ns, period_ns);
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}
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EXPORT_SYMBOL_GPL(pwm_config);
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/*
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* pwm_enable - start a PWM output toggling
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*/
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int pwm_enable(struct pwm_device *pwm)
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{
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if (!test_and_set_bit(FLAG_ENABLED, &pwm->flags))
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return pwm->chip->ops->enable(pwm->chip);
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return 0;
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}
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EXPORT_SYMBOL_GPL(pwm_enable);
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/*
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* pwm_disable - stop a PWM output toggling
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*/
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void pwm_disable(struct pwm_device *pwm)
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{
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if (test_and_clear_bit(FLAG_ENABLED, &pwm->flags))
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pwm->chip->ops->disable(pwm->chip);
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}
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EXPORT_SYMBOL_GPL(pwm_disable);
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