diff options
Diffstat (limited to 'drivers/pwm/core.c')
| -rw-r--r-- | drivers/pwm/core.c | 227 |
1 files changed, 227 insertions, 0 deletions
diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c new file mode 100644 index 00000000000..0b8a38eca23 --- /dev/null +++ b/drivers/pwm/core.c @@ -0,0 +1,227 @@ +/* + * 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); |