diff options
Diffstat (limited to 'drivers/pwm/pwm.c')
| -rw-r--r-- | drivers/pwm/pwm.c | 626 |
1 files changed, 626 insertions, 0 deletions
diff --git a/drivers/pwm/pwm.c b/drivers/pwm/pwm.c new file mode 100644 index 000000000000..32e84f86bf62 --- /dev/null +++ b/drivers/pwm/pwm.c @@ -0,0 +1,626 @@ +/* + * drivers/pwm/pwm.c + * + * Copyright (C) 2008 Bill Gatliff + * + * 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. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA + */ + +#if 0 +#define DEBUG +#endif + +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/init.h> +#include <linux/device.h> +#include <linux/spinlock.h> +#include <linux/fs.h> +#include <linux/completion.h> +#include <linux/workqueue.h> +#include <linux/pwm.h> + +static int __pwm_create_sysfs(struct pwm_device *pwm); + +static LIST_HEAD(pwm_device_list); +static DEFINE_MUTEX(device_list_mutex); +static struct class pwm_class; +static struct workqueue_struct *pwm_handler_workqueue; + +int pwm_register(struct pwm_device *pwm) +{ + struct pwm_channel *p; + int wchan; + int ret = 0; + + spin_lock_init(&pwm->list_lock); + + p = kcalloc(pwm->nchan, sizeof(struct pwm_channel), GFP_KERNEL); + if (!p) + return -ENOMEM; + + for (wchan = 0; wchan < pwm->nchan; wchan++) { + spin_lock_init(&p[wchan].lock); + init_completion(&p[wchan].complete); + p[wchan].chan = wchan; + p[wchan].pwm = pwm; + } + + pwm->channels = p; + + mutex_lock(&device_list_mutex); + + list_add_tail(&pwm->list, &pwm_device_list); + ret = __pwm_create_sysfs(pwm); + if (ret) { + mutex_unlock(&device_list_mutex); + goto err_create_sysfs; + } + + mutex_unlock(&device_list_mutex); + + pr_info("%s: %d channels\n", pwm->bus_id, pwm->nchan); + return 0; + +err_create_sysfs: + kfree(p); + + return ret; +} + +EXPORT_SYMBOL(pwm_register); + +static int __match_device(struct device *dev, void *data) +{ + return dev_get_drvdata(dev) == data; +} + +int pwm_unregister(struct pwm_device *pwm) +{ + int wchan; + struct device *dev; + + mutex_lock(&device_list_mutex); + + for (wchan = 0; wchan < pwm->nchan; wchan++) { + if (pwm->channels[wchan].flags & FLAG_REQUESTED) { + mutex_unlock(&device_list_mutex); + return -EBUSY; + } + } + + for (wchan = 0; wchan < pwm->nchan; wchan++) { + dev = class_find_device(&pwm_class, NULL, + &pwm->channels[wchan], __match_device); + if (dev) { + put_device(dev); + device_unregister(dev); + } + } + + kfree(pwm->channels); + list_del(&pwm->list); + mutex_unlock(&device_list_mutex); + + return 0; +} + +EXPORT_SYMBOL(pwm_unregister); + +static struct pwm_device *__pwm_find_device(const char *bus_id) +{ + struct pwm_device *p; + + list_for_each_entry(p, &pwm_device_list, list) { + if (!strcmp(bus_id, p->bus_id)) + return p; + } + return NULL; +} + +static int __pwm_request_channel(struct pwm_channel *p, const char *requester) +{ + int ret; + + if (test_and_set_bit(FLAG_REQUESTED, &p->flags)) + return -EBUSY; + + if (p->pwm->request) { + ret = p->pwm->request(p); + if (ret) { + clear_bit(FLAG_REQUESTED, &p->flags); + return ret; + } + } + + p->requester = requester; + return 0; +} + +struct pwm_channel *pwm_request(const char *bus_id, int chan, const char *requester) +{ + struct pwm_device *p; + int ret; + + mutex_lock(&device_list_mutex); + + p = __pwm_find_device(bus_id); + if (!p || chan >= p->nchan) + goto err_no_device; + + if (!try_module_get(p->owner)) + goto err_module_get_failed; + + ret = __pwm_request_channel(&p->channels[chan], requester); + if (ret) + goto err_request_failed; + + mutex_unlock(&device_list_mutex); + + pr_debug("%s: %s:%d returns %p\n", __func__, bus_id, chan, &p->channels[chan]); + + return &p->channels[chan]; + +err_request_failed: + module_put(p->owner); +err_module_get_failed: +err_no_device: + + mutex_unlock(&device_list_mutex); + + pr_debug("%s: %s:%d returns NULL\n", __func__, bus_id, chan); + + return NULL; +} + +EXPORT_SYMBOL(pwm_request); + +void pwm_free(struct pwm_channel *p) +{ + mutex_lock(&device_list_mutex); + + if (!test_and_clear_bit(FLAG_REQUESTED, &p->flags)) + goto done; + + pwm_stop(p); + pwm_unsynchronize(p, NULL); + pwm_set_handler(p, NULL, NULL); + + if (p->pwm->free) + p->pwm->free(p); + module_put(p->pwm->owner); + + pr_debug("%s: %s:%d free\n", __func__, p->pwm->bus_id, p->chan); + +done: + mutex_unlock(&device_list_mutex); +} + +EXPORT_SYMBOL(pwm_free); + +unsigned long pwm_ns_to_ticks(struct pwm_channel *p, unsigned long nsecs) +{ + unsigned long long ticks; + + ticks = nsecs; + ticks *= p->tick_hz; + do_div(ticks, 1000000000); + + return ticks; +} + +EXPORT_SYMBOL(pwm_ns_to_ticks); + +unsigned long pwm_ticks_to_ns(struct pwm_channel *p, unsigned long ticks) +{ + unsigned long long ns; + + if (!p->tick_hz) + return 0; + + ns = ticks; + ns *= 1000000000UL; + do_div(ns, p->tick_hz); + return ns; +} + +EXPORT_SYMBOL(pwm_ticks_to_ns); + +static void pwm_config_ns_to_ticks(struct pwm_channel *p, struct pwm_channel_config *c) +{ + if (c->config_mask & PWM_CONFIG_PERIOD_NS) { + c->period_ticks = pwm_ns_to_ticks(p, c->period_ns); + c->config_mask &= ~PWM_CONFIG_PERIOD_NS; + c->config_mask |= PWM_CONFIG_PERIOD_TICKS; + } + + if (c->config_mask & PWM_CONFIG_DUTY_NS) { + c->duty_ticks = pwm_ns_to_ticks(p, c->duty_ns); + c->config_mask &= ~PWM_CONFIG_DUTY_NS; + c->config_mask |= PWM_CONFIG_DUTY_TICKS; + } +} + +static void pwm_config_percent_to_ticks(struct pwm_channel *p, struct pwm_channel_config *c) +{ + if (c->config_mask & PWM_CONFIG_DUTY_PERCENT) { + if (c->config_mask & PWM_CONFIG_PERIOD_TICKS) + c->duty_ticks = c->period_ticks; + else + c->duty_ticks = p->period_ticks; + + c->duty_ticks *= c->duty_percent; + c->duty_ticks /= 100; + c->config_mask &= ~PWM_CONFIG_DUTY_PERCENT; + c->config_mask |= PWM_CONFIG_DUTY_TICKS; + } +} + +int pwm_config_nosleep(struct pwm_channel *p, struct pwm_channel_config *c) +{ + if (!p->pwm->config_nosleep) + return -EINVAL; + + pwm_config_ns_to_ticks(p, c); + pwm_config_percent_to_ticks(p, c); + + return p->pwm->config_nosleep(p, c); +} + +EXPORT_SYMBOL(pwm_config_nosleep); + +int pwm_config(struct pwm_channel *p, struct pwm_channel_config *c) +{ + int ret = 0; + + if (unlikely(!p->pwm->config)) { + pr_debug("%s: %s:%d has no config handler (-EINVAL)\n", + __func__, p->pwm->bus_id, p->chan); + return -EINVAL; + } + + pwm_config_ns_to_ticks(p, c); + pwm_config_percent_to_ticks(p, c); + + switch (c->config_mask & (PWM_CONFIG_PERIOD_TICKS | PWM_CONFIG_DUTY_TICKS)) { + case PWM_CONFIG_PERIOD_TICKS: + if (p->duty_ticks > c->period_ticks) { + ret = -EINVAL; + goto err; + } + break; + case PWM_CONFIG_DUTY_TICKS: + if (p->period_ticks < c->duty_ticks) { + ret = -EINVAL; + goto err; + } + break; + case PWM_CONFIG_DUTY_TICKS | PWM_CONFIG_PERIOD_TICKS: + if (c->duty_ticks > c->period_ticks) { + ret = -EINVAL; + goto err; + } + break; + default: + break; + } + +err: + pr_debug("%s: config_mask %d period_ticks %lu duty_ticks %lu" + " polarity %d duty_ns %lu period_ns %lu duty_percent %d\n", + __func__, c->config_mask, c->period_ticks, c->duty_ticks, + c->polarity, c->duty_ns, c->period_ns, c->duty_percent); + + if (ret) + return ret; + return p->pwm->config(p, c); +} + +EXPORT_SYMBOL(pwm_config); + +int pwm_set_period_ns(struct pwm_channel *p, unsigned long period_ns) +{ + struct pwm_channel_config c = { + .config_mask = PWM_CONFIG_PERIOD_TICKS, + .period_ticks = pwm_ns_to_ticks(p, period_ns), + }; + + return pwm_config(p, &c); +} + +EXPORT_SYMBOL(pwm_set_period_ns); + +unsigned long pwm_get_period_ns(struct pwm_channel *p) +{ + return pwm_ticks_to_ns(p, p->period_ticks); +} + +EXPORT_SYMBOL(pwm_get_period_ns); + +int pwm_set_duty_ns(struct pwm_channel *p, unsigned long duty_ns) +{ + struct pwm_channel_config c = { + .config_mask = PWM_CONFIG_DUTY_TICKS, + .duty_ticks = pwm_ns_to_ticks(p, duty_ns), + }; + return pwm_config(p, &c); +} + +EXPORT_SYMBOL(pwm_set_duty_ns); + +unsigned long pwm_get_duty_ns(struct pwm_channel *p) +{ + return pwm_ticks_to_ns(p, p->duty_ticks); +} + +EXPORT_SYMBOL(pwm_get_duty_ns); + +int pwm_set_duty_percent(struct pwm_channel *p, int percent) +{ + struct pwm_channel_config c = { + .config_mask = PWM_CONFIG_DUTY_PERCENT, + .duty_percent = percent, + }; + return pwm_config(p, &c); +} + +EXPORT_SYMBOL(pwm_set_duty_percent); + +int pwm_set_polarity(struct pwm_channel *p, int active_high) +{ + struct pwm_channel_config c = { + .config_mask = PWM_CONFIG_POLARITY, + .polarity = active_high, + }; + return pwm_config(p, &c); +} + +EXPORT_SYMBOL(pwm_set_polarity); + +int pwm_start(struct pwm_channel *p) +{ + struct pwm_channel_config c = { + .config_mask = PWM_CONFIG_START, + }; + return pwm_config(p, &c); +} + +EXPORT_SYMBOL(pwm_start); + +int pwm_stop(struct pwm_channel *p) +{ + struct pwm_channel_config c = { + .config_mask = PWM_CONFIG_STOP, + }; + return pwm_config(p, &c); +} + +EXPORT_SYMBOL(pwm_stop); + +int pwm_synchronize(struct pwm_channel *p, struct pwm_channel *to_p) +{ + if (p->pwm != to_p->pwm) { + /* TODO: support cross-device synchronization */ + return -EINVAL; + } + + if (!p->pwm->synchronize) + return -EINVAL; + + return p->pwm->synchronize(p, to_p); +} + +EXPORT_SYMBOL(pwm_synchronize); + +int pwm_unsynchronize(struct pwm_channel *p, struct pwm_channel *from_p) +{ + if (from_p && (p->pwm != from_p->pwm)) { + /* TODO: support cross-device synchronization */ + return -EINVAL; + } + + if (!p->pwm->unsynchronize) + return -EINVAL; + + return p->pwm->unsynchronize(p, from_p); +} + +EXPORT_SYMBOL(pwm_unsynchronize); + +static void pwm_handler(struct work_struct *w) +{ + struct pwm_channel *p = container_of(w, struct pwm_channel, + handler_work); + if (p->handler && p->handler(p, p->handler_data)) + pwm_stop(p); +} + +static void __pwm_callback(struct pwm_channel *p) +{ + queue_work(pwm_handler_workqueue, &p->handler_work); + pr_debug("%s:%d handler %p scheduled with data %p\n", + p->pwm->bus_id, p->chan, p->handler, p->handler_data); +} + +int pwm_set_handler(struct pwm_channel *p, pwm_handler_t handler, void *data) +{ + if (p->pwm->set_callback) { + p->handler_data = data; + p->handler = handler; + INIT_WORK(&p->handler_work, pwm_handler); + return p->pwm->set_callback(p, handler ? __pwm_callback : NULL); + } + return -EINVAL; +} + +EXPORT_SYMBOL(pwm_set_handler); + +static ssize_t pwm_run_store(struct device *dev, + struct device_attribute *attr, const char *buf, size_t len) +{ + struct pwm_channel *p = dev_get_drvdata(dev); + if (sysfs_streq(buf, "1")) + pwm_start(p); + else if (sysfs_streq(buf, "0")) + pwm_stop(p); + return len; +} + +static DEVICE_ATTR(run, 0200, NULL, pwm_run_store); + +static ssize_t pwm_duty_ns_show(struct device *dev, struct device_attribute *attr, char *buf) +{ + struct pwm_channel *p = dev_get_drvdata(dev); + return sprintf(buf, "%lu\n", pwm_get_duty_ns(p)); +} + +static ssize_t pwm_duty_ns_store(struct device *dev, + struct device_attribute *attr, const char *buf, size_t len) +{ + unsigned long duty_ns; + struct pwm_channel *p = dev_get_drvdata(dev); + + if (1 == sscanf(buf, "%lu", &duty_ns)) + pwm_set_duty_ns(p, duty_ns); + return len; +} + +static DEVICE_ATTR(duty_ns, 0644, pwm_duty_ns_show, pwm_duty_ns_store); + +static ssize_t pwm_period_ns_show(struct device *dev, struct device_attribute *attr, char *buf) +{ + struct pwm_channel *p = dev_get_drvdata(dev); + return sprintf(buf, "%lu\n", pwm_get_period_ns(p)); +} + +static ssize_t pwm_period_ns_store(struct device *dev, + struct device_attribute *attr, const char *buf, size_t len) +{ + unsigned long period_ns; + struct pwm_channel *p = dev_get_drvdata(dev); + + if (1 == sscanf(buf, "%lu", &period_ns)) + pwm_set_period_ns(p, period_ns); + + return len; +} + +static DEVICE_ATTR(period_ns, 0644, pwm_period_ns_show, pwm_period_ns_store); + +static ssize_t pwm_polarity_show(struct device *dev, struct device_attribute *attr, char *buf) +{ + struct pwm_channel *p = dev_get_drvdata(dev); + return sprintf(buf, "%d\n", p->active_low ? 0 : 1); +} + +static ssize_t pwm_polarity_store(struct device *dev, + struct device_attribute *attr, const char *buf, size_t len) +{ + int polarity; + struct pwm_channel *p = dev_get_drvdata(dev); + + if (1 == sscanf(buf, "%d", &polarity)) + pwm_set_polarity(p, polarity); + return len; +} + +static DEVICE_ATTR(polarity, 0644, pwm_polarity_show, pwm_polarity_store); + +static ssize_t pwm_request_show(struct device *dev, struct device_attribute *attr, char *buf) +{ + struct pwm_channel *p = dev_get_drvdata(dev); + mutex_lock(&device_list_mutex); + __pwm_request_channel(p, "sysfs"); + mutex_unlock(&device_list_mutex); + + return sprintf(buf, "%s\n", p->requester); +} + +static ssize_t pwm_request_store(struct device *dev, + struct device_attribute *attr, const char *buf, size_t len) +{ + struct pwm_channel *p = dev_get_drvdata(dev); + pwm_free(p); + return len; +} + +static DEVICE_ATTR(request, 0644, pwm_request_show, pwm_request_store); + +static const struct attribute *pwm_attrs[] = { + &dev_attr_run.attr, + &dev_attr_polarity.attr, + &dev_attr_duty_ns.attr, + &dev_attr_period_ns.attr, + &dev_attr_request.attr, + NULL, +}; + +static const struct attribute_group pwm_device_attr_group = { + .attrs = (struct attribute **)pwm_attrs, +}; + +static int __pwm_create_sysfs(struct pwm_device *pwm) +{ + int ret = 0; + struct device *dev; + int wchan; + + for (wchan = 0; wchan < pwm->nchan; wchan++) { + dev = device_create(&pwm_class, pwm->dev, MKDEV(0, 0), + pwm->channels + wchan, "%s:%d", pwm->bus_id, wchan); + if (!dev) + goto err_dev_create; + ret = sysfs_create_group(&dev->kobj, &pwm_device_attr_group); + if (ret) + goto err_dev_group_create; + } + + return ret; + +err_dev_group_create: +err_dev_create: + /* TODO: undo all the successful device_create calls */ + return -ENODEV; +} + +static struct class_attribute pwm_class_attrs[] = { + __ATTR_NULL, +}; + +static struct class pwm_class = { + .name = "pwm", + .owner = THIS_MODULE, + + .class_attrs = pwm_class_attrs, +}; + +static int __init pwm_init(void) +{ + int ret; + + /* TODO: how to deal with devices that register very early? */ + + ret = class_register(&pwm_class); + if (ret < 0) + return ret; + + pwm_handler_workqueue = create_workqueue("pwmd"); + + return 0; +} + +postcore_initcall(pwm_init); + +MODULE_LICENSE("GPL"); |