mirror of
git://projects.qi-hardware.com/openwrt-xburst.git
synced 2024-12-24 07:29:33 +02:00
299 lines
6.6 KiB
C
299 lines
6.6 KiB
C
|
/*
|
||
|
* drivers/pwm/gpio.c
|
||
|
*
|
||
|
* Models a single-channel PWM device using a timer and a GPIO pin.
|
||
|
*
|
||
|
* Copyright (C) 2010 Bill Gatliff <bgat@billgatliff.com>
|
||
|
*
|
||
|
* This program is free software; you may redistribute and/or modify
|
||
|
* it under the terms of the GNU General Public License Version 2, as
|
||
|
* published by the Free Software Foundation.
|
||
|
*
|
||
|
* 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
|
||
|
*/
|
||
|
|
||
|
#include <linux/module.h>
|
||
|
#include <linux/init.h>
|
||
|
#include <linux/hrtimer.h>
|
||
|
#include <linux/err.h>
|
||
|
#include <linux/platform_device.h>
|
||
|
#include <linux/workqueue.h>
|
||
|
#include <linux/gpio.h>
|
||
|
#include <linux/slab.h>
|
||
|
#include <linux/pwm/pwm.h>
|
||
|
|
||
|
struct gpio_pwm {
|
||
|
struct pwm_device pwm;
|
||
|
struct hrtimer timer;
|
||
|
struct work_struct work;
|
||
|
pwm_callback_t callback;
|
||
|
int gpio;
|
||
|
unsigned long polarity : 1;
|
||
|
unsigned long active : 1;
|
||
|
};
|
||
|
|
||
|
static inline struct gpio_pwm *to_gpio_pwm(const struct pwm_channel *p)
|
||
|
{
|
||
|
return container_of(p->pwm, struct gpio_pwm, pwm);
|
||
|
}
|
||
|
|
||
|
static void
|
||
|
gpio_pwm_work (struct work_struct *work)
|
||
|
{
|
||
|
struct gpio_pwm *gp = container_of(work, struct gpio_pwm, work);
|
||
|
|
||
|
if (gp->active)
|
||
|
gpio_direction_output(gp->gpio, gp->polarity ? 1 : 0);
|
||
|
else
|
||
|
gpio_direction_output(gp->gpio, gp->polarity ? 0 : 1);
|
||
|
}
|
||
|
|
||
|
static enum hrtimer_restart
|
||
|
gpio_pwm_timeout(struct hrtimer *t)
|
||
|
{
|
||
|
struct gpio_pwm *gp = container_of(t, struct gpio_pwm, timer);
|
||
|
ktime_t tnew;
|
||
|
|
||
|
if (unlikely(gp->pwm.channels[0].duty_ticks == 0))
|
||
|
gp->active = 0;
|
||
|
else if (unlikely(gp->pwm.channels[0].duty_ticks
|
||
|
== gp->pwm.channels[0].period_ticks))
|
||
|
gp->active = 1;
|
||
|
else
|
||
|
gp->active ^= 1;
|
||
|
|
||
|
if (gpio_cansleep(gp->gpio))
|
||
|
schedule_work(&gp->work);
|
||
|
else
|
||
|
gpio_pwm_work(&gp->work);
|
||
|
|
||
|
if (!gp->active && gp->pwm.channels[0].callback)
|
||
|
gp->pwm.channels[0].callback(&gp->pwm.channels[0]);
|
||
|
|
||
|
if (unlikely(!gp->active &&
|
||
|
(gp->pwm.channels[0].flags & BIT(FLAG_STOP)))) {
|
||
|
clear_bit(FLAG_STOP, &gp->pwm.channels[0].flags);
|
||
|
complete_all(&gp->pwm.channels[0].complete);
|
||
|
return HRTIMER_NORESTART;
|
||
|
}
|
||
|
|
||
|
if (gp->active)
|
||
|
tnew = ktime_set(0, gp->pwm.channels[0].duty_ticks);
|
||
|
else
|
||
|
tnew = ktime_set(0, gp->pwm.channels[0].period_ticks
|
||
|
- gp->pwm.channels[0].duty_ticks);
|
||
|
hrtimer_start(&gp->timer, tnew, HRTIMER_MODE_REL);
|
||
|
|
||
|
return HRTIMER_NORESTART;
|
||
|
}
|
||
|
|
||
|
static void gpio_pwm_start(struct pwm_channel *p)
|
||
|
{
|
||
|
struct gpio_pwm *gp = to_gpio_pwm(p);
|
||
|
|
||
|
gp->active = 0;
|
||
|
gpio_pwm_timeout(&gp->timer);
|
||
|
}
|
||
|
|
||
|
static int
|
||
|
gpio_pwm_config_nosleep(struct pwm_channel *p,
|
||
|
struct pwm_channel_config *c)
|
||
|
{
|
||
|
struct gpio_pwm *gp = to_gpio_pwm(p);
|
||
|
int ret = 0;
|
||
|
unsigned long flags;
|
||
|
|
||
|
spin_lock_irqsave(&p->lock, flags);
|
||
|
|
||
|
switch (c->config_mask) {
|
||
|
|
||
|
case PWM_CONFIG_DUTY_TICKS:
|
||
|
p->duty_ticks = c->duty_ticks;
|
||
|
break;
|
||
|
|
||
|
case PWM_CONFIG_START:
|
||
|
if (!hrtimer_active(&gp->timer)) {
|
||
|
gpio_pwm_start(p);
|
||
|
}
|
||
|
break;
|
||
|
default:
|
||
|
ret = -EINVAL;
|
||
|
break;
|
||
|
}
|
||
|
|
||
|
spin_unlock_irqrestore(&p->lock, flags);
|
||
|
return ret;
|
||
|
}
|
||
|
|
||
|
static int
|
||
|
gpio_pwm_stop_sync(struct pwm_channel *p)
|
||
|
{
|
||
|
struct gpio_pwm *gp = to_gpio_pwm(p);
|
||
|
int ret;
|
||
|
int was_on = hrtimer_active(&gp->timer);
|
||
|
|
||
|
if (was_on) {
|
||
|
do {
|
||
|
init_completion(&p->complete);
|
||
|
set_bit(FLAG_STOP, &p->flags);
|
||
|
ret = wait_for_completion_interruptible(&p->complete);
|
||
|
if (ret)
|
||
|
return ret;
|
||
|
} while (p->flags & BIT(FLAG_STOP));
|
||
|
}
|
||
|
|
||
|
return was_on;
|
||
|
}
|
||
|
|
||
|
static int
|
||
|
gpio_pwm_config(struct pwm_channel *p,
|
||
|
struct pwm_channel_config *c)
|
||
|
{
|
||
|
struct gpio_pwm *gp = to_gpio_pwm(p);
|
||
|
int was_on = 0;
|
||
|
|
||
|
if (p->pwm->config_nosleep) {
|
||
|
if (!p->pwm->config_nosleep(p, c))
|
||
|
return 0;
|
||
|
}
|
||
|
|
||
|
might_sleep();
|
||
|
|
||
|
was_on = gpio_pwm_stop_sync(p);
|
||
|
if (was_on < 0)
|
||
|
return was_on;
|
||
|
|
||
|
if (c->config_mask & PWM_CONFIG_PERIOD_TICKS)
|
||
|
p->period_ticks = c->period_ticks;
|
||
|
|
||
|
if (c->config_mask & PWM_CONFIG_DUTY_TICKS)
|
||
|
p->duty_ticks = c->duty_ticks;
|
||
|
|
||
|
if (c->config_mask & PWM_CONFIG_POLARITY) {
|
||
|
gp->polarity = c->polarity ? 1 : 0;
|
||
|
p->active_high = gp->polarity;
|
||
|
}
|
||
|
|
||
|
if ((c->config_mask & PWM_CONFIG_START)
|
||
|
|| (was_on && !(c->config_mask & PWM_CONFIG_STOP)))
|
||
|
gpio_pwm_start(p);
|
||
|
|
||
|
return 0;
|
||
|
}
|
||
|
|
||
|
static int
|
||
|
gpio_pwm_set_callback(struct pwm_channel *p,
|
||
|
pwm_callback_t callback)
|
||
|
{
|
||
|
struct gpio_pwm *gp = to_gpio_pwm(p);
|
||
|
gp->callback = callback;
|
||
|
return 0;
|
||
|
}
|
||
|
|
||
|
static int
|
||
|
gpio_pwm_request(struct pwm_channel *p)
|
||
|
{
|
||
|
p->tick_hz = 1000000000UL;
|
||
|
return 0;
|
||
|
}
|
||
|
|
||
|
static int __devinit
|
||
|
gpio_pwm_probe(struct platform_device *pdev)
|
||
|
{
|
||
|
struct gpio_pwm *gp;
|
||
|
struct gpio_pwm_platform_data *gpd = pdev->dev.platform_data;
|
||
|
int ret = 0;
|
||
|
|
||
|
/* TODO: create configfs entries, so users can assign GPIOs to
|
||
|
* PWMs at runtime instead of creating a platform_device
|
||
|
* specification and rebuilding their kernel */
|
||
|
|
||
|
if (!gpd || gpio_request(gpd->gpio, dev_name(&pdev->dev)))
|
||
|
return -EINVAL;
|
||
|
|
||
|
gp = kzalloc(sizeof(*gp), GFP_KERNEL);
|
||
|
if (!gp) {
|
||
|
ret = -ENOMEM;
|
||
|
goto err_alloc;
|
||
|
}
|
||
|
|
||
|
platform_set_drvdata(pdev, gp);
|
||
|
|
||
|
gp->pwm.dev = &pdev->dev;
|
||
|
gp->pwm.bus_id = dev_name(&pdev->dev);
|
||
|
gp->pwm.nchan = 1;
|
||
|
gp->gpio = gpd->gpio;
|
||
|
|
||
|
INIT_WORK(&gp->work, gpio_pwm_work);
|
||
|
|
||
|
hrtimer_init(&gp->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
|
||
|
gp->timer.function = gpio_pwm_timeout;
|
||
|
|
||
|
gp->pwm.owner = THIS_MODULE;
|
||
|
gp->pwm.config_nosleep = gpio_pwm_config_nosleep;
|
||
|
gp->pwm.config = gpio_pwm_config;
|
||
|
gp->pwm.request = gpio_pwm_request;
|
||
|
gp->pwm.set_callback = gpio_pwm_set_callback;
|
||
|
|
||
|
ret = pwm_register(&gp->pwm);
|
||
|
if (ret)
|
||
|
goto err_pwm_register;
|
||
|
|
||
|
return 0;
|
||
|
|
||
|
err_pwm_register:
|
||
|
platform_set_drvdata(pdev, 0);
|
||
|
kfree(gp);
|
||
|
err_alloc:
|
||
|
return ret;
|
||
|
}
|
||
|
|
||
|
static int __devexit
|
||
|
gpio_pwm_remove(struct platform_device *pdev)
|
||
|
{
|
||
|
struct gpio_pwm *gp = platform_get_drvdata(pdev);
|
||
|
int ret;
|
||
|
|
||
|
ret = pwm_unregister(&gp->pwm);
|
||
|
hrtimer_cancel(&gp->timer);
|
||
|
cancel_work_sync(&gp->work);
|
||
|
platform_set_drvdata(pdev, 0);
|
||
|
kfree(gp);
|
||
|
|
||
|
return 0;
|
||
|
}
|
||
|
|
||
|
static struct platform_driver gpio_pwm_driver = {
|
||
|
.driver = {
|
||
|
.name = "gpio_pwm",
|
||
|
.owner = THIS_MODULE,
|
||
|
},
|
||
|
.probe = gpio_pwm_probe,
|
||
|
.remove = __devexit_p(gpio_pwm_remove),
|
||
|
};
|
||
|
|
||
|
static int __init gpio_pwm_init(void)
|
||
|
{
|
||
|
return platform_driver_register(&gpio_pwm_driver);
|
||
|
}
|
||
|
module_init(gpio_pwm_init);
|
||
|
|
||
|
static void __exit gpio_pwm_exit(void)
|
||
|
{
|
||
|
platform_driver_unregister(&gpio_pwm_driver);
|
||
|
}
|
||
|
module_exit(gpio_pwm_exit);
|
||
|
|
||
|
MODULE_AUTHOR("Bill Gatliff <bgat@billgatliff.com>");
|
||
|
MODULE_DESCRIPTION("PWM output using GPIO and a high-resolution timer");
|
||
|
MODULE_LICENSE("GPL");
|
||
|
MODULE_ALIAS("platform:gpio_pwm");
|