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/*
* ledtrig-gio.c - LED Trigger Based on GPIO events
*
* Copyright 2009 Felipe Balbi <me@felipebalbi.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
*/
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/gpio.h>
#include <linux/interrupt.h>
#include <linux/workqueue.h>
#include <linux/leds.h>
#include <linux/slab.h>
#include "leds.h"
struct gpio_trig_data {
struct led_classdev *led;
struct work_struct work;
unsigned desired_brightness; /* desired brightness when led is on */
unsigned inverted; /* true when gpio is inverted */
unsigned gpio; /* gpio that triggers the leds */
};
static irqreturn_t gpio_trig_irq(int irq, void *_led)
{
struct led_classdev *led = _led;
struct gpio_trig_data *gpio_data = led->trigger_data;
/* just schedule_work since gpio_get_value can sleep */
schedule_work(&gpio_data->work);
return IRQ_HANDLED;
};
static void gpio_trig_work(struct work_struct *work)
{
struct gpio_trig_data *gpio_data = container_of(work,
struct gpio_trig_data, work);
int tmp;
if (!gpio_data->gpio)
return;
tmp = gpio_get_value(gpio_data->gpio);
if (gpio_data->inverted)
tmp = !tmp;
if (tmp) {
if (gpio_data->desired_brightness)
__led_set_brightness(gpio_data->led,
gpio_data->desired_brightness);
else
__led_set_brightness(gpio_data->led, LED_FULL);
} else {
__led_set_brightness(gpio_data->led, LED_OFF);
}
}
static ssize_t gpio_trig_brightness_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct led_classdev *led = dev_get_drvdata(dev);
struct gpio_trig_data *gpio_data = led->trigger_data;
return sprintf(buf, "%u\n", gpio_data->desired_brightness);
}
static ssize_t gpio_trig_brightness_store(struct device *dev,
struct device_attribute *attr, const char *buf, size_t n)
{
struct led_classdev *led = dev_get_drvdata(dev);
struct gpio_trig_data *gpio_data = led->trigger_data;
unsigned desired_brightness;
int ret;
ret = sscanf(buf, "%u", &desired_brightness);
if (ret < 1 || desired_brightness > 255) {
dev_err(dev, "invalid value\n");
return -EINVAL;
}
gpio_data->desired_brightness = desired_brightness;
return n;
}
static DEVICE_ATTR(desired_brightness, 0644, gpio_trig_brightness_show,
gpio_trig_brightness_store);
static ssize_t gpio_trig_inverted_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct led_classdev *led = dev_get_drvdata(dev);
struct gpio_trig_data *gpio_data = led->trigger_data;
return sprintf(buf, "%u\n", gpio_data->inverted);
}
static ssize_t gpio_trig_inverted_store(struct device *dev,
struct device_attribute *attr, const char *buf, size_t n)
{
struct led_classdev *led = dev_get_drvdata(dev);
struct gpio_trig_data *gpio_data = led->trigger_data;
unsigned long inverted;
int ret;
ret = strict_strtoul(buf, 10, &inverted);
if (ret < 0)
return ret;
if (inverted > 1)
return -EINVAL;
gpio_data->inverted = inverted;
/* After inverting, we need to update the LED. */
schedule_work(&gpio_data->work);
return n;
}
static DEVICE_ATTR(inverted, 0644, gpio_trig_inverted_show,
gpio_trig_inverted_store);
static ssize_t gpio_trig_gpio_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct led_classdev *led = dev_get_drvdata(dev);
struct gpio_trig_data *gpio_data = led->trigger_data;
return sprintf(buf, "%u\n", gpio_data->gpio);
}
static ssize_t gpio_trig_gpio_store(struct device *dev,
struct device_attribute *attr, const char *buf, size_t n)
{
struct led_classdev *led = dev_get_drvdata(dev);
struct gpio_trig_data *gpio_data = led->trigger_data;
unsigned gpio;
int ret;
ret = sscanf(buf, "%u", &gpio);
if (ret < 1) {
dev_err(dev, "couldn't read gpio number\n");
flush_work(&gpio_data->work);
return -EINVAL;
}
if (gpio_data->gpio == gpio)
return n;
if (!gpio) {
if (gpio_data->gpio != 0)
free_irq(gpio_to_irq(gpio_data->gpio), led);
gpio_data->gpio = 0;
return n;
}
ret = request_irq(gpio_to_irq(gpio), gpio_trig_irq,
IRQF_SHARED | IRQF_TRIGGER_RISING
| IRQF_TRIGGER_FALLING, "ledtrig-gpio", led);
if (ret) {
dev_err(dev, "request_irq failed with error %d\n", ret);
} else {
if (gpio_data->gpio != 0)
free_irq(gpio_to_irq(gpio_data->gpio), led);
gpio_data->gpio = gpio;
}
return ret ? ret : n;
}
static DEVICE_ATTR(gpio, 0644, gpio_trig_gpio_show, gpio_trig_gpio_store);
static void gpio_trig_activate(struct led_classdev *led)
{
struct gpio_trig_data *gpio_data;
int ret;
gpio_data = kzalloc(sizeof(*gpio_data), GFP_KERNEL);
if (!gpio_data)
return;
ret = device_create_file(led->dev, &dev_attr_gpio);
if (ret)
goto err_gpio;
ret = device_create_file(led->dev, &dev_attr_inverted);
if (ret)
goto err_inverted;
ret = device_create_file(led->dev, &dev_attr_desired_brightness);
if (ret)
goto err_brightness;
gpio_data->led = led;
led->trigger_data = gpio_data;
INIT_WORK(&gpio_data->work, gpio_trig_work);
led->activated = true;
return;
err_brightness:
device_remove_file(led->dev, &dev_attr_inverted);
err_inverted:
device_remove_file(led->dev, &dev_attr_gpio);
err_gpio:
kfree(gpio_data);
}
static void gpio_trig_deactivate(struct led_classdev *led)
{
struct gpio_trig_data *gpio_data = led->trigger_data;
if (led->activated) {
device_remove_file(led->dev, &dev_attr_gpio);
device_remove_file(led->dev, &dev_attr_inverted);
device_remove_file(led->dev, &dev_attr_desired_brightness);
flush_work(&gpio_data->work);
if (gpio_data->gpio != 0)
free_irq(gpio_to_irq(gpio_data->gpio), led);
kfree(gpio_data);
led->activated = false;
}
}
static struct led_trigger gpio_led_trigger = {
.name = "gpio",
.activate = gpio_trig_activate,
.deactivate = gpio_trig_deactivate,
};
static int __init gpio_trig_init(void)
{
return led_trigger_register(&gpio_led_trigger);
}
module_init(gpio_trig_init);
static void __exit gpio_trig_exit(void)
{
led_trigger_unregister(&gpio_led_trigger);
}
module_exit(gpio_trig_exit);
MODULE_AUTHOR("Felipe Balbi <me@felipebalbi.com>");
MODULE_DESCRIPTION("GPIO LED trigger");
MODULE_LICENSE("GPL");
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