2 * ledtrig-gio.c - LED Trigger Based on GPIO events
4 * Copyright 2009 Felipe Balbi <me@felipebalbi.com>
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
12 #include <linux/module.h>
13 #include <linux/kernel.h>
14 #include <linux/init.h>
15 #include <linux/gpio.h>
16 #include <linux/interrupt.h>
17 #include <linux/workqueue.h>
18 #include <linux/leds.h>
19 #include <linux/slab.h>
22 struct gpio_trig_data {
23 struct led_classdev *led;
24 struct work_struct work;
26 unsigned desired_brightness; /* desired brightness when led is on */
27 unsigned inverted; /* true when gpio is inverted */
28 unsigned gpio; /* gpio that triggers the leds */
31 static irqreturn_t gpio_trig_irq(int irq, void *_led)
33 struct led_classdev *led = _led;
34 struct gpio_trig_data *gpio_data = led->trigger_data;
36 /* just schedule_work since gpio_get_value can sleep */
37 schedule_work(&gpio_data->work);
42 static void gpio_trig_work(struct work_struct *work)
44 struct gpio_trig_data *gpio_data = container_of(work,
45 struct gpio_trig_data, work);
51 tmp = gpio_get_value(gpio_data->gpio);
52 if (gpio_data->inverted)
56 if (gpio_data->desired_brightness)
57 led_set_brightness(gpio_data->led,
58 gpio_data->desired_brightness);
60 led_set_brightness(gpio_data->led, LED_FULL);
62 led_set_brightness(gpio_data->led, LED_OFF);
66 static ssize_t gpio_trig_brightness_show(struct device *dev,
67 struct device_attribute *attr, char *buf)
69 struct led_classdev *led = dev_get_drvdata(dev);
70 struct gpio_trig_data *gpio_data = led->trigger_data;
72 return sprintf(buf, "%u\n", gpio_data->desired_brightness);
75 static ssize_t gpio_trig_brightness_store(struct device *dev,
76 struct device_attribute *attr, const char *buf, size_t n)
78 struct led_classdev *led = dev_get_drvdata(dev);
79 struct gpio_trig_data *gpio_data = led->trigger_data;
80 unsigned desired_brightness;
83 ret = sscanf(buf, "%u", &desired_brightness);
84 if (ret < 1 || desired_brightness > 255) {
85 dev_err(dev, "invalid value\n");
89 gpio_data->desired_brightness = desired_brightness;
93 static DEVICE_ATTR(desired_brightness, 0644, gpio_trig_brightness_show,
94 gpio_trig_brightness_store);
96 static ssize_t gpio_trig_inverted_show(struct device *dev,
97 struct device_attribute *attr, char *buf)
99 struct led_classdev *led = dev_get_drvdata(dev);
100 struct gpio_trig_data *gpio_data = led->trigger_data;
102 return sprintf(buf, "%u\n", gpio_data->inverted);
105 static ssize_t gpio_trig_inverted_store(struct device *dev,
106 struct device_attribute *attr, const char *buf, size_t n)
108 struct led_classdev *led = dev_get_drvdata(dev);
109 struct gpio_trig_data *gpio_data = led->trigger_data;
110 unsigned long inverted;
113 ret = strict_strtoul(buf, 10, &inverted);
120 gpio_data->inverted = inverted;
122 /* After inverting, we need to update the LED. */
123 schedule_work(&gpio_data->work);
127 static DEVICE_ATTR(inverted, 0644, gpio_trig_inverted_show,
128 gpio_trig_inverted_store);
130 static ssize_t gpio_trig_gpio_show(struct device *dev,
131 struct device_attribute *attr, char *buf)
133 struct led_classdev *led = dev_get_drvdata(dev);
134 struct gpio_trig_data *gpio_data = led->trigger_data;
136 return sprintf(buf, "%u\n", gpio_data->gpio);
139 static ssize_t gpio_trig_gpio_store(struct device *dev,
140 struct device_attribute *attr, const char *buf, size_t n)
142 struct led_classdev *led = dev_get_drvdata(dev);
143 struct gpio_trig_data *gpio_data = led->trigger_data;
147 ret = sscanf(buf, "%u", &gpio);
149 dev_err(dev, "couldn't read gpio number\n");
150 flush_work(&gpio_data->work);
154 if (gpio_data->gpio == gpio)
158 if (gpio_data->gpio != 0)
159 free_irq(gpio_to_irq(gpio_data->gpio), led);
164 ret = request_irq(gpio_to_irq(gpio), gpio_trig_irq,
165 IRQF_SHARED | IRQF_TRIGGER_RISING
166 | IRQF_TRIGGER_FALLING, "ledtrig-gpio", led);
168 dev_err(dev, "request_irq failed with error %d\n", ret);
170 if (gpio_data->gpio != 0)
171 free_irq(gpio_to_irq(gpio_data->gpio), led);
172 gpio_data->gpio = gpio;
175 return ret ? ret : n;
177 static DEVICE_ATTR(gpio, 0644, gpio_trig_gpio_show, gpio_trig_gpio_store);
179 static void gpio_trig_activate(struct led_classdev *led)
181 struct gpio_trig_data *gpio_data;
184 gpio_data = kzalloc(sizeof(*gpio_data), GFP_KERNEL);
188 ret = device_create_file(led->dev, &dev_attr_gpio);
192 ret = device_create_file(led->dev, &dev_attr_inverted);
196 ret = device_create_file(led->dev, &dev_attr_desired_brightness);
200 gpio_data->led = led;
201 led->trigger_data = gpio_data;
202 INIT_WORK(&gpio_data->work, gpio_trig_work);
207 device_remove_file(led->dev, &dev_attr_inverted);
210 device_remove_file(led->dev, &dev_attr_gpio);
216 static void gpio_trig_deactivate(struct led_classdev *led)
218 struct gpio_trig_data *gpio_data = led->trigger_data;
221 device_remove_file(led->dev, &dev_attr_gpio);
222 device_remove_file(led->dev, &dev_attr_inverted);
223 device_remove_file(led->dev, &dev_attr_desired_brightness);
224 flush_work(&gpio_data->work);
225 if (gpio_data->gpio != 0)
226 free_irq(gpio_to_irq(gpio_data->gpio), led);
231 static struct led_trigger gpio_led_trigger = {
233 .activate = gpio_trig_activate,
234 .deactivate = gpio_trig_deactivate,
237 static int __init gpio_trig_init(void)
239 return led_trigger_register(&gpio_led_trigger);
241 module_init(gpio_trig_init);
243 static void __exit gpio_trig_exit(void)
245 led_trigger_unregister(&gpio_led_trigger);
247 module_exit(gpio_trig_exit);
249 MODULE_AUTHOR("Felipe Balbi <me@felipebalbi.com>");
250 MODULE_DESCRIPTION("GPIO LED trigger");
251 MODULE_LICENSE("GPL");