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Felipe Balbi17354bf2009-02-17 13:18:11 +02001/*
2 * ledtrig-gio.c - LED Trigger Based on GPIO events
3 *
4 * Copyright 2009 Felipe Balbi <me@felipebalbi.com>
5 *
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.
9 *
10 */
11
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 "leds.h"
20
21struct gpio_trig_data {
22 struct led_classdev *led;
23 struct work_struct work;
24
25 unsigned desired_brightness; /* desired brightness when led is on */
26 unsigned inverted; /* true when gpio is inverted */
27 unsigned gpio; /* gpio that triggers the leds */
28};
29
30static irqreturn_t gpio_trig_irq(int irq, void *_led)
31{
32 struct led_classdev *led = _led;
33 struct gpio_trig_data *gpio_data = led->trigger_data;
34
35 /* just schedule_work since gpio_get_value can sleep */
36 schedule_work(&gpio_data->work);
37
38 return IRQ_HANDLED;
39};
40
41static void gpio_trig_work(struct work_struct *work)
42{
43 struct gpio_trig_data *gpio_data = container_of(work,
44 struct gpio_trig_data, work);
45 int tmp;
46
Thadeu Lima de Souza Cascardo74cbe202009-08-06 16:04:51 -070047 if (!gpio_data->gpio)
48 return;
Felipe Balbi17354bf2009-02-17 13:18:11 +020049
Thadeu Lima de Souza Cascardo74cbe202009-08-06 16:04:51 -070050 tmp = gpio_get_value(gpio_data->gpio);
51 if (gpio_data->inverted)
52 tmp = !tmp;
Felipe Balbi17354bf2009-02-17 13:18:11 +020053
Thadeu Lima de Souza Cascardo74cbe202009-08-06 16:04:51 -070054 if (tmp) {
55 if (gpio_data->desired_brightness)
56 led_set_brightness(gpio_data->led,
57 gpio_data->desired_brightness);
58 else
59 led_set_brightness(gpio_data->led, LED_FULL);
60 } else {
61 led_set_brightness(gpio_data->led, LED_OFF);
62 }
Felipe Balbi17354bf2009-02-17 13:18:11 +020063}
64
65static ssize_t gpio_trig_brightness_show(struct device *dev,
66 struct device_attribute *attr, char *buf)
67{
68 struct led_classdev *led = dev_get_drvdata(dev);
69 struct gpio_trig_data *gpio_data = led->trigger_data;
70
71 return sprintf(buf, "%u\n", gpio_data->desired_brightness);
72}
73
74static ssize_t gpio_trig_brightness_store(struct device *dev,
75 struct device_attribute *attr, const char *buf, size_t n)
76{
77 struct led_classdev *led = dev_get_drvdata(dev);
78 struct gpio_trig_data *gpio_data = led->trigger_data;
79 unsigned desired_brightness;
80 int ret;
81
82 ret = sscanf(buf, "%u", &desired_brightness);
83 if (ret < 1 || desired_brightness > 255) {
84 dev_err(dev, "invalid value\n");
85 return -EINVAL;
86 }
87
88 gpio_data->desired_brightness = desired_brightness;
89
90 return n;
91}
92static DEVICE_ATTR(desired_brightness, 0644, gpio_trig_brightness_show,
93 gpio_trig_brightness_store);
94
95static ssize_t gpio_trig_inverted_show(struct device *dev,
96 struct device_attribute *attr, char *buf)
97{
98 struct led_classdev *led = dev_get_drvdata(dev);
99 struct gpio_trig_data *gpio_data = led->trigger_data;
100
101 return sprintf(buf, "%s\n", gpio_data->inverted ? "yes" : "no");
102}
103
104static ssize_t gpio_trig_inverted_store(struct device *dev,
105 struct device_attribute *attr, const char *buf, size_t n)
106{
107 struct led_classdev *led = dev_get_drvdata(dev);
108 struct gpio_trig_data *gpio_data = led->trigger_data;
109 unsigned inverted;
110 int ret;
111
112 ret = sscanf(buf, "%u", &inverted);
113 if (ret < 1) {
114 dev_err(dev, "invalid value\n");
115 return -EINVAL;
116 }
117
118 gpio_data->inverted = !!inverted;
119
Thadeu Lima de Souza Cascardocc674c82009-08-26 14:29:32 -0700120 /* After inverting, we need to update the LED. */
121 schedule_work(&gpio_data->work);
122
Felipe Balbi17354bf2009-02-17 13:18:11 +0200123 return n;
124}
125static DEVICE_ATTR(inverted, 0644, gpio_trig_inverted_show,
126 gpio_trig_inverted_store);
127
128static ssize_t gpio_trig_gpio_show(struct device *dev,
129 struct device_attribute *attr, char *buf)
130{
131 struct led_classdev *led = dev_get_drvdata(dev);
132 struct gpio_trig_data *gpio_data = led->trigger_data;
133
134 return sprintf(buf, "%u\n", gpio_data->gpio);
135}
136
137static ssize_t gpio_trig_gpio_store(struct device *dev,
138 struct device_attribute *attr, const char *buf, size_t n)
139{
140 struct led_classdev *led = dev_get_drvdata(dev);
141 struct gpio_trig_data *gpio_data = led->trigger_data;
142 unsigned gpio;
143 int ret;
144
145 ret = sscanf(buf, "%u", &gpio);
146 if (ret < 1) {
147 dev_err(dev, "couldn't read gpio number\n");
148 flush_work(&gpio_data->work);
149 return -EINVAL;
150 }
151
Thadeu Lima de Souza Cascardo48cccd22009-08-26 14:29:31 -0700152 if (gpio_data->gpio == gpio)
153 return n;
154
Felipe Balbi17354bf2009-02-17 13:18:11 +0200155 if (!gpio) {
Thadeu Lima de Souza Cascardo48cccd22009-08-26 14:29:31 -0700156 if (gpio_data->gpio != 0)
157 free_irq(gpio_to_irq(gpio_data->gpio), led);
158 gpio_data->gpio = 0;
Felipe Balbi17354bf2009-02-17 13:18:11 +0200159 return n;
160 }
161
Felipe Balbi17354bf2009-02-17 13:18:11 +0200162 ret = request_irq(gpio_to_irq(gpio), gpio_trig_irq,
163 IRQF_SHARED | IRQF_TRIGGER_RISING
164 | IRQF_TRIGGER_FALLING, "ledtrig-gpio", led);
Thadeu Lima de Souza Cascardo48cccd22009-08-26 14:29:31 -0700165 if (ret) {
Felipe Balbi17354bf2009-02-17 13:18:11 +0200166 dev_err(dev, "request_irq failed with error %d\n", ret);
Thadeu Lima de Souza Cascardo48cccd22009-08-26 14:29:31 -0700167 } else {
168 if (gpio_data->gpio != 0)
169 free_irq(gpio_to_irq(gpio_data->gpio), led);
170 gpio_data->gpio = gpio;
171 }
Felipe Balbi17354bf2009-02-17 13:18:11 +0200172
173 return ret ? ret : n;
174}
175static DEVICE_ATTR(gpio, 0644, gpio_trig_gpio_show, gpio_trig_gpio_store);
176
177static void gpio_trig_activate(struct led_classdev *led)
178{
179 struct gpio_trig_data *gpio_data;
180 int ret;
181
182 gpio_data = kzalloc(sizeof(*gpio_data), GFP_KERNEL);
183 if (!gpio_data)
184 return;
185
186 ret = device_create_file(led->dev, &dev_attr_gpio);
187 if (ret)
188 goto err_gpio;
189
190 ret = device_create_file(led->dev, &dev_attr_inverted);
191 if (ret)
192 goto err_inverted;
193
194 ret = device_create_file(led->dev, &dev_attr_desired_brightness);
195 if (ret)
196 goto err_brightness;
197
198 gpio_data->led = led;
199 led->trigger_data = gpio_data;
200 INIT_WORK(&gpio_data->work, gpio_trig_work);
201
202 return;
203
204err_brightness:
205 device_remove_file(led->dev, &dev_attr_inverted);
206
207err_inverted:
208 device_remove_file(led->dev, &dev_attr_gpio);
209
210err_gpio:
211 kfree(gpio_data);
212}
213
214static void gpio_trig_deactivate(struct led_classdev *led)
215{
216 struct gpio_trig_data *gpio_data = led->trigger_data;
217
218 if (gpio_data) {
219 device_remove_file(led->dev, &dev_attr_gpio);
220 device_remove_file(led->dev, &dev_attr_inverted);
221 device_remove_file(led->dev, &dev_attr_desired_brightness);
222 flush_work(&gpio_data->work);
Thadeu Lima de Souza Cascardo48cccd22009-08-26 14:29:31 -0700223 if (gpio_data->gpio != 0)
224 free_irq(gpio_to_irq(gpio_data->gpio), led);
Felipe Balbi17354bf2009-02-17 13:18:11 +0200225 kfree(gpio_data);
226 }
227}
228
229static struct led_trigger gpio_led_trigger = {
230 .name = "gpio",
231 .activate = gpio_trig_activate,
232 .deactivate = gpio_trig_deactivate,
233};
234
235static int __init gpio_trig_init(void)
236{
237 return led_trigger_register(&gpio_led_trigger);
238}
239module_init(gpio_trig_init);
240
241static void __exit gpio_trig_exit(void)
242{
243 led_trigger_unregister(&gpio_led_trigger);
244}
245module_exit(gpio_trig_exit);
246
247MODULE_AUTHOR("Felipe Balbi <me@felipebalbi.com>");
248MODULE_DESCRIPTION("GPIO LED trigger");
249MODULE_LICENSE("GPL");