1 /*
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
21 struct 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
30 static 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
41 static 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
47 if (!gpio_data->gpio)
48 return;
49
50 tmp = gpio_get_value(gpio_data->gpio);
51 if (gpio_data->inverted)
52 tmp = !tmp;
53
54 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 }
63 }
64
65 static 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
74 static 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 }
92 static DEVICE_ATTR(desired_brightness, 0644, gpio_trig_brightness_show,
93 gpio_trig_brightness_store);
94
95 static 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
104 static 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
120 /* After inverting, we need to update the LED. */
121 schedule_work(&gpio_data->work);
122
123 return n;
124 }
125 static DEVICE_ATTR(inverted, 0644, gpio_trig_inverted_show,
126 gpio_trig_inverted_store);
127
128 static 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
137 static 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
152 if (gpio_data->gpio == gpio)
153 return n;
154
155 if (!gpio) {
156 if (gpio_data->gpio != 0)
157 free_irq(gpio_to_irq(gpio_data->gpio), led);
158 gpio_data->gpio = 0;
159 return n;
160 }
161
162 ret = request_irq(gpio_to_irq(gpio), gpio_trig_irq,
163 IRQF_SHARED | IRQF_TRIGGER_RISING
164 | IRQF_TRIGGER_FALLING, "ledtrig-gpio", led);
165 if (ret) {
166 dev_err(dev, "request_irq failed with error %d\n", ret);
167 } else {
168 if (gpio_data->gpio != 0)
169 free_irq(gpio_to_irq(gpio_data->gpio), led);
170 gpio_data->gpio = gpio;
171 }
172
173 return ret ? ret : n;
174 }
175 static DEVICE_ATTR(gpio, 0644, gpio_trig_gpio_show, gpio_trig_gpio_store);
176
177 static 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
204 err_brightness:
205 device_remove_file(led->dev, &dev_attr_inverted);
206
207 err_inverted:
208 device_remove_file(led->dev, &dev_attr_gpio);
209
210 err_gpio:
211 kfree(gpio_data);
212 }
213
214 static 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);
223 if (gpio_data->gpio != 0)
224 free_irq(gpio_to_irq(gpio_data->gpio), led);
225 kfree(gpio_data);
226 }
227 }
228
229 static struct led_trigger gpio_led_trigger = {
230 .name = "gpio",
231 .activate = gpio_trig_activate,
232 .deactivate = gpio_trig_deactivate,
233 };
234
235 static int __init gpio_trig_init(void)
236 {
237 return led_trigger_register(&gpio_led_trigger);
238 }
239 module_init(gpio_trig_init);
240
241 static void __exit gpio_trig_exit(void)
242 {
243 led_trigger_unregister(&gpio_led_trigger);
244 }
245 module_exit(gpio_trig_exit);
246
247 MODULE_AUTHOR("Felipe Balbi <me@felipebalbi.com>");
248 MODULE_DESCRIPTION("GPIO LED trigger");
249 MODULE_LICENSE("GPL");
250
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