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/leds.h>
18 #include <linux/slab.h>
19 #include "../leds.h"
20
21 struct gpio_trig_data {
22 struct led_classdev *led;
23
24 unsigned desired_brightness; /* desired brightness when led is on */
25 unsigned inverted; /* true when gpio is inverted */
26 unsigned gpio; /* gpio that triggers the leds */
27 };
28
gpio_trig_irq(int irq,void * _led)29 static irqreturn_t gpio_trig_irq(int irq, void *_led)
30 {
31 struct led_classdev *led = _led;
32 struct gpio_trig_data *gpio_data = led->trigger_data;
33 int tmp;
34
35 tmp = gpio_get_value_cansleep(gpio_data->gpio);
36 if (gpio_data->inverted)
37 tmp = !tmp;
38
39 if (tmp) {
40 if (gpio_data->desired_brightness)
41 led_set_brightness_nosleep(gpio_data->led,
42 gpio_data->desired_brightness);
43 else
44 led_set_brightness_nosleep(gpio_data->led, LED_FULL);
45 } else {
46 led_set_brightness_nosleep(gpio_data->led, LED_OFF);
47 }
48
49 return IRQ_HANDLED;
50 }
51
gpio_trig_brightness_show(struct device * dev,struct device_attribute * attr,char * buf)52 static ssize_t gpio_trig_brightness_show(struct device *dev,
53 struct device_attribute *attr, char *buf)
54 {
55 struct led_classdev *led = dev_get_drvdata(dev);
56 struct gpio_trig_data *gpio_data = led->trigger_data;
57
58 return sprintf(buf, "%u\n", gpio_data->desired_brightness);
59 }
60
gpio_trig_brightness_store(struct device * dev,struct device_attribute * attr,const char * buf,size_t n)61 static ssize_t gpio_trig_brightness_store(struct device *dev,
62 struct device_attribute *attr, const char *buf, size_t n)
63 {
64 struct led_classdev *led = dev_get_drvdata(dev);
65 struct gpio_trig_data *gpio_data = led->trigger_data;
66 unsigned desired_brightness;
67 int ret;
68
69 ret = sscanf(buf, "%u", &desired_brightness);
70 if (ret < 1 || desired_brightness > 255) {
71 dev_err(dev, "invalid value\n");
72 return -EINVAL;
73 }
74
75 gpio_data->desired_brightness = desired_brightness;
76
77 return n;
78 }
79 static DEVICE_ATTR(desired_brightness, 0644, gpio_trig_brightness_show,
80 gpio_trig_brightness_store);
81
gpio_trig_inverted_show(struct device * dev,struct device_attribute * attr,char * buf)82 static ssize_t gpio_trig_inverted_show(struct device *dev,
83 struct device_attribute *attr, char *buf)
84 {
85 struct led_classdev *led = dev_get_drvdata(dev);
86 struct gpio_trig_data *gpio_data = led->trigger_data;
87
88 return sprintf(buf, "%u\n", gpio_data->inverted);
89 }
90
gpio_trig_inverted_store(struct device * dev,struct device_attribute * attr,const char * buf,size_t n)91 static ssize_t gpio_trig_inverted_store(struct device *dev,
92 struct device_attribute *attr, const char *buf, size_t n)
93 {
94 struct led_classdev *led = dev_get_drvdata(dev);
95 struct gpio_trig_data *gpio_data = led->trigger_data;
96 unsigned long inverted;
97 int ret;
98
99 ret = kstrtoul(buf, 10, &inverted);
100 if (ret < 0)
101 return ret;
102
103 if (inverted > 1)
104 return -EINVAL;
105
106 gpio_data->inverted = inverted;
107
108 /* After inverting, we need to update the LED. */
109 gpio_trig_irq(0, led);
110
111 return n;
112 }
113 static DEVICE_ATTR(inverted, 0644, gpio_trig_inverted_show,
114 gpio_trig_inverted_store);
115
gpio_trig_gpio_show(struct device * dev,struct device_attribute * attr,char * buf)116 static ssize_t gpio_trig_gpio_show(struct device *dev,
117 struct device_attribute *attr, char *buf)
118 {
119 struct led_classdev *led = dev_get_drvdata(dev);
120 struct gpio_trig_data *gpio_data = led->trigger_data;
121
122 return sprintf(buf, "%u\n", gpio_data->gpio);
123 }
124
gpio_trig_gpio_store(struct device * dev,struct device_attribute * attr,const char * buf,size_t n)125 static ssize_t gpio_trig_gpio_store(struct device *dev,
126 struct device_attribute *attr, const char *buf, size_t n)
127 {
128 struct led_classdev *led = dev_get_drvdata(dev);
129 struct gpio_trig_data *gpio_data = led->trigger_data;
130 unsigned gpio;
131 int ret;
132
133 ret = sscanf(buf, "%u", &gpio);
134 if (ret < 1) {
135 dev_err(dev, "couldn't read gpio number\n");
136 return -EINVAL;
137 }
138
139 if (gpio_data->gpio == gpio)
140 return n;
141
142 if (!gpio) {
143 if (gpio_data->gpio != 0)
144 free_irq(gpio_to_irq(gpio_data->gpio), led);
145 gpio_data->gpio = 0;
146 return n;
147 }
148
149 ret = request_threaded_irq(gpio_to_irq(gpio), NULL, gpio_trig_irq,
150 IRQF_ONESHOT | IRQF_SHARED | IRQF_TRIGGER_RISING
151 | IRQF_TRIGGER_FALLING, "ledtrig-gpio", led);
152 if (ret) {
153 dev_err(dev, "request_irq failed with error %d\n", ret);
154 } else {
155 if (gpio_data->gpio != 0)
156 free_irq(gpio_to_irq(gpio_data->gpio), led);
157 gpio_data->gpio = gpio;
158 /* After changing the GPIO, we need to update the LED. */
159 gpio_trig_irq(0, led);
160 }
161
162 return ret ? ret : n;
163 }
164 static DEVICE_ATTR(gpio, 0644, gpio_trig_gpio_show, gpio_trig_gpio_store);
165
gpio_trig_activate(struct led_classdev * led)166 static void gpio_trig_activate(struct led_classdev *led)
167 {
168 struct gpio_trig_data *gpio_data;
169 int ret;
170
171 gpio_data = kzalloc(sizeof(*gpio_data), GFP_KERNEL);
172 if (!gpio_data)
173 return;
174
175 ret = device_create_file(led->dev, &dev_attr_gpio);
176 if (ret)
177 goto err_gpio;
178
179 ret = device_create_file(led->dev, &dev_attr_inverted);
180 if (ret)
181 goto err_inverted;
182
183 ret = device_create_file(led->dev, &dev_attr_desired_brightness);
184 if (ret)
185 goto err_brightness;
186
187 gpio_data->led = led;
188 led->trigger_data = gpio_data;
189 led->activated = true;
190
191 return;
192
193 err_brightness:
194 device_remove_file(led->dev, &dev_attr_inverted);
195
196 err_inverted:
197 device_remove_file(led->dev, &dev_attr_gpio);
198
199 err_gpio:
200 kfree(gpio_data);
201 }
202
gpio_trig_deactivate(struct led_classdev * led)203 static void gpio_trig_deactivate(struct led_classdev *led)
204 {
205 struct gpio_trig_data *gpio_data = led->trigger_data;
206
207 if (led->activated) {
208 device_remove_file(led->dev, &dev_attr_gpio);
209 device_remove_file(led->dev, &dev_attr_inverted);
210 device_remove_file(led->dev, &dev_attr_desired_brightness);
211 if (gpio_data->gpio != 0)
212 free_irq(gpio_to_irq(gpio_data->gpio), led);
213 kfree(gpio_data);
214 led->activated = false;
215 }
216 }
217
218 static struct led_trigger gpio_led_trigger = {
219 .name = "gpio",
220 .activate = gpio_trig_activate,
221 .deactivate = gpio_trig_deactivate,
222 };
223
gpio_trig_init(void)224 static int __init gpio_trig_init(void)
225 {
226 return led_trigger_register(&gpio_led_trigger);
227 }
228 module_init(gpio_trig_init);
229
gpio_trig_exit(void)230 static void __exit gpio_trig_exit(void)
231 {
232 led_trigger_unregister(&gpio_led_trigger);
233 }
234 module_exit(gpio_trig_exit);
235
236 MODULE_AUTHOR("Felipe Balbi <me@felipebalbi.com>");
237 MODULE_DESCRIPTION("GPIO LED trigger");
238 MODULE_LICENSE("GPL");
239