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 <linux/slab.h>
20 #include "../leds.h"
21
22 struct gpio_trig_data {
23 struct led_classdev *led;
24 struct work_struct work;
25
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 */
29 };
30
gpio_trig_irq(int irq,void * _led)31 static irqreturn_t gpio_trig_irq(int irq, void *_led)
32 {
33 struct led_classdev *led = _led;
34 struct gpio_trig_data *gpio_data = led->trigger_data;
35
36 /* just schedule_work since gpio_get_value can sleep */
37 schedule_work(&gpio_data->work);
38
39 return IRQ_HANDLED;
40 };
41
gpio_trig_work(struct work_struct * work)42 static void gpio_trig_work(struct work_struct *work)
43 {
44 struct gpio_trig_data *gpio_data = container_of(work,
45 struct gpio_trig_data, work);
46 int tmp;
47
48 if (!gpio_data->gpio)
49 return;
50
51 tmp = gpio_get_value_cansleep(gpio_data->gpio);
52 if (gpio_data->inverted)
53 tmp = !tmp;
54
55 if (tmp) {
56 if (gpio_data->desired_brightness)
57 __led_set_brightness(gpio_data->led,
58 gpio_data->desired_brightness);
59 else
60 __led_set_brightness(gpio_data->led, LED_FULL);
61 } else {
62 __led_set_brightness(gpio_data->led, LED_OFF);
63 }
64 }
65
gpio_trig_brightness_show(struct device * dev,struct device_attribute * attr,char * buf)66 static ssize_t gpio_trig_brightness_show(struct device *dev,
67 struct device_attribute *attr, char *buf)
68 {
69 struct led_classdev *led = dev_get_drvdata(dev);
70 struct gpio_trig_data *gpio_data = led->trigger_data;
71
72 return sprintf(buf, "%u\n", gpio_data->desired_brightness);
73 }
74
gpio_trig_brightness_store(struct device * dev,struct device_attribute * attr,const char * buf,size_t n)75 static ssize_t gpio_trig_brightness_store(struct device *dev,
76 struct device_attribute *attr, const char *buf, size_t n)
77 {
78 struct led_classdev *led = dev_get_drvdata(dev);
79 struct gpio_trig_data *gpio_data = led->trigger_data;
80 unsigned desired_brightness;
81 int ret;
82
83 ret = sscanf(buf, "%u", &desired_brightness);
84 if (ret < 1 || desired_brightness > 255) {
85 dev_err(dev, "invalid value\n");
86 return -EINVAL;
87 }
88
89 gpio_data->desired_brightness = desired_brightness;
90
91 return n;
92 }
93 static DEVICE_ATTR(desired_brightness, 0644, gpio_trig_brightness_show,
94 gpio_trig_brightness_store);
95
gpio_trig_inverted_show(struct device * dev,struct device_attribute * attr,char * buf)96 static ssize_t gpio_trig_inverted_show(struct device *dev,
97 struct device_attribute *attr, char *buf)
98 {
99 struct led_classdev *led = dev_get_drvdata(dev);
100 struct gpio_trig_data *gpio_data = led->trigger_data;
101
102 return sprintf(buf, "%u\n", gpio_data->inverted);
103 }
104
gpio_trig_inverted_store(struct device * dev,struct device_attribute * attr,const char * buf,size_t n)105 static ssize_t gpio_trig_inverted_store(struct device *dev,
106 struct device_attribute *attr, const char *buf, size_t n)
107 {
108 struct led_classdev *led = dev_get_drvdata(dev);
109 struct gpio_trig_data *gpio_data = led->trigger_data;
110 unsigned long inverted;
111 int ret;
112
113 ret = kstrtoul(buf, 10, &inverted);
114 if (ret < 0)
115 return ret;
116
117 if (inverted > 1)
118 return -EINVAL;
119
120 gpio_data->inverted = inverted;
121
122 /* After inverting, we need to update the LED. */
123 schedule_work(&gpio_data->work);
124
125 return n;
126 }
127 static DEVICE_ATTR(inverted, 0644, gpio_trig_inverted_show,
128 gpio_trig_inverted_store);
129
gpio_trig_gpio_show(struct device * dev,struct device_attribute * attr,char * buf)130 static ssize_t gpio_trig_gpio_show(struct device *dev,
131 struct device_attribute *attr, char *buf)
132 {
133 struct led_classdev *led = dev_get_drvdata(dev);
134 struct gpio_trig_data *gpio_data = led->trigger_data;
135
136 return sprintf(buf, "%u\n", gpio_data->gpio);
137 }
138
gpio_trig_gpio_store(struct device * dev,struct device_attribute * attr,const char * buf,size_t n)139 static ssize_t gpio_trig_gpio_store(struct device *dev,
140 struct device_attribute *attr, const char *buf, size_t n)
141 {
142 struct led_classdev *led = dev_get_drvdata(dev);
143 struct gpio_trig_data *gpio_data = led->trigger_data;
144 unsigned gpio;
145 int ret;
146
147 ret = sscanf(buf, "%u", &gpio);
148 if (ret < 1) {
149 dev_err(dev, "couldn't read gpio number\n");
150 flush_work(&gpio_data->work);
151 return -EINVAL;
152 }
153
154 if (gpio_data->gpio == gpio)
155 return n;
156
157 if (!gpio) {
158 if (gpio_data->gpio != 0)
159 free_irq(gpio_to_irq(gpio_data->gpio), led);
160 gpio_data->gpio = 0;
161 return n;
162 }
163
164 ret = request_irq(gpio_to_irq(gpio), gpio_trig_irq,
165 IRQF_SHARED | IRQF_TRIGGER_RISING
166 | IRQF_TRIGGER_FALLING, "ledtrig-gpio", led);
167 if (ret) {
168 dev_err(dev, "request_irq failed with error %d\n", ret);
169 } else {
170 if (gpio_data->gpio != 0)
171 free_irq(gpio_to_irq(gpio_data->gpio), led);
172 gpio_data->gpio = gpio;
173 }
174
175 return ret ? ret : n;
176 }
177 static DEVICE_ATTR(gpio, 0644, gpio_trig_gpio_show, gpio_trig_gpio_store);
178
gpio_trig_activate(struct led_classdev * led)179 static void gpio_trig_activate(struct led_classdev *led)
180 {
181 struct gpio_trig_data *gpio_data;
182 int ret;
183
184 gpio_data = kzalloc(sizeof(*gpio_data), GFP_KERNEL);
185 if (!gpio_data)
186 return;
187
188 ret = device_create_file(led->dev, &dev_attr_gpio);
189 if (ret)
190 goto err_gpio;
191
192 ret = device_create_file(led->dev, &dev_attr_inverted);
193 if (ret)
194 goto err_inverted;
195
196 ret = device_create_file(led->dev, &dev_attr_desired_brightness);
197 if (ret)
198 goto err_brightness;
199
200 gpio_data->led = led;
201 led->trigger_data = gpio_data;
202 INIT_WORK(&gpio_data->work, gpio_trig_work);
203 led->activated = true;
204
205 return;
206
207 err_brightness:
208 device_remove_file(led->dev, &dev_attr_inverted);
209
210 err_inverted:
211 device_remove_file(led->dev, &dev_attr_gpio);
212
213 err_gpio:
214 kfree(gpio_data);
215 }
216
gpio_trig_deactivate(struct led_classdev * led)217 static void gpio_trig_deactivate(struct led_classdev *led)
218 {
219 struct gpio_trig_data *gpio_data = led->trigger_data;
220
221 if (led->activated) {
222 device_remove_file(led->dev, &dev_attr_gpio);
223 device_remove_file(led->dev, &dev_attr_inverted);
224 device_remove_file(led->dev, &dev_attr_desired_brightness);
225 flush_work(&gpio_data->work);
226 if (gpio_data->gpio != 0)
227 free_irq(gpio_to_irq(gpio_data->gpio), led);
228 kfree(gpio_data);
229 led->activated = false;
230 }
231 }
232
233 static struct led_trigger gpio_led_trigger = {
234 .name = "gpio",
235 .activate = gpio_trig_activate,
236 .deactivate = gpio_trig_deactivate,
237 };
238
gpio_trig_init(void)239 static int __init gpio_trig_init(void)
240 {
241 return led_trigger_register(&gpio_led_trigger);
242 }
243 module_init(gpio_trig_init);
244
gpio_trig_exit(void)245 static void __exit gpio_trig_exit(void)
246 {
247 led_trigger_unregister(&gpio_led_trigger);
248 }
249 module_exit(gpio_trig_exit);
250
251 MODULE_AUTHOR("Felipe Balbi <me@felipebalbi.com>");
252 MODULE_DESCRIPTION("GPIO LED trigger");
253 MODULE_LICENSE("GPL");
254