summaryrefslogtreecommitdiff
path: root/drivers/leds/ledtrig-gpio.c
blob: f5913372d691a034bd18223a4494f568d337d27c (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
/*
 * ledtrig-gio.c - LED Trigger Based on GPIO events
 *
 * Copyright 2009 Felipe Balbi <me@felipebalbi.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/gpio.h>
#include <linux/interrupt.h>
#include <linux/workqueue.h>
#include <linux/leds.h>
#include "leds.h"

struct gpio_trig_data {
	struct led_classdev *led;
	struct work_struct work;

	unsigned desired_brightness;	/* desired brightness when led is on */
	unsigned inverted;		/* true when gpio is inverted */
	unsigned gpio;			/* gpio that triggers the leds */
};

static irqreturn_t gpio_trig_irq(int irq, void *_led)
{
	struct led_classdev *led = _led;
	struct gpio_trig_data *gpio_data = led->trigger_data;

	/* just schedule_work since gpio_get_value can sleep */
	schedule_work(&gpio_data->work);

	return IRQ_HANDLED;
};

static void gpio_trig_work(struct work_struct *work)
{
	struct gpio_trig_data *gpio_data = container_of(work,
			struct gpio_trig_data, work);
	int tmp;

	if (!gpio_data->gpio)
		return;

	tmp = gpio_get_value(gpio_data->gpio);
	if (gpio_data->inverted)
		tmp = !tmp;

	if (tmp) {
		if (gpio_data->desired_brightness)
			led_set_brightness(gpio_data->led,
					   gpio_data->desired_brightness);
		else
			led_set_brightness(gpio_data->led, LED_FULL);
	} else {
		led_set_brightness(gpio_data->led, LED_OFF);
	}
}

static ssize_t gpio_trig_brightness_show(struct device *dev,
		struct device_attribute *attr, char *buf)
{
	struct led_classdev *led = dev_get_drvdata(dev);
	struct gpio_trig_data *gpio_data = led->trigger_data;

	return sprintf(buf, "%u\n", gpio_data->desired_brightness);
}

static ssize_t gpio_trig_brightness_store(struct device *dev,
		struct device_attribute *attr, const char *buf, size_t n)
{
	struct led_classdev *led = dev_get_drvdata(dev);
	struct gpio_trig_data *gpio_data = led->trigger_data;
	unsigned desired_brightness;
	int ret;

	ret = sscanf(buf, "%u", &desired_brightness);
	if (ret < 1 || desired_brightness > 255) {
		dev_err(dev, "invalid value\n");
		return -EINVAL;
	}

	gpio_data->desired_brightness = desired_brightness;

	return n;
}
static DEVICE_ATTR(desired_brightness, 0644, gpio_trig_brightness_show,
		gpio_trig_brightness_store);

static ssize_t gpio_trig_inverted_show(struct device *dev,
		struct device_attribute *attr, char *buf)
{
	struct led_classdev *led = dev_get_drvdata(dev);
	struct gpio_trig_data *gpio_data = led->trigger_data;

	return sprintf(buf, "%s\n", gpio_data->inverted ? "yes" : "no");
}

static ssize_t gpio_trig_inverted_store(struct device *dev,
		struct device_attribute *attr, const char *buf, size_t n)
{
	struct led_classdev *led = dev_get_drvdata(dev);
	struct gpio_trig_data *gpio_data = led->trigger_data;
	unsigned inverted;
	int ret;

	ret = sscanf(buf, "%u", &inverted);
	if (ret < 1) {
		dev_err(dev, "invalid value\n");
		return -EINVAL;
	}

	gpio_data->inverted = !!inverted;

	/* After inverting, we need to update the LED. */
	schedule_work(&gpio_data->work);

	return n;
}
static DEVICE_ATTR(inverted, 0644, gpio_trig_inverted_show,
		gpio_trig_inverted_store);

static ssize_t gpio_trig_gpio_show(struct device *dev,
		struct device_attribute *attr, char *buf)
{
	struct led_classdev *led = dev_get_drvdata(dev);
	struct gpio_trig_data *gpio_data = led->trigger_data;

	return sprintf(buf, "%u\n", gpio_data->gpio);
}

static ssize_t gpio_trig_gpio_store(struct device *dev,
		struct device_attribute *attr, const char *buf, size_t n)
{
	struct led_classdev *led = dev_get_drvdata(dev);
	struct gpio_trig_data *gpio_data = led->trigger_data;
	unsigned gpio;
	int ret;

	ret = sscanf(buf, "%u", &gpio);
	if (ret < 1) {
		dev_err(dev, "couldn't read gpio number\n");
		flush_work(&gpio_data->work);
		return -EINVAL;
	}

	if (gpio_data->gpio == gpio)
		return n;

	if (!gpio) {
		if (gpio_data->gpio != 0)
			free_irq(gpio_to_irq(gpio_data->gpio), led);
		gpio_data->gpio = 0;
		return n;
	}

	ret = request_irq(gpio_to_irq(gpio), gpio_trig_irq,
			IRQF_SHARED | IRQF_TRIGGER_RISING
			| IRQF_TRIGGER_FALLING, "ledtrig-gpio", led);
	if (ret) {
		dev_err(dev, "request_irq failed with error %d\n", ret);
	} else {
		if (gpio_data->gpio != 0)
			free_irq(gpio_to_irq(gpio_data->gpio), led);
		gpio_data->gpio = gpio;
	}

	return ret ? ret : n;
}
static DEVICE_ATTR(gpio, 0644, gpio_trig_gpio_show, gpio_trig_gpio_store);

static void gpio_trig_activate(struct led_classdev *led)
{
	struct gpio_trig_data *gpio_data;
	int ret;

	gpio_data = kzalloc(sizeof(*gpio_data), GFP_KERNEL);
	if (!gpio_data)
		return;

	ret = device_create_file(led->dev, &dev_attr_gpio);
	if (ret)
		goto err_gpio;

	ret = device_create_file(led->dev, &dev_attr_inverted);
	if (ret)
		goto err_inverted;

	ret = device_create_file(led->dev, &dev_attr_desired_brightness);
	if (ret)
		goto err_brightness;

	gpio_data->led = led;
	led->trigger_data = gpio_data;
	INIT_WORK(&gpio_data->work, gpio_trig_work);

	return;

err_brightness:
	device_remove_file(led->dev, &dev_attr_inverted);

err_inverted:
	device_remove_file(led->dev, &dev_attr_gpio);

err_gpio:
	kfree(gpio_data);
}

static void gpio_trig_deactivate(struct led_classdev *led)
{
	struct gpio_trig_data *gpio_data = led->trigger_data;

	if (gpio_data) {
		device_remove_file(led->dev, &dev_attr_gpio);
		device_remove_file(led->dev, &dev_attr_inverted);
		device_remove_file(led->dev, &dev_attr_desired_brightness);
		flush_work(&gpio_data->work);
		if (gpio_data->gpio != 0)
			free_irq(gpio_to_irq(gpio_data->gpio), led);
		kfree(gpio_data);
	}
}

static struct led_trigger gpio_led_trigger = {
	.name		= "gpio",
	.activate	= gpio_trig_activate,
	.deactivate	= gpio_trig_deactivate,
};

static int __init gpio_trig_init(void)
{
	return led_trigger_register(&gpio_led_trigger);
}
module_init(gpio_trig_init);

static void __exit gpio_trig_exit(void)
{
	led_trigger_unregister(&gpio_led_trigger);
}
module_exit(gpio_trig_exit);

MODULE_AUTHOR("Felipe Balbi <me@felipebalbi.com>");
MODULE_DESCRIPTION("GPIO LED trigger");
MODULE_LICENSE("GPL");