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
22struct 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
31static 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
42static 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(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
66static 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
75static 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}
93static DEVICE_ATTR(desired_brightness, 0644, gpio_trig_brightness_show,
94		gpio_trig_brightness_store);
95
96static 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
105static 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 = strict_strtoul(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}
127static DEVICE_ATTR(inverted, 0644, gpio_trig_inverted_show,
128		gpio_trig_inverted_store);
129
130static 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
139static 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}
177static DEVICE_ATTR(gpio, 0644, gpio_trig_gpio_show, gpio_trig_gpio_store);
178
179static 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
204	return;
205
206err_brightness:
207	device_remove_file(led->dev, &dev_attr_inverted);
208
209err_inverted:
210	device_remove_file(led->dev, &dev_attr_gpio);
211
212err_gpio:
213	kfree(gpio_data);
214}
215
216static void gpio_trig_deactivate(struct led_classdev *led)
217{
218	struct gpio_trig_data *gpio_data = led->trigger_data;
219
220	if (gpio_data) {
221		device_remove_file(led->dev, &dev_attr_gpio);
222		device_remove_file(led->dev, &dev_attr_inverted);
223		device_remove_file(led->dev, &dev_attr_desired_brightness);
224		flush_work(&gpio_data->work);
225		if (gpio_data->gpio != 0)
226			free_irq(gpio_to_irq(gpio_data->gpio), led);
227		kfree(gpio_data);
228	}
229}
230
231static struct led_trigger gpio_led_trigger = {
232	.name		= "gpio",
233	.activate	= gpio_trig_activate,
234	.deactivate	= gpio_trig_deactivate,
235};
236
237static int __init gpio_trig_init(void)
238{
239	return led_trigger_register(&gpio_led_trigger);
240}
241module_init(gpio_trig_init);
242
243static void __exit gpio_trig_exit(void)
244{
245	led_trigger_unregister(&gpio_led_trigger);
246}
247module_exit(gpio_trig_exit);
248
249MODULE_AUTHOR("Felipe Balbi <me@felipebalbi.com>");
250MODULE_DESCRIPTION("GPIO LED trigger");
251MODULE_LICENSE("GPL");
252