Root/drivers/leds/ledtrig-gpio.c

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 = 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}
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    led->activated = true;
204
205    return;
206
207err_brightness:
208    device_remove_file(led->dev, &dev_attr_inverted);
209
210err_inverted:
211    device_remove_file(led->dev, &dev_attr_gpio);
212
213err_gpio:
214    kfree(gpio_data);
215}
216
217static 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
233static struct led_trigger gpio_led_trigger = {
234    .name = "gpio",
235    .activate = gpio_trig_activate,
236    .deactivate = gpio_trig_deactivate,
237};
238
239static int __init gpio_trig_init(void)
240{
241    return led_trigger_register(&gpio_led_trigger);
242}
243module_init(gpio_trig_init);
244
245static void __exit gpio_trig_exit(void)
246{
247    led_trigger_unregister(&gpio_led_trigger);
248}
249module_exit(gpio_trig_exit);
250
251MODULE_AUTHOR("Felipe Balbi <me@felipebalbi.com>");
252MODULE_DESCRIPTION("GPIO LED trigger");
253MODULE_LICENSE("GPL");
254

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