Root/drivers/leds/led-class.c

1/*
2 * LED Class Core
3 *
4 * Copyright (C) 2005 John Lenz <lenz@cs.wisc.edu>
5 * Copyright (C) 2005-2007 Richard Purdie <rpurdie@openedhand.com>
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation.
10 */
11
12#include <linux/module.h>
13#include <linux/kernel.h>
14#include <linux/init.h>
15#include <linux/list.h>
16#include <linux/spinlock.h>
17#include <linux/device.h>
18#include <linux/timer.h>
19#include <linux/err.h>
20#include <linux/ctype.h>
21#include <linux/leds.h>
22#include "leds.h"
23
24static struct class *leds_class;
25
26static void led_update_brightness(struct led_classdev *led_cdev)
27{
28    if (led_cdev->brightness_get)
29        led_cdev->brightness = led_cdev->brightness_get(led_cdev);
30}
31
32static ssize_t led_brightness_show(struct device *dev,
33        struct device_attribute *attr, char *buf)
34{
35    struct led_classdev *led_cdev = dev_get_drvdata(dev);
36
37    /* no lock needed for this */
38    led_update_brightness(led_cdev);
39
40    return sprintf(buf, "%u\n", led_cdev->brightness);
41}
42
43static ssize_t led_brightness_store(struct device *dev,
44        struct device_attribute *attr, const char *buf, size_t size)
45{
46    struct led_classdev *led_cdev = dev_get_drvdata(dev);
47    unsigned long state;
48    ssize_t ret = -EINVAL;
49
50    ret = kstrtoul(buf, 10, &state);
51    if (ret)
52        return ret;
53
54    if (state == LED_OFF)
55        led_trigger_remove(led_cdev);
56    __led_set_brightness(led_cdev, state);
57
58    return size;
59}
60
61static ssize_t led_max_brightness_show(struct device *dev,
62        struct device_attribute *attr, char *buf)
63{
64    struct led_classdev *led_cdev = dev_get_drvdata(dev);
65
66    return sprintf(buf, "%u\n", led_cdev->max_brightness);
67}
68
69static struct device_attribute led_class_attrs[] = {
70    __ATTR(brightness, 0644, led_brightness_show, led_brightness_store),
71    __ATTR(max_brightness, 0444, led_max_brightness_show, NULL),
72#ifdef CONFIG_LEDS_TRIGGERS
73    __ATTR(trigger, 0644, led_trigger_show, led_trigger_store),
74#endif
75    __ATTR_NULL,
76};
77
78static void led_timer_function(unsigned long data)
79{
80    struct led_classdev *led_cdev = (void *)data;
81    unsigned long brightness;
82    unsigned long delay;
83
84    if (!led_cdev->blink_delay_on || !led_cdev->blink_delay_off) {
85        __led_set_brightness(led_cdev, LED_OFF);
86        return;
87    }
88
89    if (led_cdev->flags & LED_BLINK_ONESHOT_STOP) {
90        led_cdev->flags &= ~LED_BLINK_ONESHOT_STOP;
91        return;
92    }
93
94    brightness = led_get_brightness(led_cdev);
95    if (!brightness) {
96        /* Time to switch the LED on. */
97        brightness = led_cdev->blink_brightness;
98        delay = led_cdev->blink_delay_on;
99    } else {
100        /* Store the current brightness value to be able
101         * to restore it when the delay_off period is over.
102         */
103        led_cdev->blink_brightness = brightness;
104        brightness = LED_OFF;
105        delay = led_cdev->blink_delay_off;
106    }
107
108    __led_set_brightness(led_cdev, brightness);
109
110    /* Return in next iteration if led is in one-shot mode and we are in
111     * the final blink state so that the led is toggled each delay_on +
112     * delay_off milliseconds in worst case.
113     */
114    if (led_cdev->flags & LED_BLINK_ONESHOT) {
115        if (led_cdev->flags & LED_BLINK_INVERT) {
116            if (brightness)
117                led_cdev->flags |= LED_BLINK_ONESHOT_STOP;
118        } else {
119            if (!brightness)
120                led_cdev->flags |= LED_BLINK_ONESHOT_STOP;
121        }
122    }
123
124    mod_timer(&led_cdev->blink_timer, jiffies + msecs_to_jiffies(delay));
125}
126
127static void set_brightness_delayed(struct work_struct *ws)
128{
129    struct led_classdev *led_cdev =
130        container_of(ws, struct led_classdev, set_brightness_work);
131
132    led_stop_software_blink(led_cdev);
133
134    __led_set_brightness(led_cdev, led_cdev->delayed_set_value);
135}
136
137/**
138 * led_classdev_suspend - suspend an led_classdev.
139 * @led_cdev: the led_classdev to suspend.
140 */
141void led_classdev_suspend(struct led_classdev *led_cdev)
142{
143    led_cdev->flags |= LED_SUSPENDED;
144    led_cdev->brightness_set(led_cdev, 0);
145}
146EXPORT_SYMBOL_GPL(led_classdev_suspend);
147
148/**
149 * led_classdev_resume - resume an led_classdev.
150 * @led_cdev: the led_classdev to resume.
151 */
152void led_classdev_resume(struct led_classdev *led_cdev)
153{
154    led_cdev->brightness_set(led_cdev, led_cdev->brightness);
155    led_cdev->flags &= ~LED_SUSPENDED;
156}
157EXPORT_SYMBOL_GPL(led_classdev_resume);
158
159static int led_suspend(struct device *dev, pm_message_t state)
160{
161    struct led_classdev *led_cdev = dev_get_drvdata(dev);
162
163    if (led_cdev->flags & LED_CORE_SUSPENDRESUME)
164        led_classdev_suspend(led_cdev);
165
166    return 0;
167}
168
169static int led_resume(struct device *dev)
170{
171    struct led_classdev *led_cdev = dev_get_drvdata(dev);
172
173    if (led_cdev->flags & LED_CORE_SUSPENDRESUME)
174        led_classdev_resume(led_cdev);
175
176    return 0;
177}
178
179/**
180 * led_classdev_register - register a new object of led_classdev class.
181 * @parent: The device to register.
182 * @led_cdev: the led_classdev structure for this device.
183 */
184int led_classdev_register(struct device *parent, struct led_classdev *led_cdev)
185{
186    led_cdev->dev = device_create(leds_class, parent, 0, led_cdev,
187                      "%s", led_cdev->name);
188    if (IS_ERR(led_cdev->dev))
189        return PTR_ERR(led_cdev->dev);
190
191#ifdef CONFIG_LEDS_TRIGGERS
192    init_rwsem(&led_cdev->trigger_lock);
193#endif
194    /* add to the list of leds */
195    down_write(&leds_list_lock);
196    list_add_tail(&led_cdev->node, &leds_list);
197    up_write(&leds_list_lock);
198
199    if (!led_cdev->max_brightness)
200        led_cdev->max_brightness = LED_FULL;
201
202    led_update_brightness(led_cdev);
203
204    INIT_WORK(&led_cdev->set_brightness_work, set_brightness_delayed);
205
206    init_timer(&led_cdev->blink_timer);
207    led_cdev->blink_timer.function = led_timer_function;
208    led_cdev->blink_timer.data = (unsigned long)led_cdev;
209
210#ifdef CONFIG_LEDS_TRIGGERS
211    led_trigger_set_default(led_cdev);
212#endif
213
214    dev_dbg(parent, "Registered led device: %s\n",
215            led_cdev->name);
216
217    return 0;
218}
219EXPORT_SYMBOL_GPL(led_classdev_register);
220
221/**
222 * led_classdev_unregister - unregisters a object of led_properties class.
223 * @led_cdev: the led device to unregister
224 *
225 * Unregisters a previously registered via led_classdev_register object.
226 */
227void led_classdev_unregister(struct led_classdev *led_cdev)
228{
229#ifdef CONFIG_LEDS_TRIGGERS
230    down_write(&led_cdev->trigger_lock);
231    if (led_cdev->trigger)
232        led_trigger_set(led_cdev, NULL);
233    up_write(&led_cdev->trigger_lock);
234#endif
235
236    cancel_work_sync(&led_cdev->set_brightness_work);
237
238    /* Stop blinking */
239    led_stop_software_blink(led_cdev);
240    led_set_brightness(led_cdev, LED_OFF);
241
242    device_unregister(led_cdev->dev);
243
244    down_write(&leds_list_lock);
245    list_del(&led_cdev->node);
246    up_write(&leds_list_lock);
247}
248EXPORT_SYMBOL_GPL(led_classdev_unregister);
249
250static int __init leds_init(void)
251{
252    leds_class = class_create(THIS_MODULE, "leds");
253    if (IS_ERR(leds_class))
254        return PTR_ERR(leds_class);
255    leds_class->suspend = led_suspend;
256    leds_class->resume = led_resume;
257    leds_class->dev_attrs = led_class_attrs;
258    return 0;
259}
260
261static void __exit leds_exit(void)
262{
263    class_destroy(leds_class);
264}
265
266subsys_initcall(leds_init);
267module_exit(leds_exit);
268
269MODULE_AUTHOR("John Lenz, Richard Purdie");
270MODULE_LICENSE("GPL");
271MODULE_DESCRIPTION("LED Class Interface");
272

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