linux/drivers/leds/led-class.c
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   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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