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        ssize_t ret = -EINVAL;
  48        char *after;
  49        unsigned long state = simple_strtoul(buf, &after, 10);
  50        size_t count = after - buf;
  51
  52        if (isspace(*after))
  53                count++;
  54
  55        if (count == size) {
  56                ret = count;
  57
  58                if (state == LED_OFF)
  59                        led_trigger_remove(led_cdev);
  60                led_set_brightness(led_cdev, state);
  61        }
  62
  63        return ret;
  64}
  65
  66static ssize_t led_max_brightness_show(struct device *dev,
  67                struct device_attribute *attr, char *buf)
  68{
  69        struct led_classdev *led_cdev = dev_get_drvdata(dev);
  70
  71        return sprintf(buf, "%u\n", led_cdev->max_brightness);
  72}
  73
  74static struct device_attribute led_class_attrs[] = {
  75        __ATTR(brightness, 0644, led_brightness_show, led_brightness_store),
  76        __ATTR(max_brightness, 0444, led_max_brightness_show, NULL),
  77#ifdef CONFIG_LEDS_TRIGGERS
  78        __ATTR(trigger, 0644, led_trigger_show, led_trigger_store),
  79#endif
  80        __ATTR_NULL,
  81};
  82
  83static void led_timer_function(unsigned long data)
  84{
  85        struct led_classdev *led_cdev = (void *)data;
  86        unsigned long brightness;
  87        unsigned long delay;
  88
  89        if (!led_cdev->blink_delay_on || !led_cdev->blink_delay_off) {
  90                led_set_brightness(led_cdev, LED_OFF);
  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        mod_timer(&led_cdev->blink_timer, jiffies + msecs_to_jiffies(delay));
 111}
 112
 113static void led_stop_software_blink(struct led_classdev *led_cdev)
 114{
 115        /* deactivate previous settings */
 116        del_timer_sync(&led_cdev->blink_timer);
 117        led_cdev->blink_delay_on = 0;
 118        led_cdev->blink_delay_off = 0;
 119}
 120
 121static void led_set_software_blink(struct led_classdev *led_cdev,
 122                                   unsigned long delay_on,
 123                                   unsigned long delay_off)
 124{
 125        int current_brightness;
 126
 127        current_brightness = led_get_brightness(led_cdev);
 128        if (current_brightness)
 129                led_cdev->blink_brightness = current_brightness;
 130        if (!led_cdev->blink_brightness)
 131                led_cdev->blink_brightness = led_cdev->max_brightness;
 132
 133        if (led_get_trigger_data(led_cdev) &&
 134            delay_on == led_cdev->blink_delay_on &&
 135            delay_off == led_cdev->blink_delay_off)
 136                return;
 137
 138        led_stop_software_blink(led_cdev);
 139
 140        led_cdev->blink_delay_on = delay_on;
 141        led_cdev->blink_delay_off = delay_off;
 142
 143        /* never on - don't blink */
 144        if (!delay_on)
 145                return;
 146
 147        /* never off - just set to brightness */
 148        if (!delay_off) {
 149                led_set_brightness(led_cdev, led_cdev->blink_brightness);
 150                return;
 151        }
 152
 153        mod_timer(&led_cdev->blink_timer, jiffies + 1);
 154}
 155
 156
 157/**
 158 * led_classdev_suspend - suspend an led_classdev.
 159 * @led_cdev: the led_classdev to suspend.
 160 */
 161void led_classdev_suspend(struct led_classdev *led_cdev)
 162{
 163        led_cdev->flags |= LED_SUSPENDED;
 164        led_cdev->brightness_set(led_cdev, 0);
 165}
 166EXPORT_SYMBOL_GPL(led_classdev_suspend);
 167
 168/**
 169 * led_classdev_resume - resume an led_classdev.
 170 * @led_cdev: the led_classdev to resume.
 171 */
 172void led_classdev_resume(struct led_classdev *led_cdev)
 173{
 174        led_cdev->brightness_set(led_cdev, led_cdev->brightness);
 175        led_cdev->flags &= ~LED_SUSPENDED;
 176}
 177EXPORT_SYMBOL_GPL(led_classdev_resume);
 178
 179static int led_suspend(struct device *dev, pm_message_t state)
 180{
 181        struct led_classdev *led_cdev = dev_get_drvdata(dev);
 182
 183        if (led_cdev->flags & LED_CORE_SUSPENDRESUME)
 184                led_classdev_suspend(led_cdev);
 185
 186        return 0;
 187}
 188
 189static int led_resume(struct device *dev)
 190{
 191        struct led_classdev *led_cdev = dev_get_drvdata(dev);
 192
 193        if (led_cdev->flags & LED_CORE_SUSPENDRESUME)
 194                led_classdev_resume(led_cdev);
 195
 196        return 0;
 197}
 198
 199/**
 200 * led_classdev_register - register a new object of led_classdev class.
 201 * @parent: The device to register.
 202 * @led_cdev: the led_classdev structure for this device.
 203 */
 204int led_classdev_register(struct device *parent, struct led_classdev *led_cdev)
 205{
 206        led_cdev->dev = device_create(leds_class, parent, 0, led_cdev,
 207                                      "%s", led_cdev->name);
 208        if (IS_ERR(led_cdev->dev))
 209                return PTR_ERR(led_cdev->dev);
 210
 211#ifdef CONFIG_LEDS_TRIGGERS
 212        init_rwsem(&led_cdev->trigger_lock);
 213#endif
 214        /* add to the list of leds */
 215        down_write(&leds_list_lock);
 216        list_add_tail(&led_cdev->node, &leds_list);
 217        up_write(&leds_list_lock);
 218
 219        if (!led_cdev->max_brightness)
 220                led_cdev->max_brightness = LED_FULL;
 221
 222        led_update_brightness(led_cdev);
 223
 224        init_timer(&led_cdev->blink_timer);
 225        led_cdev->blink_timer.function = led_timer_function;
 226        led_cdev->blink_timer.data = (unsigned long)led_cdev;
 227
 228#ifdef CONFIG_LEDS_TRIGGERS
 229        led_trigger_set_default(led_cdev);
 230#endif
 231
 232        printk(KERN_DEBUG "Registered led device: %s\n",
 233                        led_cdev->name);
 234
 235        return 0;
 236}
 237EXPORT_SYMBOL_GPL(led_classdev_register);
 238
 239/**
 240 * led_classdev_unregister - unregisters a object of led_properties class.
 241 * @led_cdev: the led device to unregister
 242 *
 243 * Unregisters a previously registered via led_classdev_register object.
 244 */
 245void led_classdev_unregister(struct led_classdev *led_cdev)
 246{
 247#ifdef CONFIG_LEDS_TRIGGERS
 248        down_write(&led_cdev->trigger_lock);
 249        if (led_cdev->trigger)
 250                led_trigger_set(led_cdev, NULL);
 251        up_write(&led_cdev->trigger_lock);
 252#endif
 253
 254        /* Stop blinking */
 255        led_brightness_set(led_cdev, LED_OFF);
 256
 257        device_unregister(led_cdev->dev);
 258
 259        down_write(&leds_list_lock);
 260        list_del(&led_cdev->node);
 261        up_write(&leds_list_lock);
 262}
 263EXPORT_SYMBOL_GPL(led_classdev_unregister);
 264
 265void led_blink_set(struct led_classdev *led_cdev,
 266                   unsigned long *delay_on,
 267                   unsigned long *delay_off)
 268{
 269        del_timer_sync(&led_cdev->blink_timer);
 270
 271        if (led_cdev->blink_set &&
 272            !led_cdev->blink_set(led_cdev, delay_on, delay_off))
 273                return;
 274
 275        /* blink with 1 Hz as default if nothing specified */
 276        if (!*delay_on && !*delay_off)
 277                *delay_on = *delay_off = 500;
 278
 279        led_set_software_blink(led_cdev, *delay_on, *delay_off);
 280}
 281EXPORT_SYMBOL(led_blink_set);
 282
 283void led_brightness_set(struct led_classdev *led_cdev,
 284                        enum led_brightness brightness)
 285{
 286        led_stop_software_blink(led_cdev);
 287        led_cdev->brightness_set(led_cdev, brightness);
 288}
 289EXPORT_SYMBOL(led_brightness_set);
 290
 291static int __init leds_init(void)
 292{
 293        leds_class = class_create(THIS_MODULE, "leds");
 294        if (IS_ERR(leds_class))
 295                return PTR_ERR(leds_class);
 296        leds_class->suspend = led_suspend;
 297        leds_class->resume = led_resume;
 298        leds_class->dev_attrs = led_class_attrs;
 299        return 0;
 300}
 301
 302static void __exit leds_exit(void)
 303{
 304        class_destroy(leds_class);
 305}
 306
 307subsys_initcall(leds_init);
 308module_exit(leds_exit);
 309
 310MODULE_AUTHOR("John Lenz, Richard Purdie");
 311MODULE_LICENSE("GPL");
 312MODULE_DESCRIPTION("LED Class Interface");
 313