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/sysdev.h>
  19#include <linux/timer.h>
  20#include <linux/err.h>
  21#include <linux/ctype.h>
  22#include <linux/leds.h>
  23#include "leds.h"
  24
  25static struct class *leds_class;
  26
  27static void led_update_brightness(struct led_classdev *led_cdev)
  28{
  29        if (led_cdev->brightness_get)
  30                led_cdev->brightness = led_cdev->brightness_get(led_cdev);
  31}
  32
  33static ssize_t led_brightness_show(struct device *dev, 
  34                struct device_attribute *attr, char *buf)
  35{
  36        struct led_classdev *led_cdev = dev_get_drvdata(dev);
  37
  38        /* no lock needed for this */
  39        led_update_brightness(led_cdev);
  40
  41        return sprintf(buf, "%u\n", led_cdev->brightness);
  42}
  43
  44static ssize_t led_brightness_store(struct device *dev,
  45                struct device_attribute *attr, const char *buf, size_t size)
  46{
  47        struct led_classdev *led_cdev = dev_get_drvdata(dev);
  48        ssize_t ret = -EINVAL;
  49        char *after;
  50        unsigned long state = simple_strtoul(buf, &after, 10);
  51        size_t count = after - buf;
  52
  53        if (*after && isspace(*after))
  54                count++;
  55
  56        if (count == size) {
  57                ret = count;
  58
  59                if (state == LED_OFF)
  60                        led_trigger_remove(led_cdev);
  61                led_set_brightness(led_cdev, state);
  62        }
  63
  64        return ret;
  65}
  66
  67static DEVICE_ATTR(brightness, 0644, led_brightness_show, led_brightness_store);
  68#ifdef CONFIG_LEDS_TRIGGERS
  69static DEVICE_ATTR(trigger, 0644, led_trigger_show, led_trigger_store);
  70#endif
  71
  72/**
  73 * led_classdev_suspend - suspend an led_classdev.
  74 * @led_cdev: the led_classdev to suspend.
  75 */
  76void led_classdev_suspend(struct led_classdev *led_cdev)
  77{
  78        led_cdev->flags |= LED_SUSPENDED;
  79        led_cdev->brightness_set(led_cdev, 0);
  80}
  81EXPORT_SYMBOL_GPL(led_classdev_suspend);
  82
  83/**
  84 * led_classdev_resume - resume an led_classdev.
  85 * @led_cdev: the led_classdev to resume.
  86 */
  87void led_classdev_resume(struct led_classdev *led_cdev)
  88{
  89        led_cdev->brightness_set(led_cdev, led_cdev->brightness);
  90        led_cdev->flags &= ~LED_SUSPENDED;
  91}
  92EXPORT_SYMBOL_GPL(led_classdev_resume);
  93
  94/**
  95 * led_classdev_register - register a new object of led_classdev class.
  96 * @dev: The device to register.
  97 * @led_cdev: the led_classdev structure for this device.
  98 */
  99int led_classdev_register(struct device *parent, struct led_classdev *led_cdev)
 100{
 101        int rc;
 102
 103        led_cdev->dev = device_create(leds_class, parent, 0, led_cdev,
 104                                      "%s", led_cdev->name);
 105        if (IS_ERR(led_cdev->dev))
 106                return PTR_ERR(led_cdev->dev);
 107
 108        /* register the attributes */
 109        rc = device_create_file(led_cdev->dev, &dev_attr_brightness);
 110        if (rc)
 111                goto err_out;
 112
 113#ifdef CONFIG_LEDS_TRIGGERS
 114        init_rwsem(&led_cdev->trigger_lock);
 115#endif
 116        /* add to the list of leds */
 117        down_write(&leds_list_lock);
 118        list_add_tail(&led_cdev->node, &leds_list);
 119        up_write(&leds_list_lock);
 120
 121        led_update_brightness(led_cdev);
 122
 123#ifdef CONFIG_LEDS_TRIGGERS
 124        rc = device_create_file(led_cdev->dev, &dev_attr_trigger);
 125        if (rc)
 126                goto err_out_led_list;
 127
 128        led_trigger_set_default(led_cdev);
 129#endif
 130
 131        printk(KERN_INFO "Registered led device: %s\n",
 132                        led_cdev->name);
 133
 134        return 0;
 135
 136#ifdef CONFIG_LEDS_TRIGGERS
 137err_out_led_list:
 138        device_remove_file(led_cdev->dev, &dev_attr_brightness);
 139        list_del(&led_cdev->node);
 140#endif
 141err_out:
 142        device_unregister(led_cdev->dev);
 143        return rc;
 144}
 145EXPORT_SYMBOL_GPL(led_classdev_register);
 146
 147/**
 148 * led_classdev_unregister - unregisters a object of led_properties class.
 149 * @led_cdev: the led device to unregister
 150 *
 151 * Unregisters a previously registered via led_classdev_register object.
 152 */
 153void led_classdev_unregister(struct led_classdev *led_cdev)
 154{
 155        device_remove_file(led_cdev->dev, &dev_attr_brightness);
 156#ifdef CONFIG_LEDS_TRIGGERS
 157        device_remove_file(led_cdev->dev, &dev_attr_trigger);
 158        down_write(&led_cdev->trigger_lock);
 159        if (led_cdev->trigger)
 160                led_trigger_set(led_cdev, NULL);
 161        up_write(&led_cdev->trigger_lock);
 162#endif
 163
 164        device_unregister(led_cdev->dev);
 165
 166        down_write(&leds_list_lock);
 167        list_del(&led_cdev->node);
 168        up_write(&leds_list_lock);
 169}
 170EXPORT_SYMBOL_GPL(led_classdev_unregister);
 171
 172static int __init leds_init(void)
 173{
 174        leds_class = class_create(THIS_MODULE, "leds");
 175        if (IS_ERR(leds_class))
 176                return PTR_ERR(leds_class);
 177        return 0;
 178}
 179
 180static void __exit leds_exit(void)
 181{
 182        class_destroy(leds_class);
 183}
 184
 185subsys_initcall(leds_init);
 186module_exit(leds_exit);
 187
 188MODULE_AUTHOR("John Lenz, Richard Purdie");
 189MODULE_LICENSE("GPL");
 190MODULE_DESCRIPTION("LED Class Interface");
 191