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/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
  25 static struct class *leds_class;
  26
  27 static 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
  33 static 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         ssize_t ret = 0;
  38
  39         /* no lock needed for this */
  40         led_update_brightness(led_cdev);
  41         sprintf(buf, "%u\n", led_cdev->brightness);
  42         ret = strlen(buf) + 1;
  43
  44         return ret;
  45 }
  46
  47 static ssize_t led_brightness_store(struct device *dev,
  48                 struct device_attribute *attr, const char *buf, size_t size)
  49 {
  50         struct led_classdev *led_cdev = dev_get_drvdata(dev);
  51         ssize_t ret = -EINVAL;
  52         char *after;
  53         unsigned long state = simple_strtoul(buf, &after, 10);
  54         size_t count = after - buf;
  55
  56         if (*after && isspace(*after))
  57                 count++;
  58
  59         if (count == size) {
  60                 ret = count;
  61
  62                 if (state == LED_OFF)
  63                         led_trigger_remove(led_cdev);
  64                 led_set_brightness(led_cdev, state);
  65         }
  66
  67         return ret;
  68 }
  69
  70 static DEVICE_ATTR(brightness, 0644, led_brightness_show, led_brightness_store);
  71 #ifdef CONFIG_LEDS_TRIGGERS
  72 static DEVICE_ATTR(trigger, 0644, led_trigger_show, led_trigger_store);
  73 #endif
  74
  75 /**
  76  * led_classdev_suspend - suspend an led_classdev.
  77  * @led_cdev: the led_classdev to suspend.
  78  */
  79 void led_classdev_suspend(struct led_classdev *led_cdev)
  80 {
  81         led_cdev->flags |= LED_SUSPENDED;
  82         led_cdev->brightness_set(led_cdev, 0);
  83 }
  84 EXPORT_SYMBOL_GPL(led_classdev_suspend);
  85
  86 /**
  87  * led_classdev_resume - resume an led_classdev.
  88  * @led_cdev: the led_classdev to resume.
  89  */
  90 void led_classdev_resume(struct led_classdev *led_cdev)
  91 {
  92         led_cdev->brightness_set(led_cdev, led_cdev->brightness);
  93         led_cdev->flags &= ~LED_SUSPENDED;
  94 }
  95 EXPORT_SYMBOL_GPL(led_classdev_resume);
  96
  97 /**
  98  * led_classdev_register - register a new object of led_classdev class.
  99  * @dev: The device to register.
 100  * @led_cdev: the led_classdev structure for this device.
 101  */
 102 int led_classdev_register(struct device *parent, struct led_classdev *led_cdev)
 103 {
 104         int rc;
 105
 106         led_cdev->dev = device_create(leds_class, parent, 0, "%s",
 107                                             led_cdev->name);
 108         if (IS_ERR(led_cdev->dev))
 109                 return PTR_ERR(led_cdev->dev);
 110
 111         dev_set_drvdata(led_cdev->dev, led_cdev);
 112
 113         /* register the attributes */
 114         rc = device_create_file(led_cdev->dev, &dev_attr_brightness);
 115         if (rc)
 116                 goto err_out;
 117
 118         /* add to the list of leds */
 119         down_write(&leds_list_lock);
 120         list_add_tail(&led_cdev->node, &leds_list);
 121         up_write(&leds_list_lock);
 122
 123         led_update_brightness(led_cdev);
 124
 125 #ifdef CONFIG_LEDS_TRIGGERS
 126         init_rwsem(&led_cdev->trigger_lock);
 127
 128         rc = device_create_file(led_cdev->dev, &dev_attr_trigger);
 129         if (rc)
 130                 goto err_out_led_list;
 131
 132         led_trigger_set_default(led_cdev);
 133 #endif
 134
 135         printk(KERN_INFO "Registered led device: %s\n",
 136                         led_cdev->name);
 137
 138         return 0;
 139
 140 #ifdef CONFIG_LEDS_TRIGGERS
 141 err_out_led_list:
 142         device_remove_file(led_cdev->dev, &dev_attr_brightness);
 143         list_del(&led_cdev->node);
 144 #endif
 145 err_out:
 146         device_unregister(led_cdev->dev);
 147         return rc;
 148 }
 149 EXPORT_SYMBOL_GPL(led_classdev_register);
 150
 151 /**
 152  * __led_classdev_unregister - unregisters a object of led_properties class.
 153  * @led_cdev: the led device to unregister
 154  *
 155  * Unregisters a previously registered via led_classdev_register object.
 156  */
 157 void led_classdev_unregister(struct led_classdev *led_cdev)
 158 {
 159         device_remove_file(led_cdev->dev, &dev_attr_brightness);
 160 #ifdef CONFIG_LEDS_TRIGGERS
 161         device_remove_file(led_cdev->dev, &dev_attr_trigger);
 162         down_write(&led_cdev->trigger_lock);
 163         if (led_cdev->trigger)
 164                 led_trigger_set(led_cdev, NULL);
 165         up_write(&led_cdev->trigger_lock);
 166 #endif
 167
 168         device_unregister(led_cdev->dev);
 169
 170         down_write(&leds_list_lock);
 171         list_del(&led_cdev->node);
 172         up_write(&leds_list_lock);
 173 }
 174 EXPORT_SYMBOL_GPL(led_classdev_unregister);
 175
 176 static int __init leds_init(void)
 177 {
 178         leds_class = class_create(THIS_MODULE, "leds");
 179         if (IS_ERR(leds_class))
 180                 return PTR_ERR(leds_class);
 181         return 0;
 182 }
 183
 184 static void __exit leds_exit(void)
 185 {
 186         class_destroy(leds_class);
 187 }
 188
 189 subsys_initcall(leds_init);
 190 module_exit(leds_exit);
 191
 192 MODULE_AUTHOR("John Lenz, Richard Purdie");
 193 MODULE_LICENSE("GPL");
 194 MODULE_DESCRIPTION("LED Class Interface");