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 ssize_t led_brightness_show(struct device *dev,
  28                 struct device_attribute *attr, char *buf)
  29 {
  30         struct led_classdev *led_cdev = dev_get_drvdata(dev);
  31         ssize_t ret = 0;
  32
  33         /* no lock needed for this */
  34         sprintf(buf, "%u\n", led_cdev->brightness);
  35         ret = strlen(buf) + 1;
  36
  37         return ret;
  38 }
  39
  40 static ssize_t led_brightness_store(struct device *dev,
  41                 struct device_attribute *attr, const char *buf, size_t size)
  42 {
  43         struct led_classdev *led_cdev = dev_get_drvdata(dev);
  44         ssize_t ret = -EINVAL;
  45         char *after;
  46         unsigned long state = simple_strtoul(buf, &after, 10);
  47         size_t count = after - buf;
  48
  49         if (*after && isspace(*after))
  50                 count++;
  51
  52         if (count == size) {
  53                 ret = count;
  54                 led_set_brightness(led_cdev, state);
  55         }
  56
  57         return ret;
  58 }
  59
  60 static DEVICE_ATTR(brightness, 0644, led_brightness_show, led_brightness_store);
  61 #ifdef CONFIG_LEDS_TRIGGERS
  62 static DEVICE_ATTR(trigger, 0644, led_trigger_show, led_trigger_store);
  63 #endif
  64
  65 /**
  66  * led_classdev_suspend - suspend an led_classdev.
  67  * @led_cdev: the led_classdev to suspend.
  68  */
  69 void led_classdev_suspend(struct led_classdev *led_cdev)
  70 {
  71         led_cdev->flags |= LED_SUSPENDED;
  72         led_cdev->brightness_set(led_cdev, 0);
  73 }
  74 EXPORT_SYMBOL_GPL(led_classdev_suspend);
  75
  76 /**
  77  * led_classdev_resume - resume an led_classdev.
  78  * @led_cdev: the led_classdev to resume.
  79  */
  80 void led_classdev_resume(struct led_classdev *led_cdev)
  81 {
  82         led_cdev->brightness_set(led_cdev, led_cdev->brightness);
  83         led_cdev->flags &= ~LED_SUSPENDED;
  84 }
  85 EXPORT_SYMBOL_GPL(led_classdev_resume);
  86
  87 /**
  88  * led_classdev_register - register a new object of led_classdev class.
  89  * @dev: The device to register.
  90  * @led_cdev: the led_classdev structure for this device.
  91  */
  92 int led_classdev_register(struct device *parent, struct led_classdev *led_cdev)
  93 {
  94         int rc;
  95
  96         led_cdev->dev = device_create(leds_class, parent, 0, "%s",
  97                                             led_cdev->name);
  98         if (unlikely(IS_ERR(led_cdev->dev)))
  99                 return PTR_ERR(led_cdev->dev);
 100
 101         dev_set_drvdata(led_cdev->dev, led_cdev);
 102
 103         /* register the attributes */
 104         rc = device_create_file(led_cdev->dev, &dev_attr_brightness);
 105         if (rc)
 106                 goto err_out;
 107
 108         /* add to the list of leds */
 109         write_lock(&leds_list_lock);
 110         list_add_tail(&led_cdev->node, &leds_list);
 111         write_unlock(&leds_list_lock);
 112
 113 #ifdef CONFIG_LEDS_TRIGGERS
 114         init_rwsem(&led_cdev->trigger_lock);
 115
 116         rc = device_create_file(led_cdev->dev, &dev_attr_trigger);
 117         if (rc)
 118                 goto err_out_led_list;
 119
 120         led_trigger_set_default(led_cdev);
 121 #endif
 122
 123         printk(KERN_INFO "Registered led device: %s\n",
 124                         led_cdev->name);
 125
 126         return 0;
 127
 128 #ifdef CONFIG_LEDS_TRIGGERS
 129 err_out_led_list:
 130         device_remove_file(led_cdev->dev, &dev_attr_brightness);
 131         list_del(&led_cdev->node);
 132 #endif
 133 err_out:
 134         device_unregister(led_cdev->dev);
 135         return rc;
 136 }
 137 EXPORT_SYMBOL_GPL(led_classdev_register);
 138
 139 /**
 140  * led_classdev_unregister - unregisters a object of led_properties class.
 141  * @led_cdev: the led device to unregister
 142  *
 143  * Unregisters a previously registered via led_classdev_register object.
 144  */
 145 void led_classdev_unregister(struct led_classdev *led_cdev)
 146 {
 147         device_remove_file(led_cdev->dev, &dev_attr_brightness);
 148 #ifdef CONFIG_LEDS_TRIGGERS
 149         device_remove_file(led_cdev->dev, &dev_attr_trigger);
 150         down_write(&led_cdev->trigger_lock);
 151         if (led_cdev->trigger)
 152                 led_trigger_set(led_cdev, NULL);
 153         up_write(&led_cdev->trigger_lock);
 154 #endif
 155
 156         device_unregister(led_cdev->dev);
 157
 158         write_lock(&leds_list_lock);
 159         list_del(&led_cdev->node);
 160         write_unlock(&leds_list_lock);
 161 }
 162 EXPORT_SYMBOL_GPL(led_classdev_unregister);
 163
 164 static int __init leds_init(void)
 165 {
 166         leds_class = class_create(THIS_MODULE, "leds");
 167         if (IS_ERR(leds_class))
 168                 return PTR_ERR(leds_class);
 169         return 0;
 170 }
 171
 172 static void __exit leds_exit(void)
 173 {
 174         class_destroy(leds_class);
 175 }
 176
 177 subsys_initcall(leds_init);
 178 module_exit(leds_exit);
 179
 180 MODULE_AUTHOR("John Lenz, Richard Purdie");
 181 MODULE_LICENSE("GPL");
 182 MODULE_DESCRIPTION("LED Class Interface");