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
  38         /* no lock needed for this */
  39         led_update_brightness(led_cdev);
  40
  41         return sprintf(buf, "%u\n", led_cdev->brightness);
  42 }
  43
  44 static 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
  67 static DEVICE_ATTR(brightness, 0644, led_brightness_show, led_brightness_store);
  68 #ifdef CONFIG_LEDS_TRIGGERS
  69 static 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  */
  76 void led_classdev_suspend(struct led_classdev *led_cdev)
  77 {
  78         led_cdev->flags |= LED_SUSPENDED;
  79         led_cdev->brightness_set(led_cdev, 0);
  80 }
  81 EXPORT_SYMBOL_GPL(led_classdev_suspend);
  82
  83 /**
  84  * led_classdev_resume - resume an led_classdev.
  85  * @led_cdev: the led_classdev to resume.
  86  */
  87 void 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 }
  92 EXPORT_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  */
  99 int 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         /* add to the list of leds */
 114         down_write(&leds_list_lock);
 115         list_add_tail(&led_cdev->node, &leds_list);
 116         up_write(&leds_list_lock);
 117
 118         led_update_brightness(led_cdev);
 119
 120 #ifdef CONFIG_LEDS_TRIGGERS
 121         init_rwsem(&led_cdev->trigger_lock);
 122
 123         rc = device_create_file(led_cdev->dev, &dev_attr_trigger);
 124         if (rc)
 125                 goto err_out_led_list;
 126
 127         led_trigger_set_default(led_cdev);
 128 #endif
 129
 130         printk(KERN_INFO "Registered led device: %s\n",
 131                         led_cdev->name);
 132
 133         return 0;
 134
 135 #ifdef CONFIG_LEDS_TRIGGERS
 136 err_out_led_list:
 137         device_remove_file(led_cdev->dev, &dev_attr_brightness);
 138         list_del(&led_cdev->node);
 139 #endif
 140 err_out:
 141         device_unregister(led_cdev->dev);
 142         return rc;
 143 }
 144 EXPORT_SYMBOL_GPL(led_classdev_register);
 145
 146 /**
 147  * led_classdev_unregister - unregisters a object of led_properties class.
 148  * @led_cdev: the led device to unregister
 149  *
 150  * Unregisters a previously registered via led_classdev_register object.
 151  */
 152 void led_classdev_unregister(struct led_classdev *led_cdev)
 153 {
 154         device_remove_file(led_cdev->dev, &dev_attr_brightness);
 155 #ifdef CONFIG_LEDS_TRIGGERS
 156         device_remove_file(led_cdev->dev, &dev_attr_trigger);
 157         down_write(&led_cdev->trigger_lock);
 158         if (led_cdev->trigger)
 159                 led_trigger_set(led_cdev, NULL);
 160         up_write(&led_cdev->trigger_lock);
 161 #endif
 162
 163         device_unregister(led_cdev->dev);
 164
 165         down_write(&leds_list_lock);
 166         list_del(&led_cdev->node);
 167         up_write(&leds_list_lock);
 168 }
 169 EXPORT_SYMBOL_GPL(led_classdev_unregister);
 170
 171 static int __init leds_init(void)
 172 {
 173         leds_class = class_create(THIS_MODULE, "leds");
 174         if (IS_ERR(leds_class))
 175                 return PTR_ERR(leds_class);
 176         return 0;
 177 }
 178
 179 static void __exit leds_exit(void)
 180 {
 181         class_destroy(leds_class);
 182 }
 183
 184 subsys_initcall(leds_init);
 185 module_exit(leds_exit);
 186
 187 MODULE_AUTHOR("John Lenz, Richard Purdie");
 188 MODULE_LICENSE("GPL");
 189 MODULE_DESCRIPTION("LED Class Interface");