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/timer.h>
  19 #include <linux/err.h>
  20 #include <linux/ctype.h>
  21 #include <linux/leds.h>
  22 #include "leds.h"
  23
  24 static struct class *leds_class;
  25
  26 static 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
  32 static 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
  43 static 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
  66 static 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
  74 static 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
  83 static 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
 113 /**
 114  * led_classdev_suspend - suspend an led_classdev.
 115  * @led_cdev: the led_classdev to suspend.
 116  */
 117 void led_classdev_suspend(struct led_classdev *led_cdev)
 118 {
 119         led_cdev->flags |= LED_SUSPENDED;
 120         led_cdev->brightness_set(led_cdev, 0);
 121 }
 122 EXPORT_SYMBOL_GPL(led_classdev_suspend);
 123
 124 /**
 125  * led_classdev_resume - resume an led_classdev.
 126  * @led_cdev: the led_classdev to resume.
 127  */
 128 void led_classdev_resume(struct led_classdev *led_cdev)
 129 {
 130         led_cdev->brightness_set(led_cdev, led_cdev->brightness);
 131         led_cdev->flags &= ~LED_SUSPENDED;
 132 }
 133 EXPORT_SYMBOL_GPL(led_classdev_resume);
 134
 135 static int led_suspend(struct device *dev, pm_message_t state)
 136 {
 137         struct led_classdev *led_cdev = dev_get_drvdata(dev);
 138
 139         if (led_cdev->flags & LED_CORE_SUSPENDRESUME)
 140                 led_classdev_suspend(led_cdev);
 141
 142         return 0;
 143 }
 144
 145 static int led_resume(struct device *dev)
 146 {
 147         struct led_classdev *led_cdev = dev_get_drvdata(dev);
 148
 149         if (led_cdev->flags & LED_CORE_SUSPENDRESUME)
 150                 led_classdev_resume(led_cdev);
 151
 152         return 0;
 153 }
 154
 155 /**
 156  * led_classdev_register - register a new object of led_classdev class.
 157  * @parent: The device to register.
 158  * @led_cdev: the led_classdev structure for this device.
 159  */
 160 int led_classdev_register(struct device *parent, struct led_classdev *led_cdev)
 161 {
 162         led_cdev->dev = device_create(leds_class, parent, 0, led_cdev,
 163                                       "%s", led_cdev->name);
 164         if (IS_ERR(led_cdev->dev))
 165                 return PTR_ERR(led_cdev->dev);
 166
 167 #ifdef CONFIG_LEDS_TRIGGERS
 168         init_rwsem(&led_cdev->trigger_lock);
 169 #endif
 170         /* add to the list of leds */
 171         down_write(&leds_list_lock);
 172         list_add_tail(&led_cdev->node, &leds_list);
 173         up_write(&leds_list_lock);
 174
 175         if (!led_cdev->max_brightness)
 176                 led_cdev->max_brightness = LED_FULL;
 177
 178         led_update_brightness(led_cdev);
 179
 180         init_timer(&led_cdev->blink_timer);
 181         led_cdev->blink_timer.function = led_timer_function;
 182         led_cdev->blink_timer.data = (unsigned long)led_cdev;
 183
 184 #ifdef CONFIG_LEDS_TRIGGERS
 185         led_trigger_set_default(led_cdev);
 186 #endif
 187
 188         printk(KERN_DEBUG "Registered led device: %s\n",
 189                         led_cdev->name);
 190
 191         return 0;
 192 }
 193 EXPORT_SYMBOL_GPL(led_classdev_register);
 194
 195 /**
 196  * led_classdev_unregister - unregisters a object of led_properties class.
 197  * @led_cdev: the led device to unregister
 198  *
 199  * Unregisters a previously registered via led_classdev_register object.
 200  */
 201 void led_classdev_unregister(struct led_classdev *led_cdev)
 202 {
 203 #ifdef CONFIG_LEDS_TRIGGERS
 204         down_write(&led_cdev->trigger_lock);
 205         if (led_cdev->trigger)
 206                 led_trigger_set(led_cdev, NULL);
 207         up_write(&led_cdev->trigger_lock);
 208 #endif
 209
 210         /* Stop blinking */
 211         led_brightness_set(led_cdev, LED_OFF);
 212
 213         device_unregister(led_cdev->dev);
 214
 215         down_write(&leds_list_lock);
 216         list_del(&led_cdev->node);
 217         up_write(&leds_list_lock);
 218 }
 219 EXPORT_SYMBOL_GPL(led_classdev_unregister);
 220
 221 static int __init leds_init(void)
 222 {
 223         leds_class = class_create(THIS_MODULE, "leds");
 224         if (IS_ERR(leds_class))
 225                 return PTR_ERR(leds_class);
 226         leds_class->suspend = led_suspend;
 227         leds_class->resume = led_resume;
 228         leds_class->dev_attrs = led_class_attrs;
 229         return 0;
 230 }
 231
 232 static void __exit leds_exit(void)
 233 {
 234         class_destroy(leds_class);
 235 }
 236
 237 subsys_initcall(leds_init);
 238 module_exit(leds_exit);
 239
 240 MODULE_AUTHOR("John Lenz, Richard Purdie");
 241 MODULE_LICENSE("GPL");
 242 MODULE_DESCRIPTION("LED Class Interface");