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         unsigned long state;
  48         ssize_t ret = -EINVAL;
  49
  50         ret = kstrtoul(buf, 10, &state);
  51         if (ret)
  52                 return ret;
  53
  54         if (state == LED_OFF)
  55                 led_trigger_remove(led_cdev);
  56         __led_set_brightness(led_cdev, state);
  57
  58         return size;
  59 }
  60
  61 static ssize_t led_max_brightness_show(struct device *dev,
  62                 struct device_attribute *attr, char *buf)
  63 {
  64         struct led_classdev *led_cdev = dev_get_drvdata(dev);
  65
  66         return sprintf(buf, "%u\n", led_cdev->max_brightness);
  67 }
  68
  69 static struct device_attribute led_class_attrs[] = {
  70         __ATTR(brightness, 0644, led_brightness_show, led_brightness_store),
  71         __ATTR(max_brightness, 0444, led_max_brightness_show, NULL),
  72 #ifdef CONFIG_LEDS_TRIGGERS
  73         __ATTR(trigger, 0644, led_trigger_show, led_trigger_store),
  74 #endif
  75         __ATTR_NULL,
  76 };
  77
  78 static void led_timer_function(unsigned long data)
  79 {
  80         struct led_classdev *led_cdev = (void *)data;
  81         unsigned long brightness;
  82         unsigned long delay;
  83
  84         if (!led_cdev->blink_delay_on || !led_cdev->blink_delay_off) {
  85                 __led_set_brightness(led_cdev, LED_OFF);
  86                 return;
  87         }
  88
  89         if (led_cdev->flags & LED_BLINK_ONESHOT_STOP) {
  90                 led_cdev->flags &= ~LED_BLINK_ONESHOT_STOP;
  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         /* Return in next iteration if led is in one-shot mode and we are in
 111          * the final blink state so that the led is toggled each delay_on +
 112          * delay_off milliseconds in worst case.
 113          */
 114         if (led_cdev->flags & LED_BLINK_ONESHOT) {
 115                 if (led_cdev->flags & LED_BLINK_INVERT) {
 116                         if (brightness)
 117                                 led_cdev->flags |= LED_BLINK_ONESHOT_STOP;
 118                 } else {
 119                         if (!brightness)
 120                                 led_cdev->flags |= LED_BLINK_ONESHOT_STOP;
 121                 }
 122         }
 123
 124         mod_timer(&led_cdev->blink_timer, jiffies + msecs_to_jiffies(delay));
 125 }
 126
 127 /**
 128  * led_classdev_suspend - suspend an led_classdev.
 129  * @led_cdev: the led_classdev to suspend.
 130  */
 131 void led_classdev_suspend(struct led_classdev *led_cdev)
 132 {
 133         led_cdev->flags |= LED_SUSPENDED;
 134         led_cdev->brightness_set(led_cdev, 0);
 135 }
 136 EXPORT_SYMBOL_GPL(led_classdev_suspend);
 137
 138 /**
 139  * led_classdev_resume - resume an led_classdev.
 140  * @led_cdev: the led_classdev to resume.
 141  */
 142 void led_classdev_resume(struct led_classdev *led_cdev)
 143 {
 144         led_cdev->brightness_set(led_cdev, led_cdev->brightness);
 145         led_cdev->flags &= ~LED_SUSPENDED;
 146 }
 147 EXPORT_SYMBOL_GPL(led_classdev_resume);
 148
 149 static int led_suspend(struct device *dev, pm_message_t state)
 150 {
 151         struct led_classdev *led_cdev = dev_get_drvdata(dev);
 152
 153         if (led_cdev->flags & LED_CORE_SUSPENDRESUME)
 154                 led_classdev_suspend(led_cdev);
 155
 156         return 0;
 157 }
 158
 159 static int led_resume(struct device *dev)
 160 {
 161         struct led_classdev *led_cdev = dev_get_drvdata(dev);
 162
 163         if (led_cdev->flags & LED_CORE_SUSPENDRESUME)
 164                 led_classdev_resume(led_cdev);
 165
 166         return 0;
 167 }
 168
 169 /**
 170  * led_classdev_register - register a new object of led_classdev class.
 171  * @parent: The device to register.
 172  * @led_cdev: the led_classdev structure for this device.
 173  */
 174 int led_classdev_register(struct device *parent, struct led_classdev *led_cdev)
 175 {
 176         led_cdev->dev = device_create(leds_class, parent, 0, led_cdev,
 177                                       "%s", led_cdev->name);
 178         if (IS_ERR(led_cdev->dev))
 179                 return PTR_ERR(led_cdev->dev);
 180
 181 #ifdef CONFIG_LEDS_TRIGGERS
 182         init_rwsem(&led_cdev->trigger_lock);
 183 #endif
 184         /* add to the list of leds */
 185         down_write(&leds_list_lock);
 186         list_add_tail(&led_cdev->node, &leds_list);
 187         up_write(&leds_list_lock);
 188
 189         if (!led_cdev->max_brightness)
 190                 led_cdev->max_brightness = LED_FULL;
 191
 192         led_update_brightness(led_cdev);
 193
 194         init_timer(&led_cdev->blink_timer);
 195         led_cdev->blink_timer.function = led_timer_function;
 196         led_cdev->blink_timer.data = (unsigned long)led_cdev;
 197
 198 #ifdef CONFIG_LEDS_TRIGGERS
 199         led_trigger_set_default(led_cdev);
 200 #endif
 201
 202         printk(KERN_DEBUG "Registered led device: %s\n",
 203                         led_cdev->name);
 204
 205         return 0;
 206 }
 207 EXPORT_SYMBOL_GPL(led_classdev_register);
 208
 209 /**
 210  * led_classdev_unregister - unregisters a object of led_properties class.
 211  * @led_cdev: the led device to unregister
 212  *
 213  * Unregisters a previously registered via led_classdev_register object.
 214  */
 215 void led_classdev_unregister(struct led_classdev *led_cdev)
 216 {
 217 #ifdef CONFIG_LEDS_TRIGGERS
 218         down_write(&led_cdev->trigger_lock);
 219         if (led_cdev->trigger)
 220                 led_trigger_set(led_cdev, NULL);
 221         up_write(&led_cdev->trigger_lock);
 222 #endif
 223
 224         /* Stop blinking */
 225         led_set_brightness(led_cdev, LED_OFF);
 226
 227         device_unregister(led_cdev->dev);
 228
 229         down_write(&leds_list_lock);
 230         list_del(&led_cdev->node);
 231         up_write(&leds_list_lock);
 232 }
 233 EXPORT_SYMBOL_GPL(led_classdev_unregister);
 234
 235 static int __init leds_init(void)
 236 {
 237         leds_class = class_create(THIS_MODULE, "leds");
 238         if (IS_ERR(leds_class))
 239                 return PTR_ERR(leds_class);
 240         leds_class->suspend = led_suspend;
 241         leds_class->resume = led_resume;
 242         leds_class->dev_attrs = led_class_attrs;
 243         return 0;
 244 }
 245
 246 static void __exit leds_exit(void)
 247 {
 248         class_destroy(leds_class);
 249 }
 250
 251 subsys_initcall(leds_init);
 252 module_exit(leds_exit);
 253
 254 MODULE_AUTHOR("John Lenz, Richard Purdie");
 255 MODULE_LICENSE("GPL");
 256 MODULE_DESCRIPTION("LED Class Interface");