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 (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 ssize_t led_max_brightness_show(struct device *dev,
  68                 struct device_attribute *attr, char *buf)
  69 {
  70         struct led_classdev *led_cdev = dev_get_drvdata(dev);
  71
  72         return sprintf(buf, "%u\n", led_cdev->max_brightness);
  73 }
  74
  75 static struct device_attribute led_class_attrs[] = {
  76         __ATTR(brightness, 0644, led_brightness_show, led_brightness_store),
  77         __ATTR(max_brightness, 0444, led_max_brightness_show, NULL),
  78 #ifdef CONFIG_LEDS_TRIGGERS
  79         __ATTR(trigger, 0644, led_trigger_show, led_trigger_store),
  80 #endif
  81         __ATTR_NULL,
  82 };
  83
  84 static void led_timer_function(unsigned long data)
  85 {
  86         struct led_classdev *led_cdev = (void *)data;
  87         unsigned long brightness;
  88         unsigned long delay;
  89
  90         if (!led_cdev->blink_delay_on || !led_cdev->blink_delay_off) {
  91                 led_set_brightness(led_cdev, LED_OFF);
  92                 return;
  93         }
  94
  95         brightness = led_get_brightness(led_cdev);
  96         if (!brightness) {
  97                 /* Time to switch the LED on. */
  98                 brightness = led_cdev->blink_brightness;
  99                 delay = led_cdev->blink_delay_on;
 100         } else {
 101                 /* Store the current brightness value to be able
 102                  * to restore it when the delay_off period is over.
 103                  */
 104                 led_cdev->blink_brightness = brightness;
 105                 brightness = LED_OFF;
 106                 delay = led_cdev->blink_delay_off;
 107         }
 108
 109         led_set_brightness(led_cdev, brightness);
 110
 111         mod_timer(&led_cdev->blink_timer, jiffies + msecs_to_jiffies(delay));
 112 }
 113
 114 static void led_stop_software_blink(struct led_classdev *led_cdev)
 115 {
 116         /* deactivate previous settings */
 117         del_timer_sync(&led_cdev->blink_timer);
 118         led_cdev->blink_delay_on = 0;
 119         led_cdev->blink_delay_off = 0;
 120 }
 121
 122 static void led_set_software_blink(struct led_classdev *led_cdev,
 123                                    unsigned long delay_on,
 124                                    unsigned long delay_off)
 125 {
 126         int current_brightness;
 127
 128         current_brightness = led_get_brightness(led_cdev);
 129         if (current_brightness)
 130                 led_cdev->blink_brightness = current_brightness;
 131         if (!led_cdev->blink_brightness)
 132                 led_cdev->blink_brightness = led_cdev->max_brightness;
 133
 134         if (delay_on == led_cdev->blink_delay_on &&
 135             delay_off == led_cdev->blink_delay_off)
 136                 return;
 137
 138         led_stop_software_blink(led_cdev);
 139
 140         led_cdev->blink_delay_on = delay_on;
 141         led_cdev->blink_delay_off = delay_off;
 142
 143         /* never on - don't blink */
 144         if (!delay_on)
 145                 return;
 146
 147         /* never off - just set to brightness */
 148         if (!delay_off) {
 149                 led_set_brightness(led_cdev, led_cdev->blink_brightness);
 150                 return;
 151         }
 152
 153         mod_timer(&led_cdev->blink_timer, jiffies + 1);
 154 }
 155
 156
 157 /**
 158  * led_classdev_suspend - suspend an led_classdev.
 159  * @led_cdev: the led_classdev to suspend.
 160  */
 161 void led_classdev_suspend(struct led_classdev *led_cdev)
 162 {
 163         led_cdev->flags |= LED_SUSPENDED;
 164         led_cdev->brightness_set(led_cdev, 0);
 165 }
 166 EXPORT_SYMBOL_GPL(led_classdev_suspend);
 167
 168 /**
 169  * led_classdev_resume - resume an led_classdev.
 170  * @led_cdev: the led_classdev to resume.
 171  */
 172 void led_classdev_resume(struct led_classdev *led_cdev)
 173 {
 174         led_cdev->brightness_set(led_cdev, led_cdev->brightness);
 175         led_cdev->flags &= ~LED_SUSPENDED;
 176 }
 177 EXPORT_SYMBOL_GPL(led_classdev_resume);
 178
 179 static int led_suspend(struct device *dev, pm_message_t state)
 180 {
 181         struct led_classdev *led_cdev = dev_get_drvdata(dev);
 182
 183         if (led_cdev->flags & LED_CORE_SUSPENDRESUME)
 184                 led_classdev_suspend(led_cdev);
 185
 186         return 0;
 187 }
 188
 189 static int led_resume(struct device *dev)
 190 {
 191         struct led_classdev *led_cdev = dev_get_drvdata(dev);
 192
 193         if (led_cdev->flags & LED_CORE_SUSPENDRESUME)
 194                 led_classdev_resume(led_cdev);
 195
 196         return 0;
 197 }
 198
 199 /**
 200  * led_classdev_register - register a new object of led_classdev class.
 201  * @parent: The device to register.
 202  * @led_cdev: the led_classdev structure for this device.
 203  */
 204 int led_classdev_register(struct device *parent, struct led_classdev *led_cdev)
 205 {
 206         led_cdev->dev = device_create(leds_class, parent, 0, led_cdev,
 207                                       "%s", led_cdev->name);
 208         if (IS_ERR(led_cdev->dev))
 209                 return PTR_ERR(led_cdev->dev);
 210
 211 #ifdef CONFIG_LEDS_TRIGGERS
 212         init_rwsem(&led_cdev->trigger_lock);
 213 #endif
 214         /* add to the list of leds */
 215         down_write(&leds_list_lock);
 216         list_add_tail(&led_cdev->node, &leds_list);
 217         up_write(&leds_list_lock);
 218
 219         if (!led_cdev->max_brightness)
 220                 led_cdev->max_brightness = LED_FULL;
 221
 222         led_update_brightness(led_cdev);
 223
 224         init_timer(&led_cdev->blink_timer);
 225         led_cdev->blink_timer.function = led_timer_function;
 226         led_cdev->blink_timer.data = (unsigned long)led_cdev;
 227
 228 #ifdef CONFIG_LEDS_TRIGGERS
 229         led_trigger_set_default(led_cdev);
 230 #endif
 231
 232         printk(KERN_DEBUG "Registered led device: %s\n",
 233                         led_cdev->name);
 234
 235         return 0;
 236 }
 237 EXPORT_SYMBOL_GPL(led_classdev_register);
 238
 239 /**
 240  * led_classdev_unregister - unregisters a object of led_properties class.
 241  * @led_cdev: the led device to unregister
 242  *
 243  * Unregisters a previously registered via led_classdev_register object.
 244  */
 245 void led_classdev_unregister(struct led_classdev *led_cdev)
 246 {
 247 #ifdef CONFIG_LEDS_TRIGGERS
 248         down_write(&led_cdev->trigger_lock);
 249         if (led_cdev->trigger)
 250                 led_trigger_set(led_cdev, NULL);
 251         up_write(&led_cdev->trigger_lock);
 252 #endif
 253
 254         /* Stop blinking */
 255         led_brightness_set(led_cdev, LED_OFF);
 256
 257         device_unregister(led_cdev->dev);
 258
 259         down_write(&leds_list_lock);
 260         list_del(&led_cdev->node);
 261         up_write(&leds_list_lock);
 262 }
 263 EXPORT_SYMBOL_GPL(led_classdev_unregister);
 264
 265 void led_blink_set(struct led_classdev *led_cdev,
 266                    unsigned long *delay_on,
 267                    unsigned long *delay_off)
 268 {
 269         if (led_cdev->blink_set &&
 270             led_cdev->blink_set(led_cdev, delay_on, delay_off))
 271                 return;
 272
 273         /* blink with 1 Hz as default if nothing specified */
 274         if (!*delay_on && !*delay_off)
 275                 *delay_on = *delay_off = 500;
 276
 277         led_set_software_blink(led_cdev, *delay_on, *delay_off);
 278 }
 279 EXPORT_SYMBOL(led_blink_set);
 280
 281 void led_brightness_set(struct led_classdev *led_cdev,
 282                         enum led_brightness brightness)
 283 {
 284         led_stop_software_blink(led_cdev);
 285         led_cdev->brightness_set(led_cdev, brightness);
 286 }
 287 EXPORT_SYMBOL(led_brightness_set);
 288
 289 static int __init leds_init(void)
 290 {
 291         leds_class = class_create(THIS_MODULE, "leds");
 292         if (IS_ERR(leds_class))
 293                 return PTR_ERR(leds_class);
 294         leds_class->suspend = led_suspend;
 295         leds_class->resume = led_resume;
 296         leds_class->dev_attrs = led_class_attrs;
 297         return 0;
 298 }
 299
 300 static void __exit leds_exit(void)
 301 {
 302         class_destroy(leds_class);
 303 }
 304
 305 subsys_initcall(leds_init);
 306 module_exit(leds_exit);
 307
 308 MODULE_AUTHOR("John Lenz, Richard Purdie");
 309 MODULE_LICENSE("GPL");
 310 MODULE_DESCRIPTION("LED Class Interface");