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/ctype.h>
  13 #include <linux/device.h>
  14 #include <linux/err.h>
  15 #include <linux/init.h>
  16 #include <linux/kernel.h>
  17 #include <linux/leds.h>
  18 #include <linux/list.h>
  19 #include <linux/module.h>
  20 #include <linux/slab.h>
  21 #include <linux/spinlock.h>
  22 #include <linux/timer.h>
  23 #include "leds.h"
  24
  25 static struct class *leds_class;
  26
  27 static ssize_t brightness_show(struct device *dev,
  28                 struct device_attribute *attr, char *buf)
  29 {
  30         struct led_classdev *led_cdev = dev_get_drvdata(dev);
  31
  32         /* no lock needed for this */
  33         led_update_brightness(led_cdev);
  34
  35         return sprintf(buf, "%u\n", led_cdev->brightness);
  36 }
  37
  38 static ssize_t brightness_store(struct device *dev,
  39                 struct device_attribute *attr, const char *buf, size_t size)
  40 {
  41         struct led_classdev *led_cdev = dev_get_drvdata(dev);
  42         unsigned long state;
  43         ssize_t ret;
  44
  45         mutex_lock(&led_cdev->led_access);
  46
  47         if (led_sysfs_is_disabled(led_cdev)) {
  48                 ret = -EBUSY;
  49                 goto unlock;
  50         }
  51
  52         ret = kstrtoul(buf, 10, &state);
  53         if (ret)
  54                 goto unlock;
  55
  56         if (state == LED_OFF)
  57                 led_trigger_remove(led_cdev);
  58         led_set_brightness(led_cdev, state);
  59
  60         ret = size;
  61 unlock:
  62         mutex_unlock(&led_cdev->led_access);
  63         return ret;
  64 }
  65 static DEVICE_ATTR_RW(brightness);
  66
  67 static ssize_t 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 static DEVICE_ATTR_RO(max_brightness);
  75
  76 #ifdef CONFIG_LEDS_TRIGGERS
  77 static DEVICE_ATTR(trigger, 0644, led_trigger_show, led_trigger_store);
  78 static struct attribute *led_trigger_attrs[] = {
  79         &dev_attr_trigger.attr,
  80         NULL,
  81 };
  82 static const struct attribute_group led_trigger_group = {
  83         .attrs = led_trigger_attrs,
  84 };
  85 #endif
  86
  87 static struct attribute *led_class_attrs[] = {
  88         &dev_attr_brightness.attr,
  89         &dev_attr_max_brightness.attr,
  90         NULL,
  91 };
  92
  93 static const struct attribute_group led_group = {
  94         .attrs = led_class_attrs,
  95 };
  96
  97 static const struct attribute_group *led_groups[] = {
  98         &led_group,
  99 #ifdef CONFIG_LEDS_TRIGGERS
 100         &led_trigger_group,
 101 #endif
 102         NULL,
 103 };
 104
 105 static void led_timer_function(unsigned long data)
 106 {
 107         struct led_classdev *led_cdev = (void *)data;
 108         unsigned long brightness;
 109         unsigned long delay;
 110
 111         if (!led_cdev->blink_delay_on || !led_cdev->blink_delay_off) {
 112                 led_set_brightness_async(led_cdev, LED_OFF);
 113                 return;
 114         }
 115
 116         if (led_cdev->flags & LED_BLINK_ONESHOT_STOP) {
 117                 led_cdev->flags &= ~LED_BLINK_ONESHOT_STOP;
 118                 return;
 119         }
 120
 121         brightness = led_get_brightness(led_cdev);
 122         if (!brightness) {
 123                 /* Time to switch the LED on. */
 124                 brightness = led_cdev->blink_brightness;
 125                 delay = led_cdev->blink_delay_on;
 126         } else {
 127                 /* Store the current brightness value to be able
 128                  * to restore it when the delay_off period is over.
 129                  */
 130                 led_cdev->blink_brightness = brightness;
 131                 brightness = LED_OFF;
 132                 delay = led_cdev->blink_delay_off;
 133         }
 134
 135         led_set_brightness_async(led_cdev, brightness);
 136
 137         /* Return in next iteration if led is in one-shot mode and we are in
 138          * the final blink state so that the led is toggled each delay_on +
 139          * delay_off milliseconds in worst case.
 140          */
 141         if (led_cdev->flags & LED_BLINK_ONESHOT) {
 142                 if (led_cdev->flags & LED_BLINK_INVERT) {
 143                         if (brightness)
 144                                 led_cdev->flags |= LED_BLINK_ONESHOT_STOP;
 145                 } else {
 146                         if (!brightness)
 147                                 led_cdev->flags |= LED_BLINK_ONESHOT_STOP;
 148                 }
 149         }
 150
 151         mod_timer(&led_cdev->blink_timer, jiffies + msecs_to_jiffies(delay));
 152 }
 153
 154 static void set_brightness_delayed(struct work_struct *ws)
 155 {
 156         struct led_classdev *led_cdev =
 157                 container_of(ws, struct led_classdev, set_brightness_work);
 158
 159         led_stop_software_blink(led_cdev);
 160
 161         led_set_brightness_async(led_cdev, led_cdev->delayed_set_value);
 162 }
 163
 164 /**
 165  * led_classdev_suspend - suspend an led_classdev.
 166  * @led_cdev: the led_classdev to suspend.
 167  */
 168 void led_classdev_suspend(struct led_classdev *led_cdev)
 169 {
 170         led_cdev->flags |= LED_SUSPENDED;
 171         led_cdev->brightness_set(led_cdev, 0);
 172 }
 173 EXPORT_SYMBOL_GPL(led_classdev_suspend);
 174
 175 /**
 176  * led_classdev_resume - resume an led_classdev.
 177  * @led_cdev: the led_classdev to resume.
 178  */
 179 void led_classdev_resume(struct led_classdev *led_cdev)
 180 {
 181         led_cdev->brightness_set(led_cdev, led_cdev->brightness);
 182         led_cdev->flags &= ~LED_SUSPENDED;
 183 }
 184 EXPORT_SYMBOL_GPL(led_classdev_resume);
 185
 186 static int led_suspend(struct device *dev)
 187 {
 188         struct led_classdev *led_cdev = dev_get_drvdata(dev);
 189
 190         if (led_cdev->flags & LED_CORE_SUSPENDRESUME)
 191                 led_classdev_suspend(led_cdev);
 192
 193         return 0;
 194 }
 195
 196 static int led_resume(struct device *dev)
 197 {
 198         struct led_classdev *led_cdev = dev_get_drvdata(dev);
 199
 200         if (led_cdev->flags & LED_CORE_SUSPENDRESUME)
 201                 led_classdev_resume(led_cdev);
 202
 203         return 0;
 204 }
 205
 206 static const struct dev_pm_ops leds_class_dev_pm_ops = {
 207         .suspend        = led_suspend,
 208         .resume         = led_resume,
 209 };
 210
 211 /**
 212  * led_classdev_register - register a new object of led_classdev class.
 213  * @parent: The device to register.
 214  * @led_cdev: the led_classdev structure for this device.
 215  */
 216 int led_classdev_register(struct device *parent, struct led_classdev *led_cdev)
 217 {
 218         led_cdev->dev = device_create_with_groups(leds_class, parent, 0,
 219                                         led_cdev, led_cdev->groups,
 220                                         "%s", led_cdev->name);
 221         if (IS_ERR(led_cdev->dev))
 222                 return PTR_ERR(led_cdev->dev);
 223
 224 #ifdef CONFIG_LEDS_TRIGGERS
 225         init_rwsem(&led_cdev->trigger_lock);
 226 #endif
 227         mutex_init(&led_cdev->led_access);
 228         /* add to the list of leds */
 229         down_write(&leds_list_lock);
 230         list_add_tail(&led_cdev->node, &leds_list);
 231         up_write(&leds_list_lock);
 232
 233         if (!led_cdev->max_brightness)
 234                 led_cdev->max_brightness = LED_FULL;
 235
 236         led_cdev->flags |= SET_BRIGHTNESS_ASYNC;
 237
 238         led_update_brightness(led_cdev);
 239
 240         INIT_WORK(&led_cdev->set_brightness_work, set_brightness_delayed);
 241
 242         init_timer(&led_cdev->blink_timer);
 243         led_cdev->blink_timer.function = led_timer_function;
 244         led_cdev->blink_timer.data = (unsigned long)led_cdev;
 245
 246 #ifdef CONFIG_LEDS_TRIGGERS
 247         led_trigger_set_default(led_cdev);
 248 #endif
 249
 250         dev_dbg(parent, "Registered led device: %s\n",
 251                         led_cdev->name);
 252
 253         return 0;
 254 }
 255 EXPORT_SYMBOL_GPL(led_classdev_register);
 256
 257 /**
 258  * led_classdev_unregister - unregisters a object of led_properties class.
 259  * @led_cdev: the led device to unregister
 260  *
 261  * Unregisters a previously registered via led_classdev_register object.
 262  */
 263 void led_classdev_unregister(struct led_classdev *led_cdev)
 264 {
 265 #ifdef CONFIG_LEDS_TRIGGERS
 266         down_write(&led_cdev->trigger_lock);
 267         if (led_cdev->trigger)
 268                 led_trigger_set(led_cdev, NULL);
 269         up_write(&led_cdev->trigger_lock);
 270 #endif
 271
 272         cancel_work_sync(&led_cdev->set_brightness_work);
 273
 274         /* Stop blinking */
 275         led_stop_software_blink(led_cdev);
 276         led_set_brightness(led_cdev, LED_OFF);
 277
 278         device_unregister(led_cdev->dev);
 279
 280         down_write(&leds_list_lock);
 281         list_del(&led_cdev->node);
 282         up_write(&leds_list_lock);
 283
 284         mutex_destroy(&led_cdev->led_access);
 285 }
 286 EXPORT_SYMBOL_GPL(led_classdev_unregister);
 287
 288 static int __init leds_init(void)
 289 {
 290         leds_class = class_create(THIS_MODULE, "leds");
 291         if (IS_ERR(leds_class))
 292                 return PTR_ERR(leds_class);
 293         leds_class->pm = &leds_class_dev_pm_ops;
 294         leds_class->dev_groups = led_groups;
 295         return 0;
 296 }
 297
 298 static void __exit leds_exit(void)
 299 {
 300         class_destroy(leds_class);
 301 }
 302
 303 subsys_initcall(leds_init);
 304 module_exit(leds_exit);
 305
 306 MODULE_AUTHOR("John Lenz, Richard Purdie");
 307 MODULE_LICENSE("GPL");
 308 MODULE_DESCRIPTION("LED Class Interface");