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 = -EINVAL;
  44
  45         ret = kstrtoul(buf, 10, &state);
  46         if (ret)
  47                 return ret;
  48
  49         if (state == LED_OFF)
  50                 led_trigger_remove(led_cdev);
  51         __led_set_brightness(led_cdev, state);
  52
  53         return size;
  54 }
  55 static DEVICE_ATTR_RW(brightness);
  56
  57 static ssize_t max_brightness_show(struct device *dev,
  58                 struct device_attribute *attr, char *buf)
  59 {
  60         struct led_classdev *led_cdev = dev_get_drvdata(dev);
  61
  62         return sprintf(buf, "%u\n", led_cdev->max_brightness);
  63 }
  64 static DEVICE_ATTR_RO(max_brightness);
  65
  66 #ifdef CONFIG_LEDS_TRIGGERS
  67 static DEVICE_ATTR(trigger, 0644, led_trigger_show, led_trigger_store);
  68 static struct attribute *led_trigger_attrs[] = {
  69         &dev_attr_trigger.attr,
  70         NULL,
  71 };
  72 static const struct attribute_group led_trigger_group = {
  73         .attrs = led_trigger_attrs,
  74 };
  75 #endif
  76
  77 static struct attribute *led_class_attrs[] = {
  78         &dev_attr_brightness.attr,
  79         &dev_attr_max_brightness.attr,
  80         NULL,
  81 };
  82
  83 static const struct attribute_group led_group = {
  84         .attrs = led_class_attrs,
  85 };
  86
  87 static const struct attribute_group *led_groups[] = {
  88         &led_group,
  89 #ifdef CONFIG_LEDS_TRIGGERS
  90         &led_trigger_group,
  91 #endif
  92         NULL,
  93 };
  94
  95 static void led_timer_function(unsigned long data)
  96 {
  97         struct led_classdev *led_cdev = (void *)data;
  98         unsigned long brightness;
  99         unsigned long delay;
 100
 101         if (!led_cdev->blink_delay_on || !led_cdev->blink_delay_off) {
 102                 __led_set_brightness(led_cdev, LED_OFF);
 103                 return;
 104         }
 105
 106         if (led_cdev->flags & LED_BLINK_ONESHOT_STOP) {
 107                 led_cdev->flags &= ~LED_BLINK_ONESHOT_STOP;
 108                 return;
 109         }
 110
 111         brightness = led_get_brightness(led_cdev);
 112         if (!brightness) {
 113                 /* Time to switch the LED on. */
 114                 brightness = led_cdev->blink_brightness;
 115                 delay = led_cdev->blink_delay_on;
 116         } else {
 117                 /* Store the current brightness value to be able
 118                  * to restore it when the delay_off period is over.
 119                  */
 120                 led_cdev->blink_brightness = brightness;
 121                 brightness = LED_OFF;
 122                 delay = led_cdev->blink_delay_off;
 123         }
 124
 125         __led_set_brightness(led_cdev, brightness);
 126
 127         /* Return in next iteration if led is in one-shot mode and we are in
 128          * the final blink state so that the led is toggled each delay_on +
 129          * delay_off milliseconds in worst case.
 130          */
 131         if (led_cdev->flags & LED_BLINK_ONESHOT) {
 132                 if (led_cdev->flags & LED_BLINK_INVERT) {
 133                         if (brightness)
 134                                 led_cdev->flags |= LED_BLINK_ONESHOT_STOP;
 135                 } else {
 136                         if (!brightness)
 137                                 led_cdev->flags |= LED_BLINK_ONESHOT_STOP;
 138                 }
 139         }
 140
 141         mod_timer(&led_cdev->blink_timer, jiffies + msecs_to_jiffies(delay));
 142 }
 143
 144 static void set_brightness_delayed(struct work_struct *ws)
 145 {
 146         struct led_classdev *led_cdev =
 147                 container_of(ws, struct led_classdev, set_brightness_work);
 148
 149         led_stop_software_blink(led_cdev);
 150
 151         __led_set_brightness(led_cdev, led_cdev->delayed_set_value);
 152 }
 153
 154 /**
 155  * led_classdev_suspend - suspend an led_classdev.
 156  * @led_cdev: the led_classdev to suspend.
 157  */
 158 void led_classdev_suspend(struct led_classdev *led_cdev)
 159 {
 160         led_cdev->flags |= LED_SUSPENDED;
 161         led_cdev->brightness_set(led_cdev, 0);
 162 }
 163 EXPORT_SYMBOL_GPL(led_classdev_suspend);
 164
 165 /**
 166  * led_classdev_resume - resume an led_classdev.
 167  * @led_cdev: the led_classdev to resume.
 168  */
 169 void led_classdev_resume(struct led_classdev *led_cdev)
 170 {
 171         led_cdev->brightness_set(led_cdev, led_cdev->brightness);
 172         led_cdev->flags &= ~LED_SUSPENDED;
 173 }
 174 EXPORT_SYMBOL_GPL(led_classdev_resume);
 175
 176 static int led_suspend(struct device *dev)
 177 {
 178         struct led_classdev *led_cdev = dev_get_drvdata(dev);
 179
 180         if (led_cdev->flags & LED_CORE_SUSPENDRESUME)
 181                 led_classdev_suspend(led_cdev);
 182
 183         return 0;
 184 }
 185
 186 static int led_resume(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_resume(led_cdev);
 192
 193         return 0;
 194 }
 195
 196 static const struct dev_pm_ops leds_class_dev_pm_ops = {
 197         .suspend        = led_suspend,
 198         .resume         = led_resume,
 199 };
 200
 201 /**
 202  * led_classdev_register - register a new object of led_classdev class.
 203  * @parent: The device to register.
 204  * @led_cdev: the led_classdev structure for this device.
 205  */
 206 int led_classdev_register(struct device *parent, struct led_classdev *led_cdev)
 207 {
 208         led_cdev->dev = device_create_with_groups(leds_class, parent, 0,
 209                                         led_cdev, led_cdev->groups,
 210                                         "%s", led_cdev->name);
 211         if (IS_ERR(led_cdev->dev))
 212                 return PTR_ERR(led_cdev->dev);
 213
 214 #ifdef CONFIG_LEDS_TRIGGERS
 215         init_rwsem(&led_cdev->trigger_lock);
 216 #endif
 217         /* add to the list of leds */
 218         down_write(&leds_list_lock);
 219         list_add_tail(&led_cdev->node, &leds_list);
 220         up_write(&leds_list_lock);
 221
 222         if (!led_cdev->max_brightness)
 223                 led_cdev->max_brightness = LED_FULL;
 224
 225         led_update_brightness(led_cdev);
 226
 227         INIT_WORK(&led_cdev->set_brightness_work, set_brightness_delayed);
 228
 229         init_timer(&led_cdev->blink_timer);
 230         led_cdev->blink_timer.function = led_timer_function;
 231         led_cdev->blink_timer.data = (unsigned long)led_cdev;
 232
 233 #ifdef CONFIG_LEDS_TRIGGERS
 234         led_trigger_set_default(led_cdev);
 235 #endif
 236
 237         dev_dbg(parent, "Registered led device: %s\n",
 238                         led_cdev->name);
 239
 240         return 0;
 241 }
 242 EXPORT_SYMBOL_GPL(led_classdev_register);
 243
 244 /**
 245  * led_classdev_unregister - unregisters a object of led_properties class.
 246  * @led_cdev: the led device to unregister
 247  *
 248  * Unregisters a previously registered via led_classdev_register object.
 249  */
 250 void led_classdev_unregister(struct led_classdev *led_cdev)
 251 {
 252 #ifdef CONFIG_LEDS_TRIGGERS
 253         down_write(&led_cdev->trigger_lock);
 254         if (led_cdev->trigger)
 255                 led_trigger_set(led_cdev, NULL);
 256         up_write(&led_cdev->trigger_lock);
 257 #endif
 258
 259         cancel_work_sync(&led_cdev->set_brightness_work);
 260
 261         /* Stop blinking */
 262         led_stop_software_blink(led_cdev);
 263         led_set_brightness(led_cdev, LED_OFF);
 264
 265         device_unregister(led_cdev->dev);
 266
 267         down_write(&leds_list_lock);
 268         list_del(&led_cdev->node);
 269         up_write(&leds_list_lock);
 270 }
 271 EXPORT_SYMBOL_GPL(led_classdev_unregister);
 272
 273 static int __init leds_init(void)
 274 {
 275         leds_class = class_create(THIS_MODULE, "leds");
 276         if (IS_ERR(leds_class))
 277                 return PTR_ERR(leds_class);
 278         leds_class->pm = &leds_class_dev_pm_ops;
 279         leds_class->dev_groups = led_groups;
 280         return 0;
 281 }
 282
 283 static void __exit leds_exit(void)
 284 {
 285         class_destroy(leds_class);
 286 }
 287
 288 subsys_initcall(leds_init);
 289 module_exit(leds_exit);
 290
 291 MODULE_AUTHOR("John Lenz, Richard Purdie");
 292 MODULE_LICENSE("GPL");
 293 MODULE_DESCRIPTION("LED Class Interface");