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 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 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 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         unsigned long state;
  49         ssize_t ret = -EINVAL;
  50
  51         ret = kstrtoul(buf, 10, &state);
  52         if (ret)
  53                 return ret;
  54
  55         if (state == LED_OFF)
  56                 led_trigger_remove(led_cdev);
  57         __led_set_brightness(led_cdev, state);
  58
  59         return size;
  60 }
  61 static DEVICE_ATTR_RW(brightness);
  62
  63 static ssize_t max_brightness_show(struct device *dev,
  64                 struct device_attribute *attr, char *buf)
  65 {
  66         struct led_classdev *led_cdev = dev_get_drvdata(dev);
  67
  68         return sprintf(buf, "%u\n", led_cdev->max_brightness);
  69 }
  70 static DEVICE_ATTR_RO(max_brightness);
  71
  72 #ifdef CONFIG_LEDS_TRIGGERS
  73 static DEVICE_ATTR(trigger, 0644, led_trigger_show, led_trigger_store);
  74 static struct attribute *led_trigger_attrs[] = {
  75         &dev_attr_trigger.attr,
  76         NULL,
  77 };
  78 static const struct attribute_group led_trigger_group = {
  79         .attrs = led_trigger_attrs,
  80 };
  81 #endif
  82
  83 static struct attribute *led_class_attrs[] = {
  84         &dev_attr_brightness.attr,
  85         &dev_attr_max_brightness.attr,
  86         NULL,
  87 };
  88
  89 static const struct attribute_group led_group = {
  90         .attrs = led_class_attrs,
  91 };
  92
  93 static const struct attribute_group *led_groups[] = {
  94         &led_group,
  95 #ifdef CONFIG_LEDS_TRIGGERS
  96         &led_trigger_group,
  97 #endif
  98         NULL,
  99 };
 100
 101 static void led_timer_function(unsigned long data)
 102 {
 103         struct led_classdev *led_cdev = (void *)data;
 104         unsigned long brightness;
 105         unsigned long delay;
 106
 107         if (!led_cdev->blink_delay_on || !led_cdev->blink_delay_off) {
 108                 __led_set_brightness(led_cdev, LED_OFF);
 109                 return;
 110         }
 111
 112         if (led_cdev->flags & LED_BLINK_ONESHOT_STOP) {
 113                 led_cdev->flags &= ~LED_BLINK_ONESHOT_STOP;
 114                 return;
 115         }
 116
 117         brightness = led_get_brightness(led_cdev);
 118         if (!brightness) {
 119                 /* Time to switch the LED on. */
 120                 brightness = led_cdev->blink_brightness;
 121                 delay = led_cdev->blink_delay_on;
 122         } else {
 123                 /* Store the current brightness value to be able
 124                  * to restore it when the delay_off period is over.
 125                  */
 126                 led_cdev->blink_brightness = brightness;
 127                 brightness = LED_OFF;
 128                 delay = led_cdev->blink_delay_off;
 129         }
 130
 131         __led_set_brightness(led_cdev, brightness);
 132
 133         /* Return in next iteration if led is in one-shot mode and we are in
 134          * the final blink state so that the led is toggled each delay_on +
 135          * delay_off milliseconds in worst case.
 136          */
 137         if (led_cdev->flags & LED_BLINK_ONESHOT) {
 138                 if (led_cdev->flags & LED_BLINK_INVERT) {
 139                         if (brightness)
 140                                 led_cdev->flags |= LED_BLINK_ONESHOT_STOP;
 141                 } else {
 142                         if (!brightness)
 143                                 led_cdev->flags |= LED_BLINK_ONESHOT_STOP;
 144                 }
 145         }
 146
 147         mod_timer(&led_cdev->blink_timer, jiffies + msecs_to_jiffies(delay));
 148 }
 149
 150 static void set_brightness_delayed(struct work_struct *ws)
 151 {
 152         struct led_classdev *led_cdev =
 153                 container_of(ws, struct led_classdev, set_brightness_work);
 154
 155         led_stop_software_blink(led_cdev);
 156
 157         __led_set_brightness(led_cdev, led_cdev->delayed_set_value);
 158 }
 159
 160 /**
 161  * led_classdev_suspend - suspend an led_classdev.
 162  * @led_cdev: the led_classdev to suspend.
 163  */
 164 void led_classdev_suspend(struct led_classdev *led_cdev)
 165 {
 166         led_cdev->flags |= LED_SUSPENDED;
 167         led_cdev->brightness_set(led_cdev, 0);
 168 }
 169 EXPORT_SYMBOL_GPL(led_classdev_suspend);
 170
 171 /**
 172  * led_classdev_resume - resume an led_classdev.
 173  * @led_cdev: the led_classdev to resume.
 174  */
 175 void led_classdev_resume(struct led_classdev *led_cdev)
 176 {
 177         led_cdev->brightness_set(led_cdev, led_cdev->brightness);
 178         led_cdev->flags &= ~LED_SUSPENDED;
 179 }
 180 EXPORT_SYMBOL_GPL(led_classdev_resume);
 181
 182 static int led_suspend(struct device *dev)
 183 {
 184         struct led_classdev *led_cdev = dev_get_drvdata(dev);
 185
 186         if (led_cdev->flags & LED_CORE_SUSPENDRESUME)
 187                 led_classdev_suspend(led_cdev);
 188
 189         return 0;
 190 }
 191
 192 static int led_resume(struct device *dev)
 193 {
 194         struct led_classdev *led_cdev = dev_get_drvdata(dev);
 195
 196         if (led_cdev->flags & LED_CORE_SUSPENDRESUME)
 197                 led_classdev_resume(led_cdev);
 198
 199         return 0;
 200 }
 201
 202 static const struct dev_pm_ops leds_class_dev_pm_ops = {
 203         .suspend        = led_suspend,
 204         .resume         = led_resume,
 205 };
 206
 207 /**
 208  * led_classdev_register - register a new object of led_classdev class.
 209  * @parent: The device to register.
 210  * @led_cdev: the led_classdev structure for this device.
 211  */
 212 int led_classdev_register(struct device *parent, struct led_classdev *led_cdev)
 213 {
 214         led_cdev->dev = device_create_with_groups(leds_class, parent, 0,
 215                                         led_cdev, led_cdev->groups,
 216                                         "%s", led_cdev->name);
 217         if (IS_ERR(led_cdev->dev))
 218                 return PTR_ERR(led_cdev->dev);
 219
 220 #ifdef CONFIG_LEDS_TRIGGERS
 221         init_rwsem(&led_cdev->trigger_lock);
 222 #endif
 223         /* add to the list of leds */
 224         down_write(&leds_list_lock);
 225         list_add_tail(&led_cdev->node, &leds_list);
 226         up_write(&leds_list_lock);
 227
 228         if (!led_cdev->max_brightness)
 229                 led_cdev->max_brightness = LED_FULL;
 230
 231         led_update_brightness(led_cdev);
 232
 233         INIT_WORK(&led_cdev->set_brightness_work, set_brightness_delayed);
 234
 235         init_timer(&led_cdev->blink_timer);
 236         led_cdev->blink_timer.function = led_timer_function;
 237         led_cdev->blink_timer.data = (unsigned long)led_cdev;
 238
 239 #ifdef CONFIG_LEDS_TRIGGERS
 240         led_trigger_set_default(led_cdev);
 241 #endif
 242
 243         dev_dbg(parent, "Registered led device: %s\n",
 244                         led_cdev->name);
 245
 246         return 0;
 247 }
 248 EXPORT_SYMBOL_GPL(led_classdev_register);
 249
 250 /**
 251  * led_classdev_unregister - unregisters a object of led_properties class.
 252  * @led_cdev: the led device to unregister
 253  *
 254  * Unregisters a previously registered via led_classdev_register object.
 255  */
 256 void led_classdev_unregister(struct led_classdev *led_cdev)
 257 {
 258 #ifdef CONFIG_LEDS_TRIGGERS
 259         down_write(&led_cdev->trigger_lock);
 260         if (led_cdev->trigger)
 261                 led_trigger_set(led_cdev, NULL);
 262         up_write(&led_cdev->trigger_lock);
 263 #endif
 264
 265         cancel_work_sync(&led_cdev->set_brightness_work);
 266
 267         /* Stop blinking */
 268         led_stop_software_blink(led_cdev);
 269         led_set_brightness(led_cdev, LED_OFF);
 270
 271         device_unregister(led_cdev->dev);
 272
 273         down_write(&leds_list_lock);
 274         list_del(&led_cdev->node);
 275         up_write(&leds_list_lock);
 276 }
 277 EXPORT_SYMBOL_GPL(led_classdev_unregister);
 278
 279 static int __init leds_init(void)
 280 {
 281         leds_class = class_create(THIS_MODULE, "leds");
 282         if (IS_ERR(leds_class))
 283                 return PTR_ERR(leds_class);
 284         leds_class->pm = &leds_class_dev_pm_ops;
 285         leds_class->dev_groups = led_groups;
 286         return 0;
 287 }
 288
 289 static void __exit leds_exit(void)
 290 {
 291         class_destroy(leds_class);
 292 }
 293
 294 subsys_initcall(leds_init);
 295 module_exit(leds_exit);
 296
 297 MODULE_AUTHOR("John Lenz, Richard Purdie");
 298 MODULE_LICENSE("GPL");
 299 MODULE_DESCRIPTION("LED Class Interface");