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/err.h>
  19 #include <linux/ctype.h>
  20 #include <linux/leds.h>
  21 #include <linux/workqueue.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 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 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 static DEVICE_ATTR_RW(brightness);
  61
  62 static ssize_t led_max_brightness_show(struct device *dev,
  63                 struct device_attribute *attr, char *buf)
  64 {
  65         struct led_classdev *led_cdev = dev_get_drvdata(dev);
  66
  67         return sprintf(buf, "%u\n", led_cdev->max_brightness);
  68 }
  69 static DEVICE_ATTR(max_brightness, 0444, led_max_brightness_show, NULL);
  70
  71 #ifdef CONFIG_LEDS_TRIGGERS
  72 static DEVICE_ATTR(trigger, 0644, led_trigger_show, led_trigger_store);
  73 static struct attribute *led_trigger_attrs[] = {
  74         &dev_attr_trigger.attr,
  75         NULL,
  76 };
  77 static const struct attribute_group led_trigger_group = {
  78         .attrs = led_trigger_attrs,
  79 };
  80 #endif
  81
  82 static struct attribute *led_class_attrs[] = {
  83         &dev_attr_brightness.attr,
  84         &dev_attr_max_brightness.attr,
  85         NULL,
  86 };
  87
  88 static const struct attribute_group led_group = {
  89         .attrs = led_class_attrs,
  90 };
  91
  92 static const struct attribute_group *led_groups[] = {
  93         &led_group,
  94 #ifdef CONFIG_LEDS_TRIGGERS
  95         &led_trigger_group,
  96 #endif
  97         NULL,
  98 };
  99
 100 static void led_work_function(struct work_struct *ws)
 101 {
 102         struct led_classdev *led_cdev =
 103                 container_of(ws, struct led_classdev, blink_work.work);
 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         queue_delayed_work(system_wq, &led_cdev->blink_work,
 148                            msecs_to_jiffies(delay));
 149 }
 150
 151 static void set_brightness_delayed(struct work_struct *ws)
 152 {
 153         struct led_classdev *led_cdev =
 154                 container_of(ws, struct led_classdev, set_brightness_work);
 155
 156         led_stop_software_blink(led_cdev);
 157
 158         __led_set_brightness(led_cdev, led_cdev->delayed_set_value);
 159 }
 160
 161 /**
 162  * led_classdev_suspend - suspend an led_classdev.
 163  * @led_cdev: the led_classdev to suspend.
 164  */
 165 void led_classdev_suspend(struct led_classdev *led_cdev)
 166 {
 167         led_cdev->flags |= LED_SUSPENDED;
 168         led_cdev->brightness_set(led_cdev, 0);
 169 }
 170 EXPORT_SYMBOL_GPL(led_classdev_suspend);
 171
 172 /**
 173  * led_classdev_resume - resume an led_classdev.
 174  * @led_cdev: the led_classdev to resume.
 175  */
 176 void led_classdev_resume(struct led_classdev *led_cdev)
 177 {
 178         led_cdev->brightness_set(led_cdev, led_cdev->brightness);
 179         led_cdev->flags &= ~LED_SUSPENDED;
 180 }
 181 EXPORT_SYMBOL_GPL(led_classdev_resume);
 182
 183 static int led_suspend(struct device *dev)
 184 {
 185         struct led_classdev *led_cdev = dev_get_drvdata(dev);
 186
 187         if (led_cdev->flags & LED_CORE_SUSPENDRESUME)
 188                 led_classdev_suspend(led_cdev);
 189
 190         return 0;
 191 }
 192
 193 static int led_resume(struct device *dev)
 194 {
 195         struct led_classdev *led_cdev = dev_get_drvdata(dev);
 196
 197         if (led_cdev->flags & LED_CORE_SUSPENDRESUME)
 198                 led_classdev_resume(led_cdev);
 199
 200         return 0;
 201 }
 202
 203 static const struct dev_pm_ops leds_class_dev_pm_ops = {
 204         .suspend        = led_suspend,
 205         .resume         = led_resume,
 206 };
 207
 208 /**
 209  * led_classdev_register - register a new object of led_classdev class.
 210  * @parent: The device to register.
 211  * @led_cdev: the led_classdev structure for this device.
 212  */
 213 int led_classdev_register(struct device *parent, struct led_classdev *led_cdev)
 214 {
 215         led_cdev->dev = device_create_with_groups(leds_class, parent, 0,
 216                                         led_cdev, led_cdev->groups,
 217                                         "%s", led_cdev->name);
 218         if (IS_ERR(led_cdev->dev))
 219                 return PTR_ERR(led_cdev->dev);
 220
 221 #ifdef CONFIG_LEDS_TRIGGERS
 222         init_rwsem(&led_cdev->trigger_lock);
 223 #endif
 224         /* add to the list of leds */
 225         down_write(&leds_list_lock);
 226         list_add_tail(&led_cdev->node, &leds_list);
 227         up_write(&leds_list_lock);
 228
 229         if (!led_cdev->max_brightness)
 230                 led_cdev->max_brightness = LED_FULL;
 231
 232         led_update_brightness(led_cdev);
 233
 234         INIT_WORK(&led_cdev->set_brightness_work, set_brightness_delayed);
 235
 236         INIT_DELAYED_WORK(&led_cdev->blink_work, led_work_function);
 237
 238 #ifdef CONFIG_LEDS_TRIGGERS
 239         led_trigger_set_default(led_cdev);
 240 #endif
 241
 242         dev_dbg(parent, "Registered led device: %s\n",
 243                         led_cdev->name);
 244
 245         return 0;
 246 }
 247 EXPORT_SYMBOL_GPL(led_classdev_register);
 248
 249 /**
 250  * led_classdev_unregister - unregisters a object of led_properties class.
 251  * @led_cdev: the led device to unregister
 252  *
 253  * Unregisters a previously registered via led_classdev_register object.
 254  */
 255 void led_classdev_unregister(struct led_classdev *led_cdev)
 256 {
 257 #ifdef CONFIG_LEDS_TRIGGERS
 258         down_write(&led_cdev->trigger_lock);
 259         if (led_cdev->trigger)
 260                 led_trigger_set(led_cdev, NULL);
 261         up_write(&led_cdev->trigger_lock);
 262 #endif
 263
 264         cancel_work_sync(&led_cdev->set_brightness_work);
 265
 266         /* Stop blinking */
 267         led_stop_software_blink(led_cdev);
 268         led_set_brightness(led_cdev, LED_OFF);
 269
 270         device_unregister(led_cdev->dev);
 271
 272         down_write(&leds_list_lock);
 273         list_del(&led_cdev->node);
 274         up_write(&leds_list_lock);
 275 }
 276 EXPORT_SYMBOL_GPL(led_classdev_unregister);
 277
 278 static int __init leds_init(void)
 279 {
 280         leds_class = class_create(THIS_MODULE, "leds");
 281         if (IS_ERR(leds_class))
 282                 return PTR_ERR(leds_class);
 283         leds_class->pm = &leds_class_dev_pm_ops;
 284         leds_class->dev_groups = led_groups;
 285         return 0;
 286 }
 287
 288 static void __exit leds_exit(void)
 289 {
 290         class_destroy(leds_class);
 291 }
 292
 293 subsys_initcall(leds_init);
 294 module_exit(leds_exit);
 295
 296 MODULE_AUTHOR("John Lenz, Richard Purdie");
 297 MODULE_LICENSE("GPL");
 298 MODULE_DESCRIPTION("LED Class Interface");