linux/drivers/leds/led-class.c
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   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/timer.h>
  19#include <linux/err.h>
  20#include <linux/ctype.h>
  21#include <linux/leds.h>
  22#include "leds.h"
  23
  24static struct class *leds_class;
  25
  26static 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
  32static 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
  43static 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}
  60static DEVICE_ATTR_RW(brightness);
  61
  62static 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}
  69static DEVICE_ATTR(max_brightness, 0444, led_max_brightness_show, NULL);
  70
  71#ifdef CONFIG_LEDS_TRIGGERS
  72static DEVICE_ATTR(trigger, 0644, led_trigger_show, led_trigger_store);
  73static struct attribute *led_trigger_attrs[] = {
  74        &dev_attr_trigger.attr,
  75        NULL,
  76};
  77static const struct attribute_group led_trigger_group = {
  78        .attrs = led_trigger_attrs,
  79};
  80#endif
  81
  82static struct attribute *led_class_attrs[] = {
  83        &dev_attr_brightness.attr,
  84        &dev_attr_max_brightness.attr,
  85        NULL,
  86};
  87
  88static const struct attribute_group led_group = {
  89        .attrs = led_class_attrs,
  90};
  91
  92static const struct attribute_group *led_groups[] = {
  93        &led_group,
  94#ifdef CONFIG_LEDS_TRIGGERS
  95        &led_trigger_group,
  96#endif
  97        NULL,
  98};
  99
 100static void led_timer_function(unsigned long data)
 101{
 102        struct led_classdev *led_cdev = (void *)data;
 103        unsigned long brightness;
 104        unsigned long delay;
 105
 106        if (!led_cdev->blink_delay_on || !led_cdev->blink_delay_off) {
 107                __led_set_brightness(led_cdev, LED_OFF);
 108                return;
 109        }
 110
 111        if (led_cdev->flags & LED_BLINK_ONESHOT_STOP) {
 112                led_cdev->flags &= ~LED_BLINK_ONESHOT_STOP;
 113                return;
 114        }
 115
 116        brightness = led_get_brightness(led_cdev);
 117        if (!brightness) {
 118                /* Time to switch the LED on. */
 119                brightness = led_cdev->blink_brightness;
 120                delay = led_cdev->blink_delay_on;
 121        } else {
 122                /* Store the current brightness value to be able
 123                 * to restore it when the delay_off period is over.
 124                 */
 125                led_cdev->blink_brightness = brightness;
 126                brightness = LED_OFF;
 127                delay = led_cdev->blink_delay_off;
 128        }
 129
 130        __led_set_brightness(led_cdev, brightness);
 131
 132        /* Return in next iteration if led is in one-shot mode and we are in
 133         * the final blink state so that the led is toggled each delay_on +
 134         * delay_off milliseconds in worst case.
 135         */
 136        if (led_cdev->flags & LED_BLINK_ONESHOT) {
 137                if (led_cdev->flags & LED_BLINK_INVERT) {
 138                        if (brightness)
 139                                led_cdev->flags |= LED_BLINK_ONESHOT_STOP;
 140                } else {
 141                        if (!brightness)
 142                                led_cdev->flags |= LED_BLINK_ONESHOT_STOP;
 143                }
 144        }
 145
 146        mod_timer(&led_cdev->blink_timer, jiffies + msecs_to_jiffies(delay));
 147}
 148
 149static void set_brightness_delayed(struct work_struct *ws)
 150{
 151        struct led_classdev *led_cdev =
 152                container_of(ws, struct led_classdev, set_brightness_work);
 153
 154        led_stop_software_blink(led_cdev);
 155
 156        __led_set_brightness(led_cdev, led_cdev->delayed_set_value);
 157}
 158
 159/**
 160 * led_classdev_suspend - suspend an led_classdev.
 161 * @led_cdev: the led_classdev to suspend.
 162 */
 163void led_classdev_suspend(struct led_classdev *led_cdev)
 164{
 165        led_cdev->flags |= LED_SUSPENDED;
 166        led_cdev->brightness_set(led_cdev, 0);
 167}
 168EXPORT_SYMBOL_GPL(led_classdev_suspend);
 169
 170/**
 171 * led_classdev_resume - resume an led_classdev.
 172 * @led_cdev: the led_classdev to resume.
 173 */
 174void led_classdev_resume(struct led_classdev *led_cdev)
 175{
 176        led_cdev->brightness_set(led_cdev, led_cdev->brightness);
 177        led_cdev->flags &= ~LED_SUSPENDED;
 178}
 179EXPORT_SYMBOL_GPL(led_classdev_resume);
 180
 181static int led_suspend(struct device *dev)
 182{
 183        struct led_classdev *led_cdev = dev_get_drvdata(dev);
 184
 185        if (led_cdev->flags & LED_CORE_SUSPENDRESUME)
 186                led_classdev_suspend(led_cdev);
 187
 188        return 0;
 189}
 190
 191static int led_resume(struct device *dev)
 192{
 193        struct led_classdev *led_cdev = dev_get_drvdata(dev);
 194
 195        if (led_cdev->flags & LED_CORE_SUSPENDRESUME)
 196                led_classdev_resume(led_cdev);
 197
 198        return 0;
 199}
 200
 201static const struct dev_pm_ops leds_class_dev_pm_ops = {
 202        .suspend        = led_suspend,
 203        .resume         = led_resume,
 204};
 205
 206/**
 207 * led_classdev_register - register a new object of led_classdev class.
 208 * @parent: The device to register.
 209 * @led_cdev: the led_classdev structure for this device.
 210 */
 211int led_classdev_register(struct device *parent, struct led_classdev *led_cdev)
 212{
 213        led_cdev->dev = device_create(leds_class, parent, 0, led_cdev,
 214                                      "%s", led_cdev->name);
 215        if (IS_ERR(led_cdev->dev))
 216                return PTR_ERR(led_cdev->dev);
 217
 218#ifdef CONFIG_LEDS_TRIGGERS
 219        init_rwsem(&led_cdev->trigger_lock);
 220#endif
 221        /* add to the list of leds */
 222        down_write(&leds_list_lock);
 223        list_add_tail(&led_cdev->node, &leds_list);
 224        up_write(&leds_list_lock);
 225
 226        if (!led_cdev->max_brightness)
 227                led_cdev->max_brightness = LED_FULL;
 228
 229        led_update_brightness(led_cdev);
 230
 231        INIT_WORK(&led_cdev->set_brightness_work, set_brightness_delayed);
 232
 233        init_timer(&led_cdev->blink_timer);
 234        led_cdev->blink_timer.function = led_timer_function;
 235        led_cdev->blink_timer.data = (unsigned long)led_cdev;
 236
 237#ifdef CONFIG_LEDS_TRIGGERS
 238        led_trigger_set_default(led_cdev);
 239#endif
 240
 241        dev_dbg(parent, "Registered led device: %s\n",
 242                        led_cdev->name);
 243
 244        return 0;
 245}
 246EXPORT_SYMBOL_GPL(led_classdev_register);
 247
 248/**
 249 * led_classdev_unregister - unregisters a object of led_properties class.
 250 * @led_cdev: the led device to unregister
 251 *
 252 * Unregisters a previously registered via led_classdev_register object.
 253 */
 254void led_classdev_unregister(struct led_classdev *led_cdev)
 255{
 256#ifdef CONFIG_LEDS_TRIGGERS
 257        down_write(&led_cdev->trigger_lock);
 258        if (led_cdev->trigger)
 259                led_trigger_set(led_cdev, NULL);
 260        up_write(&led_cdev->trigger_lock);
 261#endif
 262
 263        cancel_work_sync(&led_cdev->set_brightness_work);
 264
 265        /* Stop blinking */
 266        led_stop_software_blink(led_cdev);
 267        led_set_brightness(led_cdev, LED_OFF);
 268
 269        device_unregister(led_cdev->dev);
 270
 271        down_write(&leds_list_lock);
 272        list_del(&led_cdev->node);
 273        up_write(&leds_list_lock);
 274}
 275EXPORT_SYMBOL_GPL(led_classdev_unregister);
 276
 277static int __init leds_init(void)
 278{
 279        leds_class = class_create(THIS_MODULE, "leds");
 280        if (IS_ERR(leds_class))
 281                return PTR_ERR(leds_class);
 282        leds_class->pm = &leds_class_dev_pm_ops;
 283        leds_class->dev_groups = led_groups;
 284        return 0;
 285}
 286
 287static void __exit leds_exit(void)
 288{
 289        class_destroy(leds_class);
 290}
 291
 292subsys_initcall(leds_init);
 293module_exit(leds_exit);
 294
 295MODULE_AUTHOR("John Lenz, Richard Purdie");
 296MODULE_LICENSE("GPL");
 297MODULE_DESCRIPTION("LED Class Interface");
 298
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