LXR linux/drivers/leds/led-core.c

   1/*
   2 * LED Class Core
   3 *
   4 * Copyright 2005-2006 Openedhand Ltd.
   5 *
   6 * Author: Richard Purdie <rpurdie@openedhand.com>
   7 *
   8 * This program is free software; you can redistribute it and/or modify
   9 * it under the terms of the GNU General Public License version 2 as
  10 * published by the Free Software Foundation.
  11 *
  12 */
  13
  14#include <linux/kernel.h>
  15#include <linux/leds.h>
  16#include <linux/list.h>
  17#include <linux/module.h>
  18#include <linux/mutex.h>
  19#include <linux/rwsem.h>
  20#include "leds.h"
  21
  22DECLARE_RWSEM(leds_list_lock);
  23EXPORT_SYMBOL_GPL(leds_list_lock);
  24
  25LIST_HEAD(leds_list);
  26EXPORT_SYMBOL_GPL(leds_list);
  27
  28static int __led_set_brightness(struct led_classdev *led_cdev,
  29                                enum led_brightness value)
  30{
  31        if (!led_cdev->brightness_set)
  32                return -ENOTSUPP;
  33
  34        led_cdev->brightness_set(led_cdev, value);
  35
  36        return 0;
  37}
  38
  39static int __led_set_brightness_blocking(struct led_classdev *led_cdev,
  40                                         enum led_brightness value)
  41{
  42        if (!led_cdev->brightness_set_blocking)
  43                return -ENOTSUPP;
  44
  45        return led_cdev->brightness_set_blocking(led_cdev, value);
  46}
  47
  48static void led_timer_function(unsigned long data)
  49{
  50        struct led_classdev *led_cdev = (void *)data;
  51        unsigned long brightness;
  52        unsigned long delay;
  53
  54        if (!led_cdev->blink_delay_on || !led_cdev->blink_delay_off) {
  55                led_set_brightness_nosleep(led_cdev, LED_OFF);
  56                led_cdev->flags &= ~LED_BLINK_SW;
  57                return;
  58        }
  59
  60        if (led_cdev->flags & LED_BLINK_ONESHOT_STOP) {
  61                led_cdev->flags &=  ~(LED_BLINK_ONESHOT_STOP | LED_BLINK_SW);
  62                return;
  63        }
  64
  65        brightness = led_get_brightness(led_cdev);
  66        if (!brightness) {
  67                /* Time to switch the LED on. */
  68                brightness = led_cdev->blink_brightness;
  69                delay = led_cdev->blink_delay_on;
  70        } else {
  71                /* Store the current brightness value to be able
  72                 * to restore it when the delay_off period is over.
  73                 * Do it only if there is no pending blink brightness
  74                 * change, to avoid overwriting the new value.
  75                 */
  76                if (!(led_cdev->flags & LED_BLINK_BRIGHTNESS_CHANGE))
  77                        led_cdev->blink_brightness = brightness;
  78                else
  79                        led_cdev->flags &= ~LED_BLINK_BRIGHTNESS_CHANGE;
  80                brightness = LED_OFF;
  81                delay = led_cdev->blink_delay_off;
  82        }
  83
  84        led_set_brightness_nosleep(led_cdev, brightness);
  85
  86        /* Return in next iteration if led is in one-shot mode and we are in
  87         * the final blink state so that the led is toggled each delay_on +
  88         * delay_off milliseconds in worst case.
  89         */
  90        if (led_cdev->flags & LED_BLINK_ONESHOT) {
  91                if (led_cdev->flags & LED_BLINK_INVERT) {
  92                        if (brightness)
  93                                led_cdev->flags |= LED_BLINK_ONESHOT_STOP;
  94                } else {
  95                        if (!brightness)
  96                                led_cdev->flags |= LED_BLINK_ONESHOT_STOP;
  97                }
  98        }
  99
 100        mod_timer(&led_cdev->blink_timer, jiffies + msecs_to_jiffies(delay));
 101}
 102
 103static void set_brightness_delayed(struct work_struct *ws)
 104{
 105        struct led_classdev *led_cdev =
 106                container_of(ws, struct led_classdev, set_brightness_work);
 107        int ret = 0;
 108
 109        if (led_cdev->flags & LED_BLINK_DISABLE) {
 110                led_cdev->delayed_set_value = LED_OFF;
 111                led_stop_software_blink(led_cdev);
 112                led_cdev->flags &= ~LED_BLINK_DISABLE;
 113        }
 114
 115        ret = __led_set_brightness(led_cdev, led_cdev->delayed_set_value);
 116        if (ret == -ENOTSUPP)
 117                ret = __led_set_brightness_blocking(led_cdev,
 118                                        led_cdev->delayed_set_value);
 119        if (ret < 0 &&
 120            /* LED HW might have been unplugged, therefore don't warn */
 121            !(ret == -ENODEV && (led_cdev->flags & LED_UNREGISTERING) &&
 122            (led_cdev->flags & LED_HW_PLUGGABLE)))
 123                dev_err(led_cdev->dev,
 124                        "Setting an LED's brightness failed (%d)\n", ret);
 125}
 126
 127static void led_set_software_blink(struct led_classdev *led_cdev,
 128                                   unsigned long delay_on,
 129                                   unsigned long delay_off)
 130{
 131        int current_brightness;
 132
 133        current_brightness = led_get_brightness(led_cdev);
 134        if (current_brightness)
 135                led_cdev->blink_brightness = current_brightness;
 136        if (!led_cdev->blink_brightness)
 137                led_cdev->blink_brightness = led_cdev->max_brightness;
 138
 139        led_cdev->blink_delay_on = delay_on;
 140        led_cdev->blink_delay_off = delay_off;
 141
 142        /* never on - just set to off */
 143        if (!delay_on) {
 144                led_set_brightness_nosleep(led_cdev, LED_OFF);
 145                return;
 146        }
 147
 148        /* never off - just set to brightness */
 149        if (!delay_off) {
 150                led_set_brightness_nosleep(led_cdev,
 151                                           led_cdev->blink_brightness);
 152                return;
 153        }
 154
 155        led_cdev->flags |= LED_BLINK_SW;
 156        mod_timer(&led_cdev->blink_timer, jiffies + 1);
 157}
 158
 159
 160static void led_blink_setup(struct led_classdev *led_cdev,
 161                     unsigned long *delay_on,
 162                     unsigned long *delay_off)
 163{
 164        if (!(led_cdev->flags & LED_BLINK_ONESHOT) &&
 165            led_cdev->blink_set &&
 166            !led_cdev->blink_set(led_cdev, delay_on, delay_off))
 167                return;
 168
 169        /* blink with 1 Hz as default if nothing specified */
 170        if (!*delay_on && !*delay_off)
 171                *delay_on = *delay_off = 500;
 172
 173        led_set_software_blink(led_cdev, *delay_on, *delay_off);
 174}
 175
 176void led_init_core(struct led_classdev *led_cdev)
 177{
 178        INIT_WORK(&led_cdev->set_brightness_work, set_brightness_delayed);
 179
 180        setup_timer(&led_cdev->blink_timer, led_timer_function,
 181                    (unsigned long)led_cdev);
 182}
 183EXPORT_SYMBOL_GPL(led_init_core);
 184
 185void led_blink_set(struct led_classdev *led_cdev,
 186                   unsigned long *delay_on,
 187                   unsigned long *delay_off)
 188{
 189        del_timer_sync(&led_cdev->blink_timer);
 190
 191        led_cdev->flags &= ~LED_BLINK_ONESHOT;
 192        led_cdev->flags &= ~LED_BLINK_ONESHOT_STOP;
 193
 194        led_blink_setup(led_cdev, delay_on, delay_off);
 195}
 196EXPORT_SYMBOL_GPL(led_blink_set);
 197
 198void led_blink_set_oneshot(struct led_classdev *led_cdev,
 199                           unsigned long *delay_on,
 200                           unsigned long *delay_off,
 201                           int invert)
 202{
 203        if ((led_cdev->flags & LED_BLINK_ONESHOT) &&
 204             timer_pending(&led_cdev->blink_timer))
 205                return;
 206
 207        led_cdev->flags |= LED_BLINK_ONESHOT;
 208        led_cdev->flags &= ~LED_BLINK_ONESHOT_STOP;
 209
 210        if (invert)
 211                led_cdev->flags |= LED_BLINK_INVERT;
 212        else
 213                led_cdev->flags &= ~LED_BLINK_INVERT;
 214
 215        led_blink_setup(led_cdev, delay_on, delay_off);
 216}
 217EXPORT_SYMBOL_GPL(led_blink_set_oneshot);
 218
 219void led_stop_software_blink(struct led_classdev *led_cdev)
 220{
 221        del_timer_sync(&led_cdev->blink_timer);
 222        led_cdev->blink_delay_on = 0;
 223        led_cdev->blink_delay_off = 0;
 224        led_cdev->flags &= ~LED_BLINK_SW;
 225}
 226EXPORT_SYMBOL_GPL(led_stop_software_blink);
 227
 228void led_set_brightness(struct led_classdev *led_cdev,
 229                        enum led_brightness brightness)
 230{
 231        /*
 232         * If software blink is active, delay brightness setting
 233         * until the next timer tick.
 234         */
 235        if (led_cdev->flags & LED_BLINK_SW) {
 236                /*
 237                 * If we need to disable soft blinking delegate this to the
 238                 * work queue task to avoid problems in case we are called
 239                 * from hard irq context.
 240                 */
 241                if (brightness == LED_OFF) {
 242                        led_cdev->flags |= LED_BLINK_DISABLE;
 243                        schedule_work(&led_cdev->set_brightness_work);
 244                } else {
 245                        led_cdev->flags |= LED_BLINK_BRIGHTNESS_CHANGE;
 246                        led_cdev->blink_brightness = brightness;
 247                }
 248                return;
 249        }
 250
 251        led_set_brightness_nosleep(led_cdev, brightness);
 252}
 253EXPORT_SYMBOL_GPL(led_set_brightness);
 254
 255void led_set_brightness_nopm(struct led_classdev *led_cdev,
 256                              enum led_brightness value)
 257{
 258        /* Use brightness_set op if available, it is guaranteed not to sleep */
 259        if (!__led_set_brightness(led_cdev, value))
 260                return;
 261
 262        /* If brightness setting can sleep, delegate it to a work queue task */
 263        led_cdev->delayed_set_value = value;
 264        schedule_work(&led_cdev->set_brightness_work);
 265}
 266EXPORT_SYMBOL_GPL(led_set_brightness_nopm);
 267
 268void led_set_brightness_nosleep(struct led_classdev *led_cdev,
 269                                enum led_brightness value)
 270{
 271        led_cdev->brightness = min(value, led_cdev->max_brightness);
 272
 273        if (led_cdev->flags & LED_SUSPENDED)
 274                return;
 275
 276        led_set_brightness_nopm(led_cdev, led_cdev->brightness);
 277}
 278EXPORT_SYMBOL_GPL(led_set_brightness_nosleep);
 279
 280int led_set_brightness_sync(struct led_classdev *led_cdev,
 281                            enum led_brightness value)
 282{
 283        if (led_cdev->blink_delay_on || led_cdev->blink_delay_off)
 284                return -EBUSY;
 285
 286        led_cdev->brightness = min(value, led_cdev->max_brightness);
 287
 288        if (led_cdev->flags & LED_SUSPENDED)
 289                return 0;
 290
 291        return __led_set_brightness_blocking(led_cdev, led_cdev->brightness);
 292}
 293EXPORT_SYMBOL_GPL(led_set_brightness_sync);
 294
 295int led_update_brightness(struct led_classdev *led_cdev)
 296{
 297        int ret = 0;
 298
 299        if (led_cdev->brightness_get) {
 300                ret = led_cdev->brightness_get(led_cdev);
 301                if (ret >= 0) {
 302                        led_cdev->brightness = ret;
 303                        return 0;
 304                }
 305        }
 306
 307        return ret;
 308}
 309EXPORT_SYMBOL_GPL(led_update_brightness);
 310
 311/* Caller must ensure led_cdev->led_access held */
 312void led_sysfs_disable(struct led_classdev *led_cdev)
 313{
 314        lockdep_assert_held(&led_cdev->led_access);
 315
 316        led_cdev->flags |= LED_SYSFS_DISABLE;
 317}
 318EXPORT_SYMBOL_GPL(led_sysfs_disable);
 319
 320/* Caller must ensure led_cdev->led_access held */
 321void led_sysfs_enable(struct led_classdev *led_cdev)
 322{
 323        lockdep_assert_held(&led_cdev->led_access);
 324
 325        led_cdev->flags &= ~LED_SYSFS_DISABLE;
 326}
 327EXPORT_SYMBOL_GPL(led_sysfs_enable);
 328