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(struct timer_list *t)
  49{
  50        struct led_classdev *led_cdev = from_timer(led_cdev, t, blink_timer);
  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                clear_bit(LED_BLINK_SW, &led_cdev->work_flags);
  57                return;
  58        }
  59
  60        if (test_and_clear_bit(LED_BLINK_ONESHOT_STOP,
  61                               &led_cdev->work_flags)) {
  62                clear_bit(LED_BLINK_SW, &led_cdev->work_flags);
  63                return;
  64        }
  65
  66        brightness = led_get_brightness(led_cdev);
  67        if (!brightness) {
  68                /* Time to switch the LED on. */
  69                if (test_and_clear_bit(LED_BLINK_BRIGHTNESS_CHANGE,
  70                                        &led_cdev->work_flags))
  71                        brightness = led_cdev->new_blink_brightness;
  72                else
  73                        brightness = led_cdev->blink_brightness;
  74                delay = led_cdev->blink_delay_on;
  75        } else {
  76                /* Store the current brightness value to be able
  77                 * to restore it when the delay_off period is over.
  78                 */
  79                led_cdev->blink_brightness = brightness;
  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 (test_bit(LED_BLINK_ONESHOT, &led_cdev->work_flags)) {
  91                if (test_bit(LED_BLINK_INVERT, &led_cdev->work_flags)) {
  92                        if (brightness)
  93                                set_bit(LED_BLINK_ONESHOT_STOP,
  94                                        &led_cdev->work_flags);
  95                } else {
  96                        if (!brightness)
  97                                set_bit(LED_BLINK_ONESHOT_STOP,
  98                                        &led_cdev->work_flags);
  99                }
 100        }
 101
 102        mod_timer(&led_cdev->blink_timer, jiffies + msecs_to_jiffies(delay));
 103}
 104
 105static void set_brightness_delayed(struct work_struct *ws)
 106{
 107        struct led_classdev *led_cdev =
 108                container_of(ws, struct led_classdev, set_brightness_work);
 109        int ret = 0;
 110
 111        if (test_and_clear_bit(LED_BLINK_DISABLE, &led_cdev->work_flags)) {
 112                led_cdev->delayed_set_value = LED_OFF;
 113                led_stop_software_blink(led_cdev);
 114        }
 115
 116        ret = __led_set_brightness(led_cdev, led_cdev->delayed_set_value);
 117        if (ret == -ENOTSUPP)
 118                ret = __led_set_brightness_blocking(led_cdev,
 119                                        led_cdev->delayed_set_value);
 120        if (ret < 0 &&
 121            /* LED HW might have been unplugged, therefore don't warn */
 122            !(ret == -ENODEV && (led_cdev->flags & LED_UNREGISTERING) &&
 123            (led_cdev->flags & LED_HW_PLUGGABLE)))
 124                dev_err(led_cdev->dev,
 125                        "Setting an LED's brightness failed (%d)\n", ret);
 126}
 127
 128static void led_set_software_blink(struct led_classdev *led_cdev,
 129                                   unsigned long delay_on,
 130                                   unsigned long delay_off)
 131{
 132        int current_brightness;
 133
 134        current_brightness = led_get_brightness(led_cdev);
 135        if (current_brightness)
 136                led_cdev->blink_brightness = current_brightness;
 137        if (!led_cdev->blink_brightness)
 138                led_cdev->blink_brightness = led_cdev->max_brightness;
 139
 140        led_cdev->blink_delay_on = delay_on;
 141        led_cdev->blink_delay_off = delay_off;
 142
 143        /* never on - just set to off */
 144        if (!delay_on) {
 145                led_set_brightness_nosleep(led_cdev, LED_OFF);
 146                return;
 147        }
 148
 149        /* never off - just set to brightness */
 150        if (!delay_off) {
 151                led_set_brightness_nosleep(led_cdev,
 152                                           led_cdev->blink_brightness);
 153                return;
 154        }
 155
 156        set_bit(LED_BLINK_SW, &led_cdev->work_flags);
 157        mod_timer(&led_cdev->blink_timer, jiffies + 1);
 158}
 159
 160
 161static void led_blink_setup(struct led_classdev *led_cdev,
 162                     unsigned long *delay_on,
 163                     unsigned long *delay_off)
 164{
 165        if (!test_bit(LED_BLINK_ONESHOT, &led_cdev->work_flags) &&
 166            led_cdev->blink_set &&
 167            !led_cdev->blink_set(led_cdev, delay_on, delay_off))
 168                return;
 169
 170        /* blink with 1 Hz as default if nothing specified */
 171        if (!*delay_on && !*delay_off)
 172                *delay_on = *delay_off = 500;
 173
 174        led_set_software_blink(led_cdev, *delay_on, *delay_off);
 175}
 176
 177void led_init_core(struct led_classdev *led_cdev)
 178{
 179        INIT_WORK(&led_cdev->set_brightness_work, set_brightness_delayed);
 180
 181        timer_setup(&led_cdev->blink_timer, led_timer_function, 0);
 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        clear_bit(LED_BLINK_SW, &led_cdev->work_flags);
 192        clear_bit(LED_BLINK_ONESHOT, &led_cdev->work_flags);
 193        clear_bit(LED_BLINK_ONESHOT_STOP, &led_cdev->work_flags);
 194
 195        led_blink_setup(led_cdev, delay_on, delay_off);
 196}
 197EXPORT_SYMBOL_GPL(led_blink_set);
 198
 199void led_blink_set_oneshot(struct led_classdev *led_cdev,
 200                           unsigned long *delay_on,
 201                           unsigned long *delay_off,
 202                           int invert)
 203{
 204        if (test_bit(LED_BLINK_ONESHOT, &led_cdev->work_flags) &&
 205             timer_pending(&led_cdev->blink_timer))
 206                return;
 207
 208        set_bit(LED_BLINK_ONESHOT, &led_cdev->work_flags);
 209        clear_bit(LED_BLINK_ONESHOT_STOP, &led_cdev->work_flags);
 210
 211        if (invert)
 212                set_bit(LED_BLINK_INVERT, &led_cdev->work_flags);
 213        else
 214                clear_bit(LED_BLINK_INVERT, &led_cdev->work_flags);
 215
 216        led_blink_setup(led_cdev, delay_on, delay_off);
 217}
 218EXPORT_SYMBOL_GPL(led_blink_set_oneshot);
 219
 220void led_stop_software_blink(struct led_classdev *led_cdev)
 221{
 222        del_timer_sync(&led_cdev->blink_timer);
 223        led_cdev->blink_delay_on = 0;
 224        led_cdev->blink_delay_off = 0;
 225        clear_bit(LED_BLINK_SW, &led_cdev->work_flags);
 226}
 227EXPORT_SYMBOL_GPL(led_stop_software_blink);
 228
 229void led_set_brightness(struct led_classdev *led_cdev,
 230                        enum led_brightness brightness)
 231{
 232        /*
 233         * If software blink is active, delay brightness setting
 234         * until the next timer tick.
 235         */
 236        if (test_bit(LED_BLINK_SW, &led_cdev->work_flags)) {
 237                /*
 238                 * If we need to disable soft blinking delegate this to the
 239                 * work queue task to avoid problems in case we are called
 240                 * from hard irq context.
 241                 */
 242                if (brightness == LED_OFF) {
 243                        set_bit(LED_BLINK_DISABLE, &led_cdev->work_flags);
 244                        schedule_work(&led_cdev->set_brightness_work);
 245                } else {
 246                        set_bit(LED_BLINK_BRIGHTNESS_CHANGE,
 247                                &led_cdev->work_flags);
 248                        led_cdev->new_blink_brightness = brightness;
 249                }
 250                return;
 251        }
 252
 253        led_set_brightness_nosleep(led_cdev, brightness);
 254}
 255EXPORT_SYMBOL_GPL(led_set_brightness);
 256
 257void led_set_brightness_nopm(struct led_classdev *led_cdev,
 258                              enum led_brightness value)
 259{
 260        /* Use brightness_set op if available, it is guaranteed not to sleep */
 261        if (!__led_set_brightness(led_cdev, value))
 262                return;
 263
 264        /* If brightness setting can sleep, delegate it to a work queue task */
 265        led_cdev->delayed_set_value = value;
 266        schedule_work(&led_cdev->set_brightness_work);
 267}
 268EXPORT_SYMBOL_GPL(led_set_brightness_nopm);
 269
 270void led_set_brightness_nosleep(struct led_classdev *led_cdev,
 271                                enum led_brightness value)
 272{
 273        led_cdev->brightness = min(value, led_cdev->max_brightness);
 274
 275        if (led_cdev->flags & LED_SUSPENDED)
 276                return;
 277
 278        led_set_brightness_nopm(led_cdev, led_cdev->brightness);
 279}
 280EXPORT_SYMBOL_GPL(led_set_brightness_nosleep);
 281
 282int led_set_brightness_sync(struct led_classdev *led_cdev,
 283                            enum led_brightness value)
 284{
 285        if (led_cdev->blink_delay_on || led_cdev->blink_delay_off)
 286                return -EBUSY;
 287
 288        led_cdev->brightness = min(value, led_cdev->max_brightness);
 289
 290        if (led_cdev->flags & LED_SUSPENDED)
 291                return 0;
 292
 293        return __led_set_brightness_blocking(led_cdev, led_cdev->brightness);
 294}
 295EXPORT_SYMBOL_GPL(led_set_brightness_sync);
 296
 297int led_update_brightness(struct led_classdev *led_cdev)
 298{
 299        int ret = 0;
 300
 301        if (led_cdev->brightness_get) {
 302                ret = led_cdev->brightness_get(led_cdev);
 303                if (ret >= 0) {
 304                        led_cdev->brightness = ret;
 305                        return 0;
 306                }
 307        }
 308
 309        return ret;
 310}
 311EXPORT_SYMBOL_GPL(led_update_brightness);
 312
 313/* Caller must ensure led_cdev->led_access held */
 314void led_sysfs_disable(struct led_classdev *led_cdev)
 315{
 316        lockdep_assert_held(&led_cdev->led_access);
 317
 318        led_cdev->flags |= LED_SYSFS_DISABLE;
 319}
 320EXPORT_SYMBOL_GPL(led_sysfs_disable);
 321
 322/* Caller must ensure led_cdev->led_access held */
 323void led_sysfs_enable(struct led_classdev *led_cdev)
 324{
 325        lockdep_assert_held(&led_cdev->led_access);
 326
 327        led_cdev->flags &= ~LED_SYSFS_DISABLE;
 328}
 329EXPORT_SYMBOL_GPL(led_sysfs_enable);
 330