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