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