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                 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
 103 static 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
 127 static 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
 160 static 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
 176 void 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 }
 183 EXPORT_SYMBOL_GPL(led_init_core);
 184
 185 void 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 }
 196 EXPORT_SYMBOL_GPL(led_blink_set);
 197
 198 void 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 }
 217 EXPORT_SYMBOL_GPL(led_blink_set_oneshot);
 218
 219 void 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 }
 226 EXPORT_SYMBOL_GPL(led_stop_software_blink);
 227
 228 void 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 }
 253 EXPORT_SYMBOL_GPL(led_set_brightness);
 254
 255 void 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 }
 266 EXPORT_SYMBOL_GPL(led_set_brightness_nopm);
 267
 268 void 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 }
 278 EXPORT_SYMBOL_GPL(led_set_brightness_nosleep);
 279
 280 int 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 }
 293 EXPORT_SYMBOL_GPL(led_set_brightness_sync);
 294
 295 int 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 }
 309 EXPORT_SYMBOL_GPL(led_update_brightness);
 310
 311 /* Caller must ensure led_cdev->led_access held */
 312 void 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 }
 318 EXPORT_SYMBOL_GPL(led_sysfs_disable);
 319
 320 /* Caller must ensure led_cdev->led_access held */
 321 void 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 }
 327 EXPORT_SYMBOL_GPL(led_sysfs_enable);