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_SW;
 192         led_cdev->flags &= ~LED_BLINK_ONESHOT;
 193         led_cdev->flags &= ~LED_BLINK_ONESHOT_STOP;
 194
 195         led_blink_setup(led_cdev, delay_on, delay_off);
 196 }
 197 EXPORT_SYMBOL_GPL(led_blink_set);
 198
 199 void 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 ((led_cdev->flags & LED_BLINK_ONESHOT) &&
 205              timer_pending(&led_cdev->blink_timer))
 206                 return;
 207
 208         led_cdev->flags |= LED_BLINK_ONESHOT;
 209         led_cdev->flags &= ~LED_BLINK_ONESHOT_STOP;
 210
 211         if (invert)
 212                 led_cdev->flags |= LED_BLINK_INVERT;
 213         else
 214                 led_cdev->flags &= ~LED_BLINK_INVERT;
 215
 216         led_blink_setup(led_cdev, delay_on, delay_off);
 217 }
 218 EXPORT_SYMBOL_GPL(led_blink_set_oneshot);
 219
 220 void 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         led_cdev->flags &= ~LED_BLINK_SW;
 226 }
 227 EXPORT_SYMBOL_GPL(led_stop_software_blink);
 228
 229 void 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 (led_cdev->flags & LED_BLINK_SW) {
 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                         led_cdev->flags |= LED_BLINK_DISABLE;
 244                         schedule_work(&led_cdev->set_brightness_work);
 245                 } else {
 246                         led_cdev->flags |= LED_BLINK_BRIGHTNESS_CHANGE;
 247                         led_cdev->blink_brightness = brightness;
 248                 }
 249                 return;
 250         }
 251
 252         led_set_brightness_nosleep(led_cdev, brightness);
 253 }
 254 EXPORT_SYMBOL_GPL(led_set_brightness);
 255
 256 void led_set_brightness_nopm(struct led_classdev *led_cdev,
 257                               enum led_brightness value)
 258 {
 259         /* Use brightness_set op if available, it is guaranteed not to sleep */
 260         if (!__led_set_brightness(led_cdev, value))
 261                 return;
 262
 263         /* If brightness setting can sleep, delegate it to a work queue task */
 264         led_cdev->delayed_set_value = value;
 265         schedule_work(&led_cdev->set_brightness_work);
 266 }
 267 EXPORT_SYMBOL_GPL(led_set_brightness_nopm);
 268
 269 void led_set_brightness_nosleep(struct led_classdev *led_cdev,
 270                                 enum led_brightness value)
 271 {
 272         led_cdev->brightness = min(value, led_cdev->max_brightness);
 273
 274         if (led_cdev->flags & LED_SUSPENDED)
 275                 return;
 276
 277         led_set_brightness_nopm(led_cdev, led_cdev->brightness);
 278 }
 279 EXPORT_SYMBOL_GPL(led_set_brightness_nosleep);
 280
 281 int led_set_brightness_sync(struct led_classdev *led_cdev,
 282                             enum led_brightness value)
 283 {
 284         if (led_cdev->blink_delay_on || led_cdev->blink_delay_off)
 285                 return -EBUSY;
 286
 287         led_cdev->brightness = min(value, led_cdev->max_brightness);
 288
 289         if (led_cdev->flags & LED_SUSPENDED)
 290                 return 0;
 291
 292         return __led_set_brightness_blocking(led_cdev, led_cdev->brightness);
 293 }
 294 EXPORT_SYMBOL_GPL(led_set_brightness_sync);
 295
 296 int led_update_brightness(struct led_classdev *led_cdev)
 297 {
 298         int ret = 0;
 299
 300         if (led_cdev->brightness_get) {
 301                 ret = led_cdev->brightness_get(led_cdev);
 302                 if (ret >= 0) {
 303                         led_cdev->brightness = ret;
 304                         return 0;
 305                 }
 306         }
 307
 308         return ret;
 309 }
 310 EXPORT_SYMBOL_GPL(led_update_brightness);
 311
 312 /* Caller must ensure led_cdev->led_access held */
 313 void led_sysfs_disable(struct led_classdev *led_cdev)
 314 {
 315         lockdep_assert_held(&led_cdev->led_access);
 316
 317         led_cdev->flags |= LED_SYSFS_DISABLE;
 318 }
 319 EXPORT_SYMBOL_GPL(led_sysfs_disable);
 320
 321 /* Caller must ensure led_cdev->led_access held */
 322 void led_sysfs_enable(struct led_classdev *led_cdev)
 323 {
 324         lockdep_assert_held(&led_cdev->led_access);
 325
 326         led_cdev->flags &= ~LED_SYSFS_DISABLE;
 327 }
 328 EXPORT_SYMBOL_GPL(led_sysfs_enable);