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                 dev_err(led_cdev->dev,
 103                         "Setting an LED's brightness failed (%d)\n", ret);
 104 }
 105
 106 static void led_set_software_blink(struct led_classdev *led_cdev,
 107                                    unsigned long delay_on,
 108                                    unsigned long delay_off)
 109 {
 110         int current_brightness;
 111
 112         current_brightness = led_get_brightness(led_cdev);
 113         if (current_brightness)
 114                 led_cdev->blink_brightness = current_brightness;
 115         if (!led_cdev->blink_brightness)
 116                 led_cdev->blink_brightness = led_cdev->max_brightness;
 117
 118         led_cdev->blink_delay_on = delay_on;
 119         led_cdev->blink_delay_off = delay_off;
 120
 121         /* never on - just set to off */
 122         if (!delay_on) {
 123                 led_set_brightness_nosleep(led_cdev, LED_OFF);
 124                 return;
 125         }
 126
 127         /* never off - just set to brightness */
 128         if (!delay_off) {
 129                 led_set_brightness_nosleep(led_cdev,
 130                                            led_cdev->blink_brightness);
 131                 return;
 132         }
 133
 134         mod_timer(&led_cdev->blink_timer, jiffies + 1);
 135 }
 136
 137
 138 static void led_blink_setup(struct led_classdev *led_cdev,
 139                      unsigned long *delay_on,
 140                      unsigned long *delay_off)
 141 {
 142         if (!(led_cdev->flags & LED_BLINK_ONESHOT) &&
 143             led_cdev->blink_set &&
 144             !led_cdev->blink_set(led_cdev, delay_on, delay_off))
 145                 return;
 146
 147         /* blink with 1 Hz as default if nothing specified */
 148         if (!*delay_on && !*delay_off)
 149                 *delay_on = *delay_off = 500;
 150
 151         led_set_software_blink(led_cdev, *delay_on, *delay_off);
 152 }
 153
 154 void led_init_core(struct led_classdev *led_cdev)
 155 {
 156         INIT_WORK(&led_cdev->set_brightness_work, set_brightness_delayed);
 157
 158         setup_timer(&led_cdev->blink_timer, led_timer_function,
 159                     (unsigned long)led_cdev);
 160 }
 161 EXPORT_SYMBOL_GPL(led_init_core);
 162
 163 void led_blink_set(struct led_classdev *led_cdev,
 164                    unsigned long *delay_on,
 165                    unsigned long *delay_off)
 166 {
 167         del_timer_sync(&led_cdev->blink_timer);
 168
 169         led_cdev->flags &= ~LED_BLINK_ONESHOT;
 170         led_cdev->flags &= ~LED_BLINK_ONESHOT_STOP;
 171
 172         led_blink_setup(led_cdev, delay_on, delay_off);
 173 }
 174 EXPORT_SYMBOL_GPL(led_blink_set);
 175
 176 void led_blink_set_oneshot(struct led_classdev *led_cdev,
 177                            unsigned long *delay_on,
 178                            unsigned long *delay_off,
 179                            int invert)
 180 {
 181         if ((led_cdev->flags & LED_BLINK_ONESHOT) &&
 182              timer_pending(&led_cdev->blink_timer))
 183                 return;
 184
 185         led_cdev->flags |= LED_BLINK_ONESHOT;
 186         led_cdev->flags &= ~LED_BLINK_ONESHOT_STOP;
 187
 188         if (invert)
 189                 led_cdev->flags |= LED_BLINK_INVERT;
 190         else
 191                 led_cdev->flags &= ~LED_BLINK_INVERT;
 192
 193         led_blink_setup(led_cdev, delay_on, delay_off);
 194 }
 195 EXPORT_SYMBOL_GPL(led_blink_set_oneshot);
 196
 197 void led_stop_software_blink(struct led_classdev *led_cdev)
 198 {
 199         del_timer_sync(&led_cdev->blink_timer);
 200         led_cdev->blink_delay_on = 0;
 201         led_cdev->blink_delay_off = 0;
 202 }
 203 EXPORT_SYMBOL_GPL(led_stop_software_blink);
 204
 205 void led_set_brightness(struct led_classdev *led_cdev,
 206                         enum led_brightness brightness)
 207 {
 208         /*
 209          * In case blinking is on delay brightness setting
 210          * until the next timer tick.
 211          */
 212         if (led_cdev->blink_delay_on || led_cdev->blink_delay_off) {
 213                 /*
 214                  * If we need to disable soft blinking delegate this to the
 215                  * work queue task to avoid problems in case we are called
 216                  * from hard irq context.
 217                  */
 218                 if (brightness == LED_OFF) {
 219                         led_cdev->flags |= LED_BLINK_DISABLE;
 220                         schedule_work(&led_cdev->set_brightness_work);
 221                 } else {
 222                         led_cdev->flags |= LED_BLINK_BRIGHTNESS_CHANGE;
 223                         led_cdev->blink_brightness = brightness;
 224                 }
 225                 return;
 226         }
 227
 228         led_set_brightness_nosleep(led_cdev, brightness);
 229 }
 230 EXPORT_SYMBOL_GPL(led_set_brightness);
 231
 232 void led_set_brightness_nopm(struct led_classdev *led_cdev,
 233                               enum led_brightness value)
 234 {
 235         /* Use brightness_set op if available, it is guaranteed not to sleep */
 236         if (led_cdev->brightness_set) {
 237                 led_cdev->brightness_set(led_cdev, value);
 238                 return;
 239         }
 240
 241         /* If brightness setting can sleep, delegate it to a work queue task */
 242         led_cdev->delayed_set_value = value;
 243         schedule_work(&led_cdev->set_brightness_work);
 244 }
 245 EXPORT_SYMBOL_GPL(led_set_brightness_nopm);
 246
 247 void led_set_brightness_nosleep(struct led_classdev *led_cdev,
 248                                 enum led_brightness value)
 249 {
 250         led_cdev->brightness = min(value, led_cdev->max_brightness);
 251
 252         if (led_cdev->flags & LED_SUSPENDED)
 253                 return;
 254
 255         led_set_brightness_nopm(led_cdev, led_cdev->brightness);
 256 }
 257 EXPORT_SYMBOL_GPL(led_set_brightness_nosleep);
 258
 259 int led_set_brightness_sync(struct led_classdev *led_cdev,
 260                             enum led_brightness value)
 261 {
 262         if (led_cdev->blink_delay_on || led_cdev->blink_delay_off)
 263                 return -EBUSY;
 264
 265         led_cdev->brightness = min(value, led_cdev->max_brightness);
 266
 267         if (led_cdev->flags & LED_SUSPENDED)
 268                 return 0;
 269
 270         if (led_cdev->brightness_set_blocking)
 271                 return led_cdev->brightness_set_blocking(led_cdev,
 272                                                          led_cdev->brightness);
 273         return -ENOTSUPP;
 274 }
 275 EXPORT_SYMBOL_GPL(led_set_brightness_sync);
 276
 277 int led_update_brightness(struct led_classdev *led_cdev)
 278 {
 279         int ret = 0;
 280
 281         if (led_cdev->brightness_get) {
 282                 ret = led_cdev->brightness_get(led_cdev);
 283                 if (ret >= 0) {
 284                         led_cdev->brightness = ret;
 285                         return 0;
 286                 }
 287         }
 288
 289         return ret;
 290 }
 291 EXPORT_SYMBOL_GPL(led_update_brightness);
 292
 293 /* Caller must ensure led_cdev->led_access held */
 294 void led_sysfs_disable(struct led_classdev *led_cdev)
 295 {
 296         lockdep_assert_held(&led_cdev->led_access);
 297
 298         led_cdev->flags |= LED_SYSFS_DISABLE;
 299 }
 300 EXPORT_SYMBOL_GPL(led_sysfs_disable);
 301
 302 /* Caller must ensure led_cdev->led_access held */
 303 void led_sysfs_enable(struct led_classdev *led_cdev)
 304 {
 305         lockdep_assert_held(&led_cdev->led_access);
 306
 307         led_cdev->flags &= ~LED_SYSFS_DISABLE;
 308 }
 309 EXPORT_SYMBOL_GPL(led_sysfs_enable);