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/of.h>
  20 #include <linux/rwsem.h>
  21 #include <linux/slab.h>
  22 #include "leds.h"
  23
  24 DECLARE_RWSEM(leds_list_lock);
  25 EXPORT_SYMBOL_GPL(leds_list_lock);
  26
  27 LIST_HEAD(leds_list);
  28 EXPORT_SYMBOL_GPL(leds_list);
  29
  30 static int __led_set_brightness(struct led_classdev *led_cdev,
  31                                 enum led_brightness value)
  32 {
  33         if (!led_cdev->brightness_set)
  34                 return -ENOTSUPP;
  35
  36         led_cdev->brightness_set(led_cdev, value);
  37
  38         return 0;
  39 }
  40
  41 static int __led_set_brightness_blocking(struct led_classdev *led_cdev,
  42                                          enum led_brightness value)
  43 {
  44         if (!led_cdev->brightness_set_blocking)
  45                 return -ENOTSUPP;
  46
  47         return led_cdev->brightness_set_blocking(led_cdev, value);
  48 }
  49
  50 static void led_timer_function(struct timer_list *t)
  51 {
  52         struct led_classdev *led_cdev = from_timer(led_cdev, t, blink_timer);
  53         unsigned long brightness;
  54         unsigned long delay;
  55
  56         if (!led_cdev->blink_delay_on || !led_cdev->blink_delay_off) {
  57                 led_set_brightness_nosleep(led_cdev, LED_OFF);
  58                 clear_bit(LED_BLINK_SW, &led_cdev->work_flags);
  59                 return;
  60         }
  61
  62         if (test_and_clear_bit(LED_BLINK_ONESHOT_STOP,
  63                                &led_cdev->work_flags)) {
  64                 clear_bit(LED_BLINK_SW, &led_cdev->work_flags);
  65                 return;
  66         }
  67
  68         brightness = led_get_brightness(led_cdev);
  69         if (!brightness) {
  70                 /* Time to switch the LED on. */
  71                 if (test_and_clear_bit(LED_BLINK_BRIGHTNESS_CHANGE,
  72                                         &led_cdev->work_flags))
  73                         brightness = led_cdev->new_blink_brightness;
  74                 else
  75                         brightness = led_cdev->blink_brightness;
  76                 delay = led_cdev->blink_delay_on;
  77         } else {
  78                 /* Store the current brightness value to be able
  79                  * to restore it when the delay_off period is over.
  80                  */
  81                 led_cdev->blink_brightness = brightness;
  82                 brightness = LED_OFF;
  83                 delay = led_cdev->blink_delay_off;
  84         }
  85
  86         led_set_brightness_nosleep(led_cdev, brightness);
  87
  88         /* Return in next iteration if led is in one-shot mode and we are in
  89          * the final blink state so that the led is toggled each delay_on +
  90          * delay_off milliseconds in worst case.
  91          */
  92         if (test_bit(LED_BLINK_ONESHOT, &led_cdev->work_flags)) {
  93                 if (test_bit(LED_BLINK_INVERT, &led_cdev->work_flags)) {
  94                         if (brightness)
  95                                 set_bit(LED_BLINK_ONESHOT_STOP,
  96                                         &led_cdev->work_flags);
  97                 } else {
  98                         if (!brightness)
  99                                 set_bit(LED_BLINK_ONESHOT_STOP,
 100                                         &led_cdev->work_flags);
 101                 }
 102         }
 103
 104         mod_timer(&led_cdev->blink_timer, jiffies + msecs_to_jiffies(delay));
 105 }
 106
 107 static void set_brightness_delayed(struct work_struct *ws)
 108 {
 109         struct led_classdev *led_cdev =
 110                 container_of(ws, struct led_classdev, set_brightness_work);
 111         int ret = 0;
 112
 113         if (test_and_clear_bit(LED_BLINK_DISABLE, &led_cdev->work_flags)) {
 114                 led_cdev->delayed_set_value = LED_OFF;
 115                 led_stop_software_blink(led_cdev);
 116         }
 117
 118         ret = __led_set_brightness(led_cdev, led_cdev->delayed_set_value);
 119         if (ret == -ENOTSUPP)
 120                 ret = __led_set_brightness_blocking(led_cdev,
 121                                         led_cdev->delayed_set_value);
 122         if (ret < 0 &&
 123             /* LED HW might have been unplugged, therefore don't warn */
 124             !(ret == -ENODEV && (led_cdev->flags & LED_UNREGISTERING) &&
 125             (led_cdev->flags & LED_HW_PLUGGABLE)))
 126                 dev_err(led_cdev->dev,
 127                         "Setting an LED's brightness failed (%d)\n", ret);
 128 }
 129
 130 static void led_set_software_blink(struct led_classdev *led_cdev,
 131                                    unsigned long delay_on,
 132                                    unsigned long delay_off)
 133 {
 134         int current_brightness;
 135
 136         current_brightness = led_get_brightness(led_cdev);
 137         if (current_brightness)
 138                 led_cdev->blink_brightness = current_brightness;
 139         if (!led_cdev->blink_brightness)
 140                 led_cdev->blink_brightness = led_cdev->max_brightness;
 141
 142         led_cdev->blink_delay_on = delay_on;
 143         led_cdev->blink_delay_off = delay_off;
 144
 145         /* never on - just set to off */
 146         if (!delay_on) {
 147                 led_set_brightness_nosleep(led_cdev, LED_OFF);
 148                 return;
 149         }
 150
 151         /* never off - just set to brightness */
 152         if (!delay_off) {
 153                 led_set_brightness_nosleep(led_cdev,
 154                                            led_cdev->blink_brightness);
 155                 return;
 156         }
 157
 158         set_bit(LED_BLINK_SW, &led_cdev->work_flags);
 159         mod_timer(&led_cdev->blink_timer, jiffies + 1);
 160 }
 161
 162
 163 static void led_blink_setup(struct led_classdev *led_cdev,
 164                      unsigned long *delay_on,
 165                      unsigned long *delay_off)
 166 {
 167         /*
 168          * If "set brightness to 0" is pending in workqueue, we don't
 169          * want that to be reordered after blink_set()
 170          */
 171         flush_work(&led_cdev->set_brightness_work);
 172         if (!test_bit(LED_BLINK_ONESHOT, &led_cdev->work_flags) &&
 173             led_cdev->blink_set &&
 174             !led_cdev->blink_set(led_cdev, delay_on, delay_off))
 175                 return;
 176
 177         /* blink with 1 Hz as default if nothing specified */
 178         if (!*delay_on && !*delay_off)
 179                 *delay_on = *delay_off = 500;
 180
 181         led_set_software_blink(led_cdev, *delay_on, *delay_off);
 182 }
 183
 184 void led_init_core(struct led_classdev *led_cdev)
 185 {
 186         INIT_WORK(&led_cdev->set_brightness_work, set_brightness_delayed);
 187
 188         timer_setup(&led_cdev->blink_timer, led_timer_function, 0);
 189 }
 190 EXPORT_SYMBOL_GPL(led_init_core);
 191
 192 void led_blink_set(struct led_classdev *led_cdev,
 193                    unsigned long *delay_on,
 194                    unsigned long *delay_off)
 195 {
 196         del_timer_sync(&led_cdev->blink_timer);
 197
 198         clear_bit(LED_BLINK_SW, &led_cdev->work_flags);
 199         clear_bit(LED_BLINK_ONESHOT, &led_cdev->work_flags);
 200         clear_bit(LED_BLINK_ONESHOT_STOP, &led_cdev->work_flags);
 201
 202         led_blink_setup(led_cdev, delay_on, delay_off);
 203 }
 204 EXPORT_SYMBOL_GPL(led_blink_set);
 205
 206 void led_blink_set_oneshot(struct led_classdev *led_cdev,
 207                            unsigned long *delay_on,
 208                            unsigned long *delay_off,
 209                            int invert)
 210 {
 211         if (test_bit(LED_BLINK_ONESHOT, &led_cdev->work_flags) &&
 212              timer_pending(&led_cdev->blink_timer))
 213                 return;
 214
 215         set_bit(LED_BLINK_ONESHOT, &led_cdev->work_flags);
 216         clear_bit(LED_BLINK_ONESHOT_STOP, &led_cdev->work_flags);
 217
 218         if (invert)
 219                 set_bit(LED_BLINK_INVERT, &led_cdev->work_flags);
 220         else
 221                 clear_bit(LED_BLINK_INVERT, &led_cdev->work_flags);
 222
 223         led_blink_setup(led_cdev, delay_on, delay_off);
 224 }
 225 EXPORT_SYMBOL_GPL(led_blink_set_oneshot);
 226
 227 void led_stop_software_blink(struct led_classdev *led_cdev)
 228 {
 229         del_timer_sync(&led_cdev->blink_timer);
 230         led_cdev->blink_delay_on = 0;
 231         led_cdev->blink_delay_off = 0;
 232         clear_bit(LED_BLINK_SW, &led_cdev->work_flags);
 233 }
 234 EXPORT_SYMBOL_GPL(led_stop_software_blink);
 235
 236 void led_set_brightness(struct led_classdev *led_cdev,
 237                         enum led_brightness brightness)
 238 {
 239         /*
 240          * If software blink is active, delay brightness setting
 241          * until the next timer tick.
 242          */
 243         if (test_bit(LED_BLINK_SW, &led_cdev->work_flags)) {
 244                 /*
 245                  * If we need to disable soft blinking delegate this to the
 246                  * work queue task to avoid problems in case we are called
 247                  * from hard irq context.
 248                  */
 249                 if (brightness == LED_OFF) {
 250                         set_bit(LED_BLINK_DISABLE, &led_cdev->work_flags);
 251                         schedule_work(&led_cdev->set_brightness_work);
 252                 } else {
 253                         set_bit(LED_BLINK_BRIGHTNESS_CHANGE,
 254                                 &led_cdev->work_flags);
 255                         led_cdev->new_blink_brightness = brightness;
 256                 }
 257                 return;
 258         }
 259
 260         led_set_brightness_nosleep(led_cdev, brightness);
 261 }
 262 EXPORT_SYMBOL_GPL(led_set_brightness);
 263
 264 void led_set_brightness_nopm(struct led_classdev *led_cdev,
 265                               enum led_brightness value)
 266 {
 267         /* Use brightness_set op if available, it is guaranteed not to sleep */
 268         if (!__led_set_brightness(led_cdev, value))
 269                 return;
 270
 271         /* If brightness setting can sleep, delegate it to a work queue task */
 272         led_cdev->delayed_set_value = value;
 273         schedule_work(&led_cdev->set_brightness_work);
 274 }
 275 EXPORT_SYMBOL_GPL(led_set_brightness_nopm);
 276
 277 void led_set_brightness_nosleep(struct led_classdev *led_cdev,
 278                                 enum led_brightness value)
 279 {
 280         led_cdev->brightness = min(value, led_cdev->max_brightness);
 281
 282         if (led_cdev->flags & LED_SUSPENDED)
 283                 return;
 284
 285         led_set_brightness_nopm(led_cdev, led_cdev->brightness);
 286 }
 287 EXPORT_SYMBOL_GPL(led_set_brightness_nosleep);
 288
 289 int led_set_brightness_sync(struct led_classdev *led_cdev,
 290                             enum led_brightness value)
 291 {
 292         if (led_cdev->blink_delay_on || led_cdev->blink_delay_off)
 293                 return -EBUSY;
 294
 295         led_cdev->brightness = min(value, led_cdev->max_brightness);
 296
 297         if (led_cdev->flags & LED_SUSPENDED)
 298                 return 0;
 299
 300         return __led_set_brightness_blocking(led_cdev, led_cdev->brightness);
 301 }
 302 EXPORT_SYMBOL_GPL(led_set_brightness_sync);
 303
 304 int led_update_brightness(struct led_classdev *led_cdev)
 305 {
 306         int ret = 0;
 307
 308         if (led_cdev->brightness_get) {
 309                 ret = led_cdev->brightness_get(led_cdev);
 310                 if (ret >= 0) {
 311                         led_cdev->brightness = ret;
 312                         return 0;
 313                 }
 314         }
 315
 316         return ret;
 317 }
 318 EXPORT_SYMBOL_GPL(led_update_brightness);
 319
 320 u32 *led_get_default_pattern(struct led_classdev *led_cdev, unsigned int *size)
 321 {
 322         struct device_node *np = dev_of_node(led_cdev->dev);
 323         u32 *pattern;
 324         int count;
 325
 326         if (!np)
 327                 return NULL;
 328
 329         count = of_property_count_u32_elems(np, "led-pattern");
 330         if (count < 0)
 331                 return NULL;
 332
 333         pattern = kcalloc(count, sizeof(*pattern), GFP_KERNEL);
 334         if (!pattern)
 335                 return NULL;
 336
 337         if (of_property_read_u32_array(np, "led-pattern", pattern, count)) {
 338                 kfree(pattern);
 339                 return NULL;
 340         }
 341
 342         *size = count;
 343
 344         return pattern;
 345 }
 346 EXPORT_SYMBOL_GPL(led_get_default_pattern);
 347
 348 /* Caller must ensure led_cdev->led_access held */
 349 void led_sysfs_disable(struct led_classdev *led_cdev)
 350 {
 351         lockdep_assert_held(&led_cdev->led_access);
 352
 353         led_cdev->flags |= LED_SYSFS_DISABLE;
 354 }
 355 EXPORT_SYMBOL_GPL(led_sysfs_disable);
 356
 357 /* Caller must ensure led_cdev->led_access held */
 358 void led_sysfs_enable(struct led_classdev *led_cdev)
 359 {
 360         lockdep_assert_held(&led_cdev->led_access);
 361
 362         led_cdev->flags &= ~LED_SYSFS_DISABLE;
 363 }
 364 EXPORT_SYMBOL_GPL(led_sysfs_enable);