drivers/leds/led-core.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * LED Class Core
   4  *
   5  * Copyright 2005-2006 Openedhand Ltd.
   6  *
   7  * Author: Richard Purdie <rpurdie@openedhand.com>
   8  */
   9
  10 #include <linux/kernel.h>
  11 #include <linux/leds.h>
  12 #include <linux/list.h>
  13 #include <linux/module.h>
  14 #include <linux/mutex.h>
  15 #include <linux/of.h>
  16 #include <linux/rwsem.h>
  17 #include <linux/slab.h>
  18 #include "leds.h"
  19
  20 DECLARE_RWSEM(leds_list_lock);
  21 EXPORT_SYMBOL_GPL(leds_list_lock);
  22
  23 LIST_HEAD(leds_list);
  24 EXPORT_SYMBOL_GPL(leds_list);
  25
  26 static int __led_set_brightness(struct led_classdev *led_cdev,
  27                                 enum led_brightness value)
  28 {
  29         if (!led_cdev->brightness_set)
  30                 return -ENOTSUPP;
  31
  32         led_cdev->brightness_set(led_cdev, value);
  33
  34         return 0;
  35 }
  36
  37 static int __led_set_brightness_blocking(struct led_classdev *led_cdev,
  38                                          enum led_brightness value)
  39 {
  40         if (!led_cdev->brightness_set_blocking)
  41                 return -ENOTSUPP;
  42
  43         return led_cdev->brightness_set_blocking(led_cdev, value);
  44 }
  45
  46 static void led_timer_function(struct timer_list *t)
  47 {
  48         struct led_classdev *led_cdev = from_timer(led_cdev, t, blink_timer);
  49         unsigned long brightness;
  50         unsigned long delay;
  51
  52         if (!led_cdev->blink_delay_on || !led_cdev->blink_delay_off) {
  53                 led_set_brightness_nosleep(led_cdev, LED_OFF);
  54                 clear_bit(LED_BLINK_SW, &led_cdev->work_flags);
  55                 return;
  56         }
  57
  58         if (test_and_clear_bit(LED_BLINK_ONESHOT_STOP,
  59                                &led_cdev->work_flags)) {
  60                 clear_bit(LED_BLINK_SW, &led_cdev->work_flags);
  61                 return;
  62         }
  63
  64         brightness = led_get_brightness(led_cdev);
  65         if (!brightness) {
  66                 /* Time to switch the LED on. */
  67                 if (test_and_clear_bit(LED_BLINK_BRIGHTNESS_CHANGE,
  68                                         &led_cdev->work_flags))
  69                         brightness = led_cdev->new_blink_brightness;
  70                 else
  71                         brightness = led_cdev->blink_brightness;
  72                 delay = led_cdev->blink_delay_on;
  73         } else {
  74                 /* Store the current brightness value to be able
  75                  * to restore it when the delay_off period is over.
  76                  */
  77                 led_cdev->blink_brightness = brightness;
  78                 brightness = LED_OFF;
  79                 delay = led_cdev->blink_delay_off;
  80         }
  81
  82         led_set_brightness_nosleep(led_cdev, brightness);
  83
  84         /* Return in next iteration if led is in one-shot mode and we are in
  85          * the final blink state so that the led is toggled each delay_on +
  86          * delay_off milliseconds in worst case.
  87          */
  88         if (test_bit(LED_BLINK_ONESHOT, &led_cdev->work_flags)) {
  89                 if (test_bit(LED_BLINK_INVERT, &led_cdev->work_flags)) {
  90                         if (brightness)
  91                                 set_bit(LED_BLINK_ONESHOT_STOP,
  92                                         &led_cdev->work_flags);
  93                 } else {
  94                         if (!brightness)
  95                                 set_bit(LED_BLINK_ONESHOT_STOP,
  96                                         &led_cdev->work_flags);
  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 (test_and_clear_bit(LED_BLINK_DISABLE, &led_cdev->work_flags)) {
 110                 led_cdev->delayed_set_value = LED_OFF;
 111                 led_stop_software_blink(led_cdev);
 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         set_bit(LED_BLINK_SW, &led_cdev->work_flags);
 155         mod_timer(&led_cdev->blink_timer, jiffies + 1);
 156 }
 157
 158
 159 static void led_blink_setup(struct led_classdev *led_cdev,
 160                      unsigned long *delay_on,
 161                      unsigned long *delay_off)
 162 {
 163         if (!test_bit(LED_BLINK_ONESHOT, &led_cdev->work_flags) &&
 164             led_cdev->blink_set &&
 165             !led_cdev->blink_set(led_cdev, delay_on, delay_off))
 166                 return;
 167
 168         /* blink with 1 Hz as default if nothing specified */
 169         if (!*delay_on && !*delay_off)
 170                 *delay_on = *delay_off = 500;
 171
 172         led_set_software_blink(led_cdev, *delay_on, *delay_off);
 173 }
 174
 175 void led_init_core(struct led_classdev *led_cdev)
 176 {
 177         INIT_WORK(&led_cdev->set_brightness_work, set_brightness_delayed);
 178
 179         timer_setup(&led_cdev->blink_timer, led_timer_function, 0);
 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         clear_bit(LED_BLINK_SW, &led_cdev->work_flags);
 190         clear_bit(LED_BLINK_ONESHOT, &led_cdev->work_flags);
 191         clear_bit(LED_BLINK_ONESHOT_STOP, &led_cdev->work_flags);
 192
 193         led_blink_setup(led_cdev, delay_on, delay_off);
 194 }
 195 EXPORT_SYMBOL_GPL(led_blink_set);
 196
 197 void led_blink_set_oneshot(struct led_classdev *led_cdev,
 198                            unsigned long *delay_on,
 199                            unsigned long *delay_off,
 200                            int invert)
 201 {
 202         if (test_bit(LED_BLINK_ONESHOT, &led_cdev->work_flags) &&
 203              timer_pending(&led_cdev->blink_timer))
 204                 return;
 205
 206         set_bit(LED_BLINK_ONESHOT, &led_cdev->work_flags);
 207         clear_bit(LED_BLINK_ONESHOT_STOP, &led_cdev->work_flags);
 208
 209         if (invert)
 210                 set_bit(LED_BLINK_INVERT, &led_cdev->work_flags);
 211         else
 212                 clear_bit(LED_BLINK_INVERT, &led_cdev->work_flags);
 213
 214         led_blink_setup(led_cdev, delay_on, delay_off);
 215 }
 216 EXPORT_SYMBOL_GPL(led_blink_set_oneshot);
 217
 218 void led_stop_software_blink(struct led_classdev *led_cdev)
 219 {
 220         del_timer_sync(&led_cdev->blink_timer);
 221         led_cdev->blink_delay_on = 0;
 222         led_cdev->blink_delay_off = 0;
 223         clear_bit(LED_BLINK_SW, &led_cdev->work_flags);
 224 }
 225 EXPORT_SYMBOL_GPL(led_stop_software_blink);
 226
 227 void led_set_brightness(struct led_classdev *led_cdev,
 228                         enum led_brightness brightness)
 229 {
 230         /*
 231          * If software blink is active, delay brightness setting
 232          * until the next timer tick.
 233          */
 234         if (test_bit(LED_BLINK_SW, &led_cdev->work_flags)) {
 235                 /*
 236                  * If we need to disable soft blinking delegate this to the
 237                  * work queue task to avoid problems in case we are called
 238                  * from hard irq context.
 239                  */
 240                 if (brightness == LED_OFF) {
 241                         set_bit(LED_BLINK_DISABLE, &led_cdev->work_flags);
 242                         schedule_work(&led_cdev->set_brightness_work);
 243                 } else {
 244                         set_bit(LED_BLINK_BRIGHTNESS_CHANGE,
 245                                 &led_cdev->work_flags);
 246                         led_cdev->new_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 u32 *led_get_default_pattern(struct led_classdev *led_cdev, unsigned int *size)
 312 {
 313         struct device_node *np = dev_of_node(led_cdev->dev);
 314         u32 *pattern;
 315         int count;
 316
 317         if (!np)
 318                 return NULL;
 319
 320         count = of_property_count_u32_elems(np, "led-pattern");
 321         if (count < 0)
 322                 return NULL;
 323
 324         pattern = kcalloc(count, sizeof(*pattern), GFP_KERNEL);
 325         if (!pattern)
 326                 return NULL;
 327
 328         if (of_property_read_u32_array(np, "led-pattern", pattern, count)) {
 329                 kfree(pattern);
 330                 return NULL;
 331         }
 332
 333         *size = count;
 334
 335         return pattern;
 336 }
 337 EXPORT_SYMBOL_GPL(led_get_default_pattern);
 338
 339 /* Caller must ensure led_cdev->led_access held */
 340 void led_sysfs_disable(struct led_classdev *led_cdev)
 341 {
 342         lockdep_assert_held(&led_cdev->led_access);
 343
 344         led_cdev->flags |= LED_SYSFS_DISABLE;
 345 }
 346 EXPORT_SYMBOL_GPL(led_sysfs_disable);
 347
 348 /* Caller must ensure led_cdev->led_access held */
 349 void led_sysfs_enable(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_enable);