drivers/leds/led-triggers.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * LED Triggers Core
   4  *
   5  * Copyright 2005-2007 Openedhand Ltd.
   6  *
   7  * Author: Richard Purdie <rpurdie@openedhand.com>
   8  */
   9
  10 #include <linux/export.h>
  11 #include <linux/kernel.h>
  12 #include <linux/list.h>
  13 #include <linux/spinlock.h>
  14 #include <linux/device.h>
  15 #include <linux/timer.h>
  16 #include <linux/rwsem.h>
  17 #include <linux/leds.h>
  18 #include <linux/slab.h>
  19 #include <linux/mm.h>
  20 #include "leds.h"
  21
  22 /*
  23  * Nests outside led_cdev->trigger_lock
  24  */
  25 static DECLARE_RWSEM(triggers_list_lock);
  26 LIST_HEAD(trigger_list);
  27
  28  /* Used by LED Class */
  29
  30 static inline bool
  31 trigger_relevant(struct led_classdev *led_cdev, struct led_trigger *trig)
  32 {
  33         return !trig->trigger_type || trig->trigger_type == led_cdev->trigger_type;
  34 }
  35
  36 ssize_t led_trigger_write(struct file *filp, struct kobject *kobj,
  37                           struct bin_attribute *bin_attr, char *buf,
  38                           loff_t pos, size_t count)
  39 {
  40         struct device *dev = kobj_to_dev(kobj);
  41         struct led_classdev *led_cdev = dev_get_drvdata(dev);
  42         struct led_trigger *trig;
  43         int ret = count;
  44
  45         mutex_lock(&led_cdev->led_access);
  46
  47         if (led_sysfs_is_disabled(led_cdev)) {
  48                 ret = -EBUSY;
  49                 goto unlock;
  50         }
  51
  52         if (sysfs_streq(buf, "none")) {
  53                 led_trigger_remove(led_cdev);
  54                 goto unlock;
  55         }
  56
  57         down_read(&triggers_list_lock);
  58         list_for_each_entry(trig, &trigger_list, next_trig) {
  59                 if (sysfs_streq(buf, trig->name) && trigger_relevant(led_cdev, trig)) {
  60                         down_write(&led_cdev->trigger_lock);
  61                         led_trigger_set(led_cdev, trig);
  62                         up_write(&led_cdev->trigger_lock);
  63
  64                         up_read(&triggers_list_lock);
  65                         goto unlock;
  66                 }
  67         }
  68         /* we come here only if buf matches no trigger */
  69         ret = -EINVAL;
  70         up_read(&triggers_list_lock);
  71
  72 unlock:
  73         mutex_unlock(&led_cdev->led_access);
  74         return ret;
  75 }
  76 EXPORT_SYMBOL_GPL(led_trigger_write);
  77
  78 __printf(3, 4)
  79 static int led_trigger_snprintf(char *buf, ssize_t size, const char *fmt, ...)
  80 {
  81         va_list args;
  82         int i;
  83
  84         va_start(args, fmt);
  85         if (size <= 0)
  86                 i = vsnprintf(NULL, 0, fmt, args);
  87         else
  88                 i = vscnprintf(buf, size, fmt, args);
  89         va_end(args);
  90
  91         return i;
  92 }
  93
  94 static int led_trigger_format(char *buf, size_t size,
  95                               struct led_classdev *led_cdev)
  96 {
  97         struct led_trigger *trig;
  98         int len = led_trigger_snprintf(buf, size, "%s",
  99                                        led_cdev->trigger ? "none" : "[none]");
 100
 101         list_for_each_entry(trig, &trigger_list, next_trig) {
 102                 bool hit;
 103
 104                 if (!trigger_relevant(led_cdev, trig))
 105                         continue;
 106
 107                 hit = led_cdev->trigger && !strcmp(led_cdev->trigger->name, trig->name);
 108
 109                 len += led_trigger_snprintf(buf + len, size - len,
 110                                             " %s%s%s", hit ? "[" : "",
 111                                             trig->name, hit ? "]" : "");
 112         }
 113
 114         len += led_trigger_snprintf(buf + len, size - len, "\n");
 115
 116         return len;
 117 }
 118
 119 /*
 120  * It was stupid to create 10000 cpu triggers, but we are stuck with it now.
 121  * Don't make that mistake again. We work around it here by creating binary
 122  * attribute, which is not limited by length. This is _not_ good design, do not
 123  * copy it.
 124  */
 125 ssize_t led_trigger_read(struct file *filp, struct kobject *kobj,
 126                         struct bin_attribute *attr, char *buf,
 127                         loff_t pos, size_t count)
 128 {
 129         struct device *dev = kobj_to_dev(kobj);
 130         struct led_classdev *led_cdev = dev_get_drvdata(dev);
 131         void *data;
 132         int len;
 133
 134         down_read(&triggers_list_lock);
 135         down_read(&led_cdev->trigger_lock);
 136
 137         len = led_trigger_format(NULL, 0, led_cdev);
 138         data = kvmalloc(len + 1, GFP_KERNEL);
 139         if (!data) {
 140                 up_read(&led_cdev->trigger_lock);
 141                 up_read(&triggers_list_lock);
 142                 return -ENOMEM;
 143         }
 144         len = led_trigger_format(data, len + 1, led_cdev);
 145
 146         up_read(&led_cdev->trigger_lock);
 147         up_read(&triggers_list_lock);
 148
 149         len = memory_read_from_buffer(buf, count, &pos, data, len);
 150
 151         kvfree(data);
 152
 153         return len;
 154 }
 155 EXPORT_SYMBOL_GPL(led_trigger_read);
 156
 157 /* Caller must ensure led_cdev->trigger_lock held */
 158 int led_trigger_set(struct led_classdev *led_cdev, struct led_trigger *trig)
 159 {
 160         char *event = NULL;
 161         char *envp[2];
 162         const char *name;
 163         int ret;
 164
 165         if (!led_cdev->trigger && !trig)
 166                 return 0;
 167
 168         name = trig ? trig->name : "none";
 169         event = kasprintf(GFP_KERNEL, "TRIGGER=%s", name);
 170
 171         /* Remove any existing trigger */
 172         if (led_cdev->trigger) {
 173                 spin_lock(&led_cdev->trigger->leddev_list_lock);
 174                 list_del_rcu(&led_cdev->trig_list);
 175                 spin_unlock(&led_cdev->trigger->leddev_list_lock);
 176
 177                 /* ensure it's no longer visible on the led_cdevs list */
 178                 synchronize_rcu();
 179
 180                 cancel_work_sync(&led_cdev->set_brightness_work);
 181                 led_stop_software_blink(led_cdev);
 182                 if (led_cdev->trigger->deactivate)
 183                         led_cdev->trigger->deactivate(led_cdev);
 184                 device_remove_groups(led_cdev->dev, led_cdev->trigger->groups);
 185                 led_cdev->trigger = NULL;
 186                 led_cdev->trigger_data = NULL;
 187                 led_cdev->activated = false;
 188                 led_cdev->flags &= ~LED_INIT_DEFAULT_TRIGGER;
 189                 led_set_brightness(led_cdev, LED_OFF);
 190         }
 191         if (trig) {
 192                 spin_lock(&trig->leddev_list_lock);
 193                 list_add_tail_rcu(&led_cdev->trig_list, &trig->led_cdevs);
 194                 spin_unlock(&trig->leddev_list_lock);
 195                 led_cdev->trigger = trig;
 196
 197                 if (trig->activate)
 198                         ret = trig->activate(led_cdev);
 199                 else
 200                         ret = 0;
 201
 202                 if (ret)
 203                         goto err_activate;
 204
 205                 ret = device_add_groups(led_cdev->dev, trig->groups);
 206                 if (ret) {
 207                         dev_err(led_cdev->dev, "Failed to add trigger attributes\n");
 208                         goto err_add_groups;
 209                 }
 210         }
 211
 212         if (event) {
 213                 envp[0] = event;
 214                 envp[1] = NULL;
 215                 if (kobject_uevent_env(&led_cdev->dev->kobj, KOBJ_CHANGE, envp))
 216                         dev_err(led_cdev->dev,
 217                                 "%s: Error sending uevent\n", __func__);
 218                 kfree(event);
 219         }
 220
 221         return 0;
 222
 223 err_add_groups:
 224
 225         if (trig->deactivate)
 226                 trig->deactivate(led_cdev);
 227 err_activate:
 228
 229         spin_lock(&led_cdev->trigger->leddev_list_lock);
 230         list_del_rcu(&led_cdev->trig_list);
 231         spin_unlock(&led_cdev->trigger->leddev_list_lock);
 232         synchronize_rcu();
 233         led_cdev->trigger = NULL;
 234         led_cdev->trigger_data = NULL;
 235         led_set_brightness(led_cdev, LED_OFF);
 236         kfree(event);
 237
 238         return ret;
 239 }
 240 EXPORT_SYMBOL_GPL(led_trigger_set);
 241
 242 void led_trigger_remove(struct led_classdev *led_cdev)
 243 {
 244         down_write(&led_cdev->trigger_lock);
 245         led_trigger_set(led_cdev, NULL);
 246         up_write(&led_cdev->trigger_lock);
 247 }
 248 EXPORT_SYMBOL_GPL(led_trigger_remove);
 249
 250 void led_trigger_set_default(struct led_classdev *led_cdev)
 251 {
 252         struct led_trigger *trig;
 253
 254         if (!led_cdev->default_trigger)
 255                 return;
 256
 257         down_read(&triggers_list_lock);
 258         down_write(&led_cdev->trigger_lock);
 259         list_for_each_entry(trig, &trigger_list, next_trig) {
 260                 if (!strcmp(led_cdev->default_trigger, trig->name) &&
 261                     trigger_relevant(led_cdev, trig)) {
 262                         led_cdev->flags |= LED_INIT_DEFAULT_TRIGGER;
 263                         led_trigger_set(led_cdev, trig);
 264                         break;
 265                 }
 266         }
 267         up_write(&led_cdev->trigger_lock);
 268         up_read(&triggers_list_lock);
 269 }
 270 EXPORT_SYMBOL_GPL(led_trigger_set_default);
 271
 272 void led_trigger_rename_static(const char *name, struct led_trigger *trig)
 273 {
 274         /* new name must be on a temporary string to prevent races */
 275         BUG_ON(name == trig->name);
 276
 277         down_write(&triggers_list_lock);
 278         /* this assumes that trig->name was originaly allocated to
 279          * non constant storage */
 280         strcpy((char *)trig->name, name);
 281         up_write(&triggers_list_lock);
 282 }
 283 EXPORT_SYMBOL_GPL(led_trigger_rename_static);
 284
 285 /* LED Trigger Interface */
 286
 287 int led_trigger_register(struct led_trigger *trig)
 288 {
 289         struct led_classdev *led_cdev;
 290         struct led_trigger *_trig;
 291
 292         spin_lock_init(&trig->leddev_list_lock);
 293         INIT_LIST_HEAD(&trig->led_cdevs);
 294
 295         down_write(&triggers_list_lock);
 296         /* Make sure the trigger's name isn't already in use */
 297         list_for_each_entry(_trig, &trigger_list, next_trig) {
 298                 if (!strcmp(_trig->name, trig->name) &&
 299                     (trig->trigger_type == _trig->trigger_type ||
 300                      !trig->trigger_type || !_trig->trigger_type)) {
 301                         up_write(&triggers_list_lock);
 302                         return -EEXIST;
 303                 }
 304         }
 305         /* Add to the list of led triggers */
 306         list_add_tail(&trig->next_trig, &trigger_list);
 307         up_write(&triggers_list_lock);
 308
 309         /* Register with any LEDs that have this as a default trigger */
 310         down_read(&leds_list_lock);
 311         list_for_each_entry(led_cdev, &leds_list, node) {
 312                 down_write(&led_cdev->trigger_lock);
 313                 if (!led_cdev->trigger && led_cdev->default_trigger &&
 314                     !strcmp(led_cdev->default_trigger, trig->name) &&
 315                     trigger_relevant(led_cdev, trig)) {
 316                         led_cdev->flags |= LED_INIT_DEFAULT_TRIGGER;
 317                         led_trigger_set(led_cdev, trig);
 318                 }
 319                 up_write(&led_cdev->trigger_lock);
 320         }
 321         up_read(&leds_list_lock);
 322
 323         return 0;
 324 }
 325 EXPORT_SYMBOL_GPL(led_trigger_register);
 326
 327 void led_trigger_unregister(struct led_trigger *trig)
 328 {
 329         struct led_classdev *led_cdev;
 330
 331         if (list_empty_careful(&trig->next_trig))
 332                 return;
 333
 334         /* Remove from the list of led triggers */
 335         down_write(&triggers_list_lock);
 336         list_del_init(&trig->next_trig);
 337         up_write(&triggers_list_lock);
 338
 339         /* Remove anyone actively using this trigger */
 340         down_read(&leds_list_lock);
 341         list_for_each_entry(led_cdev, &leds_list, node) {
 342                 down_write(&led_cdev->trigger_lock);
 343                 if (led_cdev->trigger == trig)
 344                         led_trigger_set(led_cdev, NULL);
 345                 up_write(&led_cdev->trigger_lock);
 346         }
 347         up_read(&leds_list_lock);
 348 }
 349 EXPORT_SYMBOL_GPL(led_trigger_unregister);
 350
 351 static void devm_led_trigger_release(struct device *dev, void *res)
 352 {
 353         led_trigger_unregister(*(struct led_trigger **)res);
 354 }
 355
 356 int devm_led_trigger_register(struct device *dev,
 357                               struct led_trigger *trig)
 358 {
 359         struct led_trigger **dr;
 360         int rc;
 361
 362         dr = devres_alloc(devm_led_trigger_release, sizeof(*dr),
 363                           GFP_KERNEL);
 364         if (!dr)
 365                 return -ENOMEM;
 366
 367         *dr = trig;
 368
 369         rc = led_trigger_register(trig);
 370         if (rc)
 371                 devres_free(dr);
 372         else
 373                 devres_add(dev, dr);
 374
 375         return rc;
 376 }
 377 EXPORT_SYMBOL_GPL(devm_led_trigger_register);
 378
 379 /* Simple LED Trigger Interface */
 380
 381 void led_trigger_event(struct led_trigger *trig,
 382                         enum led_brightness brightness)
 383 {
 384         struct led_classdev *led_cdev;
 385
 386         if (!trig)
 387                 return;
 388
 389         rcu_read_lock();
 390         list_for_each_entry_rcu(led_cdev, &trig->led_cdevs, trig_list)
 391                 led_set_brightness(led_cdev, brightness);
 392         rcu_read_unlock();
 393 }
 394 EXPORT_SYMBOL_GPL(led_trigger_event);
 395
 396 static void led_trigger_blink_setup(struct led_trigger *trig,
 397                              unsigned long delay_on,
 398                              unsigned long delay_off,
 399                              int oneshot,
 400                              int invert)
 401 {
 402         struct led_classdev *led_cdev;
 403
 404         if (!trig)
 405                 return;
 406
 407         rcu_read_lock();
 408         list_for_each_entry_rcu(led_cdev, &trig->led_cdevs, trig_list) {
 409                 if (oneshot)
 410                         led_blink_set_oneshot(led_cdev, &delay_on, &delay_off,
 411                                               invert);
 412                 else
 413                         led_blink_set_nosleep(led_cdev, delay_on, delay_off);
 414         }
 415         rcu_read_unlock();
 416 }
 417
 418 void led_trigger_blink(struct led_trigger *trig,
 419                        unsigned long delay_on,
 420                        unsigned long delay_off)
 421 {
 422         led_trigger_blink_setup(trig, delay_on, delay_off, 0, 0);
 423 }
 424 EXPORT_SYMBOL_GPL(led_trigger_blink);
 425
 426 void led_trigger_blink_oneshot(struct led_trigger *trig,
 427                                unsigned long delay_on,
 428                                unsigned long delay_off,
 429                                int invert)
 430 {
 431         led_trigger_blink_setup(trig, delay_on, delay_off, 1, invert);
 432 }
 433 EXPORT_SYMBOL_GPL(led_trigger_blink_oneshot);
 434
 435 void led_trigger_register_simple(const char *name, struct led_trigger **tp)
 436 {
 437         struct led_trigger *trig;
 438         int err;
 439
 440         trig = kzalloc(sizeof(struct led_trigger), GFP_KERNEL);
 441
 442         if (trig) {
 443                 trig->name = name;
 444                 err = led_trigger_register(trig);
 445                 if (err < 0) {
 446                         kfree(trig);
 447                         trig = NULL;
 448                         pr_warn("LED trigger %s failed to register (%d)\n",
 449                                 name, err);
 450                 }
 451         } else {
 452                 pr_warn("LED trigger %s failed to register (no memory)\n",
 453                         name);
 454         }
 455         *tp = trig;
 456 }
 457 EXPORT_SYMBOL_GPL(led_trigger_register_simple);
 458
 459 void led_trigger_unregister_simple(struct led_trigger *trig)
 460 {
 461         if (trig)
 462                 led_trigger_unregister(trig);
 463         kfree(trig);
 464 }
 465 EXPORT_SYMBOL_GPL(led_trigger_unregister_simple);