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_set_brightness(led_cdev, LED_OFF);
 189         }
 190         if (trig) {
 191                 spin_lock(&trig->leddev_list_lock);
 192                 list_add_tail_rcu(&led_cdev->trig_list, &trig->led_cdevs);
 193                 spin_unlock(&trig->leddev_list_lock);
 194                 led_cdev->trigger = trig;
 195
 196                 if (trig->activate)
 197                         ret = trig->activate(led_cdev);
 198                 else
 199                         ret = 0;
 200
 201                 if (ret)
 202                         goto err_activate;
 203
 204                 ret = device_add_groups(led_cdev->dev, trig->groups);
 205                 if (ret) {
 206                         dev_err(led_cdev->dev, "Failed to add trigger attributes\n");
 207                         goto err_add_groups;
 208                 }
 209         }
 210
 211         if (event) {
 212                 envp[0] = event;
 213                 envp[1] = NULL;
 214                 if (kobject_uevent_env(&led_cdev->dev->kobj, KOBJ_CHANGE, envp))
 215                         dev_err(led_cdev->dev,
 216                                 "%s: Error sending uevent\n", __func__);
 217                 kfree(event);
 218         }
 219
 220         return 0;
 221
 222 err_add_groups:
 223
 224         if (trig->deactivate)
 225                 trig->deactivate(led_cdev);
 226 err_activate:
 227
 228         spin_lock(&led_cdev->trigger->leddev_list_lock);
 229         list_del_rcu(&led_cdev->trig_list);
 230         spin_unlock(&led_cdev->trigger->leddev_list_lock);
 231         synchronize_rcu();
 232         led_cdev->trigger = NULL;
 233         led_cdev->trigger_data = NULL;
 234         led_set_brightness(led_cdev, LED_OFF);
 235         kfree(event);
 236
 237         return ret;
 238 }
 239 EXPORT_SYMBOL_GPL(led_trigger_set);
 240
 241 void led_trigger_remove(struct led_classdev *led_cdev)
 242 {
 243         down_write(&led_cdev->trigger_lock);
 244         led_trigger_set(led_cdev, NULL);
 245         up_write(&led_cdev->trigger_lock);
 246 }
 247 EXPORT_SYMBOL_GPL(led_trigger_remove);
 248
 249 void led_trigger_set_default(struct led_classdev *led_cdev)
 250 {
 251         struct led_trigger *trig;
 252
 253         if (!led_cdev->default_trigger)
 254                 return;
 255
 256         down_read(&triggers_list_lock);
 257         down_write(&led_cdev->trigger_lock);
 258         list_for_each_entry(trig, &trigger_list, next_trig) {
 259                 if (!strcmp(led_cdev->default_trigger, trig->name) &&
 260                     trigger_relevant(led_cdev, trig)) {
 261                         led_cdev->flags |= LED_INIT_DEFAULT_TRIGGER;
 262                         led_trigger_set(led_cdev, trig);
 263                         break;
 264                 }
 265         }
 266         up_write(&led_cdev->trigger_lock);
 267         up_read(&triggers_list_lock);
 268 }
 269 EXPORT_SYMBOL_GPL(led_trigger_set_default);
 270
 271 void led_trigger_rename_static(const char *name, struct led_trigger *trig)
 272 {
 273         /* new name must be on a temporary string to prevent races */
 274         BUG_ON(name == trig->name);
 275
 276         down_write(&triggers_list_lock);
 277         /* this assumes that trig->name was originaly allocated to
 278          * non constant storage */
 279         strcpy((char *)trig->name, name);
 280         up_write(&triggers_list_lock);
 281 }
 282 EXPORT_SYMBOL_GPL(led_trigger_rename_static);
 283
 284 /* LED Trigger Interface */
 285
 286 int led_trigger_register(struct led_trigger *trig)
 287 {
 288         struct led_classdev *led_cdev;
 289         struct led_trigger *_trig;
 290
 291         spin_lock_init(&trig->leddev_list_lock);
 292         INIT_LIST_HEAD(&trig->led_cdevs);
 293
 294         down_write(&triggers_list_lock);
 295         /* Make sure the trigger's name isn't already in use */
 296         list_for_each_entry(_trig, &trigger_list, next_trig) {
 297                 if (!strcmp(_trig->name, trig->name) &&
 298                     (trig->trigger_type == _trig->trigger_type ||
 299                      !trig->trigger_type || !_trig->trigger_type)) {
 300                         up_write(&triggers_list_lock);
 301                         return -EEXIST;
 302                 }
 303         }
 304         /* Add to the list of led triggers */
 305         list_add_tail(&trig->next_trig, &trigger_list);
 306         up_write(&triggers_list_lock);
 307
 308         /* Register with any LEDs that have this as a default trigger */
 309         down_read(&leds_list_lock);
 310         list_for_each_entry(led_cdev, &leds_list, node) {
 311                 down_write(&led_cdev->trigger_lock);
 312                 if (!led_cdev->trigger && led_cdev->default_trigger &&
 313                     !strcmp(led_cdev->default_trigger, trig->name) &&
 314                     trigger_relevant(led_cdev, trig)) {
 315                         led_cdev->flags |= LED_INIT_DEFAULT_TRIGGER;
 316                         led_trigger_set(led_cdev, trig);
 317                 }
 318                 up_write(&led_cdev->trigger_lock);
 319         }
 320         up_read(&leds_list_lock);
 321
 322         return 0;
 323 }
 324 EXPORT_SYMBOL_GPL(led_trigger_register);
 325
 326 void led_trigger_unregister(struct led_trigger *trig)
 327 {
 328         struct led_classdev *led_cdev;
 329
 330         if (list_empty_careful(&trig->next_trig))
 331                 return;
 332
 333         /* Remove from the list of led triggers */
 334         down_write(&triggers_list_lock);
 335         list_del_init(&trig->next_trig);
 336         up_write(&triggers_list_lock);
 337
 338         /* Remove anyone actively using this trigger */
 339         down_read(&leds_list_lock);
 340         list_for_each_entry(led_cdev, &leds_list, node) {
 341                 down_write(&led_cdev->trigger_lock);
 342                 if (led_cdev->trigger == trig)
 343                         led_trigger_set(led_cdev, NULL);
 344                 up_write(&led_cdev->trigger_lock);
 345         }
 346         up_read(&leds_list_lock);
 347 }
 348 EXPORT_SYMBOL_GPL(led_trigger_unregister);
 349
 350 static void devm_led_trigger_release(struct device *dev, void *res)
 351 {
 352         led_trigger_unregister(*(struct led_trigger **)res);
 353 }
 354
 355 int devm_led_trigger_register(struct device *dev,
 356                               struct led_trigger *trig)
 357 {
 358         struct led_trigger **dr;
 359         int rc;
 360
 361         dr = devres_alloc(devm_led_trigger_release, sizeof(*dr),
 362                           GFP_KERNEL);
 363         if (!dr)
 364                 return -ENOMEM;
 365
 366         *dr = trig;
 367
 368         rc = led_trigger_register(trig);
 369         if (rc)
 370                 devres_free(dr);
 371         else
 372                 devres_add(dev, dr);
 373
 374         return rc;
 375 }
 376 EXPORT_SYMBOL_GPL(devm_led_trigger_register);
 377
 378 /* Simple LED Trigger Interface */
 379
 380 void led_trigger_event(struct led_trigger *trig,
 381                         enum led_brightness brightness)
 382 {
 383         struct led_classdev *led_cdev;
 384
 385         if (!trig)
 386                 return;
 387
 388         rcu_read_lock();
 389         list_for_each_entry_rcu(led_cdev, &trig->led_cdevs, trig_list)
 390                 led_set_brightness(led_cdev, brightness);
 391         rcu_read_unlock();
 392 }
 393 EXPORT_SYMBOL_GPL(led_trigger_event);
 394
 395 static void led_trigger_blink_setup(struct led_trigger *trig,
 396                              unsigned long *delay_on,
 397                              unsigned long *delay_off,
 398                              int oneshot,
 399                              int invert)
 400 {
 401         struct led_classdev *led_cdev;
 402
 403         if (!trig)
 404                 return;
 405
 406         rcu_read_lock();
 407         list_for_each_entry_rcu(led_cdev, &trig->led_cdevs, trig_list) {
 408                 if (oneshot)
 409                         led_blink_set_oneshot(led_cdev, delay_on, delay_off,
 410                                               invert);
 411                 else
 412                         led_blink_set(led_cdev, delay_on, delay_off);
 413         }
 414         rcu_read_unlock();
 415 }
 416
 417 void led_trigger_blink(struct led_trigger *trig,
 418                        unsigned long *delay_on,
 419                        unsigned long *delay_off)
 420 {
 421         led_trigger_blink_setup(trig, delay_on, delay_off, 0, 0);
 422 }
 423 EXPORT_SYMBOL_GPL(led_trigger_blink);
 424
 425 void led_trigger_blink_oneshot(struct led_trigger *trig,
 426                                unsigned long *delay_on,
 427                                unsigned long *delay_off,
 428                                int invert)
 429 {
 430         led_trigger_blink_setup(trig, delay_on, delay_off, 1, invert);
 431 }
 432 EXPORT_SYMBOL_GPL(led_trigger_blink_oneshot);
 433
 434 void led_trigger_register_simple(const char *name, struct led_trigger **tp)
 435 {
 436         struct led_trigger *trig;
 437         int err;
 438
 439         trig = kzalloc(sizeof(struct led_trigger), GFP_KERNEL);
 440
 441         if (trig) {
 442                 trig->name = name;
 443                 err = led_trigger_register(trig);
 444                 if (err < 0) {
 445                         kfree(trig);
 446                         trig = NULL;
 447                         pr_warn("LED trigger %s failed to register (%d)\n",
 448                                 name, err);
 449                 }
 450         } else {
 451                 pr_warn("LED trigger %s failed to register (no memory)\n",
 452                         name);
 453         }
 454         *tp = trig;
 455 }
 456 EXPORT_SYMBOL_GPL(led_trigger_register_simple);
 457
 458 void led_trigger_unregister_simple(struct led_trigger *trig)
 459 {
 460         if (trig)
 461                 led_trigger_unregister(trig);
 462         kfree(trig);
 463 }
 464 EXPORT_SYMBOL_GPL(led_trigger_unregister_simple);