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         unsigned long flags;
 161         char *event = NULL;
 162         char *envp[2];
 163         const char *name;
 164         int ret;
 165
 166         if (!led_cdev->trigger && !trig)
 167                 return 0;
 168
 169         name = trig ? trig->name : "none";
 170         event = kasprintf(GFP_KERNEL, "TRIGGER=%s", name);
 171
 172         /* Remove any existing trigger */
 173         if (led_cdev->trigger) {
 174                 write_lock_irqsave(&led_cdev->trigger->leddev_list_lock, flags);
 175                 list_del(&led_cdev->trig_list);
 176                 write_unlock_irqrestore(&led_cdev->trigger->leddev_list_lock,
 177                         flags);
 178                 cancel_work_sync(&led_cdev->set_brightness_work);
 179                 led_stop_software_blink(led_cdev);
 180                 if (led_cdev->trigger->deactivate)
 181                         led_cdev->trigger->deactivate(led_cdev);
 182                 device_remove_groups(led_cdev->dev, led_cdev->trigger->groups);
 183                 led_cdev->trigger = NULL;
 184                 led_cdev->trigger_data = NULL;
 185                 led_cdev->activated = false;
 186                 led_set_brightness(led_cdev, LED_OFF);
 187         }
 188         if (trig) {
 189                 write_lock_irqsave(&trig->leddev_list_lock, flags);
 190                 list_add_tail(&led_cdev->trig_list, &trig->led_cdevs);
 191                 write_unlock_irqrestore(&trig->leddev_list_lock, flags);
 192                 led_cdev->trigger = trig;
 193
 194                 if (trig->activate)
 195                         ret = trig->activate(led_cdev);
 196                 else
 197                         ret = 0;
 198
 199                 if (ret)
 200                         goto err_activate;
 201
 202                 ret = device_add_groups(led_cdev->dev, trig->groups);
 203                 if (ret) {
 204                         dev_err(led_cdev->dev, "Failed to add trigger attributes\n");
 205                         goto err_add_groups;
 206                 }
 207         }
 208
 209         if (event) {
 210                 envp[0] = event;
 211                 envp[1] = NULL;
 212                 if (kobject_uevent_env(&led_cdev->dev->kobj, KOBJ_CHANGE, envp))
 213                         dev_err(led_cdev->dev,
 214                                 "%s: Error sending uevent\n", __func__);
 215                 kfree(event);
 216         }
 217
 218         return 0;
 219
 220 err_add_groups:
 221
 222         if (trig->deactivate)
 223                 trig->deactivate(led_cdev);
 224 err_activate:
 225
 226         write_lock_irqsave(&led_cdev->trigger->leddev_list_lock, flags);
 227         list_del(&led_cdev->trig_list);
 228         write_unlock_irqrestore(&led_cdev->trigger->leddev_list_lock, flags);
 229         led_cdev->trigger = NULL;
 230         led_cdev->trigger_data = NULL;
 231         led_set_brightness(led_cdev, LED_OFF);
 232         kfree(event);
 233
 234         return ret;
 235 }
 236 EXPORT_SYMBOL_GPL(led_trigger_set);
 237
 238 void led_trigger_remove(struct led_classdev *led_cdev)
 239 {
 240         down_write(&led_cdev->trigger_lock);
 241         led_trigger_set(led_cdev, NULL);
 242         up_write(&led_cdev->trigger_lock);
 243 }
 244 EXPORT_SYMBOL_GPL(led_trigger_remove);
 245
 246 void led_trigger_set_default(struct led_classdev *led_cdev)
 247 {
 248         struct led_trigger *trig;
 249
 250         if (!led_cdev->default_trigger)
 251                 return;
 252
 253         down_read(&triggers_list_lock);
 254         down_write(&led_cdev->trigger_lock);
 255         list_for_each_entry(trig, &trigger_list, next_trig) {
 256                 if (!strcmp(led_cdev->default_trigger, trig->name) &&
 257                     trigger_relevant(led_cdev, trig)) {
 258                         led_cdev->flags |= LED_INIT_DEFAULT_TRIGGER;
 259                         led_trigger_set(led_cdev, trig);
 260                         break;
 261                 }
 262         }
 263         up_write(&led_cdev->trigger_lock);
 264         up_read(&triggers_list_lock);
 265 }
 266 EXPORT_SYMBOL_GPL(led_trigger_set_default);
 267
 268 void led_trigger_rename_static(const char *name, struct led_trigger *trig)
 269 {
 270         /* new name must be on a temporary string to prevent races */
 271         BUG_ON(name == trig->name);
 272
 273         down_write(&triggers_list_lock);
 274         /* this assumes that trig->name was originaly allocated to
 275          * non constant storage */
 276         strcpy((char *)trig->name, name);
 277         up_write(&triggers_list_lock);
 278 }
 279 EXPORT_SYMBOL_GPL(led_trigger_rename_static);
 280
 281 /* LED Trigger Interface */
 282
 283 int led_trigger_register(struct led_trigger *trig)
 284 {
 285         struct led_classdev *led_cdev;
 286         struct led_trigger *_trig;
 287
 288         rwlock_init(&trig->leddev_list_lock);
 289         INIT_LIST_HEAD(&trig->led_cdevs);
 290
 291         down_write(&triggers_list_lock);
 292         /* Make sure the trigger's name isn't already in use */
 293         list_for_each_entry(_trig, &trigger_list, next_trig) {
 294                 if (!strcmp(_trig->name, trig->name) &&
 295                     (trig->trigger_type == _trig->trigger_type ||
 296                      !trig->trigger_type || !_trig->trigger_type)) {
 297                         up_write(&triggers_list_lock);
 298                         return -EEXIST;
 299                 }
 300         }
 301         /* Add to the list of led triggers */
 302         list_add_tail(&trig->next_trig, &trigger_list);
 303         up_write(&triggers_list_lock);
 304
 305         /* Register with any LEDs that have this as a default trigger */
 306         down_read(&leds_list_lock);
 307         list_for_each_entry(led_cdev, &leds_list, node) {
 308                 down_write(&led_cdev->trigger_lock);
 309                 if (!led_cdev->trigger && led_cdev->default_trigger &&
 310                     !strcmp(led_cdev->default_trigger, trig->name) &&
 311                     trigger_relevant(led_cdev, trig)) {
 312                         led_cdev->flags |= LED_INIT_DEFAULT_TRIGGER;
 313                         led_trigger_set(led_cdev, trig);
 314                 }
 315                 up_write(&led_cdev->trigger_lock);
 316         }
 317         up_read(&leds_list_lock);
 318
 319         return 0;
 320 }
 321 EXPORT_SYMBOL_GPL(led_trigger_register);
 322
 323 void led_trigger_unregister(struct led_trigger *trig)
 324 {
 325         struct led_classdev *led_cdev;
 326
 327         if (list_empty_careful(&trig->next_trig))
 328                 return;
 329
 330         /* Remove from the list of led triggers */
 331         down_write(&triggers_list_lock);
 332         list_del_init(&trig->next_trig);
 333         up_write(&triggers_list_lock);
 334
 335         /* Remove anyone actively using this trigger */
 336         down_read(&leds_list_lock);
 337         list_for_each_entry(led_cdev, &leds_list, node) {
 338                 down_write(&led_cdev->trigger_lock);
 339                 if (led_cdev->trigger == trig)
 340                         led_trigger_set(led_cdev, NULL);
 341                 up_write(&led_cdev->trigger_lock);
 342         }
 343         up_read(&leds_list_lock);
 344 }
 345 EXPORT_SYMBOL_GPL(led_trigger_unregister);
 346
 347 static void devm_led_trigger_release(struct device *dev, void *res)
 348 {
 349         led_trigger_unregister(*(struct led_trigger **)res);
 350 }
 351
 352 int devm_led_trigger_register(struct device *dev,
 353                               struct led_trigger *trig)
 354 {
 355         struct led_trigger **dr;
 356         int rc;
 357
 358         dr = devres_alloc(devm_led_trigger_release, sizeof(*dr),
 359                           GFP_KERNEL);
 360         if (!dr)
 361                 return -ENOMEM;
 362
 363         *dr = trig;
 364
 365         rc = led_trigger_register(trig);
 366         if (rc)
 367                 devres_free(dr);
 368         else
 369                 devres_add(dev, dr);
 370
 371         return rc;
 372 }
 373 EXPORT_SYMBOL_GPL(devm_led_trigger_register);
 374
 375 /* Simple LED Trigger Interface */
 376
 377 void led_trigger_event(struct led_trigger *trig,
 378                         enum led_brightness brightness)
 379 {
 380         struct led_classdev *led_cdev;
 381         unsigned long flags;
 382
 383         if (!trig)
 384                 return;
 385
 386         read_lock_irqsave(&trig->leddev_list_lock, flags);
 387         list_for_each_entry(led_cdev, &trig->led_cdevs, trig_list)
 388                 led_set_brightness(led_cdev, brightness);
 389         read_unlock_irqrestore(&trig->leddev_list_lock, flags);
 390 }
 391 EXPORT_SYMBOL_GPL(led_trigger_event);
 392
 393 static void led_trigger_blink_setup(struct led_trigger *trig,
 394                              unsigned long *delay_on,
 395                              unsigned long *delay_off,
 396                              int oneshot,
 397                              int invert)
 398 {
 399         struct led_classdev *led_cdev;
 400         unsigned long flags;
 401
 402         if (!trig)
 403                 return;
 404
 405         read_lock_irqsave(&trig->leddev_list_lock, flags);
 406         list_for_each_entry(led_cdev, &trig->led_cdevs, trig_list) {
 407                 if (oneshot)
 408                         led_blink_set_oneshot(led_cdev, delay_on, delay_off,
 409                                               invert);
 410                 else
 411                         led_blink_set(led_cdev, delay_on, delay_off);
 412         }
 413         read_unlock_irqrestore(&trig->leddev_list_lock, flags);
 414 }
 415
 416 void led_trigger_blink(struct led_trigger *trig,
 417                        unsigned long *delay_on,
 418                        unsigned long *delay_off)
 419 {
 420         led_trigger_blink_setup(trig, delay_on, delay_off, 0, 0);
 421 }
 422 EXPORT_SYMBOL_GPL(led_trigger_blink);
 423
 424 void led_trigger_blink_oneshot(struct led_trigger *trig,
 425                                unsigned long *delay_on,
 426                                unsigned long *delay_off,
 427                                int invert)
 428 {
 429         led_trigger_blink_setup(trig, delay_on, delay_off, 1, invert);
 430 }
 431 EXPORT_SYMBOL_GPL(led_trigger_blink_oneshot);
 432
 433 void led_trigger_register_simple(const char *name, struct led_trigger **tp)
 434 {
 435         struct led_trigger *trig;
 436         int err;
 437
 438         trig = kzalloc(sizeof(struct led_trigger), GFP_KERNEL);
 439
 440         if (trig) {
 441                 trig->name = name;
 442                 err = led_trigger_register(trig);
 443                 if (err < 0) {
 444                         kfree(trig);
 445                         trig = NULL;
 446                         pr_warn("LED trigger %s failed to register (%d)\n",
 447                                 name, err);
 448                 }
 449         } else {
 450                 pr_warn("LED trigger %s failed to register (no memory)\n",
 451                         name);
 452         }
 453         *tp = trig;
 454 }
 455 EXPORT_SYMBOL_GPL(led_trigger_register_simple);
 456
 457 void led_trigger_unregister_simple(struct led_trigger *trig)
 458 {
 459         if (trig)
 460                 led_trigger_unregister(trig);
 461         kfree(trig);
 462 }
 463 EXPORT_SYMBOL_GPL(led_trigger_unregister_simple);