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 static 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 static bool led_match_default_trigger(struct led_classdev *led_cdev,
 251                                       struct led_trigger *trig)
 252 {
 253         if (!strcmp(led_cdev->default_trigger, trig->name) &&
 254             trigger_relevant(led_cdev, trig)) {
 255                 led_cdev->flags |= LED_INIT_DEFAULT_TRIGGER;
 256                 led_trigger_set(led_cdev, trig);
 257                 return true;
 258         }
 259
 260         return false;
 261 }
 262
 263 void led_trigger_set_default(struct led_classdev *led_cdev)
 264 {
 265         struct led_trigger *trig;
 266         bool found = false;
 267
 268         if (!led_cdev->default_trigger)
 269                 return;
 270
 271         down_read(&triggers_list_lock);
 272         down_write(&led_cdev->trigger_lock);
 273         list_for_each_entry(trig, &trigger_list, next_trig) {
 274                 found = led_match_default_trigger(led_cdev, trig);
 275                 if (found)
 276                         break;
 277         }
 278         up_write(&led_cdev->trigger_lock);
 279         up_read(&triggers_list_lock);
 280
 281         /*
 282          * If default trigger wasn't found, maybe trigger module isn't loaded yet.
 283          * Once loaded it will re-probe with all led_cdev's.
 284          */
 285         if (!found)
 286                 request_module_nowait("ledtrig:%s", led_cdev->default_trigger);
 287 }
 288 EXPORT_SYMBOL_GPL(led_trigger_set_default);
 289
 290 /* LED Trigger Interface */
 291
 292 int led_trigger_register(struct led_trigger *trig)
 293 {
 294         struct led_classdev *led_cdev;
 295         struct led_trigger *_trig;
 296
 297         spin_lock_init(&trig->leddev_list_lock);
 298         INIT_LIST_HEAD(&trig->led_cdevs);
 299
 300         down_write(&triggers_list_lock);
 301         /* Make sure the trigger's name isn't already in use */
 302         list_for_each_entry(_trig, &trigger_list, next_trig) {
 303                 if (!strcmp(_trig->name, trig->name) &&
 304                     (trig->trigger_type == _trig->trigger_type ||
 305                      !trig->trigger_type || !_trig->trigger_type)) {
 306                         up_write(&triggers_list_lock);
 307                         return -EEXIST;
 308                 }
 309         }
 310         /* Add to the list of led triggers */
 311         list_add_tail(&trig->next_trig, &trigger_list);
 312         up_write(&triggers_list_lock);
 313
 314         /* Register with any LEDs that have this as a default trigger */
 315         down_read(&leds_list_lock);
 316         list_for_each_entry(led_cdev, &leds_list, node) {
 317                 down_write(&led_cdev->trigger_lock);
 318                 if (!led_cdev->trigger && led_cdev->default_trigger)
 319                         led_match_default_trigger(led_cdev, trig);
 320                 up_write(&led_cdev->trigger_lock);
 321         }
 322         up_read(&leds_list_lock);
 323
 324         return 0;
 325 }
 326 EXPORT_SYMBOL_GPL(led_trigger_register);
 327
 328 void led_trigger_unregister(struct led_trigger *trig)
 329 {
 330         struct led_classdev *led_cdev;
 331
 332         if (list_empty_careful(&trig->next_trig))
 333                 return;
 334
 335         /* Remove from the list of led triggers */
 336         down_write(&triggers_list_lock);
 337         list_del_init(&trig->next_trig);
 338         up_write(&triggers_list_lock);
 339
 340         /* Remove anyone actively using this trigger */
 341         down_read(&leds_list_lock);
 342         list_for_each_entry(led_cdev, &leds_list, node) {
 343                 down_write(&led_cdev->trigger_lock);
 344                 if (led_cdev->trigger == trig)
 345                         led_trigger_set(led_cdev, NULL);
 346                 up_write(&led_cdev->trigger_lock);
 347         }
 348         up_read(&leds_list_lock);
 349 }
 350 EXPORT_SYMBOL_GPL(led_trigger_unregister);
 351
 352 static void devm_led_trigger_release(struct device *dev, void *res)
 353 {
 354         led_trigger_unregister(*(struct led_trigger **)res);
 355 }
 356
 357 int devm_led_trigger_register(struct device *dev,
 358                               struct led_trigger *trig)
 359 {
 360         struct led_trigger **dr;
 361         int rc;
 362
 363         dr = devres_alloc(devm_led_trigger_release, sizeof(*dr),
 364                           GFP_KERNEL);
 365         if (!dr)
 366                 return -ENOMEM;
 367
 368         *dr = trig;
 369
 370         rc = led_trigger_register(trig);
 371         if (rc)
 372                 devres_free(dr);
 373         else
 374                 devres_add(dev, dr);
 375
 376         return rc;
 377 }
 378 EXPORT_SYMBOL_GPL(devm_led_trigger_register);
 379
 380 /* Simple LED Trigger Interface */
 381
 382 void led_trigger_event(struct led_trigger *trig,
 383                         enum led_brightness brightness)
 384 {
 385         struct led_classdev *led_cdev;
 386
 387         if (!trig)
 388                 return;
 389
 390         rcu_read_lock();
 391         list_for_each_entry_rcu(led_cdev, &trig->led_cdevs, trig_list)
 392                 led_set_brightness(led_cdev, brightness);
 393         rcu_read_unlock();
 394 }
 395 EXPORT_SYMBOL_GPL(led_trigger_event);
 396
 397 static void led_trigger_blink_setup(struct led_trigger *trig,
 398                              unsigned long delay_on,
 399                              unsigned long delay_off,
 400                              int oneshot,
 401                              int invert)
 402 {
 403         struct led_classdev *led_cdev;
 404
 405         if (!trig)
 406                 return;
 407
 408         rcu_read_lock();
 409         list_for_each_entry_rcu(led_cdev, &trig->led_cdevs, trig_list) {
 410                 if (oneshot)
 411                         led_blink_set_oneshot(led_cdev, &delay_on, &delay_off,
 412                                               invert);
 413                 else
 414                         led_blink_set_nosleep(led_cdev, delay_on, delay_off);
 415         }
 416         rcu_read_unlock();
 417 }
 418
 419 void led_trigger_blink(struct led_trigger *trig,
 420                        unsigned long delay_on,
 421                        unsigned long delay_off)
 422 {
 423         led_trigger_blink_setup(trig, delay_on, delay_off, 0, 0);
 424 }
 425 EXPORT_SYMBOL_GPL(led_trigger_blink);
 426
 427 void led_trigger_blink_oneshot(struct led_trigger *trig,
 428                                unsigned long delay_on,
 429                                unsigned long delay_off,
 430                                int invert)
 431 {
 432         led_trigger_blink_setup(trig, delay_on, delay_off, 1, invert);
 433 }
 434 EXPORT_SYMBOL_GPL(led_trigger_blink_oneshot);
 435
 436 void led_trigger_register_simple(const char *name, struct led_trigger **tp)
 437 {
 438         struct led_trigger *trig;
 439         int err;
 440
 441         trig = kzalloc(sizeof(struct led_trigger), GFP_KERNEL);
 442
 443         if (trig) {
 444                 trig->name = name;
 445                 err = led_trigger_register(trig);
 446                 if (err < 0) {
 447                         kfree(trig);
 448                         trig = NULL;
 449                         pr_warn("LED trigger %s failed to register (%d)\n",
 450                                 name, err);
 451                 }
 452         } else {
 453                 pr_warn("LED trigger %s failed to register (no memory)\n",
 454                         name);
 455         }
 456         *tp = trig;
 457 }
 458 EXPORT_SYMBOL_GPL(led_trigger_register_simple);
 459
 460 void led_trigger_unregister_simple(struct led_trigger *trig)
 461 {
 462         if (trig)
 463                 led_trigger_unregister(trig);
 464         kfree(trig);
 465 }
 466 EXPORT_SYMBOL_GPL(led_trigger_unregister_simple);