drivers/leds/led-triggers.c

   1 /*
   2  * LED Triggers Core
   3  *
   4  * Copyright 2005-2007 Openedhand Ltd.
   5  *
   6  * Author: Richard Purdie <rpurdie@openedhand.com>
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License version 2 as
  10  * published by the Free Software Foundation.
  11  *
  12  */
  13
  14 #include <linux/export.h>
  15 #include <linux/kernel.h>
  16 #include <linux/list.h>
  17 #include <linux/spinlock.h>
  18 #include <linux/device.h>
  19 #include <linux/timer.h>
  20 #include <linux/rwsem.h>
  21 #include <linux/leds.h>
  22 #include <linux/slab.h>
  23 #include "leds.h"
  24
  25 /*
  26  * Nests outside led_cdev->trigger_lock
  27  */
  28 static DECLARE_RWSEM(triggers_list_lock);
  29 LIST_HEAD(trigger_list);
  30
  31  /* Used by LED Class */
  32
  33 ssize_t led_trigger_store(struct device *dev, struct device_attribute *attr,
  34                 const char *buf, size_t count)
  35 {
  36         struct led_classdev *led_cdev = dev_get_drvdata(dev);
  37         struct led_trigger *trig;
  38         int ret = count;
  39
  40         mutex_lock(&led_cdev->led_access);
  41
  42         if (led_sysfs_is_disabled(led_cdev)) {
  43                 ret = -EBUSY;
  44                 goto unlock;
  45         }
  46
  47         if (sysfs_streq(buf, "none")) {
  48                 led_trigger_remove(led_cdev);
  49                 goto unlock;
  50         }
  51
  52         down_read(&triggers_list_lock);
  53         list_for_each_entry(trig, &trigger_list, next_trig) {
  54                 if (sysfs_streq(buf, trig->name)) {
  55                         down_write(&led_cdev->trigger_lock);
  56                         led_trigger_set(led_cdev, trig);
  57                         up_write(&led_cdev->trigger_lock);
  58
  59                         up_read(&triggers_list_lock);
  60                         goto unlock;
  61                 }
  62         }
  63         /* we come here only if buf matches no trigger */
  64         ret = -EINVAL;
  65         up_read(&triggers_list_lock);
  66
  67 unlock:
  68         mutex_unlock(&led_cdev->led_access);
  69         return ret;
  70 }
  71 EXPORT_SYMBOL_GPL(led_trigger_store);
  72
  73 ssize_t led_trigger_show(struct device *dev, struct device_attribute *attr,
  74                 char *buf)
  75 {
  76         struct led_classdev *led_cdev = dev_get_drvdata(dev);
  77         struct led_trigger *trig;
  78         int len = 0;
  79
  80         down_read(&triggers_list_lock);
  81         down_read(&led_cdev->trigger_lock);
  82
  83         if (!led_cdev->trigger)
  84                 len += scnprintf(buf+len, PAGE_SIZE - len, "[none] ");
  85         else
  86                 len += scnprintf(buf+len, PAGE_SIZE - len, "none ");
  87
  88         list_for_each_entry(trig, &trigger_list, next_trig) {
  89                 if (led_cdev->trigger && !strcmp(led_cdev->trigger->name,
  90                                                         trig->name))
  91                         len += scnprintf(buf+len, PAGE_SIZE - len, "[%s] ",
  92                                          trig->name);
  93                 else
  94                         len += scnprintf(buf+len, PAGE_SIZE - len, "%s ",
  95                                          trig->name);
  96         }
  97         up_read(&led_cdev->trigger_lock);
  98         up_read(&triggers_list_lock);
  99
 100         len += scnprintf(len+buf, PAGE_SIZE - len, "\n");
 101         return len;
 102 }
 103 EXPORT_SYMBOL_GPL(led_trigger_show);
 104
 105 /* Caller must ensure led_cdev->trigger_lock held */
 106 int led_trigger_set(struct led_classdev *led_cdev, struct led_trigger *trig)
 107 {
 108         unsigned long flags;
 109         char *event = NULL;
 110         char *envp[2];
 111         const char *name;
 112         int ret;
 113
 114         if (!led_cdev->trigger && !trig)
 115                 return 0;
 116
 117         name = trig ? trig->name : "none";
 118         event = kasprintf(GFP_KERNEL, "TRIGGER=%s", name);
 119
 120         /* Remove any existing trigger */
 121         if (led_cdev->trigger) {
 122                 write_lock_irqsave(&led_cdev->trigger->leddev_list_lock, flags);
 123                 list_del(&led_cdev->trig_list);
 124                 write_unlock_irqrestore(&led_cdev->trigger->leddev_list_lock,
 125                         flags);
 126                 cancel_work_sync(&led_cdev->set_brightness_work);
 127                 led_stop_software_blink(led_cdev);
 128                 if (led_cdev->trigger->deactivate)
 129                         led_cdev->trigger->deactivate(led_cdev);
 130                 device_remove_groups(led_cdev->dev, led_cdev->trigger->groups);
 131                 led_cdev->trigger = NULL;
 132                 led_cdev->trigger_data = NULL;
 133                 led_cdev->activated = false;
 134                 led_set_brightness(led_cdev, LED_OFF);
 135         }
 136         if (trig) {
 137                 write_lock_irqsave(&trig->leddev_list_lock, flags);
 138                 list_add_tail(&led_cdev->trig_list, &trig->led_cdevs);
 139                 write_unlock_irqrestore(&trig->leddev_list_lock, flags);
 140                 led_cdev->trigger = trig;
 141
 142                 if (trig->activate)
 143                         ret = trig->activate(led_cdev);
 144                 else
 145                         ret = 0;
 146
 147                 if (ret)
 148                         goto err_activate;
 149
 150                 ret = device_add_groups(led_cdev->dev, trig->groups);
 151                 if (ret) {
 152                         dev_err(led_cdev->dev, "Failed to add trigger attributes\n");
 153                         goto err_add_groups;
 154                 }
 155         }
 156
 157         if (event) {
 158                 envp[0] = event;
 159                 envp[1] = NULL;
 160                 if (kobject_uevent_env(&led_cdev->dev->kobj, KOBJ_CHANGE, envp))
 161                         dev_err(led_cdev->dev,
 162                                 "%s: Error sending uevent\n", __func__);
 163                 kfree(event);
 164         }
 165
 166         return 0;
 167
 168 err_add_groups:
 169
 170         if (trig->deactivate)
 171                 trig->deactivate(led_cdev);
 172 err_activate:
 173
 174         led_cdev->trigger = NULL;
 175         led_cdev->trigger_data = NULL;
 176         write_lock_irqsave(&led_cdev->trigger->leddev_list_lock, flags);
 177         list_del(&led_cdev->trig_list);
 178         write_unlock_irqrestore(&led_cdev->trigger->leddev_list_lock, flags);
 179         led_set_brightness(led_cdev, LED_OFF);
 180
 181         return ret;
 182 }
 183 EXPORT_SYMBOL_GPL(led_trigger_set);
 184
 185 void led_trigger_remove(struct led_classdev *led_cdev)
 186 {
 187         down_write(&led_cdev->trigger_lock);
 188         led_trigger_set(led_cdev, NULL);
 189         up_write(&led_cdev->trigger_lock);
 190 }
 191 EXPORT_SYMBOL_GPL(led_trigger_remove);
 192
 193 void led_trigger_set_default(struct led_classdev *led_cdev)
 194 {
 195         struct led_trigger *trig;
 196
 197         if (!led_cdev->default_trigger)
 198                 return;
 199
 200         down_read(&triggers_list_lock);
 201         down_write(&led_cdev->trigger_lock);
 202         list_for_each_entry(trig, &trigger_list, next_trig) {
 203                 if (!strcmp(led_cdev->default_trigger, trig->name)) {
 204                         led_cdev->flags |= LED_INIT_DEFAULT_TRIGGER;
 205                         led_trigger_set(led_cdev, trig);
 206                         break;
 207                 }
 208         }
 209         up_write(&led_cdev->trigger_lock);
 210         up_read(&triggers_list_lock);
 211 }
 212 EXPORT_SYMBOL_GPL(led_trigger_set_default);
 213
 214 void led_trigger_rename_static(const char *name, struct led_trigger *trig)
 215 {
 216         /* new name must be on a temporary string to prevent races */
 217         BUG_ON(name == trig->name);
 218
 219         down_write(&triggers_list_lock);
 220         /* this assumes that trig->name was originaly allocated to
 221          * non constant storage */
 222         strcpy((char *)trig->name, name);
 223         up_write(&triggers_list_lock);
 224 }
 225 EXPORT_SYMBOL_GPL(led_trigger_rename_static);
 226
 227 /* LED Trigger Interface */
 228
 229 int led_trigger_register(struct led_trigger *trig)
 230 {
 231         struct led_classdev *led_cdev;
 232         struct led_trigger *_trig;
 233
 234         rwlock_init(&trig->leddev_list_lock);
 235         INIT_LIST_HEAD(&trig->led_cdevs);
 236
 237         down_write(&triggers_list_lock);
 238         /* Make sure the trigger's name isn't already in use */
 239         list_for_each_entry(_trig, &trigger_list, next_trig) {
 240                 if (!strcmp(_trig->name, trig->name)) {
 241                         up_write(&triggers_list_lock);
 242                         return -EEXIST;
 243                 }
 244         }
 245         /* Add to the list of led triggers */
 246         list_add_tail(&trig->next_trig, &trigger_list);
 247         up_write(&triggers_list_lock);
 248
 249         /* Register with any LEDs that have this as a default trigger */
 250         down_read(&leds_list_lock);
 251         list_for_each_entry(led_cdev, &leds_list, node) {
 252                 down_write(&led_cdev->trigger_lock);
 253                 if (!led_cdev->trigger && led_cdev->default_trigger &&
 254                             !strcmp(led_cdev->default_trigger, trig->name)) {
 255                         led_cdev->flags |= LED_INIT_DEFAULT_TRIGGER;
 256                         led_trigger_set(led_cdev, trig);
 257                 }
 258                 up_write(&led_cdev->trigger_lock);
 259         }
 260         up_read(&leds_list_lock);
 261
 262         return 0;
 263 }
 264 EXPORT_SYMBOL_GPL(led_trigger_register);
 265
 266 void led_trigger_unregister(struct led_trigger *trig)
 267 {
 268         struct led_classdev *led_cdev;
 269
 270         if (list_empty_careful(&trig->next_trig))
 271                 return;
 272
 273         /* Remove from the list of led triggers */
 274         down_write(&triggers_list_lock);
 275         list_del_init(&trig->next_trig);
 276         up_write(&triggers_list_lock);
 277
 278         /* Remove anyone actively using this trigger */
 279         down_read(&leds_list_lock);
 280         list_for_each_entry(led_cdev, &leds_list, node) {
 281                 down_write(&led_cdev->trigger_lock);
 282                 if (led_cdev->trigger == trig)
 283                         led_trigger_set(led_cdev, NULL);
 284                 up_write(&led_cdev->trigger_lock);
 285         }
 286         up_read(&leds_list_lock);
 287 }
 288 EXPORT_SYMBOL_GPL(led_trigger_unregister);
 289
 290 static void devm_led_trigger_release(struct device *dev, void *res)
 291 {
 292         led_trigger_unregister(*(struct led_trigger **)res);
 293 }
 294
 295 int devm_led_trigger_register(struct device *dev,
 296                               struct led_trigger *trig)
 297 {
 298         struct led_trigger **dr;
 299         int rc;
 300
 301         dr = devres_alloc(devm_led_trigger_release, sizeof(*dr),
 302                           GFP_KERNEL);
 303         if (!dr)
 304                 return -ENOMEM;
 305
 306         *dr = trig;
 307
 308         rc = led_trigger_register(trig);
 309         if (rc)
 310                 devres_free(dr);
 311         else
 312                 devres_add(dev, dr);
 313
 314         return rc;
 315 }
 316 EXPORT_SYMBOL_GPL(devm_led_trigger_register);
 317
 318 /* Simple LED Tigger Interface */
 319
 320 void led_trigger_event(struct led_trigger *trig,
 321                         enum led_brightness brightness)
 322 {
 323         struct led_classdev *led_cdev;
 324
 325         if (!trig)
 326                 return;
 327
 328         read_lock(&trig->leddev_list_lock);
 329         list_for_each_entry(led_cdev, &trig->led_cdevs, trig_list)
 330                 led_set_brightness(led_cdev, brightness);
 331         read_unlock(&trig->leddev_list_lock);
 332 }
 333 EXPORT_SYMBOL_GPL(led_trigger_event);
 334
 335 static void led_trigger_blink_setup(struct led_trigger *trig,
 336                              unsigned long *delay_on,
 337                              unsigned long *delay_off,
 338                              int oneshot,
 339                              int invert)
 340 {
 341         struct led_classdev *led_cdev;
 342
 343         if (!trig)
 344                 return;
 345
 346         read_lock(&trig->leddev_list_lock);
 347         list_for_each_entry(led_cdev, &trig->led_cdevs, trig_list) {
 348                 if (oneshot)
 349                         led_blink_set_oneshot(led_cdev, delay_on, delay_off,
 350                                               invert);
 351                 else
 352                         led_blink_set(led_cdev, delay_on, delay_off);
 353         }
 354         read_unlock(&trig->leddev_list_lock);
 355 }
 356
 357 void led_trigger_blink(struct led_trigger *trig,
 358                        unsigned long *delay_on,
 359                        unsigned long *delay_off)
 360 {
 361         led_trigger_blink_setup(trig, delay_on, delay_off, 0, 0);
 362 }
 363 EXPORT_SYMBOL_GPL(led_trigger_blink);
 364
 365 void led_trigger_blink_oneshot(struct led_trigger *trig,
 366                                unsigned long *delay_on,
 367                                unsigned long *delay_off,
 368                                int invert)
 369 {
 370         led_trigger_blink_setup(trig, delay_on, delay_off, 1, invert);
 371 }
 372 EXPORT_SYMBOL_GPL(led_trigger_blink_oneshot);
 373
 374 void led_trigger_register_simple(const char *name, struct led_trigger **tp)
 375 {
 376         struct led_trigger *trig;
 377         int err;
 378
 379         trig = kzalloc(sizeof(struct led_trigger), GFP_KERNEL);
 380
 381         if (trig) {
 382                 trig->name = name;
 383                 err = led_trigger_register(trig);
 384                 if (err < 0) {
 385                         kfree(trig);
 386                         trig = NULL;
 387                         pr_warn("LED trigger %s failed to register (%d)\n",
 388                                 name, err);
 389                 }
 390         } else {
 391                 pr_warn("LED trigger %s failed to register (no memory)\n",
 392                         name);
 393         }
 394         *tp = trig;
 395 }
 396 EXPORT_SYMBOL_GPL(led_trigger_register_simple);
 397
 398 void led_trigger_unregister_simple(struct led_trigger *trig)
 399 {
 400         if (trig)
 401                 led_trigger_unregister(trig);
 402         kfree(trig);
 403 }
 404 EXPORT_SYMBOL_GPL(led_trigger_unregister_simple);