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_trigger_set(led_cdev, trig);
 205         }
 206         up_write(&led_cdev->trigger_lock);
 207         up_read(&triggers_list_lock);
 208 }
 209 EXPORT_SYMBOL_GPL(led_trigger_set_default);
 210
 211 void led_trigger_rename_static(const char *name, struct led_trigger *trig)
 212 {
 213         /* new name must be on a temporary string to prevent races */
 214         BUG_ON(name == trig->name);
 215
 216         down_write(&triggers_list_lock);
 217         /* this assumes that trig->name was originaly allocated to
 218          * non constant storage */
 219         strcpy((char *)trig->name, name);
 220         up_write(&triggers_list_lock);
 221 }
 222 EXPORT_SYMBOL_GPL(led_trigger_rename_static);
 223
 224 /* LED Trigger Interface */
 225
 226 int led_trigger_register(struct led_trigger *trig)
 227 {
 228         struct led_classdev *led_cdev;
 229         struct led_trigger *_trig;
 230
 231         rwlock_init(&trig->leddev_list_lock);
 232         INIT_LIST_HEAD(&trig->led_cdevs);
 233
 234         down_write(&triggers_list_lock);
 235         /* Make sure the trigger's name isn't already in use */
 236         list_for_each_entry(_trig, &trigger_list, next_trig) {
 237                 if (!strcmp(_trig->name, trig->name)) {
 238                         up_write(&triggers_list_lock);
 239                         return -EEXIST;
 240                 }
 241         }
 242         /* Add to the list of led triggers */
 243         list_add_tail(&trig->next_trig, &trigger_list);
 244         up_write(&triggers_list_lock);
 245
 246         /* Register with any LEDs that have this as a default trigger */
 247         down_read(&leds_list_lock);
 248         list_for_each_entry(led_cdev, &leds_list, node) {
 249                 down_write(&led_cdev->trigger_lock);
 250                 if (!led_cdev->trigger && led_cdev->default_trigger &&
 251                             !strcmp(led_cdev->default_trigger, trig->name))
 252                         led_trigger_set(led_cdev, trig);
 253                 up_write(&led_cdev->trigger_lock);
 254         }
 255         up_read(&leds_list_lock);
 256
 257         return 0;
 258 }
 259 EXPORT_SYMBOL_GPL(led_trigger_register);
 260
 261 void led_trigger_unregister(struct led_trigger *trig)
 262 {
 263         struct led_classdev *led_cdev;
 264
 265         if (list_empty_careful(&trig->next_trig))
 266                 return;
 267
 268         /* Remove from the list of led triggers */
 269         down_write(&triggers_list_lock);
 270         list_del_init(&trig->next_trig);
 271         up_write(&triggers_list_lock);
 272
 273         /* Remove anyone actively using this trigger */
 274         down_read(&leds_list_lock);
 275         list_for_each_entry(led_cdev, &leds_list, node) {
 276                 down_write(&led_cdev->trigger_lock);
 277                 if (led_cdev->trigger == trig)
 278                         led_trigger_set(led_cdev, NULL);
 279                 up_write(&led_cdev->trigger_lock);
 280         }
 281         up_read(&leds_list_lock);
 282 }
 283 EXPORT_SYMBOL_GPL(led_trigger_unregister);
 284
 285 static void devm_led_trigger_release(struct device *dev, void *res)
 286 {
 287         led_trigger_unregister(*(struct led_trigger **)res);
 288 }
 289
 290 int devm_led_trigger_register(struct device *dev,
 291                               struct led_trigger *trig)
 292 {
 293         struct led_trigger **dr;
 294         int rc;
 295
 296         dr = devres_alloc(devm_led_trigger_release, sizeof(*dr),
 297                           GFP_KERNEL);
 298         if (!dr)
 299                 return -ENOMEM;
 300
 301         *dr = trig;
 302
 303         rc = led_trigger_register(trig);
 304         if (rc)
 305                 devres_free(dr);
 306         else
 307                 devres_add(dev, dr);
 308
 309         return rc;
 310 }
 311 EXPORT_SYMBOL_GPL(devm_led_trigger_register);
 312
 313 /* Simple LED Tigger Interface */
 314
 315 void led_trigger_event(struct led_trigger *trig,
 316                         enum led_brightness brightness)
 317 {
 318         struct led_classdev *led_cdev;
 319
 320         if (!trig)
 321                 return;
 322
 323         read_lock(&trig->leddev_list_lock);
 324         list_for_each_entry(led_cdev, &trig->led_cdevs, trig_list)
 325                 led_set_brightness(led_cdev, brightness);
 326         read_unlock(&trig->leddev_list_lock);
 327 }
 328 EXPORT_SYMBOL_GPL(led_trigger_event);
 329
 330 static void led_trigger_blink_setup(struct led_trigger *trig,
 331                              unsigned long *delay_on,
 332                              unsigned long *delay_off,
 333                              int oneshot,
 334                              int invert)
 335 {
 336         struct led_classdev *led_cdev;
 337
 338         if (!trig)
 339                 return;
 340
 341         read_lock(&trig->leddev_list_lock);
 342         list_for_each_entry(led_cdev, &trig->led_cdevs, trig_list) {
 343                 if (oneshot)
 344                         led_blink_set_oneshot(led_cdev, delay_on, delay_off,
 345                                               invert);
 346                 else
 347                         led_blink_set(led_cdev, delay_on, delay_off);
 348         }
 349         read_unlock(&trig->leddev_list_lock);
 350 }
 351
 352 void led_trigger_blink(struct led_trigger *trig,
 353                        unsigned long *delay_on,
 354                        unsigned long *delay_off)
 355 {
 356         led_trigger_blink_setup(trig, delay_on, delay_off, 0, 0);
 357 }
 358 EXPORT_SYMBOL_GPL(led_trigger_blink);
 359
 360 void led_trigger_blink_oneshot(struct led_trigger *trig,
 361                                unsigned long *delay_on,
 362                                unsigned long *delay_off,
 363                                int invert)
 364 {
 365         led_trigger_blink_setup(trig, delay_on, delay_off, 1, invert);
 366 }
 367 EXPORT_SYMBOL_GPL(led_trigger_blink_oneshot);
 368
 369 void led_trigger_register_simple(const char *name, struct led_trigger **tp)
 370 {
 371         struct led_trigger *trig;
 372         int err;
 373
 374         trig = kzalloc(sizeof(struct led_trigger), GFP_KERNEL);
 375
 376         if (trig) {
 377                 trig->name = name;
 378                 err = led_trigger_register(trig);
 379                 if (err < 0) {
 380                         kfree(trig);
 381                         trig = NULL;
 382                         pr_warn("LED trigger %s failed to register (%d)\n",
 383                                 name, err);
 384                 }
 385         } else {
 386                 pr_warn("LED trigger %s failed to register (no memory)\n",
 387                         name);
 388         }
 389         *tp = trig;
 390 }
 391 EXPORT_SYMBOL_GPL(led_trigger_register_simple);
 392
 393 void led_trigger_unregister_simple(struct led_trigger *trig)
 394 {
 395         if (trig)
 396                 led_trigger_unregister(trig);
 397         kfree(trig);
 398 }
 399 EXPORT_SYMBOL_GPL(led_trigger_unregister_simple);