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         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, flags);
 177         led_cdev->trigger = NULL;
 178         led_cdev->trigger_data = NULL;
 179         led_set_brightness(led_cdev, LED_OFF);
 180         kfree(event);
 181
 182         return ret;
 183 }
 184 EXPORT_SYMBOL_GPL(led_trigger_set);
 185
 186 void led_trigger_remove(struct led_classdev *led_cdev)
 187 {
 188         down_write(&led_cdev->trigger_lock);
 189         led_trigger_set(led_cdev, NULL);
 190         up_write(&led_cdev->trigger_lock);
 191 }
 192 EXPORT_SYMBOL_GPL(led_trigger_remove);
 193
 194 void led_trigger_set_default(struct led_classdev *led_cdev)
 195 {
 196         struct led_trigger *trig;
 197
 198         if (!led_cdev->default_trigger)
 199                 return;
 200
 201         down_read(&triggers_list_lock);
 202         down_write(&led_cdev->trigger_lock);
 203         list_for_each_entry(trig, &trigger_list, next_trig) {
 204                 if (!strcmp(led_cdev->default_trigger, trig->name))
 205                         led_trigger_set(led_cdev, trig);
 206         }
 207         up_write(&led_cdev->trigger_lock);
 208         up_read(&triggers_list_lock);
 209 }
 210 EXPORT_SYMBOL_GPL(led_trigger_set_default);
 211
 212 void led_trigger_rename_static(const char *name, struct led_trigger *trig)
 213 {
 214         /* new name must be on a temporary string to prevent races */
 215         BUG_ON(name == trig->name);
 216
 217         down_write(&triggers_list_lock);
 218         /* this assumes that trig->name was originaly allocated to
 219          * non constant storage */
 220         strcpy((char *)trig->name, name);
 221         up_write(&triggers_list_lock);
 222 }
 223 EXPORT_SYMBOL_GPL(led_trigger_rename_static);
 224
 225 /* LED Trigger Interface */
 226
 227 int led_trigger_register(struct led_trigger *trig)
 228 {
 229         struct led_classdev *led_cdev;
 230         struct led_trigger *_trig;
 231
 232         rwlock_init(&trig->leddev_list_lock);
 233         INIT_LIST_HEAD(&trig->led_cdevs);
 234
 235         down_write(&triggers_list_lock);
 236         /* Make sure the trigger's name isn't already in use */
 237         list_for_each_entry(_trig, &trigger_list, next_trig) {
 238                 if (!strcmp(_trig->name, trig->name)) {
 239                         up_write(&triggers_list_lock);
 240                         return -EEXIST;
 241                 }
 242         }
 243         /* Add to the list of led triggers */
 244         list_add_tail(&trig->next_trig, &trigger_list);
 245         up_write(&triggers_list_lock);
 246
 247         /* Register with any LEDs that have this as a default trigger */
 248         down_read(&leds_list_lock);
 249         list_for_each_entry(led_cdev, &leds_list, node) {
 250                 down_write(&led_cdev->trigger_lock);
 251                 if (!led_cdev->trigger && led_cdev->default_trigger &&
 252                             !strcmp(led_cdev->default_trigger, trig->name))
 253                         led_trigger_set(led_cdev, trig);
 254                 up_write(&led_cdev->trigger_lock);
 255         }
 256         up_read(&leds_list_lock);
 257
 258         return 0;
 259 }
 260 EXPORT_SYMBOL_GPL(led_trigger_register);
 261
 262 void led_trigger_unregister(struct led_trigger *trig)
 263 {
 264         struct led_classdev *led_cdev;
 265
 266         if (list_empty_careful(&trig->next_trig))
 267                 return;
 268
 269         /* Remove from the list of led triggers */
 270         down_write(&triggers_list_lock);
 271         list_del_init(&trig->next_trig);
 272         up_write(&triggers_list_lock);
 273
 274         /* Remove anyone actively using this trigger */
 275         down_read(&leds_list_lock);
 276         list_for_each_entry(led_cdev, &leds_list, node) {
 277                 down_write(&led_cdev->trigger_lock);
 278                 if (led_cdev->trigger == trig)
 279                         led_trigger_set(led_cdev, NULL);
 280                 up_write(&led_cdev->trigger_lock);
 281         }
 282         up_read(&leds_list_lock);
 283 }
 284 EXPORT_SYMBOL_GPL(led_trigger_unregister);
 285
 286 static void devm_led_trigger_release(struct device *dev, void *res)
 287 {
 288         led_trigger_unregister(*(struct led_trigger **)res);
 289 }
 290
 291 int devm_led_trigger_register(struct device *dev,
 292                               struct led_trigger *trig)
 293 {
 294         struct led_trigger **dr;
 295         int rc;
 296
 297         dr = devres_alloc(devm_led_trigger_release, sizeof(*dr),
 298                           GFP_KERNEL);
 299         if (!dr)
 300                 return -ENOMEM;
 301
 302         *dr = trig;
 303
 304         rc = led_trigger_register(trig);
 305         if (rc)
 306                 devres_free(dr);
 307         else
 308                 devres_add(dev, dr);
 309
 310         return rc;
 311 }
 312 EXPORT_SYMBOL_GPL(devm_led_trigger_register);
 313
 314 /* Simple LED Tigger Interface */
 315
 316 void led_trigger_event(struct led_trigger *trig,
 317                         enum led_brightness brightness)
 318 {
 319         struct led_classdev *led_cdev;
 320         unsigned long flags;
 321
 322         if (!trig)
 323                 return;
 324
 325         read_lock_irqsave(&trig->leddev_list_lock, flags);
 326         list_for_each_entry(led_cdev, &trig->led_cdevs, trig_list)
 327                 led_set_brightness(led_cdev, brightness);
 328         read_unlock_irqrestore(&trig->leddev_list_lock, flags);
 329 }
 330 EXPORT_SYMBOL_GPL(led_trigger_event);
 331
 332 static void led_trigger_blink_setup(struct led_trigger *trig,
 333                              unsigned long *delay_on,
 334                              unsigned long *delay_off,
 335                              int oneshot,
 336                              int invert)
 337 {
 338         struct led_classdev *led_cdev;
 339         unsigned long flags;
 340
 341         if (!trig)
 342                 return;
 343
 344         read_lock_irqsave(&trig->leddev_list_lock, flags);
 345         list_for_each_entry(led_cdev, &trig->led_cdevs, trig_list) {
 346                 if (oneshot)
 347                         led_blink_set_oneshot(led_cdev, delay_on, delay_off,
 348                                               invert);
 349                 else
 350                         led_blink_set(led_cdev, delay_on, delay_off);
 351         }
 352         read_unlock_irqrestore(&trig->leddev_list_lock, flags);
 353 }
 354
 355 void led_trigger_blink(struct led_trigger *trig,
 356                        unsigned long *delay_on,
 357                        unsigned long *delay_off)
 358 {
 359         led_trigger_blink_setup(trig, delay_on, delay_off, 0, 0);
 360 }
 361 EXPORT_SYMBOL_GPL(led_trigger_blink);
 362
 363 void led_trigger_blink_oneshot(struct led_trigger *trig,
 364                                unsigned long *delay_on,
 365                                unsigned long *delay_off,
 366                                int invert)
 367 {
 368         led_trigger_blink_setup(trig, delay_on, delay_off, 1, invert);
 369 }
 370 EXPORT_SYMBOL_GPL(led_trigger_blink_oneshot);
 371
 372 void led_trigger_register_simple(const char *name, struct led_trigger **tp)
 373 {
 374         struct led_trigger *trig;
 375         int err;
 376
 377         trig = kzalloc(sizeof(struct led_trigger), GFP_KERNEL);
 378
 379         if (trig) {
 380                 trig->name = name;
 381                 err = led_trigger_register(trig);
 382                 if (err < 0) {
 383                         kfree(trig);
 384                         trig = NULL;
 385                         pr_warn("LED trigger %s failed to register (%d)\n",
 386                                 name, err);
 387                 }
 388         } else {
 389                 pr_warn("LED trigger %s failed to register (no memory)\n",
 390                         name);
 391         }
 392         *tp = trig;
 393 }
 394 EXPORT_SYMBOL_GPL(led_trigger_register_simple);
 395
 396 void led_trigger_unregister_simple(struct led_trigger *trig)
 397 {
 398         if (trig)
 399                 led_trigger_unregister(trig);
 400         kfree(trig);
 401 }
 402 EXPORT_SYMBOL_GPL(led_trigger_unregister_simple);