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 void 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
 113         if (!led_cdev->trigger && !trig)
 114                 return;
 115
 116         name = trig ? trig->name : "none";
 117         event = kasprintf(GFP_KERNEL, "TRIGGER=%s", name);
 118
 119         /* Remove any existing trigger */
 120         if (led_cdev->trigger) {
 121                 write_lock_irqsave(&led_cdev->trigger->leddev_list_lock, flags);
 122                 list_del(&led_cdev->trig_list);
 123                 write_unlock_irqrestore(&led_cdev->trigger->leddev_list_lock,
 124                         flags);
 125                 cancel_work_sync(&led_cdev->set_brightness_work);
 126                 led_stop_software_blink(led_cdev);
 127                 if (led_cdev->trigger->deactivate)
 128                         led_cdev->trigger->deactivate(led_cdev);
 129                 led_cdev->trigger = NULL;
 130                 led_set_brightness(led_cdev, LED_OFF);
 131         }
 132         if (trig) {
 133                 write_lock_irqsave(&trig->leddev_list_lock, flags);
 134                 list_add_tail(&led_cdev->trig_list, &trig->led_cdevs);
 135                 write_unlock_irqrestore(&trig->leddev_list_lock, flags);
 136                 led_cdev->trigger = trig;
 137                 if (trig->activate)
 138                         trig->activate(led_cdev);
 139         }
 140
 141         if (event) {
 142                 envp[0] = event;
 143                 envp[1] = NULL;
 144                 if (kobject_uevent_env(&led_cdev->dev->kobj, KOBJ_CHANGE, envp))
 145                         dev_err(led_cdev->dev,
 146                                 "%s: Error sending uevent\n", __func__);
 147                 kfree(event);
 148         }
 149 }
 150 EXPORT_SYMBOL_GPL(led_trigger_set);
 151
 152 void led_trigger_remove(struct led_classdev *led_cdev)
 153 {
 154         down_write(&led_cdev->trigger_lock);
 155         led_trigger_set(led_cdev, NULL);
 156         up_write(&led_cdev->trigger_lock);
 157 }
 158 EXPORT_SYMBOL_GPL(led_trigger_remove);
 159
 160 void led_trigger_set_default(struct led_classdev *led_cdev)
 161 {
 162         struct led_trigger *trig;
 163
 164         if (!led_cdev->default_trigger)
 165                 return;
 166
 167         down_read(&triggers_list_lock);
 168         down_write(&led_cdev->trigger_lock);
 169         list_for_each_entry(trig, &trigger_list, next_trig) {
 170                 if (!strcmp(led_cdev->default_trigger, trig->name))
 171                         led_trigger_set(led_cdev, trig);
 172         }
 173         up_write(&led_cdev->trigger_lock);
 174         up_read(&triggers_list_lock);
 175 }
 176 EXPORT_SYMBOL_GPL(led_trigger_set_default);
 177
 178 void led_trigger_rename_static(const char *name, struct led_trigger *trig)
 179 {
 180         /* new name must be on a temporary string to prevent races */
 181         BUG_ON(name == trig->name);
 182
 183         down_write(&triggers_list_lock);
 184         /* this assumes that trig->name was originaly allocated to
 185          * non constant storage */
 186         strcpy((char *)trig->name, name);
 187         up_write(&triggers_list_lock);
 188 }
 189 EXPORT_SYMBOL_GPL(led_trigger_rename_static);
 190
 191 /* LED Trigger Interface */
 192
 193 int led_trigger_register(struct led_trigger *trig)
 194 {
 195         struct led_classdev *led_cdev;
 196         struct led_trigger *_trig;
 197
 198         rwlock_init(&trig->leddev_list_lock);
 199         INIT_LIST_HEAD(&trig->led_cdevs);
 200
 201         down_write(&triggers_list_lock);
 202         /* Make sure the trigger's name isn't already in use */
 203         list_for_each_entry(_trig, &trigger_list, next_trig) {
 204                 if (!strcmp(_trig->name, trig->name)) {
 205                         up_write(&triggers_list_lock);
 206                         return -EEXIST;
 207                 }
 208         }
 209         /* Add to the list of led triggers */
 210         list_add_tail(&trig->next_trig, &trigger_list);
 211         up_write(&triggers_list_lock);
 212
 213         /* Register with any LEDs that have this as a default trigger */
 214         down_read(&leds_list_lock);
 215         list_for_each_entry(led_cdev, &leds_list, node) {
 216                 down_write(&led_cdev->trigger_lock);
 217                 if (!led_cdev->trigger && led_cdev->default_trigger &&
 218                             !strcmp(led_cdev->default_trigger, trig->name))
 219                         led_trigger_set(led_cdev, trig);
 220                 up_write(&led_cdev->trigger_lock);
 221         }
 222         up_read(&leds_list_lock);
 223
 224         return 0;
 225 }
 226 EXPORT_SYMBOL_GPL(led_trigger_register);
 227
 228 void led_trigger_unregister(struct led_trigger *trig)
 229 {
 230         struct led_classdev *led_cdev;
 231
 232         if (list_empty_careful(&trig->next_trig))
 233                 return;
 234
 235         /* Remove from the list of led triggers */
 236         down_write(&triggers_list_lock);
 237         list_del_init(&trig->next_trig);
 238         up_write(&triggers_list_lock);
 239
 240         /* Remove anyone actively using this trigger */
 241         down_read(&leds_list_lock);
 242         list_for_each_entry(led_cdev, &leds_list, node) {
 243                 down_write(&led_cdev->trigger_lock);
 244                 if (led_cdev->trigger == trig)
 245                         led_trigger_set(led_cdev, NULL);
 246                 up_write(&led_cdev->trigger_lock);
 247         }
 248         up_read(&leds_list_lock);
 249 }
 250 EXPORT_SYMBOL_GPL(led_trigger_unregister);
 251
 252 static void devm_led_trigger_release(struct device *dev, void *res)
 253 {
 254         led_trigger_unregister(*(struct led_trigger **)res);
 255 }
 256
 257 int devm_led_trigger_register(struct device *dev,
 258                               struct led_trigger *trig)
 259 {
 260         struct led_trigger **dr;
 261         int rc;
 262
 263         dr = devres_alloc(devm_led_trigger_release, sizeof(*dr),
 264                           GFP_KERNEL);
 265         if (!dr)
 266                 return -ENOMEM;
 267
 268         *dr = trig;
 269
 270         rc = led_trigger_register(trig);
 271         if (rc)
 272                 devres_free(dr);
 273         else
 274                 devres_add(dev, dr);
 275
 276         return rc;
 277 }
 278 EXPORT_SYMBOL_GPL(devm_led_trigger_register);
 279
 280 /* Simple LED Tigger Interface */
 281
 282 void led_trigger_event(struct led_trigger *trig,
 283                         enum led_brightness brightness)
 284 {
 285         struct led_classdev *led_cdev;
 286
 287         if (!trig)
 288                 return;
 289
 290         read_lock(&trig->leddev_list_lock);
 291         list_for_each_entry(led_cdev, &trig->led_cdevs, trig_list)
 292                 led_set_brightness(led_cdev, brightness);
 293         read_unlock(&trig->leddev_list_lock);
 294 }
 295 EXPORT_SYMBOL_GPL(led_trigger_event);
 296
 297 static void led_trigger_blink_setup(struct led_trigger *trig,
 298                              unsigned long *delay_on,
 299                              unsigned long *delay_off,
 300                              int oneshot,
 301                              int invert)
 302 {
 303         struct led_classdev *led_cdev;
 304
 305         if (!trig)
 306                 return;
 307
 308         read_lock(&trig->leddev_list_lock);
 309         list_for_each_entry(led_cdev, &trig->led_cdevs, trig_list) {
 310                 if (oneshot)
 311                         led_blink_set_oneshot(led_cdev, delay_on, delay_off,
 312                                               invert);
 313                 else
 314                         led_blink_set(led_cdev, delay_on, delay_off);
 315         }
 316         read_unlock(&trig->leddev_list_lock);
 317 }
 318
 319 void led_trigger_blink(struct led_trigger *trig,
 320                        unsigned long *delay_on,
 321                        unsigned long *delay_off)
 322 {
 323         led_trigger_blink_setup(trig, delay_on, delay_off, 0, 0);
 324 }
 325 EXPORT_SYMBOL_GPL(led_trigger_blink);
 326
 327 void led_trigger_blink_oneshot(struct led_trigger *trig,
 328                                unsigned long *delay_on,
 329                                unsigned long *delay_off,
 330                                int invert)
 331 {
 332         led_trigger_blink_setup(trig, delay_on, delay_off, 1, invert);
 333 }
 334 EXPORT_SYMBOL_GPL(led_trigger_blink_oneshot);
 335
 336 void led_trigger_register_simple(const char *name, struct led_trigger **tp)
 337 {
 338         struct led_trigger *trig;
 339         int err;
 340
 341         trig = kzalloc(sizeof(struct led_trigger), GFP_KERNEL);
 342
 343         if (trig) {
 344                 trig->name = name;
 345                 err = led_trigger_register(trig);
 346                 if (err < 0) {
 347                         kfree(trig);
 348                         trig = NULL;
 349                         pr_warn("LED trigger %s failed to register (%d)\n",
 350                                 name, err);
 351                 }
 352         } else {
 353                 pr_warn("LED trigger %s failed to register (no memory)\n",
 354                         name);
 355         }
 356         *tp = trig;
 357 }
 358 EXPORT_SYMBOL_GPL(led_trigger_register_simple);
 359
 360 void led_trigger_unregister_simple(struct led_trigger *trig)
 361 {
 362         if (trig)
 363                 led_trigger_unregister(trig);
 364         kfree(trig);
 365 }
 366 EXPORT_SYMBOL_GPL(led_trigger_unregister_simple);