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/module.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 += sprintf(buf+len, "[none] ");
  85         else
  86                 len += sprintf(buf+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 += sprintf(buf+len, "[%s] ", trig->name);
  92                 else
  93                         len += sprintf(buf+len, "%s ", trig->name);
  94         }
  95         up_read(&led_cdev->trigger_lock);
  96         up_read(&triggers_list_lock);
  97
  98         len += sprintf(len+buf, "\n");
  99         return len;
 100 }
 101 EXPORT_SYMBOL_GPL(led_trigger_show);
 102
 103 /* Caller must ensure led_cdev->trigger_lock held */
 104 void led_trigger_set(struct led_classdev *led_cdev, struct led_trigger *trig)
 105 {
 106         unsigned long flags;
 107         char *event = NULL;
 108         char *envp[2];
 109         const char *name;
 110
 111         name = trig ? trig->name : "none";
 112         event = kasprintf(GFP_KERNEL, "TRIGGER=%s", name);
 113
 114         /* Remove any existing trigger */
 115         if (led_cdev->trigger) {
 116                 write_lock_irqsave(&led_cdev->trigger->leddev_list_lock, flags);
 117                 list_del(&led_cdev->trig_list);
 118                 write_unlock_irqrestore(&led_cdev->trigger->leddev_list_lock,
 119                         flags);
 120                 cancel_work_sync(&led_cdev->set_brightness_work);
 121                 led_stop_software_blink(led_cdev);
 122                 if (led_cdev->trigger->deactivate)
 123                         led_cdev->trigger->deactivate(led_cdev);
 124                 led_cdev->trigger = NULL;
 125                 led_set_brightness(led_cdev, LED_OFF);
 126         }
 127         if (trig) {
 128                 write_lock_irqsave(&trig->leddev_list_lock, flags);
 129                 list_add_tail(&led_cdev->trig_list, &trig->led_cdevs);
 130                 write_unlock_irqrestore(&trig->leddev_list_lock, flags);
 131                 led_cdev->trigger = trig;
 132                 if (trig->activate)
 133                         trig->activate(led_cdev);
 134         }
 135
 136         if (event) {
 137                 envp[0] = event;
 138                 envp[1] = NULL;
 139                 kobject_uevent_env(&led_cdev->dev->kobj, KOBJ_CHANGE, envp);
 140                 kfree(event);
 141         }
 142 }
 143 EXPORT_SYMBOL_GPL(led_trigger_set);
 144
 145 void led_trigger_remove(struct led_classdev *led_cdev)
 146 {
 147         down_write(&led_cdev->trigger_lock);
 148         led_trigger_set(led_cdev, NULL);
 149         up_write(&led_cdev->trigger_lock);
 150 }
 151 EXPORT_SYMBOL_GPL(led_trigger_remove);
 152
 153 void led_trigger_set_default(struct led_classdev *led_cdev)
 154 {
 155         struct led_trigger *trig;
 156
 157         if (!led_cdev->default_trigger)
 158                 return;
 159
 160         down_read(&triggers_list_lock);
 161         down_write(&led_cdev->trigger_lock);
 162         list_for_each_entry(trig, &trigger_list, next_trig) {
 163                 if (!strcmp(led_cdev->default_trigger, trig->name))
 164                         led_trigger_set(led_cdev, trig);
 165         }
 166         up_write(&led_cdev->trigger_lock);
 167         up_read(&triggers_list_lock);
 168 }
 169 EXPORT_SYMBOL_GPL(led_trigger_set_default);
 170
 171 void led_trigger_rename_static(const char *name, struct led_trigger *trig)
 172 {
 173         /* new name must be on a temporary string to prevent races */
 174         BUG_ON(name == trig->name);
 175
 176         down_write(&triggers_list_lock);
 177         /* this assumes that trig->name was originaly allocated to
 178          * non constant storage */
 179         strcpy((char *)trig->name, name);
 180         up_write(&triggers_list_lock);
 181 }
 182 EXPORT_SYMBOL_GPL(led_trigger_rename_static);
 183
 184 /* LED Trigger Interface */
 185
 186 int led_trigger_register(struct led_trigger *trig)
 187 {
 188         struct led_classdev *led_cdev;
 189         struct led_trigger *_trig;
 190
 191         rwlock_init(&trig->leddev_list_lock);
 192         INIT_LIST_HEAD(&trig->led_cdevs);
 193
 194         down_write(&triggers_list_lock);
 195         /* Make sure the trigger's name isn't already in use */
 196         list_for_each_entry(_trig, &trigger_list, next_trig) {
 197                 if (!strcmp(_trig->name, trig->name)) {
 198                         up_write(&triggers_list_lock);
 199                         return -EEXIST;
 200                 }
 201         }
 202         /* Add to the list of led triggers */
 203         list_add_tail(&trig->next_trig, &trigger_list);
 204         up_write(&triggers_list_lock);
 205
 206         /* Register with any LEDs that have this as a default trigger */
 207         down_read(&leds_list_lock);
 208         list_for_each_entry(led_cdev, &leds_list, node) {
 209                 down_write(&led_cdev->trigger_lock);
 210                 if (!led_cdev->trigger && led_cdev->default_trigger &&
 211                             !strcmp(led_cdev->default_trigger, trig->name))
 212                         led_trigger_set(led_cdev, trig);
 213                 up_write(&led_cdev->trigger_lock);
 214         }
 215         up_read(&leds_list_lock);
 216
 217         return 0;
 218 }
 219 EXPORT_SYMBOL_GPL(led_trigger_register);
 220
 221 void led_trigger_unregister(struct led_trigger *trig)
 222 {
 223         struct led_classdev *led_cdev;
 224
 225         if (list_empty_careful(&trig->next_trig))
 226                 return;
 227
 228         /* Remove from the list of led triggers */
 229         down_write(&triggers_list_lock);
 230         list_del_init(&trig->next_trig);
 231         up_write(&triggers_list_lock);
 232
 233         /* Remove anyone actively using this trigger */
 234         down_read(&leds_list_lock);
 235         list_for_each_entry(led_cdev, &leds_list, node) {
 236                 down_write(&led_cdev->trigger_lock);
 237                 if (led_cdev->trigger == trig)
 238                         led_trigger_set(led_cdev, NULL);
 239                 up_write(&led_cdev->trigger_lock);
 240         }
 241         up_read(&leds_list_lock);
 242 }
 243 EXPORT_SYMBOL_GPL(led_trigger_unregister);
 244
 245 static void devm_led_trigger_release(struct device *dev, void *res)
 246 {
 247         led_trigger_unregister(*(struct led_trigger **)res);
 248 }
 249
 250 int devm_led_trigger_register(struct device *dev,
 251                               struct led_trigger *trig)
 252 {
 253         struct led_trigger **dr;
 254         int rc;
 255
 256         dr = devres_alloc(devm_led_trigger_release, sizeof(*dr),
 257                           GFP_KERNEL);
 258         if (!dr)
 259                 return -ENOMEM;
 260
 261         *dr = trig;
 262
 263         rc = led_trigger_register(trig);
 264         if (rc)
 265                 devres_free(dr);
 266         else
 267                 devres_add(dev, dr);
 268
 269         return rc;
 270 }
 271 EXPORT_SYMBOL_GPL(devm_led_trigger_register);
 272
 273 /* Simple LED Tigger Interface */
 274
 275 void led_trigger_event(struct led_trigger *trig,
 276                         enum led_brightness brightness)
 277 {
 278         struct led_classdev *led_cdev;
 279
 280         if (!trig)
 281                 return;
 282
 283         read_lock(&trig->leddev_list_lock);
 284         list_for_each_entry(led_cdev, &trig->led_cdevs, trig_list)
 285                 led_set_brightness(led_cdev, brightness);
 286         read_unlock(&trig->leddev_list_lock);
 287 }
 288 EXPORT_SYMBOL_GPL(led_trigger_event);
 289
 290 static void led_trigger_blink_setup(struct led_trigger *trig,
 291                              unsigned long *delay_on,
 292                              unsigned long *delay_off,
 293                              int oneshot,
 294                              int invert)
 295 {
 296         struct led_classdev *led_cdev;
 297
 298         if (!trig)
 299                 return;
 300
 301         read_lock(&trig->leddev_list_lock);
 302         list_for_each_entry(led_cdev, &trig->led_cdevs, trig_list) {
 303                 if (oneshot)
 304                         led_blink_set_oneshot(led_cdev, delay_on, delay_off,
 305                                               invert);
 306                 else
 307                         led_blink_set(led_cdev, delay_on, delay_off);
 308         }
 309         read_unlock(&trig->leddev_list_lock);
 310 }
 311
 312 void led_trigger_blink(struct led_trigger *trig,
 313                        unsigned long *delay_on,
 314                        unsigned long *delay_off)
 315 {
 316         led_trigger_blink_setup(trig, delay_on, delay_off, 0, 0);
 317 }
 318 EXPORT_SYMBOL_GPL(led_trigger_blink);
 319
 320 void led_trigger_blink_oneshot(struct led_trigger *trig,
 321                                unsigned long *delay_on,
 322                                unsigned long *delay_off,
 323                                int invert)
 324 {
 325         led_trigger_blink_setup(trig, delay_on, delay_off, 1, invert);
 326 }
 327 EXPORT_SYMBOL_GPL(led_trigger_blink_oneshot);
 328
 329 void led_trigger_register_simple(const char *name, struct led_trigger **tp)
 330 {
 331         struct led_trigger *trig;
 332         int err;
 333
 334         trig = kzalloc(sizeof(struct led_trigger), GFP_KERNEL);
 335
 336         if (trig) {
 337                 trig->name = name;
 338                 err = led_trigger_register(trig);
 339                 if (err < 0) {
 340                         kfree(trig);
 341                         trig = NULL;
 342                         pr_warn("LED trigger %s failed to register (%d)\n",
 343                                 name, err);
 344                 }
 345         } else {
 346                 pr_warn("LED trigger %s failed to register (no memory)\n",
 347                         name);
 348         }
 349         *tp = trig;
 350 }
 351 EXPORT_SYMBOL_GPL(led_trigger_register_simple);
 352
 353 void led_trigger_unregister_simple(struct led_trigger *trig)
 354 {
 355         if (trig)
 356                 led_trigger_unregister(trig);
 357         kfree(trig);
 358 }
 359 EXPORT_SYMBOL_GPL(led_trigger_unregister_simple);
 360
 361 MODULE_AUTHOR("Richard Purdie");
 362 MODULE_LICENSE("GPL");
 363 MODULE_DESCRIPTION("LED Triggers Core");