kernel/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 static 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         char trigger_name[TRIG_NAME_MAX];
  38         struct led_trigger *trig;
  39         size_t len;
  40         int ret = count;
  41
  42         mutex_lock(&led_cdev->led_access);
  43
  44         if (led_sysfs_is_disabled(led_cdev)) {
  45                 ret = -EBUSY;
  46                 goto unlock;
  47         }
  48
  49         trigger_name[sizeof(trigger_name) - 1] = '\0';
  50         strncpy(trigger_name, buf, sizeof(trigger_name) - 1);
  51         len = strlen(trigger_name);
  52
  53         if (len && trigger_name[len - 1] == '\n')
  54                 trigger_name[len - 1] = '\0';
  55
  56         if (!strcmp(trigger_name, "none")) {
  57                 led_trigger_remove(led_cdev);
  58                 goto unlock;
  59         }
  60
  61         down_read(&triggers_list_lock);
  62         list_for_each_entry(trig, &trigger_list, next_trig) {
  63                 if (!strcmp(trigger_name, trig->name)) {
  64                         down_write(&led_cdev->trigger_lock);
  65                         led_trigger_set(led_cdev, trig);
  66                         up_write(&led_cdev->trigger_lock);
  67
  68                         up_read(&triggers_list_lock);
  69                         goto unlock;
  70                 }
  71         }
  72         up_read(&triggers_list_lock);
  73
  74 unlock:
  75         mutex_unlock(&led_cdev->led_access);
  76         return ret;
  77 }
  78 EXPORT_SYMBOL_GPL(led_trigger_store);
  79
  80 ssize_t led_trigger_show(struct device *dev, struct device_attribute *attr,
  81                 char *buf)
  82 {
  83         struct led_classdev *led_cdev = dev_get_drvdata(dev);
  84         struct led_trigger *trig;
  85         int len = 0;
  86
  87         down_read(&triggers_list_lock);
  88         down_read(&led_cdev->trigger_lock);
  89
  90         if (!led_cdev->trigger)
  91                 len += sprintf(buf+len, "[none] ");
  92         else
  93                 len += sprintf(buf+len, "none ");
  94
  95         list_for_each_entry(trig, &trigger_list, next_trig) {
  96                 if (led_cdev->trigger && !strcmp(led_cdev->trigger->name,
  97                                                         trig->name))
  98                         len += sprintf(buf+len, "[%s] ", trig->name);
  99                 else
 100                         len += sprintf(buf+len, "%s ", trig->name);
 101         }
 102         up_read(&led_cdev->trigger_lock);
 103         up_read(&triggers_list_lock);
 104
 105         len += sprintf(len+buf, "\n");
 106         return len;
 107 }
 108 EXPORT_SYMBOL_GPL(led_trigger_show);
 109
 110 /* Caller must ensure led_cdev->trigger_lock held */
 111 void led_trigger_set(struct led_classdev *led_cdev, struct led_trigger *trig)
 112 {
 113         unsigned long flags;
 114         char *event = NULL;
 115         char *envp[2];
 116         const char *name;
 117
 118         name = trig ? trig->name : "none";
 119         event = kasprintf(GFP_KERNEL, "TRIGGER=%s", name);
 120
 121         /* Remove any existing trigger */
 122         if (led_cdev->trigger) {
 123                 write_lock_irqsave(&led_cdev->trigger->leddev_list_lock, flags);
 124                 list_del(&led_cdev->trig_list);
 125                 write_unlock_irqrestore(&led_cdev->trigger->leddev_list_lock,
 126                         flags);
 127                 cancel_work_sync(&led_cdev->set_brightness_work);
 128                 led_stop_software_blink(led_cdev);
 129                 if (led_cdev->trigger->deactivate)
 130                         led_cdev->trigger->deactivate(led_cdev);
 131                 led_cdev->trigger = NULL;
 132                 led_set_brightness(led_cdev, LED_OFF);
 133         }
 134         if (trig) {
 135                 write_lock_irqsave(&trig->leddev_list_lock, flags);
 136                 list_add_tail(&led_cdev->trig_list, &trig->led_cdevs);
 137                 write_unlock_irqrestore(&trig->leddev_list_lock, flags);
 138                 led_cdev->trigger = trig;
 139                 if (trig->activate)
 140                         trig->activate(led_cdev);
 141         }
 142
 143         if (event) {
 144                 envp[0] = event;
 145                 envp[1] = NULL;
 146                 kobject_uevent_env(&led_cdev->dev->kobj, KOBJ_CHANGE, envp);
 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 /* Simple LED Tigger Interface */
 253
 254 void led_trigger_event(struct led_trigger *trig,
 255                         enum led_brightness brightness)
 256 {
 257         struct led_classdev *led_cdev;
 258
 259         if (!trig)
 260                 return;
 261
 262         read_lock(&trig->leddev_list_lock);
 263         list_for_each_entry(led_cdev, &trig->led_cdevs, trig_list)
 264                 led_set_brightness(led_cdev, brightness);
 265         read_unlock(&trig->leddev_list_lock);
 266 }
 267 EXPORT_SYMBOL_GPL(led_trigger_event);
 268
 269 static void led_trigger_blink_setup(struct led_trigger *trig,
 270                              unsigned long *delay_on,
 271                              unsigned long *delay_off,
 272                              int oneshot,
 273                              int invert)
 274 {
 275         struct led_classdev *led_cdev;
 276
 277         if (!trig)
 278                 return;
 279
 280         read_lock(&trig->leddev_list_lock);
 281         list_for_each_entry(led_cdev, &trig->led_cdevs, trig_list) {
 282                 if (oneshot)
 283                         led_blink_set_oneshot(led_cdev, delay_on, delay_off,
 284                                               invert);
 285                 else
 286                         led_blink_set(led_cdev, delay_on, delay_off);
 287         }
 288         read_unlock(&trig->leddev_list_lock);
 289 }
 290
 291 void led_trigger_blink(struct led_trigger *trig,
 292                        unsigned long *delay_on,
 293                        unsigned long *delay_off)
 294 {
 295         led_trigger_blink_setup(trig, delay_on, delay_off, 0, 0);
 296 }
 297 EXPORT_SYMBOL_GPL(led_trigger_blink);
 298
 299 void led_trigger_blink_oneshot(struct led_trigger *trig,
 300                                unsigned long *delay_on,
 301                                unsigned long *delay_off,
 302                                int invert)
 303 {
 304         led_trigger_blink_setup(trig, delay_on, delay_off, 1, invert);
 305 }
 306 EXPORT_SYMBOL_GPL(led_trigger_blink_oneshot);
 307
 308 void led_trigger_register_simple(const char *name, struct led_trigger **tp)
 309 {
 310         struct led_trigger *trig;
 311         int err;
 312
 313         trig = kzalloc(sizeof(struct led_trigger), GFP_KERNEL);
 314
 315         if (trig) {
 316                 trig->name = name;
 317                 err = led_trigger_register(trig);
 318                 if (err < 0) {
 319                         kfree(trig);
 320                         trig = NULL;
 321                         pr_warn("LED trigger %s failed to register (%d)\n",
 322                                 name, err);
 323                 }
 324         } else {
 325                 pr_warn("LED trigger %s failed to register (no memory)\n",
 326                         name);
 327         }
 328         *tp = trig;
 329 }
 330 EXPORT_SYMBOL_GPL(led_trigger_register_simple);
 331
 332 void led_trigger_unregister_simple(struct led_trigger *trig)
 333 {
 334         if (trig)
 335                 led_trigger_unregister(trig);
 336         kfree(trig);
 337 }
 338 EXPORT_SYMBOL_GPL(led_trigger_unregister_simple);
 339
 340 MODULE_AUTHOR("Richard Purdie");
 341 MODULE_LICENSE("GPL");
 342 MODULE_DESCRIPTION("LED Triggers Core");