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/init.h>
  17 #include <linux/list.h>
  18 #include <linux/spinlock.h>
  19 #include <linux/device.h>
  20 #include <linux/timer.h>
  21 #include <linux/rwsem.h>
  22 #include <linux/leds.h>
  23 #include <linux/slab.h>
  24 #include "leds.h"
  25
  26 /*
  27  * Nests outside led_cdev->trigger_lock
  28  */
  29 static DECLARE_RWSEM(triggers_list_lock);
  30 static LIST_HEAD(trigger_list);
  31
  32  /* Used by LED Class */
  33
  34 ssize_t led_trigger_store(struct device *dev, struct device_attribute *attr,
  35                 const char *buf, size_t count)
  36 {
  37         struct led_classdev *led_cdev = dev_get_drvdata(dev);
  38         char trigger_name[TRIG_NAME_MAX];
  39         struct led_trigger *trig;
  40         size_t len;
  41
  42         trigger_name[sizeof(trigger_name) - 1] = '\0';
  43         strncpy(trigger_name, buf, sizeof(trigger_name) - 1);
  44         len = strlen(trigger_name);
  45
  46         if (len && trigger_name[len - 1] == '\n')
  47                 trigger_name[len - 1] = '\0';
  48
  49         if (!strcmp(trigger_name, "none")) {
  50                 led_trigger_remove(led_cdev);
  51                 return count;
  52         }
  53
  54         down_read(&triggers_list_lock);
  55         list_for_each_entry(trig, &trigger_list, next_trig) {
  56                 if (!strcmp(trigger_name, trig->name)) {
  57                         down_write(&led_cdev->trigger_lock);
  58                         led_trigger_set(led_cdev, trig);
  59                         up_write(&led_cdev->trigger_lock);
  60
  61                         up_read(&triggers_list_lock);
  62                         return count;
  63                 }
  64         }
  65         up_read(&triggers_list_lock);
  66
  67         return -EINVAL;
  68 }
  69 EXPORT_SYMBOL_GPL(led_trigger_store);
  70
  71 ssize_t led_trigger_show(struct device *dev, struct device_attribute *attr,
  72                 char *buf)
  73 {
  74         struct led_classdev *led_cdev = dev_get_drvdata(dev);
  75         struct led_trigger *trig;
  76         int len = 0;
  77
  78         down_read(&triggers_list_lock);
  79         down_read(&led_cdev->trigger_lock);
  80
  81         if (!led_cdev->trigger)
  82                 len += sprintf(buf+len, "[none] ");
  83         else
  84                 len += sprintf(buf+len, "none ");
  85
  86         list_for_each_entry(trig, &trigger_list, next_trig) {
  87                 if (led_cdev->trigger && !strcmp(led_cdev->trigger->name,
  88                                                         trig->name))
  89                         len += sprintf(buf+len, "[%s] ", trig->name);
  90                 else
  91                         len += sprintf(buf+len, "%s ", trig->name);
  92         }
  93         up_read(&led_cdev->trigger_lock);
  94         up_read(&triggers_list_lock);
  95
  96         len += sprintf(len+buf, "\n");
  97         return len;
  98 }
  99 EXPORT_SYMBOL_GPL(led_trigger_show);
 100
 101 /* Caller must ensure led_cdev->trigger_lock held */
 102 void led_trigger_set(struct led_classdev *led_cdev, struct led_trigger *trig)
 103 {
 104         unsigned long flags;
 105         char *event = NULL;
 106         char *envp[2];
 107         const char *name;
 108
 109         name = trig ? trig->name : "none";
 110         event = kasprintf(GFP_KERNEL, "TRIGGER=%s", name);
 111
 112         /* Remove any existing trigger */
 113         if (led_cdev->trigger) {
 114                 write_lock_irqsave(&led_cdev->trigger->leddev_list_lock, flags);
 115                 list_del(&led_cdev->trig_list);
 116                 write_unlock_irqrestore(&led_cdev->trigger->leddev_list_lock,
 117                         flags);
 118                 cancel_work_sync(&led_cdev->set_brightness_work);
 119                 led_stop_software_blink(led_cdev);
 120                 if (led_cdev->trigger->deactivate)
 121                         led_cdev->trigger->deactivate(led_cdev);
 122                 led_cdev->trigger = NULL;
 123                 led_set_brightness(led_cdev, LED_OFF);
 124         }
 125         if (trig) {
 126                 write_lock_irqsave(&trig->leddev_list_lock, flags);
 127                 list_add_tail(&led_cdev->trig_list, &trig->led_cdevs);
 128                 write_unlock_irqrestore(&trig->leddev_list_lock, flags);
 129                 led_cdev->trigger = trig;
 130                 if (trig->activate)
 131                         trig->activate(led_cdev);
 132         }
 133
 134         if (event) {
 135                 envp[0] = event;
 136                 envp[1] = NULL;
 137                 kobject_uevent_env(&led_cdev->dev->kobj, KOBJ_CHANGE, envp);
 138                 kfree(event);
 139         }
 140 }
 141 EXPORT_SYMBOL_GPL(led_trigger_set);
 142
 143 void led_trigger_remove(struct led_classdev *led_cdev)
 144 {
 145         down_write(&led_cdev->trigger_lock);
 146         led_trigger_set(led_cdev, NULL);
 147         up_write(&led_cdev->trigger_lock);
 148 }
 149 EXPORT_SYMBOL_GPL(led_trigger_remove);
 150
 151 void led_trigger_set_default(struct led_classdev *led_cdev)
 152 {
 153         struct led_trigger *trig;
 154
 155         if (!led_cdev->default_trigger)
 156                 return;
 157
 158         down_read(&triggers_list_lock);
 159         down_write(&led_cdev->trigger_lock);
 160         list_for_each_entry(trig, &trigger_list, next_trig) {
 161                 if (!strcmp(led_cdev->default_trigger, trig->name))
 162                         led_trigger_set(led_cdev, trig);
 163         }
 164         up_write(&led_cdev->trigger_lock);
 165         up_read(&triggers_list_lock);
 166 }
 167 EXPORT_SYMBOL_GPL(led_trigger_set_default);
 168
 169 void led_trigger_rename_static(const char *name, struct led_trigger *trig)
 170 {
 171         /* new name must be on a temporary string to prevent races */
 172         BUG_ON(name == trig->name);
 173
 174         down_write(&triggers_list_lock);
 175         /* this assumes that trig->name was originaly allocated to
 176          * non constant storage */
 177         strcpy((char *)trig->name, name);
 178         up_write(&triggers_list_lock);
 179 }
 180 EXPORT_SYMBOL_GPL(led_trigger_rename_static);
 181
 182 /* LED Trigger Interface */
 183
 184 int led_trigger_register(struct led_trigger *trig)
 185 {
 186         struct led_classdev *led_cdev;
 187         struct led_trigger *_trig;
 188
 189         rwlock_init(&trig->leddev_list_lock);
 190         INIT_LIST_HEAD(&trig->led_cdevs);
 191
 192         down_write(&triggers_list_lock);
 193         /* Make sure the trigger's name isn't already in use */
 194         list_for_each_entry(_trig, &trigger_list, next_trig) {
 195                 if (!strcmp(_trig->name, trig->name)) {
 196                         up_write(&triggers_list_lock);
 197                         return -EEXIST;
 198                 }
 199         }
 200         /* Add to the list of led triggers */
 201         list_add_tail(&trig->next_trig, &trigger_list);
 202         up_write(&triggers_list_lock);
 203
 204         /* Register with any LEDs that have this as a default trigger */
 205         down_read(&leds_list_lock);
 206         list_for_each_entry(led_cdev, &leds_list, node) {
 207                 down_write(&led_cdev->trigger_lock);
 208                 if (!led_cdev->trigger && led_cdev->default_trigger &&
 209                             !strcmp(led_cdev->default_trigger, trig->name))
 210                         led_trigger_set(led_cdev, trig);
 211                 up_write(&led_cdev->trigger_lock);
 212         }
 213         up_read(&leds_list_lock);
 214
 215         return 0;
 216 }
 217 EXPORT_SYMBOL_GPL(led_trigger_register);
 218
 219 void led_trigger_unregister(struct led_trigger *trig)
 220 {
 221         struct led_classdev *led_cdev;
 222
 223         /* Remove from the list of led triggers */
 224         down_write(&triggers_list_lock);
 225         list_del(&trig->next_trig);
 226         up_write(&triggers_list_lock);
 227
 228         /* Remove anyone actively using this trigger */
 229         down_read(&leds_list_lock);
 230         list_for_each_entry(led_cdev, &leds_list, node) {
 231                 down_write(&led_cdev->trigger_lock);
 232                 if (led_cdev->trigger == trig)
 233                         led_trigger_set(led_cdev, NULL);
 234                 up_write(&led_cdev->trigger_lock);
 235         }
 236         up_read(&leds_list_lock);
 237 }
 238 EXPORT_SYMBOL_GPL(led_trigger_unregister);
 239
 240 /* Simple LED Tigger Interface */
 241
 242 void led_trigger_event(struct led_trigger *trig,
 243                         enum led_brightness brightness)
 244 {
 245         struct led_classdev *led_cdev;
 246
 247         if (!trig)
 248                 return;
 249
 250         read_lock(&trig->leddev_list_lock);
 251         list_for_each_entry(led_cdev, &trig->led_cdevs, trig_list)
 252                 led_set_brightness(led_cdev, brightness);
 253         read_unlock(&trig->leddev_list_lock);
 254 }
 255 EXPORT_SYMBOL_GPL(led_trigger_event);
 256
 257 static void led_trigger_blink_setup(struct led_trigger *trig,
 258                              unsigned long *delay_on,
 259                              unsigned long *delay_off,
 260                              int oneshot,
 261                              int invert)
 262 {
 263         struct led_classdev *led_cdev;
 264
 265         if (!trig)
 266                 return;
 267
 268         read_lock(&trig->leddev_list_lock);
 269         list_for_each_entry(led_cdev, &trig->led_cdevs, trig_list) {
 270                 if (oneshot)
 271                         led_blink_set_oneshot(led_cdev, delay_on, delay_off,
 272                                               invert);
 273                 else
 274                         led_blink_set(led_cdev, delay_on, delay_off);
 275         }
 276         read_unlock(&trig->leddev_list_lock);
 277 }
 278
 279 void led_trigger_blink(struct led_trigger *trig,
 280                        unsigned long *delay_on,
 281                        unsigned long *delay_off)
 282 {
 283         led_trigger_blink_setup(trig, delay_on, delay_off, 0, 0);
 284 }
 285 EXPORT_SYMBOL_GPL(led_trigger_blink);
 286
 287 void led_trigger_blink_oneshot(struct led_trigger *trig,
 288                                unsigned long *delay_on,
 289                                unsigned long *delay_off,
 290                                int invert)
 291 {
 292         led_trigger_blink_setup(trig, delay_on, delay_off, 1, invert);
 293 }
 294 EXPORT_SYMBOL_GPL(led_trigger_blink_oneshot);
 295
 296 void led_trigger_register_simple(const char *name, struct led_trigger **tp)
 297 {
 298         struct led_trigger *trig;
 299         int err;
 300
 301         trig = kzalloc(sizeof(struct led_trigger), GFP_KERNEL);
 302
 303         if (trig) {
 304                 trig->name = name;
 305                 err = led_trigger_register(trig);
 306                 if (err < 0) {
 307                         kfree(trig);
 308                         trig = NULL;
 309                         pr_warn("LED trigger %s failed to register (%d)\n",
 310                                 name, err);
 311                 }
 312         } else {
 313                 pr_warn("LED trigger %s failed to register (no memory)\n",
 314                         name);
 315         }
 316         *tp = trig;
 317 }
 318 EXPORT_SYMBOL_GPL(led_trigger_register_simple);
 319
 320 void led_trigger_unregister_simple(struct led_trigger *trig)
 321 {
 322         if (trig)
 323                 led_trigger_unregister(trig);
 324         kfree(trig);
 325 }
 326 EXPORT_SYMBOL_GPL(led_trigger_unregister_simple);
 327
 328 MODULE_AUTHOR("Richard Purdie");
 329 MODULE_LICENSE("GPL");
 330 MODULE_DESCRIPTION("LED Triggers Core");