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 /* LED Trigger Interface */
 170
 171 int led_trigger_register(struct led_trigger *trig)
 172 {
 173         struct led_classdev *led_cdev;
 174         struct led_trigger *_trig;
 175
 176         rwlock_init(&trig->leddev_list_lock);
 177         INIT_LIST_HEAD(&trig->led_cdevs);
 178
 179         down_write(&triggers_list_lock);
 180         /* Make sure the trigger's name isn't already in use */
 181         list_for_each_entry(_trig, &trigger_list, next_trig) {
 182                 if (!strcmp(_trig->name, trig->name)) {
 183                         up_write(&triggers_list_lock);
 184                         return -EEXIST;
 185                 }
 186         }
 187         /* Add to the list of led triggers */
 188         list_add_tail(&trig->next_trig, &trigger_list);
 189         up_write(&triggers_list_lock);
 190
 191         /* Register with any LEDs that have this as a default trigger */
 192         down_read(&leds_list_lock);
 193         list_for_each_entry(led_cdev, &leds_list, node) {
 194                 down_write(&led_cdev->trigger_lock);
 195                 if (!led_cdev->trigger && led_cdev->default_trigger &&
 196                             !strcmp(led_cdev->default_trigger, trig->name))
 197                         led_trigger_set(led_cdev, trig);
 198                 up_write(&led_cdev->trigger_lock);
 199         }
 200         up_read(&leds_list_lock);
 201
 202         return 0;
 203 }
 204 EXPORT_SYMBOL_GPL(led_trigger_register);
 205
 206 void led_trigger_unregister(struct led_trigger *trig)
 207 {
 208         struct led_classdev *led_cdev;
 209
 210         /* Remove from the list of led triggers */
 211         down_write(&triggers_list_lock);
 212         list_del(&trig->next_trig);
 213         up_write(&triggers_list_lock);
 214
 215         /* Remove anyone actively using this trigger */
 216         down_read(&leds_list_lock);
 217         list_for_each_entry(led_cdev, &leds_list, node) {
 218                 down_write(&led_cdev->trigger_lock);
 219                 if (led_cdev->trigger == trig)
 220                         led_trigger_set(led_cdev, NULL);
 221                 up_write(&led_cdev->trigger_lock);
 222         }
 223         up_read(&leds_list_lock);
 224 }
 225 EXPORT_SYMBOL_GPL(led_trigger_unregister);
 226
 227 /* Simple LED Tigger Interface */
 228
 229 void led_trigger_event(struct led_trigger *trig,
 230                         enum led_brightness brightness)
 231 {
 232         struct list_head *entry;
 233
 234         if (!trig)
 235                 return;
 236
 237         read_lock(&trig->leddev_list_lock);
 238         list_for_each(entry, &trig->led_cdevs) {
 239                 struct led_classdev *led_cdev;
 240
 241                 led_cdev = list_entry(entry, struct led_classdev, trig_list);
 242                 led_set_brightness(led_cdev, brightness);
 243         }
 244         read_unlock(&trig->leddev_list_lock);
 245 }
 246 EXPORT_SYMBOL_GPL(led_trigger_event);
 247
 248 static void led_trigger_blink_setup(struct led_trigger *trig,
 249                              unsigned long *delay_on,
 250                              unsigned long *delay_off,
 251                              int oneshot,
 252                              int invert)
 253 {
 254         struct list_head *entry;
 255
 256         if (!trig)
 257                 return;
 258
 259         read_lock(&trig->leddev_list_lock);
 260         list_for_each(entry, &trig->led_cdevs) {
 261                 struct led_classdev *led_cdev;
 262
 263                 led_cdev = list_entry(entry, struct led_classdev, trig_list);
 264                 if (oneshot)
 265                         led_blink_set_oneshot(led_cdev, delay_on, delay_off,
 266                                               invert);
 267                 else
 268                         led_blink_set(led_cdev, delay_on, delay_off);
 269         }
 270         read_unlock(&trig->leddev_list_lock);
 271 }
 272
 273 void led_trigger_blink(struct led_trigger *trig,
 274                        unsigned long *delay_on,
 275                        unsigned long *delay_off)
 276 {
 277         led_trigger_blink_setup(trig, delay_on, delay_off, 0, 0);
 278 }
 279 EXPORT_SYMBOL_GPL(led_trigger_blink);
 280
 281 void led_trigger_blink_oneshot(struct led_trigger *trig,
 282                                unsigned long *delay_on,
 283                                unsigned long *delay_off,
 284                                int invert)
 285 {
 286         led_trigger_blink_setup(trig, delay_on, delay_off, 1, invert);
 287 }
 288 EXPORT_SYMBOL_GPL(led_trigger_blink_oneshot);
 289
 290 void led_trigger_register_simple(const char *name, struct led_trigger **tp)
 291 {
 292         struct led_trigger *trig;
 293         int err;
 294
 295         trig = kzalloc(sizeof(struct led_trigger), GFP_KERNEL);
 296
 297         if (trig) {
 298                 trig->name = name;
 299                 err = led_trigger_register(trig);
 300                 if (err < 0) {
 301                         kfree(trig);
 302                         trig = NULL;
 303                         printk(KERN_WARNING "LED trigger %s failed to register"
 304                                 " (%d)\n", name, err);
 305                 }
 306         } else
 307                 printk(KERN_WARNING "LED trigger %s failed to register"
 308                         " (no memory)\n", name);
 309
 310         *tp = trig;
 311 }
 312 EXPORT_SYMBOL_GPL(led_trigger_register_simple);
 313
 314 void led_trigger_unregister_simple(struct led_trigger *trig)
 315 {
 316         if (trig)
 317                 led_trigger_unregister(trig);
 318         kfree(trig);
 319 }
 320 EXPORT_SYMBOL_GPL(led_trigger_unregister_simple);
 321
 322 MODULE_AUTHOR("Richard Purdie");
 323 MODULE_LICENSE("GPL");
 324 MODULE_DESCRIPTION("LED Triggers Core");