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/sysdev.h>
  21 #include <linux/timer.h>
  22 #include <linux/rwsem.h>
  23 #include <linux/leds.h>
  24 #include <linux/slab.h>
  25 #include "leds.h"
  26
  27 /*
  28  * Nests outside led_cdev->trigger_lock
  29  */
  30 static DECLARE_RWSEM(triggers_list_lock);
  31 static LIST_HEAD(trigger_list);
  32
  33  /* Used by LED Class */
  34
  35 ssize_t led_trigger_store(struct device *dev, struct device_attribute *attr,
  36                 const char *buf, size_t count)
  37 {
  38         struct led_classdev *led_cdev = dev_get_drvdata(dev);
  39         char trigger_name[TRIG_NAME_MAX];
  40         struct led_trigger *trig;
  41         size_t len;
  42
  43         trigger_name[sizeof(trigger_name) - 1] = '\0';
  44         strncpy(trigger_name, buf, sizeof(trigger_name) - 1);
  45         len = strlen(trigger_name);
  46
  47         if (len && trigger_name[len - 1] == '\n')
  48                 trigger_name[len - 1] = '\0';
  49
  50         if (!strcmp(trigger_name, "none")) {
  51                 led_trigger_remove(led_cdev);
  52                 return count;
  53         }
  54
  55         down_read(&triggers_list_lock);
  56         list_for_each_entry(trig, &trigger_list, next_trig) {
  57                 if (!strcmp(trigger_name, trig->name)) {
  58                         down_write(&led_cdev->trigger_lock);
  59                         led_trigger_set(led_cdev, trig);
  60                         up_write(&led_cdev->trigger_lock);
  61
  62                         up_read(&triggers_list_lock);
  63                         return count;
  64                 }
  65         }
  66         up_read(&triggers_list_lock);
  67
  68         return -EINVAL;
  69 }
  70 EXPORT_SYMBOL_GPL(led_trigger_store);
  71
  72 ssize_t led_trigger_show(struct device *dev, struct device_attribute *attr,
  73                 char *buf)
  74 {
  75         struct led_classdev *led_cdev = dev_get_drvdata(dev);
  76         struct led_trigger *trig;
  77         int len = 0;
  78
  79         down_read(&triggers_list_lock);
  80         down_read(&led_cdev->trigger_lock);
  81
  82         if (!led_cdev->trigger)
  83                 len += sprintf(buf+len, "[none] ");
  84         else
  85                 len += sprintf(buf+len, "none ");
  86
  87         list_for_each_entry(trig, &trigger_list, next_trig) {
  88                 if (led_cdev->trigger && !strcmp(led_cdev->trigger->name,
  89                                                         trig->name))
  90                         len += sprintf(buf+len, "[%s] ", trig->name);
  91                 else
  92                         len += sprintf(buf+len, "%s ", trig->name);
  93         }
  94         up_read(&led_cdev->trigger_lock);
  95         up_read(&triggers_list_lock);
  96
  97         len += sprintf(len+buf, "\n");
  98         return len;
  99 }
 100 EXPORT_SYMBOL_GPL(led_trigger_show);
 101
 102 /* Caller must ensure led_cdev->trigger_lock held */
 103 void led_trigger_set(struct led_classdev *led_cdev, struct led_trigger *trigger)
 104 {
 105         unsigned long flags;
 106
 107         /* Remove any existing trigger */
 108         if (led_cdev->trigger) {
 109                 write_lock_irqsave(&led_cdev->trigger->leddev_list_lock, flags);
 110                 list_del(&led_cdev->trig_list);
 111                 write_unlock_irqrestore(&led_cdev->trigger->leddev_list_lock,
 112                         flags);
 113                 if (led_cdev->trigger->deactivate)
 114                         led_cdev->trigger->deactivate(led_cdev);
 115                 led_cdev->trigger = NULL;
 116                 led_brightness_set(led_cdev, LED_OFF);
 117         }
 118         if (trigger) {
 119                 write_lock_irqsave(&trigger->leddev_list_lock, flags);
 120                 list_add_tail(&led_cdev->trig_list, &trigger->led_cdevs);
 121                 write_unlock_irqrestore(&trigger->leddev_list_lock, flags);
 122                 led_cdev->trigger = trigger;
 123                 if (trigger->activate)
 124                         trigger->activate(led_cdev);
 125         }
 126 }
 127 EXPORT_SYMBOL_GPL(led_trigger_set);
 128
 129 void led_trigger_remove(struct led_classdev *led_cdev)
 130 {
 131         down_write(&led_cdev->trigger_lock);
 132         led_trigger_set(led_cdev, NULL);
 133         up_write(&led_cdev->trigger_lock);
 134 }
 135 EXPORT_SYMBOL_GPL(led_trigger_remove);
 136
 137 void led_trigger_set_default(struct led_classdev *led_cdev)
 138 {
 139         struct led_trigger *trig;
 140
 141         if (!led_cdev->default_trigger)
 142                 return;
 143
 144         down_read(&triggers_list_lock);
 145         down_write(&led_cdev->trigger_lock);
 146         list_for_each_entry(trig, &trigger_list, next_trig) {
 147                 if (!strcmp(led_cdev->default_trigger, trig->name))
 148                         led_trigger_set(led_cdev, trig);
 149         }
 150         up_write(&led_cdev->trigger_lock);
 151         up_read(&triggers_list_lock);
 152 }
 153 EXPORT_SYMBOL_GPL(led_trigger_set_default);
 154
 155 /* LED Trigger Interface */
 156
 157 int led_trigger_register(struct led_trigger *trigger)
 158 {
 159         struct led_classdev *led_cdev;
 160         struct led_trigger *trig;
 161
 162         rwlock_init(&trigger->leddev_list_lock);
 163         INIT_LIST_HEAD(&trigger->led_cdevs);
 164
 165         down_write(&triggers_list_lock);
 166         /* Make sure the trigger's name isn't already in use */
 167         list_for_each_entry(trig, &trigger_list, next_trig) {
 168                 if (!strcmp(trig->name, trigger->name)) {
 169                         up_write(&triggers_list_lock);
 170                         return -EEXIST;
 171                 }
 172         }
 173         /* Add to the list of led triggers */
 174         list_add_tail(&trigger->next_trig, &trigger_list);
 175         up_write(&triggers_list_lock);
 176
 177         /* Register with any LEDs that have this as a default trigger */
 178         down_read(&leds_list_lock);
 179         list_for_each_entry(led_cdev, &leds_list, node) {
 180                 down_write(&led_cdev->trigger_lock);
 181                 if (!led_cdev->trigger && led_cdev->default_trigger &&
 182                             !strcmp(led_cdev->default_trigger, trigger->name))
 183                         led_trigger_set(led_cdev, trigger);
 184                 up_write(&led_cdev->trigger_lock);
 185         }
 186         up_read(&leds_list_lock);
 187
 188         return 0;
 189 }
 190 EXPORT_SYMBOL_GPL(led_trigger_register);
 191
 192 void led_trigger_unregister(struct led_trigger *trigger)
 193 {
 194         struct led_classdev *led_cdev;
 195
 196         /* Remove from the list of led triggers */
 197         down_write(&triggers_list_lock);
 198         list_del(&trigger->next_trig);
 199         up_write(&triggers_list_lock);
 200
 201         /* Remove anyone actively using this trigger */
 202         down_read(&leds_list_lock);
 203         list_for_each_entry(led_cdev, &leds_list, node) {
 204                 down_write(&led_cdev->trigger_lock);
 205                 if (led_cdev->trigger == trigger)
 206                         led_trigger_set(led_cdev, NULL);
 207                 up_write(&led_cdev->trigger_lock);
 208         }
 209         up_read(&leds_list_lock);
 210 }
 211 EXPORT_SYMBOL_GPL(led_trigger_unregister);
 212
 213 /* Simple LED Tigger Interface */
 214
 215 void led_trigger_event(struct led_trigger *trigger,
 216                         enum led_brightness brightness)
 217 {
 218         struct list_head *entry;
 219
 220         if (!trigger)
 221                 return;
 222
 223         read_lock(&trigger->leddev_list_lock);
 224         list_for_each(entry, &trigger->led_cdevs) {
 225                 struct led_classdev *led_cdev;
 226
 227                 led_cdev = list_entry(entry, struct led_classdev, trig_list);
 228                 led_set_brightness(led_cdev, brightness);
 229         }
 230         read_unlock(&trigger->leddev_list_lock);
 231 }
 232 EXPORT_SYMBOL_GPL(led_trigger_event);
 233
 234 void led_trigger_register_simple(const char *name, struct led_trigger **tp)
 235 {
 236         struct led_trigger *trigger;
 237         int err;
 238
 239         trigger = kzalloc(sizeof(struct led_trigger), GFP_KERNEL);
 240
 241         if (trigger) {
 242                 trigger->name = name;
 243                 err = led_trigger_register(trigger);
 244                 if (err < 0)
 245                         printk(KERN_WARNING "LED trigger %s failed to register"
 246                                 " (%d)\n", name, err);
 247         } else
 248                 printk(KERN_WARNING "LED trigger %s failed to register"
 249                         " (no memory)\n", name);
 250
 251         *tp = trigger;
 252 }
 253 EXPORT_SYMBOL_GPL(led_trigger_register_simple);
 254
 255 void led_trigger_unregister_simple(struct led_trigger *trigger)
 256 {
 257         if (trigger)
 258                 led_trigger_unregister(trigger);
 259         kfree(trigger);
 260 }
 261 EXPORT_SYMBOL_GPL(led_trigger_unregister_simple);
 262
 263 MODULE_AUTHOR("Richard Purdie");
 264 MODULE_LICENSE("GPL");
 265 MODULE_DESCRIPTION("LED Triggers Core");