drivers/leds/led-triggers.c

   1 /*
   2  * LED Triggers Core
   3  *
   4  * Copyright 2005-2006 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/config.h>
  15 #include <linux/module.h>
  16 #include <linux/kernel.h>
  17 #include <linux/init.h>
  18 #include <linux/list.h>
  19 #include <linux/spinlock.h>
  20 #include <linux/device.h>
  21 #include <linux/sysdev.h>
  22 #include <linux/timer.h>
  23 #include <linux/leds.h>
  24 #include "leds.h"
  25
  26 /*
  27  * Nests outside led_cdev->trigger_lock
  28  */
  29 static rwlock_t triggers_list_lock = RW_LOCK_UNLOCKED;
  30 static LIST_HEAD(trigger_list);
  31
  32 ssize_t led_trigger_store(struct class_device *dev, const char *buf,
  33                         size_t count)
  34 {
  35         struct led_classdev *led_cdev = class_get_devdata(dev);
  36         char trigger_name[TRIG_NAME_MAX];
  37         struct led_trigger *trig;
  38         size_t len;
  39
  40         trigger_name[sizeof(trigger_name) - 1] = '\0';
  41         strncpy(trigger_name, buf, sizeof(trigger_name) - 1);
  42         len = strlen(trigger_name);
  43
  44         if (len && trigger_name[len - 1] == '\n')
  45                 trigger_name[len - 1] = '\0';
  46
  47         if (!strcmp(trigger_name, "none")) {
  48                 write_lock(&led_cdev->trigger_lock);
  49                 led_trigger_set(led_cdev, NULL);
  50                 write_unlock(&led_cdev->trigger_lock);
  51                 return count;
  52         }
  53
  54         read_lock(&triggers_list_lock);
  55         list_for_each_entry(trig, &trigger_list, next_trig) {
  56                 if (!strcmp(trigger_name, trig->name)) {
  57                         write_lock(&led_cdev->trigger_lock);
  58                         led_trigger_set(led_cdev, trig);
  59                         write_unlock(&led_cdev->trigger_lock);
  60
  61                         read_unlock(&triggers_list_lock);
  62                         return count;
  63                 }
  64         }
  65         read_unlock(&triggers_list_lock);
  66
  67         return -EINVAL;
  68 }
  69
  70
  71 ssize_t led_trigger_show(struct class_device *dev, char *buf)
  72 {
  73         struct led_classdev *led_cdev = class_get_devdata(dev);
  74         struct led_trigger *trig;
  75         int len = 0;
  76
  77         read_lock(&triggers_list_lock);
  78         read_lock(&led_cdev->trigger_lock);
  79
  80         if (!led_cdev->trigger)
  81                 len += sprintf(buf+len, "[none] ");
  82         else
  83                 len += sprintf(buf+len, "none ");
  84
  85         list_for_each_entry(trig, &trigger_list, next_trig) {
  86                 if (led_cdev->trigger && !strcmp(led_cdev->trigger->name,
  87                                                         trig->name))
  88                         len += sprintf(buf+len, "[%s] ", trig->name);
  89                 else
  90                         len += sprintf(buf+len, "%s ", trig->name);
  91         }
  92         read_unlock(&led_cdev->trigger_lock);
  93         read_unlock(&triggers_list_lock);
  94
  95         len += sprintf(len+buf, "\n");
  96         return len;
  97 }
  98
  99 void led_trigger_event(struct led_trigger *trigger,
 100                         enum led_brightness brightness)
 101 {
 102         struct list_head *entry;
 103
 104         if (!trigger)
 105                 return;
 106
 107         read_lock(&trigger->leddev_list_lock);
 108         list_for_each(entry, &trigger->led_cdevs) {
 109                 struct led_classdev *led_cdev;
 110
 111                 led_cdev = list_entry(entry, struct led_classdev, trig_list);
 112                 led_set_brightness(led_cdev, brightness);
 113         }
 114         read_unlock(&trigger->leddev_list_lock);
 115 }
 116
 117 /* Caller must ensure led_cdev->trigger_lock held */
 118 void led_trigger_set(struct led_classdev *led_cdev, struct led_trigger *trigger)
 119 {
 120         unsigned long flags;
 121
 122         /* Remove any existing trigger */
 123         if (led_cdev->trigger) {
 124                 write_lock_irqsave(&led_cdev->trigger->leddev_list_lock, flags);
 125                 list_del(&led_cdev->trig_list);
 126                 write_unlock_irqrestore(&led_cdev->trigger->leddev_list_lock, flags);
 127                 if (led_cdev->trigger->deactivate)
 128                         led_cdev->trigger->deactivate(led_cdev);
 129         }
 130         if (trigger) {
 131                 write_lock_irqsave(&trigger->leddev_list_lock, flags);
 132                 list_add_tail(&led_cdev->trig_list, &trigger->led_cdevs);
 133                 write_unlock_irqrestore(&trigger->leddev_list_lock, flags);
 134                 if (trigger->activate)
 135                         trigger->activate(led_cdev);
 136         }
 137         led_cdev->trigger = trigger;
 138 }
 139
 140 void led_trigger_set_default(struct led_classdev *led_cdev)
 141 {
 142         struct led_trigger *trig;
 143
 144         if (!led_cdev->default_trigger)
 145                 return;
 146
 147         read_lock(&triggers_list_lock);
 148         write_lock(&led_cdev->trigger_lock);
 149         list_for_each_entry(trig, &trigger_list, next_trig) {
 150                 if (!strcmp(led_cdev->default_trigger, trig->name))
 151                         led_trigger_set(led_cdev, trig);
 152         }
 153         write_unlock(&led_cdev->trigger_lock);
 154         read_unlock(&triggers_list_lock);
 155 }
 156
 157 int led_trigger_register(struct led_trigger *trigger)
 158 {
 159         struct led_classdev *led_cdev;
 160
 161         rwlock_init(&trigger->leddev_list_lock);
 162         INIT_LIST_HEAD(&trigger->led_cdevs);
 163
 164         /* Add to the list of led triggers */
 165         write_lock(&triggers_list_lock);
 166         list_add_tail(&trigger->next_trig, &trigger_list);
 167         write_unlock(&triggers_list_lock);
 168
 169         /* Register with any LEDs that have this as a default trigger */
 170         read_lock(&leds_list_lock);
 171         list_for_each_entry(led_cdev, &leds_list, node) {
 172                 write_lock(&led_cdev->trigger_lock);
 173                 if (!led_cdev->trigger && led_cdev->default_trigger &&
 174                             !strcmp(led_cdev->default_trigger, trigger->name))
 175                         led_trigger_set(led_cdev, trigger);
 176                 write_unlock(&led_cdev->trigger_lock);
 177         }
 178         read_unlock(&leds_list_lock);
 179
 180         return 0;
 181 }
 182
 183 void led_trigger_register_simple(const char *name, struct led_trigger **tp)
 184 {
 185         struct led_trigger *trigger;
 186
 187         trigger = kzalloc(sizeof(struct led_trigger), GFP_KERNEL);
 188
 189         if (trigger) {
 190                 trigger->name = name;
 191                 led_trigger_register(trigger);
 192         }
 193         *tp = trigger;
 194 }
 195
 196 void led_trigger_unregister(struct led_trigger *trigger)
 197 {
 198         struct led_classdev *led_cdev;
 199
 200         /* Remove from the list of led triggers */
 201         write_lock(&triggers_list_lock);
 202         list_del(&trigger->next_trig);
 203         write_unlock(&triggers_list_lock);
 204
 205         /* Remove anyone actively using this trigger */
 206         read_lock(&leds_list_lock);
 207         list_for_each_entry(led_cdev, &leds_list, node) {
 208                 write_lock(&led_cdev->trigger_lock);
 209                 if (led_cdev->trigger == trigger)
 210                         led_trigger_set(led_cdev, NULL);
 211                 write_unlock(&led_cdev->trigger_lock);
 212         }
 213         read_unlock(&leds_list_lock);
 214 }
 215
 216 void led_trigger_unregister_simple(struct led_trigger *trigger)
 217 {
 218         led_trigger_unregister(trigger);
 219         kfree(trigger);
 220 }
 221
 222 /* Used by LED Class */
 223 EXPORT_SYMBOL_GPL(led_trigger_set);
 224 EXPORT_SYMBOL_GPL(led_trigger_set_default);
 225 EXPORT_SYMBOL_GPL(led_trigger_show);
 226 EXPORT_SYMBOL_GPL(led_trigger_store);
 227
 228 /* LED Trigger Interface */
 229 EXPORT_SYMBOL_GPL(led_trigger_register);
 230 EXPORT_SYMBOL_GPL(led_trigger_unregister);
 231
 232 /* Simple LED Tigger Interface */
 233 EXPORT_SYMBOL_GPL(led_trigger_register_simple);
 234 EXPORT_SYMBOL_GPL(led_trigger_unregister_simple);
 235 EXPORT_SYMBOL_GPL(led_trigger_event);
 236
 237 MODULE_AUTHOR("Richard Purdie");
 238 MODULE_LICENSE("GPL");
 239 MODULE_DESCRIPTION("LED Triggers Core");