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/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/leds.h>
  23 #include "leds.h"
  24
  25 /*
  26  * Nests outside led_cdev->trigger_lock
  27  */
  28 static DEFINE_RWLOCK(triggers_list_lock);
  29 static LIST_HEAD(trigger_list);
  30
  31 ssize_t led_trigger_store(struct class_device *dev, const char *buf,
  32                         size_t count)
  33 {
  34         struct led_classdev *led_cdev = class_get_devdata(dev);
  35         char trigger_name[TRIG_NAME_MAX];
  36         struct led_trigger *trig;
  37         size_t len;
  38
  39         trigger_name[sizeof(trigger_name) - 1] = '\0';
  40         strncpy(trigger_name, buf, sizeof(trigger_name) - 1);
  41         len = strlen(trigger_name);
  42
  43         if (len && trigger_name[len - 1] == '\n')
  44                 trigger_name[len - 1] = '\0';
  45
  46         if (!strcmp(trigger_name, "none")) {
  47                 write_lock(&led_cdev->trigger_lock);
  48                 led_trigger_set(led_cdev, NULL);
  49                 write_unlock(&led_cdev->trigger_lock);
  50                 return count;
  51         }
  52
  53         read_lock(&triggers_list_lock);
  54         list_for_each_entry(trig, &trigger_list, next_trig) {
  55                 if (!strcmp(trigger_name, trig->name)) {
  56                         write_lock(&led_cdev->trigger_lock);
  57                         led_trigger_set(led_cdev, trig);
  58                         write_unlock(&led_cdev->trigger_lock);
  59
  60                         read_unlock(&triggers_list_lock);
  61                         return count;
  62                 }
  63         }
  64         read_unlock(&triggers_list_lock);
  65
  66         return -EINVAL;
  67 }
  68
  69
  70 ssize_t led_trigger_show(struct class_device *dev, char *buf)
  71 {
  72         struct led_classdev *led_cdev = class_get_devdata(dev);
  73         struct led_trigger *trig;
  74         int len = 0;
  75
  76         read_lock(&triggers_list_lock);
  77         read_lock(&led_cdev->trigger_lock);
  78
  79         if (!led_cdev->trigger)
  80                 len += sprintf(buf+len, "[none] ");
  81         else
  82                 len += sprintf(buf+len, "none ");
  83
  84         list_for_each_entry(trig, &trigger_list, next_trig) {
  85                 if (led_cdev->trigger && !strcmp(led_cdev->trigger->name,
  86                                                         trig->name))
  87                         len += sprintf(buf+len, "[%s] ", trig->name);
  88                 else
  89                         len += sprintf(buf+len, "%s ", trig->name);
  90         }
  91         read_unlock(&led_cdev->trigger_lock);
  92         read_unlock(&triggers_list_lock);
  93
  94         len += sprintf(len+buf, "\n");
  95         return len;
  96 }
  97
  98 void led_trigger_event(struct led_trigger *trigger,
  99                         enum led_brightness brightness)
 100 {
 101         struct list_head *entry;
 102
 103         if (!trigger)
 104                 return;
 105
 106         read_lock(&trigger->leddev_list_lock);
 107         list_for_each(entry, &trigger->led_cdevs) {
 108                 struct led_classdev *led_cdev;
 109
 110                 led_cdev = list_entry(entry, struct led_classdev, trig_list);
 111                 led_set_brightness(led_cdev, brightness);
 112         }
 113         read_unlock(&trigger->leddev_list_lock);
 114 }
 115
 116 /* Caller must ensure led_cdev->trigger_lock held */
 117 void led_trigger_set(struct led_classdev *led_cdev, struct led_trigger *trigger)
 118 {
 119         unsigned long flags;
 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, flags);
 126                 if (led_cdev->trigger->deactivate)
 127                         led_cdev->trigger->deactivate(led_cdev);
 128                 led_set_brightness(led_cdev, LED_OFF);
 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         int err;
 187
 188         trigger = kzalloc(sizeof(struct led_trigger), GFP_KERNEL);
 189
 190         if (trigger) {
 191                 trigger->name = name;
 192                 err = led_trigger_register(trigger);
 193                 if (err < 0)
 194                         printk(KERN_WARNING "LED trigger %s failed to register"
 195                                 " (%d)\n", name, err);
 196         } else
 197                 printk(KERN_WARNING "LED trigger %s failed to register"
 198                         " (no memory)\n", name);
 199
 200         *tp = trigger;
 201 }
 202
 203 void led_trigger_unregister(struct led_trigger *trigger)
 204 {
 205         struct led_classdev *led_cdev;
 206
 207         /* Remove from the list of led triggers */
 208         write_lock(&triggers_list_lock);
 209         list_del(&trigger->next_trig);
 210         write_unlock(&triggers_list_lock);
 211
 212         /* Remove anyone actively using this trigger */
 213         read_lock(&leds_list_lock);
 214         list_for_each_entry(led_cdev, &leds_list, node) {
 215                 write_lock(&led_cdev->trigger_lock);
 216                 if (led_cdev->trigger == trigger)
 217                         led_trigger_set(led_cdev, NULL);
 218                 write_unlock(&led_cdev->trigger_lock);
 219         }
 220         read_unlock(&leds_list_lock);
 221 }
 222
 223 void led_trigger_unregister_simple(struct led_trigger *trigger)
 224 {
 225         if (trigger)
 226                 led_trigger_unregister(trigger);
 227         kfree(trigger);
 228 }
 229
 230 /* Used by LED Class */
 231 EXPORT_SYMBOL_GPL(led_trigger_set);
 232 EXPORT_SYMBOL_GPL(led_trigger_set_default);
 233 EXPORT_SYMBOL_GPL(led_trigger_show);
 234 EXPORT_SYMBOL_GPL(led_trigger_store);
 235
 236 /* LED Trigger Interface */
 237 EXPORT_SYMBOL_GPL(led_trigger_register);
 238 EXPORT_SYMBOL_GPL(led_trigger_unregister);
 239
 240 /* Simple LED Tigger Interface */
 241 EXPORT_SYMBOL_GPL(led_trigger_register_simple);
 242 EXPORT_SYMBOL_GPL(led_trigger_unregister_simple);
 243 EXPORT_SYMBOL_GPL(led_trigger_event);
 244
 245 MODULE_AUTHOR("Richard Purdie");
 246 MODULE_LICENSE("GPL");
 247 MODULE_DESCRIPTION("LED Triggers Core");