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         }
 129         if (trigger) {
 130                 write_lock_irqsave(&trigger->leddev_list_lock, flags);
 131                 list_add_tail(&led_cdev->trig_list, &trigger->led_cdevs);
 132                 write_unlock_irqrestore(&trigger->leddev_list_lock, flags);
 133                 if (trigger->activate)
 134                         trigger->activate(led_cdev);
 135         }
 136         led_cdev->trigger = trigger;
 137 }
 138
 139 void led_trigger_set_default(struct led_classdev *led_cdev)
 140 {
 141         struct led_trigger *trig;
 142
 143         if (!led_cdev->default_trigger)
 144                 return;
 145
 146         read_lock(&triggers_list_lock);
 147         write_lock(&led_cdev->trigger_lock);
 148         list_for_each_entry(trig, &trigger_list, next_trig) {
 149                 if (!strcmp(led_cdev->default_trigger, trig->name))
 150                         led_trigger_set(led_cdev, trig);
 151         }
 152         write_unlock(&led_cdev->trigger_lock);
 153         read_unlock(&triggers_list_lock);
 154 }
 155
 156 int led_trigger_register(struct led_trigger *trigger)
 157 {
 158         struct led_classdev *led_cdev;
 159
 160         rwlock_init(&trigger->leddev_list_lock);
 161         INIT_LIST_HEAD(&trigger->led_cdevs);
 162
 163         /* Add to the list of led triggers */
 164         write_lock(&triggers_list_lock);
 165         list_add_tail(&trigger->next_trig, &trigger_list);
 166         write_unlock(&triggers_list_lock);
 167
 168         /* Register with any LEDs that have this as a default trigger */
 169         read_lock(&leds_list_lock);
 170         list_for_each_entry(led_cdev, &leds_list, node) {
 171                 write_lock(&led_cdev->trigger_lock);
 172                 if (!led_cdev->trigger && led_cdev->default_trigger &&
 173                             !strcmp(led_cdev->default_trigger, trigger->name))
 174                         led_trigger_set(led_cdev, trigger);
 175                 write_unlock(&led_cdev->trigger_lock);
 176         }
 177         read_unlock(&leds_list_lock);
 178
 179         return 0;
 180 }
 181
 182 void led_trigger_register_simple(const char *name, struct led_trigger **tp)
 183 {
 184         struct led_trigger *trigger;
 185
 186         trigger = kzalloc(sizeof(struct led_trigger), GFP_KERNEL);
 187
 188         if (trigger) {
 189                 trigger->name = name;
 190                 led_trigger_register(trigger);
 191         }
 192         *tp = trigger;
 193 }
 194
 195 void led_trigger_unregister(struct led_trigger *trigger)
 196 {
 197         struct led_classdev *led_cdev;
 198
 199         /* Remove from the list of led triggers */
 200         write_lock(&triggers_list_lock);
 201         list_del(&trigger->next_trig);
 202         write_unlock(&triggers_list_lock);
 203
 204         /* Remove anyone actively using this trigger */
 205         read_lock(&leds_list_lock);
 206         list_for_each_entry(led_cdev, &leds_list, node) {
 207                 write_lock(&led_cdev->trigger_lock);
 208                 if (led_cdev->trigger == trigger)
 209                         led_trigger_set(led_cdev, NULL);
 210                 write_unlock(&led_cdev->trigger_lock);
 211         }
 212         read_unlock(&leds_list_lock);
 213 }
 214
 215 void led_trigger_unregister_simple(struct led_trigger *trigger)
 216 {
 217         led_trigger_unregister(trigger);
 218         kfree(trigger);
 219 }
 220
 221 /* Used by LED Class */
 222 EXPORT_SYMBOL_GPL(led_trigger_set);
 223 EXPORT_SYMBOL_GPL(led_trigger_set_default);
 224 EXPORT_SYMBOL_GPL(led_trigger_show);
 225 EXPORT_SYMBOL_GPL(led_trigger_store);
 226
 227 /* LED Trigger Interface */
 228 EXPORT_SYMBOL_GPL(led_trigger_register);
 229 EXPORT_SYMBOL_GPL(led_trigger_unregister);
 230
 231 /* Simple LED Tigger Interface */
 232 EXPORT_SYMBOL_GPL(led_trigger_register_simple);
 233 EXPORT_SYMBOL_GPL(led_trigger_unregister_simple);
 234 EXPORT_SYMBOL_GPL(led_trigger_event);
 235
 236 MODULE_AUTHOR("Richard Purdie");
 237 MODULE_LICENSE("GPL");
 238 MODULE_DESCRIPTION("LED Triggers Core");