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/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 device *dev, struct device_attribute *attr,
  32                 const char *buf, size_t count)
  33 {
  34         struct led_classdev *led_cdev = dev_get_drvdata(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 device *dev, struct device_attribute *attr,
  71                 char *buf)
  72 {
  73         struct led_classdev *led_cdev = dev_get_drvdata(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                 led_set_brightness(led_cdev, LED_OFF);
 130         }
 131         if (trigger) {
 132                 write_lock_irqsave(&trigger->leddev_list_lock, flags);
 133                 list_add_tail(&led_cdev->trig_list, &trigger->led_cdevs);
 134                 write_unlock_irqrestore(&trigger->leddev_list_lock, flags);
 135                 if (trigger->activate)
 136                         trigger->activate(led_cdev);
 137         }
 138         led_cdev->trigger = trigger;
 139 }
 140
 141 void led_trigger_set_default(struct led_classdev *led_cdev)
 142 {
 143         struct led_trigger *trig;
 144
 145         if (!led_cdev->default_trigger)
 146                 return;
 147
 148         read_lock(&triggers_list_lock);
 149         write_lock(&led_cdev->trigger_lock);
 150         list_for_each_entry(trig, &trigger_list, next_trig) {
 151                 if (!strcmp(led_cdev->default_trigger, trig->name))
 152                         led_trigger_set(led_cdev, trig);
 153         }
 154         write_unlock(&led_cdev->trigger_lock);
 155         read_unlock(&triggers_list_lock);
 156 }
 157
 158 int led_trigger_register(struct led_trigger *trigger)
 159 {
 160         struct led_classdev *led_cdev;
 161
 162         rwlock_init(&trigger->leddev_list_lock);
 163         INIT_LIST_HEAD(&trigger->led_cdevs);
 164
 165         /* Add to the list of led triggers */
 166         write_lock(&triggers_list_lock);
 167         list_add_tail(&trigger->next_trig, &trigger_list);
 168         write_unlock(&triggers_list_lock);
 169
 170         /* Register with any LEDs that have this as a default trigger */
 171         read_lock(&leds_list_lock);
 172         list_for_each_entry(led_cdev, &leds_list, node) {
 173                 write_lock(&led_cdev->trigger_lock);
 174                 if (!led_cdev->trigger && led_cdev->default_trigger &&
 175                             !strcmp(led_cdev->default_trigger, trigger->name))
 176                         led_trigger_set(led_cdev, trigger);
 177                 write_unlock(&led_cdev->trigger_lock);
 178         }
 179         read_unlock(&leds_list_lock);
 180
 181         return 0;
 182 }
 183
 184 void led_trigger_register_simple(const char *name, struct led_trigger **tp)
 185 {
 186         struct led_trigger *trigger;
 187         int err;
 188
 189         trigger = kzalloc(sizeof(struct led_trigger), GFP_KERNEL);
 190
 191         if (trigger) {
 192                 trigger->name = name;
 193                 err = led_trigger_register(trigger);
 194                 if (err < 0)
 195                         printk(KERN_WARNING "LED trigger %s failed to register"
 196                                 " (%d)\n", name, err);
 197         } else
 198                 printk(KERN_WARNING "LED trigger %s failed to register"
 199                         " (no memory)\n", name);
 200
 201         *tp = trigger;
 202 }
 203
 204 void led_trigger_unregister(struct led_trigger *trigger)
 205 {
 206         struct led_classdev *led_cdev;
 207
 208         /* Remove from the list of led triggers */
 209         write_lock(&triggers_list_lock);
 210         list_del(&trigger->next_trig);
 211         write_unlock(&triggers_list_lock);
 212
 213         /* Remove anyone actively using this trigger */
 214         read_lock(&leds_list_lock);
 215         list_for_each_entry(led_cdev, &leds_list, node) {
 216                 write_lock(&led_cdev->trigger_lock);
 217                 if (led_cdev->trigger == trigger)
 218                         led_trigger_set(led_cdev, NULL);
 219                 write_unlock(&led_cdev->trigger_lock);
 220         }
 221         read_unlock(&leds_list_lock);
 222 }
 223
 224 void led_trigger_unregister_simple(struct led_trigger *trigger)
 225 {
 226         if (trigger)
 227                 led_trigger_unregister(trigger);
 228         kfree(trigger);
 229 }
 230
 231 /* Used by LED Class */
 232 EXPORT_SYMBOL_GPL(led_trigger_set);
 233 EXPORT_SYMBOL_GPL(led_trigger_set_default);
 234 EXPORT_SYMBOL_GPL(led_trigger_show);
 235 EXPORT_SYMBOL_GPL(led_trigger_store);
 236
 237 /* LED Trigger Interface */
 238 EXPORT_SYMBOL_GPL(led_trigger_register);
 239 EXPORT_SYMBOL_GPL(led_trigger_unregister);
 240
 241 /* Simple LED Tigger Interface */
 242 EXPORT_SYMBOL_GPL(led_trigger_register_simple);
 243 EXPORT_SYMBOL_GPL(led_trigger_unregister_simple);
 244 EXPORT_SYMBOL_GPL(led_trigger_event);
 245
 246 MODULE_AUTHOR("Richard Purdie");
 247 MODULE_LICENSE("GPL");
 248 MODULE_DESCRIPTION("LED Triggers Core");