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/list.h>
  17 #include <linux/spinlock.h>
  18 #include <linux/device.h>
  19 #include <linux/timer.h>
  20 #include <linux/rwsem.h>
  21 #include <linux/leds.h>
  22 #include <linux/slab.h>
  23 #include "leds.h"
  24
  25 /*
  26  * Nests outside led_cdev->trigger_lock
  27  */
  28 static DECLARE_RWSEM(triggers_list_lock);
  29 static LIST_HEAD(trigger_list);
  30
  31  /* Used by LED Class */
  32
  33 ssize_t led_trigger_store(struct device *dev, struct device_attribute *attr,
  34                 const char *buf, size_t count)
  35 {
  36         struct led_classdev *led_cdev = dev_get_drvdata(dev);
  37         char trigger_name[TRIG_NAME_MAX];
  38         struct led_trigger *trig;
  39         size_t len;
  40
  41         trigger_name[sizeof(trigger_name) - 1] = '\0';
  42         strncpy(trigger_name, buf, sizeof(trigger_name) - 1);
  43         len = strlen(trigger_name);
  44
  45         if (len && trigger_name[len - 1] == '\n')
  46                 trigger_name[len - 1] = '\0';
  47
  48         if (!strcmp(trigger_name, "none")) {
  49                 led_trigger_remove(led_cdev);
  50                 return count;
  51         }
  52
  53         down_read(&triggers_list_lock);
  54         list_for_each_entry(trig, &trigger_list, next_trig) {
  55                 if (!strcmp(trigger_name, trig->name)) {
  56                         down_write(&led_cdev->trigger_lock);
  57                         led_trigger_set(led_cdev, trig);
  58                         up_write(&led_cdev->trigger_lock);
  59
  60                         up_read(&triggers_list_lock);
  61                         return count;
  62                 }
  63         }
  64         up_read(&triggers_list_lock);
  65
  66         return -EINVAL;
  67 }
  68 EXPORT_SYMBOL_GPL(led_trigger_store);
  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         down_read(&triggers_list_lock);
  78         down_read(&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         up_read(&led_cdev->trigger_lock);
  93         up_read(&triggers_list_lock);
  94
  95         len += sprintf(len+buf, "\n");
  96         return len;
  97 }
  98 EXPORT_SYMBOL_GPL(led_trigger_show);
  99
 100 /* Caller must ensure led_cdev->trigger_lock held */
 101 void led_trigger_set(struct led_classdev *led_cdev, struct led_trigger *trig)
 102 {
 103         unsigned long flags;
 104         char *event = NULL;
 105         char *envp[2];
 106         const char *name;
 107
 108         name = trig ? trig->name : "none";
 109         event = kasprintf(GFP_KERNEL, "TRIGGER=%s", name);
 110
 111         /* Remove any existing trigger */
 112         if (led_cdev->trigger) {
 113                 write_lock_irqsave(&led_cdev->trigger->leddev_list_lock, flags);
 114                 list_del(&led_cdev->trig_list);
 115                 write_unlock_irqrestore(&led_cdev->trigger->leddev_list_lock,
 116                         flags);
 117                 cancel_work_sync(&led_cdev->set_brightness_work);
 118                 led_stop_software_blink(led_cdev);
 119                 if (led_cdev->trigger->deactivate)
 120                         led_cdev->trigger->deactivate(led_cdev);
 121                 led_cdev->trigger = NULL;
 122                 led_set_brightness(led_cdev, LED_OFF);
 123         }
 124         if (trig) {
 125                 write_lock_irqsave(&trig->leddev_list_lock, flags);
 126                 list_add_tail(&led_cdev->trig_list, &trig->led_cdevs);
 127                 write_unlock_irqrestore(&trig->leddev_list_lock, flags);
 128                 led_cdev->trigger = trig;
 129                 if (trig->activate)
 130                         trig->activate(led_cdev);
 131         }
 132
 133         if (event) {
 134                 envp[0] = event;
 135                 envp[1] = NULL;
 136                 kobject_uevent_env(&led_cdev->dev->kobj, KOBJ_CHANGE, envp);
 137                 kfree(event);
 138         }
 139 }
 140 EXPORT_SYMBOL_GPL(led_trigger_set);
 141
 142 void led_trigger_remove(struct led_classdev *led_cdev)
 143 {
 144         down_write(&led_cdev->trigger_lock);
 145         led_trigger_set(led_cdev, NULL);
 146         up_write(&led_cdev->trigger_lock);
 147 }
 148 EXPORT_SYMBOL_GPL(led_trigger_remove);
 149
 150 void led_trigger_set_default(struct led_classdev *led_cdev)
 151 {
 152         struct led_trigger *trig;
 153
 154         if (!led_cdev->default_trigger)
 155                 return;
 156
 157         down_read(&triggers_list_lock);
 158         down_write(&led_cdev->trigger_lock);
 159         list_for_each_entry(trig, &trigger_list, next_trig) {
 160                 if (!strcmp(led_cdev->default_trigger, trig->name))
 161                         led_trigger_set(led_cdev, trig);
 162         }
 163         up_write(&led_cdev->trigger_lock);
 164         up_read(&triggers_list_lock);
 165 }
 166 EXPORT_SYMBOL_GPL(led_trigger_set_default);
 167
 168 void led_trigger_rename_static(const char *name, struct led_trigger *trig)
 169 {
 170         /* new name must be on a temporary string to prevent races */
 171         BUG_ON(name == trig->name);
 172
 173         down_write(&triggers_list_lock);
 174         /* this assumes that trig->name was originaly allocated to
 175          * non constant storage */
 176         strcpy((char *)trig->name, name);
 177         up_write(&triggers_list_lock);
 178 }
 179 EXPORT_SYMBOL_GPL(led_trigger_rename_static);
 180
 181 /* LED Trigger Interface */
 182
 183 int led_trigger_register(struct led_trigger *trig)
 184 {
 185         struct led_classdev *led_cdev;
 186         struct led_trigger *_trig;
 187
 188         rwlock_init(&trig->leddev_list_lock);
 189         INIT_LIST_HEAD(&trig->led_cdevs);
 190
 191         down_write(&triggers_list_lock);
 192         /* Make sure the trigger's name isn't already in use */
 193         list_for_each_entry(_trig, &trigger_list, next_trig) {
 194                 if (!strcmp(_trig->name, trig->name)) {
 195                         up_write(&triggers_list_lock);
 196                         return -EEXIST;
 197                 }
 198         }
 199         /* Add to the list of led triggers */
 200         list_add_tail(&trig->next_trig, &trigger_list);
 201         up_write(&triggers_list_lock);
 202
 203         /* Register with any LEDs that have this as a default trigger */
 204         down_read(&leds_list_lock);
 205         list_for_each_entry(led_cdev, &leds_list, node) {
 206                 down_write(&led_cdev->trigger_lock);
 207                 if (!led_cdev->trigger && led_cdev->default_trigger &&
 208                             !strcmp(led_cdev->default_trigger, trig->name))
 209                         led_trigger_set(led_cdev, trig);
 210                 up_write(&led_cdev->trigger_lock);
 211         }
 212         up_read(&leds_list_lock);
 213
 214         return 0;
 215 }
 216 EXPORT_SYMBOL_GPL(led_trigger_register);
 217
 218 void led_trigger_unregister(struct led_trigger *trig)
 219 {
 220         struct led_classdev *led_cdev;
 221
 222         if (list_empty_careful(&trig->next_trig))
 223                 return;
 224
 225         /* Remove from the list of led triggers */
 226         down_write(&triggers_list_lock);
 227         list_del_init(&trig->next_trig);
 228         up_write(&triggers_list_lock);
 229
 230         /* Remove anyone actively using this trigger */
 231         down_read(&leds_list_lock);
 232         list_for_each_entry(led_cdev, &leds_list, node) {
 233                 down_write(&led_cdev->trigger_lock);
 234                 if (led_cdev->trigger == trig)
 235                         led_trigger_set(led_cdev, NULL);
 236                 up_write(&led_cdev->trigger_lock);
 237         }
 238         up_read(&leds_list_lock);
 239 }
 240 EXPORT_SYMBOL_GPL(led_trigger_unregister);
 241
 242 /* Simple LED Tigger Interface */
 243
 244 void led_trigger_event(struct led_trigger *trig,
 245                         enum led_brightness brightness)
 246 {
 247         struct led_classdev *led_cdev;
 248
 249         if (!trig)
 250                 return;
 251
 252         read_lock(&trig->leddev_list_lock);
 253         list_for_each_entry(led_cdev, &trig->led_cdevs, trig_list)
 254                 led_set_brightness(led_cdev, brightness);
 255         read_unlock(&trig->leddev_list_lock);
 256 }
 257 EXPORT_SYMBOL_GPL(led_trigger_event);
 258
 259 static void led_trigger_blink_setup(struct led_trigger *trig,
 260                              unsigned long *delay_on,
 261                              unsigned long *delay_off,
 262                              int oneshot,
 263                              int invert)
 264 {
 265         struct led_classdev *led_cdev;
 266
 267         if (!trig)
 268                 return;
 269
 270         read_lock(&trig->leddev_list_lock);
 271         list_for_each_entry(led_cdev, &trig->led_cdevs, trig_list) {
 272                 if (oneshot)
 273                         led_blink_set_oneshot(led_cdev, delay_on, delay_off,
 274                                               invert);
 275                 else
 276                         led_blink_set(led_cdev, delay_on, delay_off);
 277         }
 278         read_unlock(&trig->leddev_list_lock);
 279 }
 280
 281 void led_trigger_blink(struct led_trigger *trig,
 282                        unsigned long *delay_on,
 283                        unsigned long *delay_off)
 284 {
 285         led_trigger_blink_setup(trig, delay_on, delay_off, 0, 0);
 286 }
 287 EXPORT_SYMBOL_GPL(led_trigger_blink);
 288
 289 void led_trigger_blink_oneshot(struct led_trigger *trig,
 290                                unsigned long *delay_on,
 291                                unsigned long *delay_off,
 292                                int invert)
 293 {
 294         led_trigger_blink_setup(trig, delay_on, delay_off, 1, invert);
 295 }
 296 EXPORT_SYMBOL_GPL(led_trigger_blink_oneshot);
 297
 298 void led_trigger_register_simple(const char *name, struct led_trigger **tp)
 299 {
 300         struct led_trigger *trig;
 301         int err;
 302
 303         trig = kzalloc(sizeof(struct led_trigger), GFP_KERNEL);
 304
 305         if (trig) {
 306                 trig->name = name;
 307                 err = led_trigger_register(trig);
 308                 if (err < 0) {
 309                         kfree(trig);
 310                         trig = NULL;
 311                         pr_warn("LED trigger %s failed to register (%d)\n",
 312                                 name, err);
 313                 }
 314         } else {
 315                 pr_warn("LED trigger %s failed to register (no memory)\n",
 316                         name);
 317         }
 318         *tp = trig;
 319 }
 320 EXPORT_SYMBOL_GPL(led_trigger_register_simple);
 321
 322 void led_trigger_unregister_simple(struct led_trigger *trig)
 323 {
 324         if (trig)
 325                 led_trigger_unregister(trig);
 326         kfree(trig);
 327 }
 328 EXPORT_SYMBOL_GPL(led_trigger_unregister_simple);
 329
 330 MODULE_AUTHOR("Richard Purdie");
 331 MODULE_LICENSE("GPL");
 332 MODULE_DESCRIPTION("LED Triggers Core");