/*
   * Backlight emulation LED trigger
   *
   * Copyright 2008 (C) Rodolfo Giometti <giometti@linux.it>
   * Copyright 2008 (C) Eurotech S.p.A. <info@eurotech.it>
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License version 2 as
   * published by the Free Software Foundation.
   *
   */
  
  #include <linux/module.h>
  #include <linux/kernel.h>

  #include <linux/slab.h>

  #include <linux/init.h>
  #include <linux/fb.h>
  #include <linux/leds.h>
  #include "leds.h"
  
  #define BLANK		1
  #define UNBLANK		0
  
  struct bl_trig_notifier {
  	struct led_classdev *led;
  	int brightness;
  	int old_status;
  	struct notifier_block notifier;

  	unsigned invert;

  };
  
  static int fb_notifier_callback(struct notifier_block *p,
  				unsigned long event, void *data)
  {
  	struct bl_trig_notifier *n = container_of(p,
  					struct bl_trig_notifier, notifier);
  	struct led_classdev *led = n->led;
  	struct fb_event *fb_event = data;
  	int *blank = fb_event->data;

  	int new_status = *blank ? BLANK : UNBLANK;

  
  	switch (event) {
  	case FB_EVENT_BLANK :

  		if (new_status == n->old_status)
  			break;
  
  		if ((n->old_status == UNBLANK) ^ n->invert) {

  			n->brightness = led->brightness;
  			led_set_brightness(led, LED_OFF);

  		} else {

  			led_set_brightness(led, n->brightness);

  		}

  
  		n->old_status = new_status;

  		break;
  	}
  
  	return 0;
  }

  static ssize_t bl_trig_invert_show(struct device *dev,
  		struct device_attribute *attr, char *buf)
  {
  	struct led_classdev *led = dev_get_drvdata(dev);
  	struct bl_trig_notifier *n = led->trigger_data;
  
  	return sprintf(buf, "%u
  ", n->invert);
  }
  
  static ssize_t bl_trig_invert_store(struct device *dev,
  		struct device_attribute *attr, const char *buf, size_t num)
  {
  	struct led_classdev *led = dev_get_drvdata(dev);
  	struct bl_trig_notifier *n = led->trigger_data;
  	unsigned long invert;
  	int ret;
  
  	ret = strict_strtoul(buf, 10, &invert);
  	if (ret < 0)
  		return ret;
  
  	if (invert > 1)
  		return -EINVAL;
  
  	n->invert = invert;
  
  	/* After inverting, we need to update the LED. */
  	if ((n->old_status == BLANK) ^ n->invert)
  		led_set_brightness(led, LED_OFF);
  	else
  		led_set_brightness(led, n->brightness);
  
  	return num;
  }
  static DEVICE_ATTR(inverted, 0644, bl_trig_invert_show, bl_trig_invert_store);

  static void bl_trig_activate(struct led_classdev *led)
  {
  	int ret;
  
  	struct bl_trig_notifier *n;
  
  	n = kzalloc(sizeof(struct bl_trig_notifier), GFP_KERNEL);
  	led->trigger_data = n;
  	if (!n) {
  		dev_err(led->dev, "unable to allocate backlight trigger
  ");
  		return;
  	}

  	ret = device_create_file(led->dev, &dev_attr_inverted);
  	if (ret)
  		goto err_invert;

  	n->led = led;
  	n->brightness = led->brightness;
  	n->old_status = UNBLANK;
  	n->notifier.notifier_call = fb_notifier_callback;
  
  	ret = fb_register_client(&n->notifier);
  	if (ret)
  		dev_err(led->dev, "unable to register backlight trigger
  ");

  
  	return;
  
  err_invert:
  	led->trigger_data = NULL;
  	kfree(n);

  }
  
  static void bl_trig_deactivate(struct led_classdev *led)
  {
  	struct bl_trig_notifier *n =
  		(struct bl_trig_notifier *) led->trigger_data;
  
  	if (n) {

  		device_remove_file(led->dev, &dev_attr_inverted);

  		fb_unregister_client(&n->notifier);
  		kfree(n);
  	}
  }
  
  static struct led_trigger bl_led_trigger = {
  	.name		= "backlight",
  	.activate	= bl_trig_activate,
  	.deactivate	= bl_trig_deactivate
  };
  
  static int __init bl_trig_init(void)
  {
  	return led_trigger_register(&bl_led_trigger);
  }
  
  static void __exit bl_trig_exit(void)
  {
  	led_trigger_unregister(&bl_led_trigger);
  }
  
  module_init(bl_trig_init);
  module_exit(bl_trig_exit);
  
  MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");
  MODULE_DESCRIPTION("Backlight emulation LED trigger");
  MODULE_LICENSE("GPL v2");