/*
   * LED Kernel Transient Trigger
   *
   * Copyright (C) 2012 Shuah Khan <shuahkhan@gmail.com>
   *
   * Based on Richard Purdie's ledtrig-timer.c and Atsushi Nemoto's
   * ledtrig-heartbeat.c
   * Design and use-case input from Jonas Bonn <jonas@southpole.se> and
   * Neil Brown <neilb@suse.de>
   *
   * 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.
   *
   */
  /*
   * Transient trigger allows one shot timer activation. Please refer to
   * Documentation/leds/ledtrig-transient.txt for details
  */
  
  #include <linux/module.h>
  #include <linux/kernel.h>
  #include <linux/init.h>
  #include <linux/device.h>
  #include <linux/slab.h>
  #include <linux/timer.h>
  #include <linux/leds.h>
  #include "../leds.h"
  
  struct transient_trig_data {
  	int activate;
  	int state;
  	int restore_state;
  	unsigned long duration;
  	struct timer_list timer;
  };
  
  static void transient_timer_function(unsigned long data)
  {
  	struct led_classdev *led_cdev = (struct led_classdev *) data;
  	struct transient_trig_data *transient_data = led_cdev->trigger_data;
  
  	transient_data->activate = 0;
  	__led_set_brightness(led_cdev, transient_data->restore_state);
  }
  
  static ssize_t transient_activate_show(struct device *dev,
  		struct device_attribute *attr, char *buf)
  {
  	struct led_classdev *led_cdev = dev_get_drvdata(dev);
  	struct transient_trig_data *transient_data = led_cdev->trigger_data;
  
  	return sprintf(buf, "%d
  ", transient_data->activate);
  }
  
  static ssize_t transient_activate_store(struct device *dev,
  		struct device_attribute *attr, const char *buf, size_t size)
  {
  	struct led_classdev *led_cdev = dev_get_drvdata(dev);
  	struct transient_trig_data *transient_data = led_cdev->trigger_data;
  	unsigned long state;
  	ssize_t ret;
  
  	ret = kstrtoul(buf, 10, &state);
  	if (ret)
  		return ret;
  
  	if (state != 1 && state != 0)
  		return -EINVAL;
  
  	/* cancel the running timer */
  	if (state == 0 && transient_data->activate == 1) {
  		del_timer(&transient_data->timer);
  		transient_data->activate = state;
  		__led_set_brightness(led_cdev, transient_data->restore_state);
  		return size;
  	}
  
  	/* start timer if there is no active timer */
  	if (state == 1 && transient_data->activate == 0 &&
  	    transient_data->duration != 0) {
  		transient_data->activate = state;
  		__led_set_brightness(led_cdev, transient_data->state);
  		transient_data->restore_state =
  		    (transient_data->state == LED_FULL) ? LED_OFF : LED_FULL;
  		mod_timer(&transient_data->timer,
  			  jiffies + transient_data->duration);
  	}
  
  	/* state == 0 && transient_data->activate == 0
  		timer is not active - just return */
  	/* state == 1 && transient_data->activate == 1
  		timer is already active - just return */
  
  	return size;
  }
  
  static ssize_t transient_duration_show(struct device *dev,
  		struct device_attribute *attr, char *buf)
  {
  	struct led_classdev *led_cdev = dev_get_drvdata(dev);
  	struct transient_trig_data *transient_data = led_cdev->trigger_data;
  
  	return sprintf(buf, "%lu
  ", transient_data->duration);
  }
  
  static ssize_t transient_duration_store(struct device *dev,
  		struct device_attribute *attr, const char *buf, size_t size)
  {
  	struct led_classdev *led_cdev = dev_get_drvdata(dev);
  	struct transient_trig_data *transient_data = led_cdev->trigger_data;
  	unsigned long state;
  	ssize_t ret;
  
  	ret = kstrtoul(buf, 10, &state);
  	if (ret)
  		return ret;
  
  	transient_data->duration = state;
  	return size;
  }
  
  static ssize_t transient_state_show(struct device *dev,
  		struct device_attribute *attr, char *buf)
  {
  	struct led_classdev *led_cdev = dev_get_drvdata(dev);
  	struct transient_trig_data *transient_data = led_cdev->trigger_data;
  	int state;
  
  	state = (transient_data->state == LED_FULL) ? 1 : 0;
  	return sprintf(buf, "%d
  ", state);
  }
  
  static ssize_t transient_state_store(struct device *dev,
  		struct device_attribute *attr, const char *buf, size_t size)
  {
  	struct led_classdev *led_cdev = dev_get_drvdata(dev);
  	struct transient_trig_data *transient_data = led_cdev->trigger_data;
  	unsigned long state;
  	ssize_t ret;
  
  	ret = kstrtoul(buf, 10, &state);
  	if (ret)
  		return ret;
  
  	if (state != 1 && state != 0)
  		return -EINVAL;
  
  	transient_data->state = (state == 1) ? LED_FULL : LED_OFF;
  	return size;
  }
  
  static DEVICE_ATTR(activate, 0644, transient_activate_show,
  		   transient_activate_store);
  static DEVICE_ATTR(duration, 0644, transient_duration_show,
  		   transient_duration_store);
  static DEVICE_ATTR(state, 0644, transient_state_show, transient_state_store);
  
  static void transient_trig_activate(struct led_classdev *led_cdev)
  {
  	int rc;
  	struct transient_trig_data *tdata;
  
  	tdata = kzalloc(sizeof(struct transient_trig_data), GFP_KERNEL);
  	if (!tdata) {
  		dev_err(led_cdev->dev,
  			"unable to allocate transient trigger
  ");
  		return;
  	}
  	led_cdev->trigger_data = tdata;
  
  	rc = device_create_file(led_cdev->dev, &dev_attr_activate);
  	if (rc)
  		goto err_out;
  
  	rc = device_create_file(led_cdev->dev, &dev_attr_duration);
  	if (rc)
  		goto err_out_duration;
  
  	rc = device_create_file(led_cdev->dev, &dev_attr_state);
  	if (rc)
  		goto err_out_state;
  
  	setup_timer(&tdata->timer, transient_timer_function,
  		    (unsigned long) led_cdev);
  	led_cdev->activated = true;
  
  	return;
  
  err_out_state:
  	device_remove_file(led_cdev->dev, &dev_attr_duration);
  err_out_duration:
  	device_remove_file(led_cdev->dev, &dev_attr_activate);
  err_out:
  	dev_err(led_cdev->dev, "unable to register transient trigger
  ");
  	led_cdev->trigger_data = NULL;
  	kfree(tdata);
  }
  
  static void transient_trig_deactivate(struct led_classdev *led_cdev)
  {
  	struct transient_trig_data *transient_data = led_cdev->trigger_data;
  
  	if (led_cdev->activated) {
  		del_timer_sync(&transient_data->timer);
  		__led_set_brightness(led_cdev, transient_data->restore_state);
  		device_remove_file(led_cdev->dev, &dev_attr_activate);
  		device_remove_file(led_cdev->dev, &dev_attr_duration);
  		device_remove_file(led_cdev->dev, &dev_attr_state);
  		led_cdev->trigger_data = NULL;
  		led_cdev->activated = false;
  		kfree(transient_data);
  	}
  }
  
  static struct led_trigger transient_trigger = {
  	.name     = "transient",
  	.activate = transient_trig_activate,
  	.deactivate = transient_trig_deactivate,
  };
  
  static int __init transient_trig_init(void)
  {
  	return led_trigger_register(&transient_trigger);
  }
  
  static void __exit transient_trig_exit(void)
  {
  	led_trigger_unregister(&transient_trigger);
  }
  
  module_init(transient_trig_init);
  module_exit(transient_trig_exit);
  
  MODULE_AUTHOR("Shuah Khan <shuahkhan@gmail.com>");
  MODULE_DESCRIPTION("Transient LED trigger");
  MODULE_LICENSE("GPL");