/*
   *  fair_share.c - A simple weight based Thermal governor
   *
   *  Copyright (C) 2012 Intel Corp
   *  Copyright (C) 2012 Durgadoss R <durgadoss.r@intel.com>
   *
   *  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   *
   *  This program is free software; you can redistribute it and/or modify
   *  it under the terms of the GNU General Public License as published by
   *  the Free Software Foundation; version 2 of the License.
   *
   *  This program is distributed in the hope that it will be useful, but
   *  WITHOUT ANY WARRANTY; without even the implied warranty of
   *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   *  General Public License for more details.
   *
   *  You should have received a copy of the GNU General Public License along
   *  with this program; if not, write to the Free Software Foundation, Inc.,
   *  59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
   *
   * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   */

  #include <linux/thermal.h>
  
  #include "thermal_core.h"
  
  /**
   * get_trip_level: - obtains the current trip level for a zone
   * @tz:		thermal zone device
   */
  static int get_trip_level(struct thermal_zone_device *tz)
  {
  	int count = 0;
  	unsigned long trip_temp;
  
  	if (tz->trips == 0 || !tz->ops->get_trip_temp)
  		return 0;
  
  	for (count = 0; count < tz->trips; count++) {
  		tz->ops->get_trip_temp(tz, count, &trip_temp);
  		if (tz->temperature < trip_temp)
  			break;
  	}
  	return count;
  }
  
  static long get_target_state(struct thermal_zone_device *tz,
  		struct thermal_cooling_device *cdev, int weight, int level)
  {
  	unsigned long max_state;
  
  	cdev->ops->get_max_state(cdev, &max_state);
  
  	return (long)(weight * level * max_state) / (100 * tz->trips);
  }
  
  /**
   * fair_share_throttle - throttles devices asscciated with the given zone
   * @tz - thermal_zone_device
   *
   * Throttling Logic: This uses three parameters to calculate the new
   * throttle state of the cooling devices associated with the given zone.
   *
   * Parameters used for Throttling:
   * P1. max_state: Maximum throttle state exposed by the cooling device.
   * P2. weight[i]/100:
   *	How 'effective' the 'i'th device is, in cooling the given zone.
   * P3. cur_trip_level/max_no_of_trips:
   *	This describes the extent to which the devices should be throttled.
   *	We do not want to throttle too much when we trip a lower temperature,
   *	whereas the throttling is at full swing if we trip critical levels.
   *	(Heavily assumes the trip points are in ascending order)
   * new_state of cooling device = P3 * P2 * P1
   */

  static int fair_share_throttle(struct thermal_zone_device *tz, int trip)

  {
  	const struct thermal_zone_params *tzp;
  	struct thermal_cooling_device *cdev;
  	struct thermal_instance *instance;
  	int i;
  	int cur_trip_level = get_trip_level(tz);
  
  	if (!tz->tzp || !tz->tzp->tbp)
  		return -EINVAL;
  
  	tzp = tz->tzp;
  
  	for (i = 0; i < tzp->num_tbps; i++) {
  		if (!tzp->tbp[i].cdev)
  			continue;
  
  		cdev = tzp->tbp[i].cdev;
  		instance = get_thermal_instance(tz, cdev, trip);
  		if (!instance)
  			continue;
  
  		instance->target = get_target_state(tz, cdev,
  					tzp->tbp[i].weight, cur_trip_level);
  
  		instance->cdev->updated = false;
  		thermal_cdev_update(cdev);
  	}
  	return 0;
  }

  static struct thermal_governor thermal_gov_fair_share = {

  	.name		= "fair_share",
  	.throttle	= fair_share_throttle,

  };

  int thermal_gov_fair_share_register(void)

  {
  	return thermal_register_governor(&thermal_gov_fair_share);
  }

  void thermal_gov_fair_share_unregister(void)

  {
  	thermal_unregister_governor(&thermal_gov_fair_share);
  }