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Commit 4ccc5743 authored by Durgadoss R's avatar Durgadoss R Committed by Zhang Rui
Browse files

Thermal: Introduce fair_share thermal governor 



This patch introduces a simple 'weight' based
governor named fair_share governor. Whenever the
thermal framework gets notified of the trip point
violation, this governor (if configured), throttles
the cooling devices associated with a thermal zone.

This mapping between a thermal zone and a cooling device
and the effectiveness of cooling are provided in the
platform layer.

Signed-off-by: default avatarDurgadoss R <durgadoss.r@intel.com>
Signed-off-by: default avatarZhang Rui <rui.zhang@intel.com>
parent dc765482

drivers/thermal/Kconfig

+6 −0
Original line number Diff line number Diff line
@@ -55,3 +55,9 @@ config EXYNOS_THERMAL 
	help

	  If you say yes here you get support for TMU (Thermal Managment

	  Unit) on SAMSUNG EXYNOS series of SoC.



config FAIR_SHARE

	bool "Fair-share thermal governor"

	depends on THERMAL

	help

	  Enable this to manage platform thermals using fair-share governor.

drivers/thermal/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -7,3 +7,4 @@ obj-$(CONFIG_CPU_THERMAL) += cpu_cooling.o 
obj-$(CONFIG_SPEAR_THERMAL)		+= spear_thermal.o

obj-$(CONFIG_RCAR_THERMAL)	+= rcar_thermal.o

obj-$(CONFIG_EXYNOS_THERMAL)		+= exynos_thermal.o

obj-$(CONFIG_FAIR_SHARE)		+= fair_share.o

drivers/thermal/fair_share.c

0 → 100644
+133 −0
Original line number Diff line number Diff line 
/*

 *  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.

 *

 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

 */



#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt



#include <linux/module.h>

#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

 */

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;

}



struct thermal_governor thermal_gov_fair_share = {

	.name		= "fair_share",

	.throttle	= fair_share_throttle,

	.owner		= THIS_MODULE,

};



static int __init thermal_gov_fair_share_init(void)

{

	return thermal_register_governor(&thermal_gov_fair_share);

}



static void __exit thermal_gov_fair_share_exit(void)

{

	thermal_unregister_governor(&thermal_gov_fair_share);

}



/* This should load after thermal framework */

fs_initcall(thermal_gov_fair_share_init);

module_exit(thermal_gov_fair_share_exit);



MODULE_AUTHOR("Durgadoss R");

MODULE_DESCRIPTION("A simple weight based thermal throttling governor");

MODULE_LICENSE("GPL");