Commit e151a202 authored by Durgadoss R's avatar Durgadoss R Committed by Zhang Rui
Browse files

Thermal: Introduce a step_wise thermal governor 



This patch adds a simple step_wise governor to the
generic thermal layer. This algorithm throttles the
cooling devices in a linear fashion. If the 'trend'
is heating, it throttles by one step. And if the
thermal trend is cooling it de-throttles by one step.

This actually moves the throttling logic from thermal_sys.c
and puts inside step_wise.c, without any change.

Signed-off-by: default avatarDurgadoss R <durgadoss.r@intel.com>
Signed-off-by: default avatarZhang Rui <rui.zhang@intel.com>
parent 4ccc5743

drivers/thermal/Kconfig

+6 −0
Original line number Diff line number Diff line
@@ -61,3 +61,9 @@ config FAIR_SHARE 
	depends on THERMAL

	help

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



config STEP_WISE

	bool "Step_wise thermal governor"

	depends on THERMAL

	help

	  Enable this to manage platform thermals using a simple linear

drivers/thermal/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -8,3 +8,4 @@ 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

obj-$(CONFIG_STEP_WISE)			+= step_wise.o

drivers/thermal/step_wise.c

0 → 100644
+194 −0
Original line number Diff line number Diff line 
/*

 *  step_wise.c - A step-by-step Thermal throttling 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"



/*

 * If the temperature is higher than a trip point,

 *    a. if the trend is THERMAL_TREND_RAISING, use higher cooling

 *       state for this trip point

 *    b. if the trend is THERMAL_TREND_DROPPING, use lower cooling

 *       state for this trip point

 */

static unsigned long get_target_state(struct thermal_instance *instance,

					enum thermal_trend trend)

{

	struct thermal_cooling_device *cdev = instance->cdev;

	unsigned long cur_state;



	cdev->ops->get_cur_state(cdev, &cur_state);



	if (trend == THERMAL_TREND_RAISING) {

		cur_state = cur_state < instance->upper ?

			    (cur_state + 1) : instance->upper;

	} else if (trend == THERMAL_TREND_DROPPING) {

		cur_state = cur_state > instance->lower ?

			    (cur_state - 1) : instance->lower;

	}



	return cur_state;

}



static void update_passive_instance(struct thermal_zone_device *tz,

				enum thermal_trip_type type, int value)

{

	/*

	 * If value is +1, activate a passive instance.

	 * If value is -1, deactivate a passive instance.

	 */

	if (type == THERMAL_TRIP_PASSIVE || type == THERMAL_TRIPS_NONE)

		tz->passive += value;

}



static void update_instance_for_throttle(struct thermal_zone_device *tz,

				int trip, enum thermal_trip_type trip_type,

				enum thermal_trend trend)

{

	struct thermal_instance *instance;



	list_for_each_entry(instance, &tz->thermal_instances, tz_node) {

		if (instance->trip != trip)

			continue;



		instance->target = get_target_state(instance, trend);



		/* Activate a passive thermal instance */

		if (instance->target == THERMAL_NO_TARGET)

			update_passive_instance(tz, trip_type, 1);



		instance->cdev->updated = false; /* cdev needs update */

	}

}



static void update_instance_for_dethrottle(struct thermal_zone_device *tz,

				int trip, enum thermal_trip_type trip_type)

{

	struct thermal_instance *instance;

	struct thermal_cooling_device *cdev;

	unsigned long cur_state;



	list_for_each_entry(instance, &tz->thermal_instances, tz_node) {

		if (instance->trip != trip ||

			instance->target == THERMAL_NO_TARGET)

			continue;



		cdev = instance->cdev;

		cdev->ops->get_cur_state(cdev, &cur_state);



		instance->target = cur_state > instance->lower ?

			    (cur_state - 1) : THERMAL_NO_TARGET;



		/* Deactivate a passive thermal instance */

		if (instance->target == THERMAL_NO_TARGET)

			update_passive_instance(tz, trip_type, -1);



		cdev->updated = false; /* cdev needs update */

	}

}



static void thermal_zone_trip_update(struct thermal_zone_device *tz, int trip)

{

	long trip_temp;

	enum thermal_trip_type trip_type;

	enum thermal_trend trend;



	if (trip == THERMAL_TRIPS_NONE) {

		trip_temp = tz->forced_passive;

		trip_type = THERMAL_TRIPS_NONE;

	} else {

		tz->ops->get_trip_temp(tz, trip, &trip_temp);

		tz->ops->get_trip_type(tz, trip, &trip_type);

	}



	trend = get_tz_trend(tz, trip);



	mutex_lock(&tz->lock);



	if (tz->temperature >= trip_temp)

		update_instance_for_throttle(tz, trip, trip_type, trend);

	else

		update_instance_for_dethrottle(tz, trip, trip_type);



	mutex_unlock(&tz->lock);

}



/**

 * step_wise_throttle - throttles devices asscciated with the given zone

 * @tz - thermal_zone_device

 * @trip - the trip point

 * @trip_type - type of the trip point

 *

 * Throttling Logic: This uses the trend of the thermal zone to throttle.

 * If the thermal zone is 'heating up' this throttles all the cooling

 * devices associated with the zone and its particular trip point, by one

 * step. If the zone is 'cooling down' it brings back the performance of

 * the devices by one step.

 */

int step_wise_throttle(struct thermal_zone_device *tz, int trip)

{

	struct thermal_instance *instance;



	thermal_zone_trip_update(tz, trip);



	if (tz->forced_passive)

		thermal_zone_trip_update(tz, THERMAL_TRIPS_NONE);



	mutex_lock(&tz->lock);



	list_for_each_entry(instance, &tz->thermal_instances, tz_node)

		thermal_cdev_update(instance->cdev);



	mutex_unlock(&tz->lock);



	return 0;

}



struct thermal_governor thermal_gov_step_wise = {

	.name		= DEFAULT_THERMAL_GOVERNOR,

	.throttle	= step_wise_throttle,

	.owner		= THIS_MODULE,

};



static int __init thermal_gov_step_wise_init(void)

{

	return thermal_register_governor(&thermal_gov_step_wise);

}



static void __exit thermal_gov_step_wise_exit(void)

{

	thermal_unregister_governor(&thermal_gov_step_wise);

}



/* This should load after thermal framework */

fs_initcall(thermal_gov_step_wise_init);

module_exit(thermal_gov_step_wise_exit);



MODULE_AUTHOR("Durgadoss R");

MODULE_DESCRIPTION("A step-by-step thermal throttling governor");

MODULE_LICENSE("GPL");

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