/*
* 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.
*
* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
*/
#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
* c. if the trend is THERMAL_TREND_RAISE_FULL, use upper limit
* for this trip point
* d. if the trend is THERMAL_TREND_DROP_FULL, use lower limit
* for this trip point
* If the temperature is lower than a trip point,
* a. if the trend is THERMAL_TREND_RAISING, do nothing
* b. if the trend is THERMAL_TREND_DROPPING, use lower cooling
* state for this trip point, if the cooling state already
* equals lower limit, deactivate the thermal instance
* c. if the trend is THERMAL_TREND_RAISE_FULL, do nothing
* d. if the trend is THERMAL_TREND_DROP_FULL, use lower limit,
* if the cooling state already equals lower limit,
* deactive the thermal instance
*/
static unsigned long get_target_state(struct thermal_instance *instance,
enum thermal_trend trend, bool throttle)
{
struct thermal_cooling_device *cdev = instance->cdev;
unsigned long cur_state;
unsigned long next_target;
/*
* We keep this instance the way it is by default.
* Otherwise, we use the current state of the
* cdev in use to determine the next_target.
*/
cdev->ops->get_cur_state(cdev, &cur_state);
next_target = instance->target;
dev_dbg(&cdev->device, "cur_state=%ld\n", cur_state);
switch (trend) {
case THERMAL_TREND_RAISING:
if (throttle) {
next_target = cur_state < instance->upper ?
(cur_state + 1) : instance->upper;
if (next_target < instance->lower)
next_target = instance->lower;
}
break;
case THERMAL_TREND_RAISE_FULL:
if (throttle)
next_target = instance->upper;
break;
case THERMAL_TREND_DROPPING:
if (cur_state == instance->lower) {
if (!throttle)
next_target = THERMAL_NO_TARGET;
} else {
next_target = cur_state - 1;
if (next_target > instance->upper)
next_target = instance->upper;
}
break;
case THERMAL_TREND_DROP_FULL:
if (cur_state == instance->lower) {
if (!throttle)
next_target = THERMAL_NO_TARGET;
} else
next_target = instance->lower;
break;
default:
break;
}
return next_target;
}
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 thermal_zone_trip_update(struct thermal_zone_device *tz, int trip)
{
long trip_temp;
enum thermal_trip_type trip_type;
enum thermal_trend trend;
struct thermal_instance *instance;
bool throttle = false;
int old_target;
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);
if (tz->temperature >= trip_temp)
throttle = true;
dev_dbg(&tz->device, "Trip%d[type=%d,temp=%ld]:trend=%d,throttle=%d\n",
trip, trip_type, trip_temp, trend, throttle);
mutex_lock(&tz->lock);
list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
if (instance->trip != trip)
continue;
old_target = instance->target;
instance->target = get_target_state(instance, trend, throttle);
dev_dbg(&instance->cdev->device, "old_target=%d, target=%d\n",
old_target, (int)instance->target);
if (old_target == instance->target)
continue;
/* Activate a passive thermal instance */
if (old_target == THERMAL_NO_TARGET &&
instance->target != THERMAL_NO_TARGET)
update_passive_instance(tz, trip_type, 1);
/* Deactivate a passive thermal instance */
else if (old_target != THERMAL_NO_TARGET &&
instance->target == THERMAL_NO_TARGET)
update_passive_instance(tz, trip_type, -1);
instance->cdev->updated = false; /* cdev needs update */
}
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.
*/
static 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;
}
static struct thermal_governor thermal_gov_step_wise = {
.name = "step_wise",
.throttle = step_wise_throttle,
};
int thermal_gov_step_wise_register(void)
{
return thermal_register_governor(&thermal_gov_step_wise);
}
void thermal_gov_step_wise_unregister(void)
{
thermal_unregister_governor(&thermal_gov_step_wise);
}
