/*
* 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.
*/
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,
.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");
