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// SPDX-License-Identifier: GPL-2.0-only
/*
* step_wise.c - A step-by-step Thermal throttling governor
*
* Copyright (C) 2012 Intel Corp
* Copyright (C) 2012 Durgadoss R <durgadoss.r@intel.com>
*
* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
*
* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
*/
#include <linux/thermal.h>
#include <linux/minmax.h>
#include "thermal_trace.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, do nothing
* 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
*/
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;
/*
* 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);
dev_dbg(&cdev->device, "cur_state=%ld\n", cur_state);
if (!instance->initialized) {
if (throttle)
return clamp(cur_state + 1, instance->lower, instance->upper);
return THERMAL_NO_TARGET;
}
if (throttle) {
if (trend == THERMAL_TREND_RAISING)
return clamp(cur_state + 1, instance->lower, instance->upper);
} else if (trend == THERMAL_TREND_DROPPING) {
if (cur_state <= instance->lower)
return THERMAL_NO_TARGET;
/*
* If 'throttle' is false, no mitigation is necessary, so
* request the lower state for this instance.
*/
return instance->lower;
}
return instance->target;
}
static void thermal_zone_trip_update(struct thermal_zone_device *tz,
const struct thermal_trip *trip,
int trip_threshold)
{
enum thermal_trend trend = get_tz_trend(tz, trip);
int trip_id = thermal_zone_trip_id(tz, trip);
struct thermal_instance *instance;
bool throttle = false;
if (tz->temperature >= trip_threshold) {
throttle = true;
trace_thermal_zone_trip(tz, trip_id, trip->type);
}
dev_dbg(&tz->device, "Trip%d[type=%d,temp=%d]:trend=%d,throttle=%d\n",
trip_id, trip->type, trip_threshold, trend, throttle);
list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
int old_target;
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=%ld\n",
old_target, instance->target);
if (instance->initialized && old_target == instance->target)
continue;
instance->initialized = true;
mutex_lock(&instance->cdev->lock);
instance->cdev->updated = false; /* cdev needs update */
mutex_unlock(&instance->cdev->lock);
}
}
static void step_wise_manage(struct thermal_zone_device *tz)
{
const struct thermal_trip_desc *td;
struct thermal_instance *instance;
lockdep_assert_held(&tz->lock);
/*
* Throttling Logic: Use the trend of the thermal zone to throttle.
* If the thermal zone is 'heating up', throttle all of the cooling
* devices associated with each trip point by one step. If the zone
* is 'cooling down', it brings back the performance of the devices
* by one step.
*/
for_each_trip_desc(tz, td) {
const struct thermal_trip *trip = &td->trip;
if (trip->temperature == THERMAL_TEMP_INVALID ||
trip->type == THERMAL_TRIP_CRITICAL ||
trip->type == THERMAL_TRIP_HOT)
continue;
thermal_zone_trip_update(tz, trip, td->threshold);
}
list_for_each_entry(instance, &tz->thermal_instances, tz_node)
thermal_cdev_update(instance->cdev);
}
static struct thermal_governor thermal_gov_step_wise = {
.name = "step_wise",
.manage = step_wise_manage,
};
THERMAL_GOVERNOR_DECLARE(thermal_gov_step_wise);
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