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119 lines
3.3 KiB
119 lines
3.3 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* |
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* gov_bang_bang.c - A simple thermal throttling governor using hysteresis |
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* |
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* Copyright (C) 2014 Peter Kaestle <[email protected]> |
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* |
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* Based on step_wise.c with following Copyrights: |
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* Copyright (C) 2012 Intel Corp |
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* Copyright (C) 2012 Durgadoss R <[email protected]> |
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*/ |
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#include <linux/thermal.h> |
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#include "thermal_core.h" |
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static void thermal_zone_trip_update(struct thermal_zone_device *tz, int trip) |
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{ |
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int trip_temp, trip_hyst; |
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struct thermal_instance *instance; |
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tz->ops->get_trip_temp(tz, trip, &trip_temp); |
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if (!tz->ops->get_trip_hyst) { |
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pr_warn_once("Undefined get_trip_hyst for thermal zone %s - " |
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"running with default hysteresis zero\n", tz->type); |
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trip_hyst = 0; |
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} else |
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tz->ops->get_trip_hyst(tz, trip, &trip_hyst); |
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dev_dbg(&tz->device, "Trip%d[temp=%d]:temp=%d:hyst=%d\n", |
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trip, trip_temp, tz->temperature, |
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trip_hyst); |
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mutex_lock(&tz->lock); |
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list_for_each_entry(instance, &tz->thermal_instances, tz_node) { |
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if (instance->trip != trip) |
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continue; |
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/* in case fan is in initial state, switch the fan off */ |
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if (instance->target == THERMAL_NO_TARGET) |
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instance->target = 0; |
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/* in case fan is neither on nor off set the fan to active */ |
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if (instance->target != 0 && instance->target != 1) { |
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pr_warn("Thermal instance %s controlled by bang-bang has unexpected state: %ld\n", |
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instance->name, instance->target); |
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instance->target = 1; |
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} |
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/* |
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* enable fan when temperature exceeds trip_temp and disable |
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* the fan in case it falls below trip_temp minus hysteresis |
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*/ |
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if (instance->target == 0 && tz->temperature >= trip_temp) |
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instance->target = 1; |
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else if (instance->target == 1 && |
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tz->temperature <= trip_temp - trip_hyst) |
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instance->target = 0; |
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dev_dbg(&instance->cdev->device, "target=%d\n", |
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(int)instance->target); |
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mutex_lock(&instance->cdev->lock); |
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instance->cdev->updated = false; /* cdev needs update */ |
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mutex_unlock(&instance->cdev->lock); |
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} |
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mutex_unlock(&tz->lock); |
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} |
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/** |
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* bang_bang_control - controls devices associated with the given zone |
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* @tz: thermal_zone_device |
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* @trip: the trip point |
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* |
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* Regulation Logic: a two point regulation, deliver cooling state depending |
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* on the previous state shown in this diagram: |
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* |
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* Fan: OFF ON |
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* |
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* | |
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* | |
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* trip_temp: +---->+ |
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* | | ^ |
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* | | | |
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* | | Temperature |
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* (trip_temp - hyst): +<----+ |
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* | |
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* | |
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* | |
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* |
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* * If the fan is not running and temperature exceeds trip_temp, the fan |
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* gets turned on. |
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* * In case the fan is running, temperature must fall below |
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* (trip_temp - hyst) so that the fan gets turned off again. |
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* |
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*/ |
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static int bang_bang_control(struct thermal_zone_device *tz, int trip) |
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{ |
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struct thermal_instance *instance; |
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thermal_zone_trip_update(tz, trip); |
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mutex_lock(&tz->lock); |
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list_for_each_entry(instance, &tz->thermal_instances, tz_node) |
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thermal_cdev_update(instance->cdev); |
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mutex_unlock(&tz->lock); |
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return 0; |
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} |
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static struct thermal_governor thermal_gov_bang_bang = { |
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.name = "bang_bang", |
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.throttle = bang_bang_control, |
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}; |
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THERMAL_GOVERNOR_DECLARE(thermal_gov_bang_bang);
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