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[ Upstream commit2c7b4bfade] Replace the integer trip number stored in struct thermal_instance with a pointer to the relevant trip and adjust the code using the structure in question accordingly. The main reason for making this change is to allow the trip point to cooling device binding code more straightforward, as illustrated by subsequent modifications of the ACPI thermal driver, but it also helps to clarify the overall design and allows the governor code overhead to be reduced (through subsequent modifications). The only case in which it adds complexity is trip_point_show() that needs to walk the trips[] table to find the index of the given trip point, but this is not a critical path and the interface that trip_point_show() belongs to is problematic anyway (for instance, it doesn't cover the case when the same cooling devices is associated with multiple trip points). This is a preliminary change and the affected code will be refined by a series of subsequent modifications of thermal governors, the core and the ACPI thermal driver. The general functionality is not expected to be affected by this change. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Reviewed-by: Daniel Lezcano <daniel.lezcano@linaro.org> Stable-dep-of:e95fa74047("thermal: gov_power_allocator: avoid inability to reset a cdev") Signed-off-by: Sasha Levin <sashal@kernel.org>
114 lines
3.2 KiB
C
114 lines
3.2 KiB
C
// 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 <peter@piie.net>
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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 <durgadoss.r@intel.com>
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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 int thermal_zone_trip_update(struct thermal_zone_device *tz, int trip_index)
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{
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const struct thermal_trip *trip = &tz->trips[trip_index];
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struct thermal_instance *instance;
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if (!trip->hysteresis)
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dev_info_once(&tz->device,
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"Zero hysteresis value for thermal zone %s\n", tz->type);
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dev_dbg(&tz->device, "Trip%d[temp=%d]:temp=%d:hyst=%d\n",
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trip_index, trip->temperature, tz->temperature,
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trip->hysteresis);
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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->temperature)
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instance->target = 1;
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else if (instance->target == 1 &&
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tz->temperature <= trip->temperature - trip->hysteresis)
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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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return 0;
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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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int ret;
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lockdep_assert_held(&tz->lock);
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ret = thermal_zone_trip_update(tz, trip);
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if (ret)
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return ret;
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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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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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