linux/drivers/thermal/gov_bang_bang.c
Daniel Lezcano 57c5b2ec90 thermal/drivers/core: Use governor table to initialize
Now that the governor table is in place and the macro allows to browse the
table, declare the governor so the entry is added in the governor table
in the init section.

The [un]register_thermal_governors function does no longer need to use the
exported [un]register thermal governor's specific function which in turn
call the [un]register_thermal_governor. The governors are fully
self-encapsulated.

The cyclic dependency is no longer needed, remove it.

Reviewed-by: Amit Kucheria <amit.kucheria@linaro.org>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Zhang Rui <rui.zhang@intel.com>
2019-06-27 21:22:14 +08:00

120 lines
3.3 KiB
C

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