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// SPDX-License-Identifier: GPL-2.0-only
/*
* fair_share.c - A simple weight based Thermal governor
*
* Copyright (C) 2012 Intel Corp
* Copyright (C) 2012 Durgadoss R <durgadoss.r@intel.com>
*
* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
*
* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
*/
#include <linux/thermal.h>
#include "thermal_trace.h"
#include "thermal_core.h"
static int get_trip_level(struct thermal_zone_device *tz)
{
const struct thermal_trip_desc *level_td = NULL;
const struct thermal_trip_desc *td;
int trip_level = -1;
for_each_trip_desc(tz, td) {
if (td->threshold > tz->temperature)
continue;
trip_level++;
if (!level_td || td->threshold > level_td->threshold)
level_td = td;
}
/* Bail out if the temperature is not greater than any trips. */
if (trip_level < 0)
return 0;
trace_thermal_zone_trip(tz, thermal_zone_trip_id(tz, &level_td->trip),
level_td->trip.type);
return trip_level;
}
/**
* fair_share_throttle - throttles devices associated with the given zone
* @tz: thermal_zone_device
* @trip: trip point
* @trip_level: number of trips crossed by the zone temperature
*
* Throttling Logic: This uses three parameters to calculate the new
* throttle state of the cooling devices associated with the given zone.
*
* Parameters used for Throttling:
* P1. max_state: Maximum throttle state exposed by the cooling device.
* P2. weight[i]/total_weight:
* How 'effective' the 'i'th device is, in cooling the given zone.
* P3. trip_level/max_no_of_trips:
* This describes the extent to which the devices should be throttled.
* We do not want to throttle too much when we trip a lower temperature,
* whereas the throttling is at full swing if we trip critical levels.
* new_state of cooling device = P3 * P2 * P1
*/
static void fair_share_throttle(struct thermal_zone_device *tz,
const struct thermal_trip *trip,
int trip_level)
{
struct thermal_instance *instance;
int total_weight = 0;
int nr_instances = 0;
list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
if (instance->trip != trip)
continue;
total_weight += instance->weight;
nr_instances++;
}
list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
struct thermal_cooling_device *cdev = instance->cdev;
u64 dividend;
u32 divisor;
if (instance->trip != trip)
continue;
dividend = trip_level;
dividend *= cdev->max_state;
divisor = tz->num_trips;
if (total_weight) {
dividend *= instance->weight;
divisor *= total_weight;
} else {
divisor *= nr_instances;
}
instance->target = div_u64(dividend, divisor);
mutex_lock(&cdev->lock);
__thermal_cdev_update(cdev);
mutex_unlock(&cdev->lock);
}
}
static void fair_share_manage(struct thermal_zone_device *tz)
{
int trip_level = get_trip_level(tz);
const struct thermal_trip_desc *td;
lockdep_assert_held(&tz->lock);
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;
fair_share_throttle(tz, trip, trip_level);
}
}
static struct thermal_governor thermal_gov_fair_share = {
.name = "fair_share",
.manage = fair_share_manage,
};
THERMAL_GOVERNOR_DECLARE(thermal_gov_fair_share);
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