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