1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 *  fair_share.c - A simple weight based Thermal governor
  4 *
  5 *  Copyright (C) 2012 Intel Corp
  6 *  Copyright (C) 2012 Durgadoss R <durgadoss.r@intel.com>
  7 *
  8 *  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  9 *
 10 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 11 */
 12
 13#include <linux/thermal.h>
 14#include "thermal_trace.h"
 15
 16#include "thermal_core.h"
 17
 18static int get_trip_level(struct thermal_zone_device *tz)
 19{
 20	const struct thermal_trip *trip, *level_trip = NULL;
 21	int trip_level = -1;
 22
 23	for_each_trip(tz, trip) {
 24		if (trip->temperature >= tz->temperature)
 25			continue;
 26
 27		trip_level++;
 28
 29		if (!level_trip || trip->temperature > level_trip->temperature)
 30			level_trip = trip;
 31	}
 32
 33	/*  Bail out if the temperature is not greater than any trips. */
 34	if (trip_level < 0)
 35		return 0;
 36
 37	trace_thermal_zone_trip(tz, thermal_zone_trip_id(tz, level_trip),
 38				level_trip->type);
 39
 40	return trip_level;
 41}
 42
 43static long get_target_state(struct thermal_zone_device *tz,
 44		struct thermal_cooling_device *cdev, int percentage, int level)
 45{
 46	return (long)(percentage * level * cdev->max_state) / (100 * tz->num_trips);
 47}
 48
 49/**
 50 * fair_share_throttle - throttles devices associated with the given zone
 51 * @tz: thermal_zone_device
 52 * @trip: trip point
 53 *
 54 * Throttling Logic: This uses three parameters to calculate the new
 55 * throttle state of the cooling devices associated with the given zone.
 56 *
 57 * Parameters used for Throttling:
 58 * P1. max_state: Maximum throttle state exposed by the cooling device.
 59 * P2. percentage[i]/100:
 60 *	How 'effective' the 'i'th device is, in cooling the given zone.
 61 * P3. cur_trip_level/max_no_of_trips:
 62 *	This describes the extent to which the devices should be throttled.
 63 *	We do not want to throttle too much when we trip a lower temperature,
 64 *	whereas the throttling is at full swing if we trip critical levels.
 65 *	(Heavily assumes the trip points are in ascending order)
 66 * new_state of cooling device = P3 * P2 * P1
 67 */
 68static int fair_share_throttle(struct thermal_zone_device *tz,
 69			       const struct thermal_trip *trip)
 70{
 71	struct thermal_instance *instance;
 72	int total_weight = 0;
 73	int total_instance = 0;
 74	int cur_trip_level = get_trip_level(tz);
 75
 76	lockdep_assert_held(&tz->lock);
 77
 78	list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
 79		if (instance->trip != trip)
 80			continue;
 81
 82		total_weight += instance->weight;
 83		total_instance++;
 84	}
 85
 86	list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
 87		int percentage;
 88		struct thermal_cooling_device *cdev = instance->cdev;
 89
 90		if (instance->trip != trip)
 91			continue;
 92
 93		if (!total_weight)
 94			percentage = 100 / total_instance;
 95		else
 96			percentage = (instance->weight * 100) / total_weight;
 97
 98		instance->target = get_target_state(tz, cdev, percentage,
 99						    cur_trip_level);
100
101		mutex_lock(&cdev->lock);
102		__thermal_cdev_update(cdev);
103		mutex_unlock(&cdev->lock);
104	}
105
106	return 0;
107}
108
109static struct thermal_governor thermal_gov_fair_share = {
110	.name		= "fair_share",
111	.throttle	= fair_share_throttle,
112};
113THERMAL_GOVERNOR_DECLARE(thermal_gov_fair_share);