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 <trace/events/thermal.h>
 15
 16#include "thermal_core.h"
 17
 18/**
 19 * get_trip_level: - obtains the current trip level for a zone
 20 * @tz:		thermal zone device
 21 */
 22static int get_trip_level(struct thermal_zone_device *tz)
 23{
 24	int count = 0;
 25	int trip_temp;
 26	enum thermal_trip_type trip_type;
 27
 28	if (tz->trips == 0 || !tz->ops->get_trip_temp)
 29		return 0;
 30
 31	for (count = 0; count < tz->trips; count++) {
 32		tz->ops->get_trip_temp(tz, count, &trip_temp);
 33		if (tz->temperature < trip_temp)
 34			break;
 35	}
 36
 37	/*
 38	 * count > 0 only if temperature is greater than first trip
 39	 * point, in which case, trip_point = count - 1
 40	 */
 41	if (count > 0) {
 42		tz->ops->get_trip_type(tz, count - 1, &trip_type);
 43		trace_thermal_zone_trip(tz, count - 1, trip_type);
 44	}
 45
 46	return count;
 47}
 48
 49static long get_target_state(struct thermal_zone_device *tz,
 50		struct thermal_cooling_device *cdev, int percentage, int level)
 51{
 52	unsigned long max_state;
 53
 54	cdev->ops->get_max_state(cdev, &max_state);
 55
 56	return (long)(percentage * level * max_state) / (100 * tz->trips);
 57}
 58
 59/**
 60 * fair_share_throttle - throttles devices associated with the given zone
 61 * @tz - thermal_zone_device
 62 * @trip - trip point index
 63 *
 64 * Throttling Logic: This uses three parameters to calculate the new
 65 * throttle state of the cooling devices associated with the given zone.
 66 *
 67 * Parameters used for Throttling:
 68 * P1. max_state: Maximum throttle state exposed by the cooling device.
 69 * P2. percentage[i]/100:
 70 *	How 'effective' the 'i'th device is, in cooling the given zone.
 71 * P3. cur_trip_level/max_no_of_trips:
 72 *	This describes the extent to which the devices should be throttled.
 73 *	We do not want to throttle too much when we trip a lower temperature,
 74 *	whereas the throttling is at full swing if we trip critical levels.
 75 *	(Heavily assumes the trip points are in ascending order)
 76 * new_state of cooling device = P3 * P2 * P1
 77 */
 78static int fair_share_throttle(struct thermal_zone_device *tz, int trip)
 79{
 80	struct thermal_instance *instance;
 81	int total_weight = 0;
 82	int total_instance = 0;
 83	int cur_trip_level = get_trip_level(tz);
 84
 85	list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
 86		if (instance->trip != trip)
 87			continue;
 88
 89		total_weight += instance->weight;
 90		total_instance++;
 91	}
 92
 93	list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
 94		int percentage;
 95		struct thermal_cooling_device *cdev = instance->cdev;
 96
 97		if (instance->trip != trip)
 98			continue;
 99
100		if (!total_weight)
101			percentage = 100 / total_instance;
102		else
103			percentage = (instance->weight * 100) / total_weight;
104
105		instance->target = get_target_state(tz, cdev, percentage,
106						    cur_trip_level);
107
108		mutex_lock(&instance->cdev->lock);
109		instance->cdev->updated = false;
110		mutex_unlock(&instance->cdev->lock);
111		thermal_cdev_update(cdev);
112	}
113	return 0;
114}
115
116static struct thermal_governor thermal_gov_fair_share = {
117	.name		= "fair_share",
118	.throttle	= fair_share_throttle,
119};
120THERMAL_GOVERNOR_DECLARE(thermal_gov_fair_share);