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