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);
114