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	mutex_lock(&tz->lock);
86
87	list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
88		if (instance->trip != trip)
89			continue;
90
91		total_weight += instance->weight;
92		total_instance++;
93	}
94
95	list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
96		int percentage;
97		struct thermal_cooling_device *cdev = instance->cdev;
98
99		if (instance->trip != trip)
100			continue;
101
102		if (!total_weight)
103			percentage = 100 / total_instance;
104		else
105			percentage = (instance->weight * 100) / total_weight;
106
107		instance->target = get_target_state(tz, cdev, percentage,
108						    cur_trip_level);
109
110		mutex_lock(&instance->cdev->lock);
111		instance->cdev->updated = false;
112		mutex_unlock(&instance->cdev->lock);
113		thermal_cdev_update(cdev);
114	}
115
116	mutex_unlock(&tz->lock);
117	return 0;
118}
119
120static struct thermal_governor thermal_gov_fair_share = {
121	.name		= "fair_share",
122	.throttle	= fair_share_throttle,
123};
124THERMAL_GOVERNOR_DECLARE(thermal_gov_fair_share);
125