tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
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linux
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->num_trips == 0 || !tz->ops->get_trip_temp)
29 return 0;
30
31 for (count = 0; count < tz->num_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 return (long)(percentage * level * cdev->max_state) / (100 * tz->num_trips);
53}
54
55/**
56 * fair_share_throttle - throttles devices associated with the given zone
57 * @tz: thermal_zone_device
58 * @trip: trip point index
59 *
60 * Throttling Logic: This uses three parameters to calculate the new
61 * throttle state of the cooling devices associated with the given zone.
62 *
63 * Parameters used for Throttling:
64 * P1. max_state: Maximum throttle state exposed by the cooling device.
65 * P2. percentage[i]/100:
66 * How 'effective' the 'i'th device is, in cooling the given zone.
67 * P3. cur_trip_level/max_no_of_trips:
68 * This describes the extent to which the devices should be throttled.
69 * We do not want to throttle too much when we trip a lower temperature,
70 * whereas the throttling is at full swing if we trip critical levels.
71 * (Heavily assumes the trip points are in ascending order)
72 * new_state of cooling device = P3 * P2 * P1
73 */
74static int fair_share_throttle(struct thermal_zone_device *tz, int trip)
75{
76 struct thermal_instance *instance;
77 int total_weight = 0;
78 int total_instance = 0;
79 int cur_trip_level = get_trip_level(tz);
80
81 lockdep_assert_held(&tz->lock);
82
83 list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
84 if (instance->trip != trip)
85 continue;
86
87 total_weight += instance->weight;
88 total_instance++;
89 }
90
91 list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
92 int percentage;
93 struct thermal_cooling_device *cdev = instance->cdev;
94
95 if (instance->trip != trip)
96 continue;
97
98 if (!total_weight)
99 percentage = 100 / total_instance;
100 else
101 percentage = (instance->weight * 100) / total_weight;
102
103 instance->target = get_target_state(tz, cdev, percentage,
104 cur_trip_level);
105
106 mutex_lock(&cdev->lock);
107 __thermal_cdev_update(cdev);
108 mutex_unlock(&cdev->lock);
109 }
110
111 return 0;
112}
113
114static struct thermal_governor thermal_gov_fair_share = {
115 .name = "fair_share",
116 .throttle = fair_share_throttle,
117};
118THERMAL_GOVERNOR_DECLARE(thermal_gov_fair_share);