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 | |
18 | static 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, trip: thermal_zone_trip_id(tz, trip: level_trip), |
38 | trip_type: level_trip->type); |
39 | |
40 | return trip_level; |
41 | } |
42 | |
43 | static 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 | */ |
68 | static 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 | level: cur_trip_level); |
100 | |
101 | mutex_lock(&cdev->lock); |
102 | __thermal_cdev_update(cdev); |
103 | mutex_unlock(lock: &cdev->lock); |
104 | } |
105 | |
106 | return 0; |
107 | } |
108 | |
109 | static struct thermal_governor thermal_gov_fair_share = { |
110 | .name = "fair_share" , |
111 | .throttle = fair_share_throttle, |
112 | }; |
113 | THERMAL_GOVERNOR_DECLARE(thermal_gov_fair_share); |
114 | |