1 | // SPDX-License-Identifier: GPL-2.0-only |
2 | /* |
3 | * step_wise.c - A step-by-step Thermal throttling 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 <linux/minmax.h> |
15 | #include "thermal_trace.h" |
16 | |
17 | #include "thermal_core.h" |
18 | |
19 | /* |
20 | * If the temperature is higher than a trip point, |
21 | * a. if the trend is THERMAL_TREND_RAISING, use higher cooling |
22 | * state for this trip point |
23 | * b. if the trend is THERMAL_TREND_DROPPING, do nothing |
24 | * If the temperature is lower than a trip point, |
25 | * a. if the trend is THERMAL_TREND_RAISING, do nothing |
26 | * b. if the trend is THERMAL_TREND_DROPPING, use lower cooling |
27 | * state for this trip point, if the cooling state already |
28 | * equals lower limit, deactivate the thermal instance |
29 | */ |
30 | static unsigned long get_target_state(struct thermal_instance *instance, |
31 | enum thermal_trend trend, bool throttle) |
32 | { |
33 | struct thermal_cooling_device *cdev = instance->cdev; |
34 | unsigned long cur_state; |
35 | unsigned long next_target; |
36 | |
37 | /* |
38 | * We keep this instance the way it is by default. |
39 | * Otherwise, we use the current state of the |
40 | * cdev in use to determine the next_target. |
41 | */ |
42 | cdev->ops->get_cur_state(cdev, &cur_state); |
43 | next_target = instance->target; |
44 | dev_dbg(&cdev->device, "cur_state=%ld\n" , cur_state); |
45 | |
46 | if (!instance->initialized) { |
47 | if (throttle) { |
48 | next_target = clamp((cur_state + 1), instance->lower, instance->upper); |
49 | } else { |
50 | next_target = THERMAL_NO_TARGET; |
51 | } |
52 | |
53 | return next_target; |
54 | } |
55 | |
56 | if (throttle) { |
57 | if (trend == THERMAL_TREND_RAISING) |
58 | next_target = clamp((cur_state + 1), instance->lower, instance->upper); |
59 | } else { |
60 | if (trend == THERMAL_TREND_DROPPING) { |
61 | if (cur_state <= instance->lower) |
62 | next_target = THERMAL_NO_TARGET; |
63 | else |
64 | next_target = clamp((cur_state - 1), instance->lower, instance->upper); |
65 | } |
66 | } |
67 | |
68 | return next_target; |
69 | } |
70 | |
71 | static void thermal_zone_trip_update(struct thermal_zone_device *tz, |
72 | const struct thermal_trip *trip) |
73 | { |
74 | int trip_id = thermal_zone_trip_id(tz, trip); |
75 | enum thermal_trend trend; |
76 | struct thermal_instance *instance; |
77 | bool throttle = false; |
78 | int old_target; |
79 | |
80 | trend = get_tz_trend(tz, trip); |
81 | |
82 | if (tz->temperature >= trip->temperature) { |
83 | throttle = true; |
84 | trace_thermal_zone_trip(tz, trip: trip_id, trip_type: trip->type); |
85 | } |
86 | |
87 | dev_dbg(&tz->device, "Trip%d[type=%d,temp=%d]:trend=%d,throttle=%d\n" , |
88 | trip_id, trip->type, trip->temperature, trend, throttle); |
89 | |
90 | list_for_each_entry(instance, &tz->thermal_instances, tz_node) { |
91 | if (instance->trip != trip) |
92 | continue; |
93 | |
94 | old_target = instance->target; |
95 | instance->target = get_target_state(instance, trend, throttle); |
96 | dev_dbg(&instance->cdev->device, "old_target=%d, target=%d\n" , |
97 | old_target, (int)instance->target); |
98 | |
99 | if (instance->initialized && old_target == instance->target) |
100 | continue; |
101 | |
102 | if (old_target == THERMAL_NO_TARGET && |
103 | instance->target != THERMAL_NO_TARGET) { |
104 | /* Activate a passive thermal instance */ |
105 | if (trip->type == THERMAL_TRIP_PASSIVE) |
106 | tz->passive++; |
107 | } else if (old_target != THERMAL_NO_TARGET && |
108 | instance->target == THERMAL_NO_TARGET) { |
109 | /* Deactivate a passive thermal instance */ |
110 | if (trip->type == THERMAL_TRIP_PASSIVE) |
111 | tz->passive--; |
112 | } |
113 | |
114 | instance->initialized = true; |
115 | mutex_lock(&instance->cdev->lock); |
116 | instance->cdev->updated = false; /* cdev needs update */ |
117 | mutex_unlock(lock: &instance->cdev->lock); |
118 | } |
119 | } |
120 | |
121 | /** |
122 | * step_wise_throttle - throttles devices associated with the given zone |
123 | * @tz: thermal_zone_device |
124 | * @trip: trip point |
125 | * |
126 | * Throttling Logic: This uses the trend of the thermal zone to throttle. |
127 | * If the thermal zone is 'heating up' this throttles all the cooling |
128 | * devices associated with the zone and its particular trip point, by one |
129 | * step. If the zone is 'cooling down' it brings back the performance of |
130 | * the devices by one step. |
131 | */ |
132 | static int step_wise_throttle(struct thermal_zone_device *tz, |
133 | const struct thermal_trip *trip) |
134 | { |
135 | struct thermal_instance *instance; |
136 | |
137 | lockdep_assert_held(&tz->lock); |
138 | |
139 | thermal_zone_trip_update(tz, trip); |
140 | |
141 | list_for_each_entry(instance, &tz->thermal_instances, tz_node) |
142 | thermal_cdev_update(instance->cdev); |
143 | |
144 | return 0; |
145 | } |
146 | |
147 | static struct thermal_governor thermal_gov_step_wise = { |
148 | .name = "step_wise" , |
149 | .throttle = step_wise_throttle, |
150 | }; |
151 | THERMAL_GOVERNOR_DECLARE(thermal_gov_step_wise); |
152 | |