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 */
get_target_state(struct thermal_instance * instance,enum thermal_trend trend,bool throttle)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
update_passive_instance(struct thermal_zone_device * tz,enum thermal_trip_type type,int value)71 static void update_passive_instance(struct thermal_zone_device *tz,
72 enum thermal_trip_type type, int value)
73 {
74 /*
75 * If value is +1, activate a passive instance.
76 * If value is -1, deactivate a passive instance.
77 */
78 if (type == THERMAL_TRIP_PASSIVE)
79 tz->passive += value;
80 }
81
thermal_zone_trip_update(struct thermal_zone_device * tz,int trip_id)82 static void thermal_zone_trip_update(struct thermal_zone_device *tz, int trip_id)
83 {
84 const struct thermal_trip *trip = &tz->trips[trip_id];
85 enum thermal_trend trend;
86 struct thermal_instance *instance;
87 bool throttle = false;
88 int old_target;
89
90 trend = get_tz_trend(tz, trip_id);
91
92 if (tz->temperature >= trip->temperature) {
93 throttle = true;
94 trace_thermal_zone_trip(tz, trip_id, trip->type);
95 }
96
97 dev_dbg(&tz->device, "Trip%d[type=%d,temp=%d]:trend=%d,throttle=%d\n",
98 trip_id, trip->type, trip->temperature, trend, throttle);
99
100 list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
101 if (instance->trip != trip)
102 continue;
103
104 old_target = instance->target;
105 instance->target = get_target_state(instance, trend, throttle);
106 dev_dbg(&instance->cdev->device, "old_target=%d, target=%d\n",
107 old_target, (int)instance->target);
108
109 if (instance->initialized && old_target == instance->target)
110 continue;
111
112 /* Activate a passive thermal instance */
113 if (old_target == THERMAL_NO_TARGET &&
114 instance->target != THERMAL_NO_TARGET)
115 update_passive_instance(tz, trip->type, 1);
116 /* Deactivate a passive thermal instance */
117 else if (old_target != THERMAL_NO_TARGET &&
118 instance->target == THERMAL_NO_TARGET)
119 update_passive_instance(tz, trip->type, -1);
120
121 instance->initialized = true;
122 mutex_lock(&instance->cdev->lock);
123 instance->cdev->updated = false; /* cdev needs update */
124 mutex_unlock(&instance->cdev->lock);
125 }
126 }
127
128 /**
129 * step_wise_throttle - throttles devices associated with the given zone
130 * @tz: thermal_zone_device
131 * @trip: trip point index
132 *
133 * Throttling Logic: This uses the trend of the thermal zone to throttle.
134 * If the thermal zone is 'heating up' this throttles all the cooling
135 * devices associated with the zone and its particular trip point, by one
136 * step. If the zone is 'cooling down' it brings back the performance of
137 * the devices by one step.
138 */
step_wise_throttle(struct thermal_zone_device * tz,int trip)139 static int step_wise_throttle(struct thermal_zone_device *tz, int trip)
140 {
141 struct thermal_instance *instance;
142
143 lockdep_assert_held(&tz->lock);
144
145 thermal_zone_trip_update(tz, trip);
146
147 list_for_each_entry(instance, &tz->thermal_instances, tz_node)
148 thermal_cdev_update(instance->cdev);
149
150 return 0;
151 }
152
153 static struct thermal_governor thermal_gov_step_wise = {
154 .name = "step_wise",
155 .throttle = step_wise_throttle,
156 };
157 THERMAL_GOVERNOR_DECLARE(thermal_gov_step_wise);
158