Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
os
linux
1/*
2 * step_wise.c - A step-by-step Thermal throttling governor
3 *
4 * Copyright (C) 2012 Intel Corp
5 * Copyright (C) 2012 Durgadoss R <durgadoss.r@intel.com>
6 *
7 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
8 *
9 * This program is free software; you can redistribute it and/or modify
10 * it under the terms of the GNU General Public License as published by
11 * the Free Software Foundation; version 2 of the License.
12 *
13 * This program is distributed in the hope that it will be useful, but
14 * WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 * General Public License for more details.
17 *
18 * You should have received a copy of the GNU General Public License along
19 * with this program; if not, write to the Free Software Foundation, Inc.,
20 * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
21 *
22 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
23 */
24
25#include <linux/thermal.h>
26#include <trace/events/thermal.h>
27
28#include "thermal_core.h"
29
30/*
31 * If the temperature is higher than a trip point,
32 * a. if the trend is THERMAL_TREND_RAISING, use higher cooling
33 * state for this trip point
34 * b. if the trend is THERMAL_TREND_DROPPING, use lower cooling
35 * state for this trip point
36 * c. if the trend is THERMAL_TREND_RAISE_FULL, use upper limit
37 * for this trip point
38 * d. if the trend is THERMAL_TREND_DROP_FULL, use lower limit
39 * for this trip point
40 * If the temperature is lower than a trip point,
41 * a. if the trend is THERMAL_TREND_RAISING, do nothing
42 * b. if the trend is THERMAL_TREND_DROPPING, use lower cooling
43 * state for this trip point, if the cooling state already
44 * equals lower limit, deactivate the thermal instance
45 * c. if the trend is THERMAL_TREND_RAISE_FULL, do nothing
46 * d. if the trend is THERMAL_TREND_DROP_FULL, use lower limit,
47 * if the cooling state already equals lower limit,
48 * deactive the thermal instance
49 */
50static unsigned long get_target_state(struct thermal_instance *instance,
51 enum thermal_trend trend, bool throttle)
52{
53 struct thermal_cooling_device *cdev = instance->cdev;
54 unsigned long cur_state;
55 unsigned long next_target;
56
57 /*
58 * We keep this instance the way it is by default.
59 * Otherwise, we use the current state of the
60 * cdev in use to determine the next_target.
61 */
62 cdev->ops->get_cur_state(cdev, &cur_state);
63 next_target = instance->target;
64 dev_dbg(&cdev->device, "cur_state=%ld\n", cur_state);
65
66 switch (trend) {
67 case THERMAL_TREND_RAISING:
68 if (throttle) {
69 next_target = cur_state < instance->upper ?
70 (cur_state + 1) : instance->upper;
71 if (next_target < instance->lower)
72 next_target = instance->lower;
73 }
74 break;
75 case THERMAL_TREND_RAISE_FULL:
76 if (throttle)
77 next_target = instance->upper;
78 break;
79 case THERMAL_TREND_DROPPING:
80 if (cur_state <= instance->lower) {
81 if (!throttle)
82 next_target = THERMAL_NO_TARGET;
83 } else {
84 next_target = cur_state - 1;
85 if (next_target > instance->upper)
86 next_target = instance->upper;
87 }
88 break;
89 case THERMAL_TREND_DROP_FULL:
90 if (cur_state == instance->lower) {
91 if (!throttle)
92 next_target = THERMAL_NO_TARGET;
93 } else
94 next_target = instance->lower;
95 break;
96 default:
97 break;
98 }
99
100 return next_target;
101}
102
103static void update_passive_instance(struct thermal_zone_device *tz,
104 enum thermal_trip_type type, int value)
105{
106 /*
107 * If value is +1, activate a passive instance.
108 * If value is -1, deactivate a passive instance.
109 */
110 if (type == THERMAL_TRIP_PASSIVE || type == THERMAL_TRIPS_NONE)
111 tz->passive += value;
112}
113
114static void thermal_zone_trip_update(struct thermal_zone_device *tz, int trip)
115{
116 long trip_temp;
117 enum thermal_trip_type trip_type;
118 enum thermal_trend trend;
119 struct thermal_instance *instance;
120 bool throttle = false;
121 int old_target;
122
123 if (trip == THERMAL_TRIPS_NONE) {
124 trip_temp = tz->forced_passive;
125 trip_type = THERMAL_TRIPS_NONE;
126 } else {
127 tz->ops->get_trip_temp(tz, trip, &trip_temp);
128 tz->ops->get_trip_type(tz, trip, &trip_type);
129 }
130
131 trend = get_tz_trend(tz, trip);
132
133 if (tz->temperature >= trip_temp) {
134 throttle = true;
135 trace_thermal_zone_trip(tz, trip, trip_type);
136 }
137
138 dev_dbg(&tz->device, "Trip%d[type=%d,temp=%ld]:trend=%d,throttle=%d\n",
139 trip, trip_type, trip_temp, trend, throttle);
140
141 mutex_lock(&tz->lock);
142
143 list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
144 if (instance->trip != trip)
145 continue;
146
147 old_target = instance->target;
148 instance->target = get_target_state(instance, trend, throttle);
149 dev_dbg(&instance->cdev->device, "old_target=%d, target=%d\n",
150 old_target, (int)instance->target);
151
152 if (old_target == instance->target)
153 continue;
154
155 /* Activate a passive thermal instance */
156 if (old_target == THERMAL_NO_TARGET &&
157 instance->target != THERMAL_NO_TARGET)
158 update_passive_instance(tz, trip_type, 1);
159 /* Deactivate a passive thermal instance */
160 else if (old_target != THERMAL_NO_TARGET &&
161 instance->target == THERMAL_NO_TARGET)
162 update_passive_instance(tz, trip_type, -1);
163
164
165 instance->cdev->updated = false; /* cdev needs update */
166 }
167
168 mutex_unlock(&tz->lock);
169}
170
171/**
172 * step_wise_throttle - throttles devices asscciated with the given zone
173 * @tz - thermal_zone_device
174 * @trip - the trip point
175 * @trip_type - type of the trip point
176 *
177 * Throttling Logic: This uses the trend of the thermal zone to throttle.
178 * If the thermal zone is 'heating up' this throttles all the cooling
179 * devices associated with the zone and its particular trip point, by one
180 * step. If the zone is 'cooling down' it brings back the performance of
181 * the devices by one step.
182 */
183static int step_wise_throttle(struct thermal_zone_device *tz, int trip)
184{
185 struct thermal_instance *instance;
186
187 thermal_zone_trip_update(tz, trip);
188
189 if (tz->forced_passive)
190 thermal_zone_trip_update(tz, THERMAL_TRIPS_NONE);
191
192 mutex_lock(&tz->lock);
193
194 list_for_each_entry(instance, &tz->thermal_instances, tz_node)
195 thermal_cdev_update(instance->cdev);
196
197 mutex_unlock(&tz->lock);
198
199 return 0;
200}
201
202static struct thermal_governor thermal_gov_step_wise = {
203 .name = "step_wise",
204 .throttle = step_wise_throttle,
205};
206
207int thermal_gov_step_wise_register(void)
208{
209 return thermal_register_governor(&thermal_gov_step_wise);
210}
211
212void thermal_gov_step_wise_unregister(void)
213{
214 thermal_unregister_governor(&thermal_gov_step_wise);
215}