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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 * deactivate 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 if (!instance->initialized) {
67 if (throttle) {
68 next_target = (cur_state + 1) >= instance->upper ?
69 instance->upper :
70 ((cur_state + 1) < instance->lower ?
71 instance->lower : (cur_state + 1));
72 } else {
73 next_target = THERMAL_NO_TARGET;
74 }
75
76 return next_target;
77 }
78
79 switch (trend) {
80 case THERMAL_TREND_RAISING:
81 if (throttle) {
82 next_target = cur_state < instance->upper ?
83 (cur_state + 1) : instance->upper;
84 if (next_target < instance->lower)
85 next_target = instance->lower;
86 }
87 break;
88 case THERMAL_TREND_RAISE_FULL:
89 if (throttle)
90 next_target = instance->upper;
91 break;
92 case THERMAL_TREND_DROPPING:
93 if (cur_state <= instance->lower) {
94 if (!throttle)
95 next_target = THERMAL_NO_TARGET;
96 } else {
97 next_target = cur_state - 1;
98 if (next_target > instance->upper)
99 next_target = instance->upper;
100 }
101 break;
102 case THERMAL_TREND_DROP_FULL:
103 if (cur_state == instance->lower) {
104 if (!throttle)
105 next_target = THERMAL_NO_TARGET;
106 } else
107 next_target = instance->lower;
108 break;
109 default:
110 break;
111 }
112
113 return next_target;
114}
115
116static void update_passive_instance(struct thermal_zone_device *tz,
117 enum thermal_trip_type type, int value)
118{
119 /*
120 * If value is +1, activate a passive instance.
121 * If value is -1, deactivate a passive instance.
122 */
123 if (type == THERMAL_TRIP_PASSIVE || type == THERMAL_TRIPS_NONE)
124 tz->passive += value;
125}
126
127static void thermal_zone_trip_update(struct thermal_zone_device *tz, int trip)
128{
129 int trip_temp;
130 enum thermal_trip_type trip_type;
131 enum thermal_trend trend;
132 struct thermal_instance *instance;
133 bool throttle = false;
134 int old_target;
135
136 if (trip == THERMAL_TRIPS_NONE) {
137 trip_temp = tz->forced_passive;
138 trip_type = THERMAL_TRIPS_NONE;
139 } else {
140 tz->ops->get_trip_temp(tz, trip, &trip_temp);
141 tz->ops->get_trip_type(tz, trip, &trip_type);
142 }
143
144 trend = get_tz_trend(tz, trip);
145
146 if (tz->temperature >= trip_temp) {
147 throttle = true;
148 trace_thermal_zone_trip(tz, trip, trip_type);
149 }
150
151 dev_dbg(&tz->device, "Trip%d[type=%d,temp=%d]:trend=%d,throttle=%d\n",
152 trip, trip_type, trip_temp, trend, throttle);
153
154 mutex_lock(&tz->lock);
155
156 list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
157 if (instance->trip != trip)
158 continue;
159
160 old_target = instance->target;
161 instance->target = get_target_state(instance, trend, throttle);
162 dev_dbg(&instance->cdev->device, "old_target=%d, target=%d\n",
163 old_target, (int)instance->target);
164
165 if (instance->initialized && old_target == instance->target)
166 continue;
167
168 /* Activate a passive thermal instance */
169 if (old_target == THERMAL_NO_TARGET &&
170 instance->target != THERMAL_NO_TARGET)
171 update_passive_instance(tz, trip_type, 1);
172 /* Deactivate a passive thermal instance */
173 else if (old_target != THERMAL_NO_TARGET &&
174 instance->target == THERMAL_NO_TARGET)
175 update_passive_instance(tz, trip_type, -1);
176
177 instance->initialized = true;
178 instance->cdev->updated = false; /* cdev needs update */
179 }
180
181 mutex_unlock(&tz->lock);
182}
183
184/**
185 * step_wise_throttle - throttles devices associated with the given zone
186 * @tz - thermal_zone_device
187 * @trip - the trip point
188 * @trip_type - type of the trip point
189 *
190 * Throttling Logic: This uses the trend of the thermal zone to throttle.
191 * If the thermal zone is 'heating up' this throttles all the cooling
192 * devices associated with the zone and its particular trip point, by one
193 * step. If the zone is 'cooling down' it brings back the performance of
194 * the devices by one step.
195 */
196static int step_wise_throttle(struct thermal_zone_device *tz, int trip)
197{
198 struct thermal_instance *instance;
199
200 thermal_zone_trip_update(tz, trip);
201
202 if (tz->forced_passive)
203 thermal_zone_trip_update(tz, THERMAL_TRIPS_NONE);
204
205 mutex_lock(&tz->lock);
206
207 list_for_each_entry(instance, &tz->thermal_instances, tz_node)
208 thermal_cdev_update(instance->cdev);
209
210 mutex_unlock(&tz->lock);
211
212 return 0;
213}
214
215static struct thermal_governor thermal_gov_step_wise = {
216 .name = "step_wise",
217 .throttle = step_wise_throttle,
218};
219
220int thermal_gov_step_wise_register(void)
221{
222 return thermal_register_governor(&thermal_gov_step_wise);
223}
224
225void thermal_gov_step_wise_unregister(void)
226{
227 thermal_unregister_governor(&thermal_gov_step_wise);
228}