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, do nothing
35 * c. if the trend is THERMAL_TREND_RAISE_FULL, use upper limit
36 * for this trip point
37 * d. if the trend is THERMAL_TREND_DROP_FULL, use lower limit
38 * for this trip point
39 * If the temperature is lower than a trip point,
40 * a. if the trend is THERMAL_TREND_RAISING, do nothing
41 * b. if the trend is THERMAL_TREND_DROPPING, use lower cooling
42 * state for this trip point, if the cooling state already
43 * equals lower limit, deactivate the thermal instance
44 * c. if the trend is THERMAL_TREND_RAISE_FULL, do nothing
45 * d. if the trend is THERMAL_TREND_DROP_FULL, use lower limit,
46 * if the cooling state already equals lower limit,
47 * deactivate the thermal instance
48 */
get_target_state(struct thermal_instance * instance,enum thermal_trend trend,bool throttle)49 static unsigned long get_target_state(struct thermal_instance *instance,
50 enum thermal_trend trend, bool throttle)
51 {
52 struct thermal_cooling_device *cdev = instance->cdev;
53 unsigned long cur_state;
54 unsigned long next_target;
55
56 /*
57 * We keep this instance the way it is by default.
58 * Otherwise, we use the current state of the
59 * cdev in use to determine the next_target.
60 */
61 cdev->ops->get_cur_state(cdev, &cur_state);
62 next_target = instance->target;
63 dev_dbg(&cdev->device, "cur_state=%ld\n", cur_state);
64
65 if (!instance->initialized) {
66 if (throttle) {
67 next_target = (cur_state + 1) >= instance->upper ?
68 instance->upper :
69 ((cur_state + 1) < instance->lower ?
70 instance->lower : (cur_state + 1));
71 } else {
72 next_target = THERMAL_NO_TARGET;
73 }
74
75 return next_target;
76 }
77
78 switch (trend) {
79 case THERMAL_TREND_RAISING:
80 if (throttle) {
81 next_target = cur_state < instance->upper ?
82 (cur_state + 1) : instance->upper;
83 if (next_target < instance->lower)
84 next_target = instance->lower;
85 }
86 break;
87 case THERMAL_TREND_RAISE_FULL:
88 if (throttle)
89 next_target = instance->upper;
90 break;
91 case THERMAL_TREND_DROPPING:
92 if (cur_state <= instance->lower) {
93 if (!throttle)
94 next_target = THERMAL_NO_TARGET;
95 } else {
96 if (!throttle) {
97 next_target = cur_state - 1;
98 if (next_target > instance->upper)
99 next_target = instance->upper;
100 }
101 }
102 break;
103 case THERMAL_TREND_DROP_FULL:
104 if (cur_state == instance->lower) {
105 if (!throttle)
106 next_target = THERMAL_NO_TARGET;
107 } else
108 next_target = instance->lower;
109 break;
110 default:
111 break;
112 }
113
114 return next_target;
115 }
116
update_passive_instance(struct thermal_zone_device * tz,enum thermal_trip_type type,int value)117 static void update_passive_instance(struct thermal_zone_device *tz,
118 enum thermal_trip_type type, int value)
119 {
120 /*
121 * If value is +1, activate a passive instance.
122 * If value is -1, deactivate a passive instance.
123 */
124 if (type == THERMAL_TRIP_PASSIVE || type == THERMAL_TRIPS_NONE)
125 tz->passive += value;
126 }
127
thermal_zone_trip_update(struct thermal_zone_device * tz,int trip)128 static void thermal_zone_trip_update(struct thermal_zone_device *tz, int trip)
129 {
130 int trip_temp;
131 enum thermal_trip_type trip_type;
132 enum thermal_trend trend;
133 struct thermal_instance *instance;
134 bool throttle = false;
135 int old_target;
136
137 if (trip == THERMAL_TRIPS_NONE) {
138 trip_temp = tz->forced_passive;
139 trip_type = THERMAL_TRIPS_NONE;
140 } else {
141 tz->ops->get_trip_temp(tz, trip, &trip_temp);
142 tz->ops->get_trip_type(tz, trip, &trip_type);
143 }
144
145 trend = get_tz_trend(tz, trip);
146
147 if (tz->temperature >= trip_temp) {
148 throttle = true;
149 trace_thermal_zone_trip(tz, trip, trip_type);
150 }
151
152 dev_dbg(&tz->device, "Trip%d[type=%d,temp=%d]:trend=%d,throttle=%d\n",
153 trip, trip_type, trip_temp, trend, throttle);
154
155 mutex_lock(&tz->lock);
156
157 list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
158 if (instance->trip != trip)
159 continue;
160
161 old_target = instance->target;
162 instance->target = get_target_state(instance, trend, throttle);
163 dev_dbg(&instance->cdev->device, "old_target=%d, target=%d\n",
164 old_target, (int)instance->target);
165
166 if (instance->initialized && old_target == instance->target)
167 continue;
168
169 /* Activate a passive thermal instance */
170 if (old_target == THERMAL_NO_TARGET &&
171 instance->target != THERMAL_NO_TARGET)
172 update_passive_instance(tz, trip_type, 1);
173 /* Deactivate a passive thermal instance */
174 else if (old_target != THERMAL_NO_TARGET &&
175 instance->target == THERMAL_NO_TARGET)
176 update_passive_instance(tz, trip_type, -1);
177
178 instance->initialized = true;
179 mutex_lock(&instance->cdev->lock);
180 instance->cdev->updated = false; /* cdev needs update */
181 mutex_unlock(&instance->cdev->lock);
182 }
183
184 mutex_unlock(&tz->lock);
185 }
186
187 /**
188 * step_wise_throttle - throttles devices associated with the given zone
189 * @tz - thermal_zone_device
190 * @trip - trip point index
191 *
192 * Throttling Logic: This uses the trend of the thermal zone to throttle.
193 * If the thermal zone is 'heating up' this throttles all the cooling
194 * devices associated with the zone and its particular trip point, by one
195 * step. If the zone is 'cooling down' it brings back the performance of
196 * the devices by one step.
197 */
step_wise_throttle(struct thermal_zone_device * tz,int trip)198 static int step_wise_throttle(struct thermal_zone_device *tz, int trip)
199 {
200 struct thermal_instance *instance;
201
202 thermal_zone_trip_update(tz, trip);
203
204 if (tz->forced_passive)
205 thermal_zone_trip_update(tz, THERMAL_TRIPS_NONE);
206
207 mutex_lock(&tz->lock);
208
209 list_for_each_entry(instance, &tz->thermal_instances, tz_node)
210 thermal_cdev_update(instance->cdev);
211
212 mutex_unlock(&tz->lock);
213
214 return 0;
215 }
216
217 static struct thermal_governor thermal_gov_step_wise = {
218 .name = "step_wise",
219 .throttle = step_wise_throttle,
220 };
221
thermal_gov_step_wise_register(void)222 int thermal_gov_step_wise_register(void)
223 {
224 return thermal_register_governor(&thermal_gov_step_wise);
225 }
226
thermal_gov_step_wise_unregister(void)227 void thermal_gov_step_wise_unregister(void)
228 {
229 thermal_unregister_governor(&thermal_gov_step_wise);
230 }
231
