tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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
27#include "thermal_core.h"
28
29/*
30 * If the temperature is higher than a trip point,
31 * a. if the trend is THERMAL_TREND_RAISING, use higher cooling
32 * state for this trip point
33 * b. if the trend is THERMAL_TREND_DROPPING, use lower cooling
34 * state for this trip point
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 * deactive the thermal instance
48 */
49static 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 switch (trend) {
66 case THERMAL_TREND_RAISING:
67 if (throttle) {
68 next_target = cur_state < instance->upper ?
69 (cur_state + 1) : instance->upper;
70 if (next_target < instance->lower)
71 next_target = instance->lower;
72 }
73 break;
74 case THERMAL_TREND_RAISE_FULL:
75 if (throttle)
76 next_target = instance->upper;
77 break;
78 case THERMAL_TREND_DROPPING:
79 if (cur_state == instance->lower) {
80 if (!throttle)
81 next_target = THERMAL_NO_TARGET;
82 } else {
83 next_target = cur_state - 1;
84 if (next_target > instance->upper)
85 next_target = instance->upper;
86 }
87 break;
88 case THERMAL_TREND_DROP_FULL:
89 if (cur_state == instance->lower) {
90 if (!throttle)
91 next_target = THERMAL_NO_TARGET;
92 } else
93 next_target = instance->lower;
94 break;
95 default:
96 break;
97 }
98
99 return next_target;
100}
101
102static void update_passive_instance(struct thermal_zone_device *tz,
103 enum thermal_trip_type type, int value)
104{
105 /*
106 * If value is +1, activate a passive instance.
107 * If value is -1, deactivate a passive instance.
108 */
109 if (type == THERMAL_TRIP_PASSIVE || type == THERMAL_TRIPS_NONE)
110 tz->passive += value;
111}
112
113static void thermal_zone_trip_update(struct thermal_zone_device *tz, int trip)
114{
115 long trip_temp;
116 enum thermal_trip_type trip_type;
117 enum thermal_trend trend;
118 struct thermal_instance *instance;
119 bool throttle = false;
120 int old_target;
121
122 if (trip == THERMAL_TRIPS_NONE) {
123 trip_temp = tz->forced_passive;
124 trip_type = THERMAL_TRIPS_NONE;
125 } else {
126 tz->ops->get_trip_temp(tz, trip, &trip_temp);
127 tz->ops->get_trip_type(tz, trip, &trip_type);
128 }
129
130 trend = get_tz_trend(tz, trip);
131
132 if (tz->temperature >= trip_temp)
133 throttle = true;
134
135 dev_dbg(&tz->device, "Trip%d[type=%d,temp=%ld]:trend=%d,throttle=%d\n",
136 trip, trip_type, trip_temp, trend, throttle);
137
138 mutex_lock(&tz->lock);
139
140 list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
141 if (instance->trip != trip)
142 continue;
143
144 old_target = instance->target;
145 instance->target = get_target_state(instance, trend, throttle);
146 dev_dbg(&instance->cdev->device, "old_target=%d, target=%d\n",
147 old_target, (int)instance->target);
148
149 if (old_target == instance->target)
150 continue;
151
152 /* Activate a passive thermal instance */
153 if (old_target == THERMAL_NO_TARGET &&
154 instance->target != THERMAL_NO_TARGET)
155 update_passive_instance(tz, trip_type, 1);
156 /* Deactivate a passive thermal instance */
157 else if (old_target != THERMAL_NO_TARGET &&
158 instance->target == THERMAL_NO_TARGET)
159 update_passive_instance(tz, trip_type, -1);
160
161
162 instance->cdev->updated = false; /* cdev needs update */
163 }
164
165 mutex_unlock(&tz->lock);
166}
167
168/**
169 * step_wise_throttle - throttles devices asscciated with the given zone
170 * @tz - thermal_zone_device
171 * @trip - the trip point
172 * @trip_type - type of the trip point
173 *
174 * Throttling Logic: This uses the trend of the thermal zone to throttle.
175 * If the thermal zone is 'heating up' this throttles all the cooling
176 * devices associated with the zone and its particular trip point, by one
177 * step. If the zone is 'cooling down' it brings back the performance of
178 * the devices by one step.
179 */
180static int step_wise_throttle(struct thermal_zone_device *tz, int trip)
181{
182 struct thermal_instance *instance;
183
184 thermal_zone_trip_update(tz, trip);
185
186 if (tz->forced_passive)
187 thermal_zone_trip_update(tz, THERMAL_TRIPS_NONE);
188
189 mutex_lock(&tz->lock);
190
191 list_for_each_entry(instance, &tz->thermal_instances, tz_node)
192 thermal_cdev_update(instance->cdev);
193
194 mutex_unlock(&tz->lock);
195
196 return 0;
197}
198
199static struct thermal_governor thermal_gov_step_wise = {
200 .name = "step_wise",
201 .throttle = step_wise_throttle,
202};
203
204int thermal_gov_step_wise_register(void)
205{
206 return thermal_register_governor(&thermal_gov_step_wise);
207}
208
209void thermal_gov_step_wise_unregister(void)
210{
211 thermal_unregister_governor(&thermal_gov_step_wise);
212}