2 * step_wise.c - A step-by-step Thermal throttling governor
4 * Copyright (C) 2012 Intel Corp
5 * Copyright (C) 2012 Durgadoss R <durgadoss.r@intel.com>
7 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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.
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.
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.
22 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
25 #include <linux/thermal.h>
27 #include "thermal_core.h"
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
37 * d. if the trend is THERMAL_TREND_DROP_FULL, use lower limit
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
49 static unsigned long get_target_state(struct thermal_instance *instance,
50 enum thermal_trend trend, bool throttle)
52 struct thermal_cooling_device *cdev = instance->cdev;
53 unsigned long cur_state;
55 cdev->ops->get_cur_state(cdev, &cur_state);
56 dev_dbg(&cdev->device, "cur_state=%ld\n", cur_state);
59 case THERMAL_TREND_RAISING:
61 cur_state = cur_state < instance->upper ?
62 (cur_state + 1) : instance->upper;
63 if (cur_state < instance->lower)
64 cur_state = instance->lower;
67 case THERMAL_TREND_RAISE_FULL:
69 cur_state = instance->upper;
71 case THERMAL_TREND_DROPPING:
72 if (cur_state == instance->lower) {
77 if (cur_state > instance->upper)
78 cur_state = instance->upper;
81 case THERMAL_TREND_DROP_FULL:
82 if (cur_state == instance->lower) {
86 cur_state = instance->lower;
95 static void update_passive_instance(struct thermal_zone_device *tz,
96 enum thermal_trip_type type, int value)
99 * If value is +1, activate a passive instance.
100 * If value is -1, deactivate a passive instance.
102 if (type == THERMAL_TRIP_PASSIVE || type == THERMAL_TRIPS_NONE)
103 tz->passive += value;
106 static void thermal_zone_trip_update(struct thermal_zone_device *tz, int trip)
109 enum thermal_trip_type trip_type;
110 enum thermal_trend trend;
111 struct thermal_instance *instance;
112 bool throttle = false;
115 if (trip == THERMAL_TRIPS_NONE) {
116 trip_temp = tz->forced_passive;
117 trip_type = THERMAL_TRIPS_NONE;
119 tz->ops->get_trip_temp(tz, trip, &trip_temp);
120 tz->ops->get_trip_type(tz, trip, &trip_type);
123 trend = get_tz_trend(tz, trip);
125 if (tz->temperature >= trip_temp)
128 dev_dbg(&tz->device, "Trip%d[type=%d,temp=%ld]:trend=%d,throttle=%d\n",
129 trip, trip_type, trip_temp, trend, throttle);
131 mutex_lock(&tz->lock);
133 list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
134 if (instance->trip != trip)
137 old_target = instance->target;
138 instance->target = get_target_state(instance, trend, throttle);
139 dev_dbg(&instance->cdev->device, "old_target=%d, target=%d\n",
140 old_target, (int)instance->target);
142 /* Activate a passive thermal instance */
143 if (old_target == THERMAL_NO_TARGET &&
144 instance->target != THERMAL_NO_TARGET)
145 update_passive_instance(tz, trip_type, 1);
146 /* Deactivate a passive thermal instance */
147 else if (old_target != THERMAL_NO_TARGET &&
148 instance->target == THERMAL_NO_TARGET)
149 update_passive_instance(tz, trip_type, -1);
152 instance->cdev->updated = false; /* cdev needs update */
155 mutex_unlock(&tz->lock);
159 * step_wise_throttle - throttles devices asscciated with the given zone
160 * @tz - thermal_zone_device
161 * @trip - the trip point
162 * @trip_type - type of the trip point
164 * Throttling Logic: This uses the trend of the thermal zone to throttle.
165 * If the thermal zone is 'heating up' this throttles all the cooling
166 * devices associated with the zone and its particular trip point, by one
167 * step. If the zone is 'cooling down' it brings back the performance of
168 * the devices by one step.
170 static int step_wise_throttle(struct thermal_zone_device *tz, int trip)
172 struct thermal_instance *instance;
174 thermal_zone_trip_update(tz, trip);
176 if (tz->forced_passive)
177 thermal_zone_trip_update(tz, THERMAL_TRIPS_NONE);
179 mutex_lock(&tz->lock);
181 list_for_each_entry(instance, &tz->thermal_instances, tz_node)
182 thermal_cdev_update(instance->cdev);
184 mutex_unlock(&tz->lock);
189 static struct thermal_governor thermal_gov_step_wise = {
191 .throttle = step_wise_throttle,
194 int thermal_gov_step_wise_register(void)
196 return thermal_register_governor(&thermal_gov_step_wise);
199 void thermal_gov_step_wise_unregister(void)
201 thermal_unregister_governor(&thermal_gov_step_wise);