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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
27 #include <linux/module.h>
28 #include <linux/thermal.h>
30 #include "thermal_core.h"
33 * If the temperature is higher than a trip point,
34 * a. if the trend is THERMAL_TREND_RAISING, use higher cooling
35 * state for this trip point
36 * b. if the trend is THERMAL_TREND_DROPPING, use lower cooling
37 * state for this trip point
38 * c. if the trend is THERMAL_TREND_RAISE_FULL, use upper limit
40 * d. if the trend is THERMAL_TREND_DROP_FULL, use lower limit
42 * If the temperature is lower than a trip point,
43 * a. if the trend is THERMAL_TREND_RAISING, do nothing
44 * b. if the trend is THERMAL_TREND_DROPPING, use lower cooling
45 * state for this trip point, if the cooling state already
46 * equals lower limit, deactivate the thermal instance
47 * c. if the trend is THERMAL_TREND_RAISE_FULL, do nothing
48 * d. if the trend is THERMAL_TREND_DROP_FULL, use lower limit,
49 * if the cooling state already equals lower limit,
50 * deactive the thermal instance
52 static unsigned long get_target_state(struct thermal_instance *instance,
53 enum thermal_trend trend, bool throttle)
55 struct thermal_cooling_device *cdev = instance->cdev;
56 unsigned long cur_state;
58 cdev->ops->get_cur_state(cdev, &cur_state);
61 case THERMAL_TREND_RAISING:
63 cur_state = cur_state < instance->upper ?
64 (cur_state + 1) : instance->upper;
65 if (cur_state < instance->lower)
66 cur_state = instance->lower;
69 case THERMAL_TREND_RAISE_FULL:
71 cur_state = instance->upper;
73 case THERMAL_TREND_DROPPING:
74 if (cur_state == instance->lower) {
79 if (cur_state > instance->upper)
80 cur_state = instance->upper;
83 case THERMAL_TREND_DROP_FULL:
84 if (cur_state == instance->lower) {
88 cur_state = instance->lower;
97 static void update_passive_instance(struct thermal_zone_device *tz,
98 enum thermal_trip_type type, int value)
101 * If value is +1, activate a passive instance.
102 * If value is -1, deactivate a passive instance.
104 if (type == THERMAL_TRIP_PASSIVE || type == THERMAL_TRIPS_NONE)
105 tz->passive += value;
108 static void thermal_zone_trip_update(struct thermal_zone_device *tz, int trip)
111 enum thermal_trip_type trip_type;
112 enum thermal_trend trend;
113 struct thermal_instance *instance;
114 bool throttle = false;
117 if (trip == THERMAL_TRIPS_NONE) {
118 trip_temp = tz->forced_passive;
119 trip_type = THERMAL_TRIPS_NONE;
121 tz->ops->get_trip_temp(tz, trip, &trip_temp);
122 tz->ops->get_trip_type(tz, trip, &trip_type);
125 trend = get_tz_trend(tz, trip);
127 if (tz->temperature >= trip_temp)
130 mutex_lock(&tz->lock);
132 list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
133 if (instance->trip != trip)
136 old_target = instance->target;
137 instance->target = get_target_state(instance, trend, throttle);
139 /* Activate a passive thermal instance */
140 if (old_target == THERMAL_NO_TARGET &&
141 instance->target != THERMAL_NO_TARGET)
142 update_passive_instance(tz, trip_type, 1);
143 /* Deactivate a passive thermal instance */
144 else if (old_target != THERMAL_NO_TARGET &&
145 instance->target == THERMAL_NO_TARGET)
146 update_passive_instance(tz, trip_type, -1);
149 instance->cdev->updated = false; /* cdev needs update */
152 mutex_unlock(&tz->lock);
156 * step_wise_throttle - throttles devices asscciated with the given zone
157 * @tz - thermal_zone_device
158 * @trip - the trip point
159 * @trip_type - type of the trip point
161 * Throttling Logic: This uses the trend of the thermal zone to throttle.
162 * If the thermal zone is 'heating up' this throttles all the cooling
163 * devices associated with the zone and its particular trip point, by one
164 * step. If the zone is 'cooling down' it brings back the performance of
165 * the devices by one step.
167 static int step_wise_throttle(struct thermal_zone_device *tz, int trip)
169 struct thermal_instance *instance;
171 thermal_zone_trip_update(tz, trip);
173 if (tz->forced_passive)
174 thermal_zone_trip_update(tz, THERMAL_TRIPS_NONE);
176 mutex_lock(&tz->lock);
178 list_for_each_entry(instance, &tz->thermal_instances, tz_node)
179 thermal_cdev_update(instance->cdev);
181 mutex_unlock(&tz->lock);
186 static struct thermal_governor thermal_gov_step_wise = {
188 .throttle = step_wise_throttle,
189 .owner = THIS_MODULE,
192 static int __init thermal_gov_step_wise_init(void)
194 return thermal_register_governor(&thermal_gov_step_wise);
197 static void __exit thermal_gov_step_wise_exit(void)
199 thermal_unregister_governor(&thermal_gov_step_wise);
202 /* This should load after thermal framework */
203 fs_initcall(thermal_gov_step_wise_init);
204 module_exit(thermal_gov_step_wise_exit);
206 MODULE_AUTHOR("Durgadoss R");
207 MODULE_DESCRIPTION("A step-by-step thermal throttling governor");
208 MODULE_LICENSE("GPL");