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
39 static unsigned long get_target_state(struct thermal_instance *instance,
40 enum thermal_trend trend)
42 struct thermal_cooling_device *cdev = instance->cdev;
43 unsigned long cur_state;
45 cdev->ops->get_cur_state(cdev, &cur_state);
47 if (trend == THERMAL_TREND_RAISING) {
48 cur_state = cur_state < instance->upper ?
49 (cur_state + 1) : instance->upper;
50 } else if (trend == THERMAL_TREND_DROPPING) {
51 cur_state = cur_state > instance->lower ?
52 (cur_state - 1) : instance->lower;
58 static void update_passive_instance(struct thermal_zone_device *tz,
59 enum thermal_trip_type type, int value)
62 * If value is +1, activate a passive instance.
63 * If value is -1, deactivate a passive instance.
65 if (type == THERMAL_TRIP_PASSIVE || type == THERMAL_TRIPS_NONE)
69 static void update_instance_for_throttle(struct thermal_zone_device *tz,
70 int trip, enum thermal_trip_type trip_type,
71 enum thermal_trend trend)
73 struct thermal_instance *instance;
74 unsigned long old_target;
76 list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
77 if (instance->trip != trip)
80 old_target = instance->target;
81 instance->target = get_target_state(instance, trend);
83 /* Activate a passive thermal instance */
84 if (old_target == THERMAL_NO_TARGET &&
85 instance->target != THERMAL_NO_TARGET)
86 update_passive_instance(tz, trip_type, 1);
88 instance->cdev->updated = false; /* cdev needs update */
92 static void update_instance_for_dethrottle(struct thermal_zone_device *tz,
93 int trip, enum thermal_trip_type trip_type)
95 struct thermal_instance *instance;
96 struct thermal_cooling_device *cdev;
97 unsigned long cur_state;
98 unsigned long old_target;
100 list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
101 if (instance->trip != trip ||
102 instance->target == THERMAL_NO_TARGET)
105 cdev = instance->cdev;
106 cdev->ops->get_cur_state(cdev, &cur_state);
108 old_target = instance->target;
109 instance->target = cur_state > instance->lower ?
110 (cur_state - 1) : THERMAL_NO_TARGET;
112 /* Deactivate a passive thermal instance */
113 if (old_target != THERMAL_NO_TARGET &&
114 instance->target == THERMAL_NO_TARGET)
115 update_passive_instance(tz, trip_type, -1);
117 cdev->updated = false; /* cdev needs update */
121 static void thermal_zone_trip_update(struct thermal_zone_device *tz, int trip)
124 enum thermal_trip_type trip_type;
125 enum thermal_trend trend;
127 if (trip == THERMAL_TRIPS_NONE) {
128 trip_temp = tz->forced_passive;
129 trip_type = THERMAL_TRIPS_NONE;
131 tz->ops->get_trip_temp(tz, trip, &trip_temp);
132 tz->ops->get_trip_type(tz, trip, &trip_type);
135 trend = get_tz_trend(tz, trip);
137 mutex_lock(&tz->lock);
139 if (tz->temperature >= trip_temp)
140 update_instance_for_throttle(tz, trip, trip_type, trend);
142 update_instance_for_dethrottle(tz, trip, trip_type);
144 mutex_unlock(&tz->lock);
148 * step_wise_throttle - throttles devices asscciated with the given zone
149 * @tz - thermal_zone_device
150 * @trip - the trip point
151 * @trip_type - type of the trip point
153 * Throttling Logic: This uses the trend of the thermal zone to throttle.
154 * If the thermal zone is 'heating up' this throttles all the cooling
155 * devices associated with the zone and its particular trip point, by one
156 * step. If the zone is 'cooling down' it brings back the performance of
157 * the devices by one step.
159 static int step_wise_throttle(struct thermal_zone_device *tz, int trip)
161 struct thermal_instance *instance;
163 thermal_zone_trip_update(tz, trip);
165 if (tz->forced_passive)
166 thermal_zone_trip_update(tz, THERMAL_TRIPS_NONE);
168 mutex_lock(&tz->lock);
170 list_for_each_entry(instance, &tz->thermal_instances, tz_node)
171 thermal_cdev_update(instance->cdev);
173 mutex_unlock(&tz->lock);
178 static struct thermal_governor thermal_gov_step_wise = {
180 .throttle = step_wise_throttle,
181 .owner = THIS_MODULE,
184 static int __init thermal_gov_step_wise_init(void)
186 return thermal_register_governor(&thermal_gov_step_wise);
189 static void __exit thermal_gov_step_wise_exit(void)
191 thermal_unregister_governor(&thermal_gov_step_wise);
194 /* This should load after thermal framework */
195 fs_initcall(thermal_gov_step_wise_init);
196 module_exit(thermal_gov_step_wise_exit);
198 MODULE_AUTHOR("Durgadoss R");
199 MODULE_DESCRIPTION("A step-by-step thermal throttling governor");
200 MODULE_LICENSE("GPL");