drivers/thermal/step_wise.c

   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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  26
  27 #include <linux/module.h>
  28 #include <linux/thermal.h>
  29
  30 #include "thermal_core.h"
  31
  32 /*
  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  */
  39 static unsigned long get_target_state(struct thermal_instance *instance,
  40                                         enum thermal_trend trend)
  41 {
  42         struct thermal_cooling_device *cdev = instance->cdev;
  43         unsigned long cur_state;
  44
  45         cdev->ops->get_cur_state(cdev, &cur_state);
  46
  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;
  53         }
  54
  55         return cur_state;
  56 }
  57
  58 static void update_passive_instance(struct thermal_zone_device *tz,
  59                                 enum thermal_trip_type type, int value)
  60 {
  61         /*
  62          * If value is +1, activate a passive instance.
  63          * If value is -1, deactivate a passive instance.
  64          */
  65         if (type == THERMAL_TRIP_PASSIVE || type == THERMAL_TRIPS_NONE)
  66                 tz->passive += value;
  67 }
  68
  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)
  72 {
  73         struct thermal_instance *instance;
  74
  75         list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
  76                 if (instance->trip != trip)
  77                         continue;
  78
  79                 instance->target = get_target_state(instance, trend);
  80
  81                 /* Activate a passive thermal instance */
  82                 if (instance->target == THERMAL_NO_TARGET)
  83                         update_passive_instance(tz, trip_type, 1);
  84
  85                 instance->cdev->updated = false; /* cdev needs update */
  86         }
  87 }
  88
  89 static void update_instance_for_dethrottle(struct thermal_zone_device *tz,
  90                                 int trip, enum thermal_trip_type trip_type)
  91 {
  92         struct thermal_instance *instance;
  93         struct thermal_cooling_device *cdev;
  94         unsigned long cur_state;
  95
  96         list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
  97                 if (instance->trip != trip ||
  98                         instance->target == THERMAL_NO_TARGET)
  99                         continue;
 100
 101                 cdev = instance->cdev;
 102                 cdev->ops->get_cur_state(cdev, &cur_state);
 103
 104                 instance->target = cur_state > instance->lower ?
 105                             (cur_state - 1) : THERMAL_NO_TARGET;
 106
 107                 /* Deactivate a passive thermal instance */
 108                 if (instance->target == THERMAL_NO_TARGET)
 109                         update_passive_instance(tz, trip_type, -1);
 110
 111                 cdev->updated = false; /* cdev needs update */
 112         }
 113 }
 114
 115 static void thermal_zone_trip_update(struct thermal_zone_device *tz, int trip)
 116 {
 117         long trip_temp;
 118         enum thermal_trip_type trip_type;
 119         enum thermal_trend trend;
 120
 121         if (trip == THERMAL_TRIPS_NONE) {
 122                 trip_temp = tz->forced_passive;
 123                 trip_type = THERMAL_TRIPS_NONE;
 124         } else {
 125                 tz->ops->get_trip_temp(tz, trip, &trip_temp);
 126                 tz->ops->get_trip_type(tz, trip, &trip_type);
 127         }
 128
 129         trend = get_tz_trend(tz, trip);
 130
 131         mutex_lock(&tz->lock);
 132
 133         if (tz->temperature >= trip_temp)
 134                 update_instance_for_throttle(tz, trip, trip_type, trend);
 135         else
 136                 update_instance_for_dethrottle(tz, trip, trip_type);
 137
 138         mutex_unlock(&tz->lock);
 139 }
 140
 141 /**
 142  * step_wise_throttle - throttles devices asscciated with the given zone
 143  * @tz - thermal_zone_device
 144  * @trip - the trip point
 145  * @trip_type - type of the trip point
 146  *
 147  * Throttling Logic: This uses the trend of the thermal zone to throttle.
 148  * If the thermal zone is 'heating up' this throttles all the cooling
 149  * devices associated with the zone and its particular trip point, by one
 150  * step. If the zone is 'cooling down' it brings back the performance of
 151  * the devices by one step.
 152  */
 153 static int step_wise_throttle(struct thermal_zone_device *tz, int trip)
 154 {
 155         struct thermal_instance *instance;
 156
 157         thermal_zone_trip_update(tz, trip);
 158
 159         if (tz->forced_passive)
 160                 thermal_zone_trip_update(tz, THERMAL_TRIPS_NONE);
 161
 162         mutex_lock(&tz->lock);
 163
 164         list_for_each_entry(instance, &tz->thermal_instances, tz_node)
 165                 thermal_cdev_update(instance->cdev);
 166
 167         mutex_unlock(&tz->lock);
 168
 169         return 0;
 170 }
 171
 172 static struct thermal_governor thermal_gov_step_wise = {
 173         .name           = "step_wise",
 174         .throttle       = step_wise_throttle,
 175         .owner          = THIS_MODULE,
 176 };
 177
 178 static int __init thermal_gov_step_wise_init(void)
 179 {
 180         return thermal_register_governor(&thermal_gov_step_wise);
 181 }
 182
 183 static void __exit thermal_gov_step_wise_exit(void)
 184 {
 185         thermal_unregister_governor(&thermal_gov_step_wise);
 186 }
 187
 188 /* This should load after thermal framework */
 189 fs_initcall(thermal_gov_step_wise_init);
 190 module_exit(thermal_gov_step_wise_exit);
 191
 192 MODULE_AUTHOR("Durgadoss R");
 193 MODULE_DESCRIPTION("A step-by-step thermal throttling governor");
 194 MODULE_LICENSE("GPL");