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 #include <linux/thermal.h>
  26 #include <trace/events/thermal.h>
  27
  28 #include "thermal_core.h"
  29
  30 /*
  31  * If the temperature is higher than a trip point,
  32  *    a. if the trend is THERMAL_TREND_RAISING, use higher cooling
  33  *       state for this trip point
  34  *    b. if the trend is THERMAL_TREND_DROPPING, use lower cooling
  35  *       state for this trip point
  36  *    c. if the trend is THERMAL_TREND_RAISE_FULL, use upper limit
  37  *       for this trip point
  38  *    d. if the trend is THERMAL_TREND_DROP_FULL, use lower limit
  39  *       for this trip point
  40  * If the temperature is lower than a trip point,
  41  *    a. if the trend is THERMAL_TREND_RAISING, do nothing
  42  *    b. if the trend is THERMAL_TREND_DROPPING, use lower cooling
  43  *       state for this trip point, if the cooling state already
  44  *       equals lower limit, deactivate the thermal instance
  45  *    c. if the trend is THERMAL_TREND_RAISE_FULL, do nothing
  46  *    d. if the trend is THERMAL_TREND_DROP_FULL, use lower limit,
  47  *       if the cooling state already equals lower limit,
  48  *       deactivate the thermal instance
  49  */
  50 static unsigned long get_target_state(struct thermal_instance *instance,
  51                                 enum thermal_trend trend, bool throttle)
  52 {
  53         struct thermal_cooling_device *cdev = instance->cdev;
  54         unsigned long cur_state;
  55         unsigned long next_target;
  56
  57         /*
  58          * We keep this instance the way it is by default.
  59          * Otherwise, we use the current state of the
  60          * cdev in use to determine the next_target.
  61          */
  62         cdev->ops->get_cur_state(cdev, &cur_state);
  63         next_target = instance->target;
  64         dev_dbg(&cdev->device, "cur_state=%ld\n", cur_state);
  65
  66         if (!instance->initialized) {
  67                 if (throttle) {
  68                         next_target = (cur_state + 1) >= instance->upper ?
  69                                         instance->upper :
  70                                         ((cur_state + 1) < instance->lower ?
  71                                         instance->lower : (cur_state + 1));
  72                 } else {
  73                         next_target = THERMAL_NO_TARGET;
  74                 }
  75
  76                 return next_target;
  77         }
  78
  79         switch (trend) {
  80         case THERMAL_TREND_RAISING:
  81                 if (throttle) {
  82                         next_target = cur_state < instance->upper ?
  83                                     (cur_state + 1) : instance->upper;
  84                         if (next_target < instance->lower)
  85                                 next_target = instance->lower;
  86                 }
  87                 break;
  88         case THERMAL_TREND_RAISE_FULL:
  89                 if (throttle)
  90                         next_target = instance->upper;
  91                 break;
  92         case THERMAL_TREND_DROPPING:
  93                 if (cur_state <= instance->lower) {
  94                         if (!throttle)
  95                                 next_target = THERMAL_NO_TARGET;
  96                 } else {
  97                         next_target = cur_state - 1;
  98                         if (next_target > instance->upper)
  99                                 next_target = instance->upper;
 100                 }
 101                 break;
 102         case THERMAL_TREND_DROP_FULL:
 103                 if (cur_state == instance->lower) {
 104                         if (!throttle)
 105                                 next_target = THERMAL_NO_TARGET;
 106                 } else
 107                         next_target = instance->lower;
 108                 break;
 109         default:
 110                 break;
 111         }
 112
 113         return next_target;
 114 }
 115
 116 static void update_passive_instance(struct thermal_zone_device *tz,
 117                                 enum thermal_trip_type type, int value)
 118 {
 119         /*
 120          * If value is +1, activate a passive instance.
 121          * If value is -1, deactivate a passive instance.
 122          */
 123         if (type == THERMAL_TRIP_PASSIVE || type == THERMAL_TRIPS_NONE)
 124                 tz->passive += value;
 125 }
 126
 127 static void thermal_zone_trip_update(struct thermal_zone_device *tz, int trip)
 128 {
 129         int trip_temp;
 130         enum thermal_trip_type trip_type;
 131         enum thermal_trend trend;
 132         struct thermal_instance *instance;
 133         bool throttle = false;
 134         int old_target;
 135
 136         if (trip == THERMAL_TRIPS_NONE) {
 137                 trip_temp = tz->forced_passive;
 138                 trip_type = THERMAL_TRIPS_NONE;
 139         } else {
 140                 tz->ops->get_trip_temp(tz, trip, &trip_temp);
 141                 tz->ops->get_trip_type(tz, trip, &trip_type);
 142         }
 143
 144         trend = get_tz_trend(tz, trip);
 145
 146         if (tz->temperature >= trip_temp) {
 147                 throttle = true;
 148                 trace_thermal_zone_trip(tz, trip, trip_type);
 149         }
 150
 151         dev_dbg(&tz->device, "Trip%d[type=%d,temp=%d]:trend=%d,throttle=%d\n",
 152                                 trip, trip_type, trip_temp, trend, throttle);
 153
 154         mutex_lock(&tz->lock);
 155
 156         list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
 157                 if (instance->trip != trip)
 158                         continue;
 159
 160                 old_target = instance->target;
 161                 instance->target = get_target_state(instance, trend, throttle);
 162                 dev_dbg(&instance->cdev->device, "old_target=%d, target=%d\n",
 163                                         old_target, (int)instance->target);
 164
 165                 if (instance->initialized && old_target == instance->target)
 166                         continue;
 167
 168                 /* Activate a passive thermal instance */
 169                 if (old_target == THERMAL_NO_TARGET &&
 170                         instance->target != THERMAL_NO_TARGET)
 171                         update_passive_instance(tz, trip_type, 1);
 172                 /* Deactivate a passive thermal instance */
 173                 else if (old_target != THERMAL_NO_TARGET &&
 174                         instance->target == THERMAL_NO_TARGET)
 175                         update_passive_instance(tz, trip_type, -1);
 176
 177                 instance->initialized = true;
 178                 instance->cdev->updated = false; /* cdev needs update */
 179         }
 180
 181         mutex_unlock(&tz->lock);
 182 }
 183
 184 /**
 185  * step_wise_throttle - throttles devices associated with the given zone
 186  * @tz - thermal_zone_device
 187  * @trip - the trip point
 188  * @trip_type - type of the trip point
 189  *
 190  * Throttling Logic: This uses the trend of the thermal zone to throttle.
 191  * If the thermal zone is 'heating up' this throttles all the cooling
 192  * devices associated with the zone and its particular trip point, by one
 193  * step. If the zone is 'cooling down' it brings back the performance of
 194  * the devices by one step.
 195  */
 196 static int step_wise_throttle(struct thermal_zone_device *tz, int trip)
 197 {
 198         struct thermal_instance *instance;
 199
 200         thermal_zone_trip_update(tz, trip);
 201
 202         if (tz->forced_passive)
 203                 thermal_zone_trip_update(tz, THERMAL_TRIPS_NONE);
 204
 205         mutex_lock(&tz->lock);
 206
 207         list_for_each_entry(instance, &tz->thermal_instances, tz_node)
 208                 thermal_cdev_update(instance->cdev);
 209
 210         mutex_unlock(&tz->lock);
 211
 212         return 0;
 213 }
 214
 215 static struct thermal_governor thermal_gov_step_wise = {
 216         .name           = "step_wise",
 217         .throttle       = step_wise_throttle,
 218 };
 219
 220 int thermal_gov_step_wise_register(void)
 221 {
 222         return thermal_register_governor(&thermal_gov_step_wise);
 223 }
 224
 225 void thermal_gov_step_wise_unregister(void)
 226 {
 227         thermal_unregister_governor(&thermal_gov_step_wise);
 228 }