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, do nothing
  35  *    c. if the trend is THERMAL_TREND_RAISE_FULL, use upper limit
  36  *       for this trip point
  37  *    d. if the trend is THERMAL_TREND_DROP_FULL, use lower limit
  38  *       for this trip point
  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  *       deactivate the thermal instance
  48  */
  49 static unsigned long get_target_state(struct thermal_instance *instance,
  50                                 enum thermal_trend trend, bool throttle)
  51 {
  52         struct thermal_cooling_device *cdev = instance->cdev;
  53         unsigned long cur_state;
  54         unsigned long next_target;
  55
  56         /*
  57          * We keep this instance the way it is by default.
  58          * Otherwise, we use the current state of the
  59          * cdev in use to determine the next_target.
  60          */
  61         cdev->ops->get_cur_state(cdev, &cur_state);
  62         next_target = instance->target;
  63         dev_dbg(&cdev->device, "cur_state=%ld\n", cur_state);
  64
  65         if (!instance->initialized) {
  66                 if (throttle) {
  67                         next_target = (cur_state + 1) >= instance->upper ?
  68                                         instance->upper :
  69                                         ((cur_state + 1) < instance->lower ?
  70                                         instance->lower : (cur_state + 1));
  71                 } else {
  72                         next_target = THERMAL_NO_TARGET;
  73                 }
  74
  75                 return next_target;
  76         }
  77
  78         switch (trend) {
  79         case THERMAL_TREND_RAISING:
  80                 if (throttle) {
  81                         next_target = cur_state < instance->upper ?
  82                                     (cur_state + 1) : instance->upper;
  83                         if (next_target < instance->lower)
  84                                 next_target = instance->lower;
  85                 }
  86                 break;
  87         case THERMAL_TREND_RAISE_FULL:
  88                 if (throttle)
  89                         next_target = instance->upper;
  90                 break;
  91         case THERMAL_TREND_DROPPING:
  92                 if (cur_state <= instance->lower) {
  93                         if (!throttle)
  94                                 next_target = THERMAL_NO_TARGET;
  95                 } else {
  96                         if (!throttle) {
  97                                 next_target = cur_state - 1;
  98                                 if (next_target > instance->upper)
  99                                         next_target = instance->upper;
 100                         }
 101                 }
 102                 break;
 103         case THERMAL_TREND_DROP_FULL:
 104                 if (cur_state == instance->lower) {
 105                         if (!throttle)
 106                                 next_target = THERMAL_NO_TARGET;
 107                 } else
 108                         next_target = instance->lower;
 109                 break;
 110         default:
 111                 break;
 112         }
 113
 114         return next_target;
 115 }
 116
 117 static void update_passive_instance(struct thermal_zone_device *tz,
 118                                 enum thermal_trip_type type, int value)
 119 {
 120         /*
 121          * If value is +1, activate a passive instance.
 122          * If value is -1, deactivate a passive instance.
 123          */
 124         if (type == THERMAL_TRIP_PASSIVE || type == THERMAL_TRIPS_NONE)
 125                 tz->passive += value;
 126 }
 127
 128 static void thermal_zone_trip_update(struct thermal_zone_device *tz, int trip)
 129 {
 130         int trip_temp;
 131         enum thermal_trip_type trip_type;
 132         enum thermal_trend trend;
 133         struct thermal_instance *instance;
 134         bool throttle = false;
 135         int old_target;
 136
 137         if (trip == THERMAL_TRIPS_NONE) {
 138                 trip_temp = tz->forced_passive;
 139                 trip_type = THERMAL_TRIPS_NONE;
 140         } else {
 141                 tz->ops->get_trip_temp(tz, trip, &trip_temp);
 142                 tz->ops->get_trip_type(tz, trip, &trip_type);
 143         }
 144
 145         trend = get_tz_trend(tz, trip);
 146
 147         if (tz->temperature >= trip_temp) {
 148                 throttle = true;
 149                 trace_thermal_zone_trip(tz, trip, trip_type);
 150         }
 151
 152         dev_dbg(&tz->device, "Trip%d[type=%d,temp=%d]:trend=%d,throttle=%d\n",
 153                                 trip, trip_type, trip_temp, trend, throttle);
 154
 155         mutex_lock(&tz->lock);
 156
 157         list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
 158                 if (instance->trip != trip)
 159                         continue;
 160
 161                 old_target = instance->target;
 162                 instance->target = get_target_state(instance, trend, throttle);
 163                 dev_dbg(&instance->cdev->device, "old_target=%d, target=%d\n",
 164                                         old_target, (int)instance->target);
 165
 166                 if (instance->initialized && old_target == instance->target)
 167                         continue;
 168
 169                 /* Activate a passive thermal instance */
 170                 if (old_target == THERMAL_NO_TARGET &&
 171                         instance->target != THERMAL_NO_TARGET)
 172                         update_passive_instance(tz, trip_type, 1);
 173                 /* Deactivate a passive thermal instance */
 174                 else if (old_target != THERMAL_NO_TARGET &&
 175                         instance->target == THERMAL_NO_TARGET)
 176                         update_passive_instance(tz, trip_type, -1);
 177
 178                 instance->initialized = true;
 179                 mutex_lock(&instance->cdev->lock);
 180                 instance->cdev->updated = false; /* cdev needs update */
 181                 mutex_unlock(&instance->cdev->lock);
 182         }
 183
 184         mutex_unlock(&tz->lock);
 185 }
 186
 187 /**
 188  * step_wise_throttle - throttles devices associated with the given zone
 189  * @tz - thermal_zone_device
 190  * @trip - the trip point
 191  * @trip_type - type of the trip point
 192  *
 193  * Throttling Logic: This uses the trend of the thermal zone to throttle.
 194  * If the thermal zone is 'heating up' this throttles all the cooling
 195  * devices associated with the zone and its particular trip point, by one
 196  * step. If the zone is 'cooling down' it brings back the performance of
 197  * the devices by one step.
 198  */
 199 static int step_wise_throttle(struct thermal_zone_device *tz, int trip)
 200 {
 201         struct thermal_instance *instance;
 202
 203         thermal_zone_trip_update(tz, trip);
 204
 205         if (tz->forced_passive)
 206                 thermal_zone_trip_update(tz, THERMAL_TRIPS_NONE);
 207
 208         mutex_lock(&tz->lock);
 209
 210         list_for_each_entry(instance, &tz->thermal_instances, tz_node)
 211                 thermal_cdev_update(instance->cdev);
 212
 213         mutex_unlock(&tz->lock);
 214
 215         return 0;
 216 }
 217
 218 static struct thermal_governor thermal_gov_step_wise = {
 219         .name           = "step_wise",
 220         .throttle       = step_wise_throttle,
 221 };
 222
 223 int thermal_gov_step_wise_register(void)
 224 {
 225         return thermal_register_governor(&thermal_gov_step_wise);
 226 }
 227
 228 void thermal_gov_step_wise_unregister(void)
 229 {
 230         thermal_unregister_governor(&thermal_gov_step_wise);
 231 }