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         switch (trend) {
  67         case THERMAL_TREND_RAISING:
  68                 if (throttle) {
  69                         next_target = cur_state < instance->upper ?
  70                                     (cur_state + 1) : instance->upper;
  71                         if (next_target < instance->lower)
  72                                 next_target = instance->lower;
  73                 }
  74                 break;
  75         case THERMAL_TREND_RAISE_FULL:
  76                 if (throttle)
  77                         next_target = instance->upper;
  78                 break;
  79         case THERMAL_TREND_DROPPING:
  80                 if (cur_state <= instance->lower) {
  81                         if (!throttle)
  82                                 next_target = THERMAL_NO_TARGET;
  83                 } else {
  84                         next_target = cur_state - 1;
  85                         if (next_target > instance->upper)
  86                                 next_target = instance->upper;
  87                 }
  88                 break;
  89         case THERMAL_TREND_DROP_FULL:
  90                 if (cur_state == instance->lower) {
  91                         if (!throttle)
  92                                 next_target = THERMAL_NO_TARGET;
  93                 } else
  94                         next_target = instance->lower;
  95                 break;
  96         default:
  97                 break;
  98         }
  99
 100         return next_target;
 101 }
 102
 103 static void update_passive_instance(struct thermal_zone_device *tz,
 104                                 enum thermal_trip_type type, int value)
 105 {
 106         /*
 107          * If value is +1, activate a passive instance.
 108          * If value is -1, deactivate a passive instance.
 109          */
 110         if (type == THERMAL_TRIP_PASSIVE || type == THERMAL_TRIPS_NONE)
 111                 tz->passive += value;
 112 }
 113
 114 static void thermal_zone_trip_update(struct thermal_zone_device *tz, int trip)
 115 {
 116         long trip_temp;
 117         enum thermal_trip_type trip_type;
 118         enum thermal_trend trend;
 119         struct thermal_instance *instance;
 120         bool throttle = false;
 121         int old_target;
 122
 123         if (trip == THERMAL_TRIPS_NONE) {
 124                 trip_temp = tz->forced_passive;
 125                 trip_type = THERMAL_TRIPS_NONE;
 126         } else {
 127                 tz->ops->get_trip_temp(tz, trip, &trip_temp);
 128                 tz->ops->get_trip_type(tz, trip, &trip_type);
 129         }
 130
 131         trend = get_tz_trend(tz, trip);
 132
 133         if (tz->temperature >= trip_temp) {
 134                 throttle = true;
 135                 trace_thermal_zone_trip(tz, trip, trip_type);
 136         }
 137
 138         dev_dbg(&tz->device, "Trip%d[type=%d,temp=%ld]:trend=%d,throttle=%d\n",
 139                                 trip, trip_type, trip_temp, trend, throttle);
 140
 141         mutex_lock(&tz->lock);
 142
 143         list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
 144                 if (instance->trip != trip)
 145                         continue;
 146
 147                 old_target = instance->target;
 148                 instance->target = get_target_state(instance, trend, throttle);
 149                 dev_dbg(&instance->cdev->device, "old_target=%d, target=%d\n",
 150                                         old_target, (int)instance->target);
 151
 152                 if (old_target == instance->target)
 153                         continue;
 154
 155                 /* Activate a passive thermal instance */
 156                 if (old_target == THERMAL_NO_TARGET &&
 157                         instance->target != THERMAL_NO_TARGET)
 158                         update_passive_instance(tz, trip_type, 1);
 159                 /* Deactivate a passive thermal instance */
 160                 else if (old_target != THERMAL_NO_TARGET &&
 161                         instance->target == THERMAL_NO_TARGET)
 162                         update_passive_instance(tz, trip_type, -1);
 163
 164
 165                 instance->cdev->updated = false; /* cdev needs update */
 166         }
 167
 168         mutex_unlock(&tz->lock);
 169 }
 170
 171 /**
 172  * step_wise_throttle - throttles devices associated with the given zone
 173  * @tz - thermal_zone_device
 174  * @trip - the trip point
 175  * @trip_type - type of the trip point
 176  *
 177  * Throttling Logic: This uses the trend of the thermal zone to throttle.
 178  * If the thermal zone is 'heating up' this throttles all the cooling
 179  * devices associated with the zone and its particular trip point, by one
 180  * step. If the zone is 'cooling down' it brings back the performance of
 181  * the devices by one step.
 182  */
 183 static int step_wise_throttle(struct thermal_zone_device *tz, int trip)
 184 {
 185         struct thermal_instance *instance;
 186
 187         thermal_zone_trip_update(tz, trip);
 188
 189         if (tz->forced_passive)
 190                 thermal_zone_trip_update(tz, THERMAL_TRIPS_NONE);
 191
 192         mutex_lock(&tz->lock);
 193
 194         list_for_each_entry(instance, &tz->thermal_instances, tz_node)
 195                 thermal_cdev_update(instance->cdev);
 196
 197         mutex_unlock(&tz->lock);
 198
 199         return 0;
 200 }
 201
 202 static struct thermal_governor thermal_gov_step_wise = {
 203         .name           = "step_wise",
 204         .throttle       = step_wise_throttle,
 205 };
 206
 207 int thermal_gov_step_wise_register(void)
 208 {
 209         return thermal_register_governor(&thermal_gov_step_wise);
 210 }
 211
 212 void thermal_gov_step_wise_unregister(void)
 213 {
 214         thermal_unregister_governor(&thermal_gov_step_wise);
 215 }