drivers/thermal/step_wise.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  *  step_wise.c - A step-by-step Thermal throttling governor
   4  *
   5  *  Copyright (C) 2012 Intel Corp
   6  *  Copyright (C) 2012 Durgadoss R <durgadoss.r@intel.com>
   7  *
   8  *  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   9  *
  10  * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  11  */
  12
  13 #include <linux/thermal.h>
  14 #include <trace/events/thermal.h>
  15
  16 #include "thermal_core.h"
  17
  18 /*
  19  * If the temperature is higher than a trip point,
  20  *    a. if the trend is THERMAL_TREND_RAISING, use higher cooling
  21  *       state for this trip point
  22  *    b. if the trend is THERMAL_TREND_DROPPING, do nothing
  23  *    c. if the trend is THERMAL_TREND_RAISE_FULL, use upper limit
  24  *       for this trip point
  25  *    d. if the trend is THERMAL_TREND_DROP_FULL, use lower limit
  26  *       for this trip point
  27  * If the temperature is lower than a trip point,
  28  *    a. if the trend is THERMAL_TREND_RAISING, do nothing
  29  *    b. if the trend is THERMAL_TREND_DROPPING, use lower cooling
  30  *       state for this trip point, if the cooling state already
  31  *       equals lower limit, deactivate the thermal instance
  32  *    c. if the trend is THERMAL_TREND_RAISE_FULL, do nothing
  33  *    d. if the trend is THERMAL_TREND_DROP_FULL, use lower limit,
  34  *       if the cooling state already equals lower limit,
  35  *       deactivate the thermal instance
  36  */
  37 static unsigned long get_target_state(struct thermal_instance *instance,
  38                                 enum thermal_trend trend, bool throttle)
  39 {
  40         struct thermal_cooling_device *cdev = instance->cdev;
  41         unsigned long cur_state;
  42         unsigned long next_target;
  43
  44         /*
  45          * We keep this instance the way it is by default.
  46          * Otherwise, we use the current state of the
  47          * cdev in use to determine the next_target.
  48          */
  49         cdev->ops->get_cur_state(cdev, &cur_state);
  50         next_target = instance->target;
  51         dev_dbg(&cdev->device, "cur_state=%ld\n", cur_state);
  52
  53         if (!instance->initialized) {
  54                 if (throttle) {
  55                         next_target = (cur_state + 1) >= instance->upper ?
  56                                         instance->upper :
  57                                         ((cur_state + 1) < instance->lower ?
  58                                         instance->lower : (cur_state + 1));
  59                 } else {
  60                         next_target = THERMAL_NO_TARGET;
  61                 }
  62
  63                 return next_target;
  64         }
  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                         if (!throttle) {
  85                                 next_target = cur_state - 1;
  86                                 if (next_target > instance->upper)
  87                                         next_target = instance->upper;
  88                         }
  89                 }
  90                 break;
  91         case THERMAL_TREND_DROP_FULL:
  92                 if (cur_state == instance->lower) {
  93                         if (!throttle)
  94                                 next_target = THERMAL_NO_TARGET;
  95                 } else
  96                         next_target = instance->lower;
  97                 break;
  98         default:
  99                 break;
 100         }
 101
 102         return next_target;
 103 }
 104
 105 static void update_passive_instance(struct thermal_zone_device *tz,
 106                                 enum thermal_trip_type type, int value)
 107 {
 108         /*
 109          * If value is +1, activate a passive instance.
 110          * If value is -1, deactivate a passive instance.
 111          */
 112         if (type == THERMAL_TRIP_PASSIVE || type == THERMAL_TRIPS_NONE)
 113                 tz->passive += value;
 114 }
 115
 116 static void thermal_zone_trip_update(struct thermal_zone_device *tz, int trip)
 117 {
 118         int trip_temp;
 119         enum thermal_trip_type trip_type;
 120         enum thermal_trend trend;
 121         struct thermal_instance *instance;
 122         bool throttle = false;
 123         int old_target;
 124
 125         if (trip == THERMAL_TRIPS_NONE) {
 126                 trip_temp = tz->forced_passive;
 127                 trip_type = THERMAL_TRIPS_NONE;
 128         } else {
 129                 tz->ops->get_trip_temp(tz, trip, &trip_temp);
 130                 tz->ops->get_trip_type(tz, trip, &trip_type);
 131         }
 132
 133         trend = get_tz_trend(tz, trip);
 134
 135         if (tz->temperature >= trip_temp) {
 136                 throttle = true;
 137                 trace_thermal_zone_trip(tz, trip, trip_type);
 138         }
 139
 140         dev_dbg(&tz->device, "Trip%d[type=%d,temp=%d]:trend=%d,throttle=%d\n",
 141                                 trip, trip_type, trip_temp, trend, throttle);
 142
 143         mutex_lock(&tz->lock);
 144
 145         list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
 146                 if (instance->trip != trip)
 147                         continue;
 148
 149                 old_target = instance->target;
 150                 instance->target = get_target_state(instance, trend, throttle);
 151                 dev_dbg(&instance->cdev->device, "old_target=%d, target=%d\n",
 152                                         old_target, (int)instance->target);
 153
 154                 if (instance->initialized && old_target == instance->target)
 155                         continue;
 156
 157                 /* Activate a passive thermal instance */
 158                 if (old_target == THERMAL_NO_TARGET &&
 159                         instance->target != THERMAL_NO_TARGET)
 160                         update_passive_instance(tz, trip_type, 1);
 161                 /* Deactivate a passive thermal instance */
 162                 else if (old_target != THERMAL_NO_TARGET &&
 163                         instance->target == THERMAL_NO_TARGET)
 164                         update_passive_instance(tz, trip_type, -1);
 165
 166                 instance->initialized = true;
 167                 mutex_lock(&instance->cdev->lock);
 168                 instance->cdev->updated = false; /* cdev needs update */
 169                 mutex_unlock(&instance->cdev->lock);
 170         }
 171
 172         mutex_unlock(&tz->lock);
 173 }
 174
 175 /**
 176  * step_wise_throttle - throttles devices associated with the given zone
 177  * @tz - thermal_zone_device
 178  * @trip - trip point index
 179  *
 180  * Throttling Logic: This uses the trend of the thermal zone to throttle.
 181  * If the thermal zone is 'heating up' this throttles all the cooling
 182  * devices associated with the zone and its particular trip point, by one
 183  * step. If the zone is 'cooling down' it brings back the performance of
 184  * the devices by one step.
 185  */
 186 static int step_wise_throttle(struct thermal_zone_device *tz, int trip)
 187 {
 188         struct thermal_instance *instance;
 189
 190         thermal_zone_trip_update(tz, trip);
 191
 192         if (tz->forced_passive)
 193                 thermal_zone_trip_update(tz, THERMAL_TRIPS_NONE);
 194
 195         mutex_lock(&tz->lock);
 196
 197         list_for_each_entry(instance, &tz->thermal_instances, tz_node)
 198                 thermal_cdev_update(instance->cdev);
 199
 200         mutex_unlock(&tz->lock);
 201
 202         return 0;
 203 }
 204
 205 static struct thermal_governor thermal_gov_step_wise = {
 206         .name           = "step_wise",
 207         .throttle       = step_wise_throttle,
 208 };
 209
 210 int thermal_gov_step_wise_register(void)
 211 {
 212         return thermal_register_governor(&thermal_gov_step_wise);
 213 }
 214
 215 void thermal_gov_step_wise_unregister(void)
 216 {
 217         thermal_unregister_governor(&thermal_gov_step_wise);
 218 }