drivers/thermal/gov_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 <linux/minmax.h>
  15 #include <trace/events/thermal.h>
  16
  17 #include "thermal_core.h"
  18
  19 /*
  20  * If the temperature is higher than a trip point,
  21  *    a. if the trend is THERMAL_TREND_RAISING, use higher cooling
  22  *       state for this trip point
  23  *    b. if the trend is THERMAL_TREND_DROPPING, do nothing
  24  *    c. if the trend is THERMAL_TREND_RAISE_FULL, use upper limit
  25  *       for this trip point
  26  *    d. if the trend is THERMAL_TREND_DROP_FULL, use lower limit
  27  *       for this trip point
  28  * If the temperature is lower than a trip point,
  29  *    a. if the trend is THERMAL_TREND_RAISING, do nothing
  30  *    b. if the trend is THERMAL_TREND_DROPPING, use lower cooling
  31  *       state for this trip point, if the cooling state already
  32  *       equals lower limit, deactivate the thermal instance
  33  *    c. if the trend is THERMAL_TREND_RAISE_FULL, do nothing
  34  *    d. if the trend is THERMAL_TREND_DROP_FULL, use lower limit,
  35  *       if the cooling state already equals lower limit,
  36  *       deactivate the thermal instance
  37  */
  38 static unsigned long get_target_state(struct thermal_instance *instance,
  39                                 enum thermal_trend trend, bool throttle)
  40 {
  41         struct thermal_cooling_device *cdev = instance->cdev;
  42         unsigned long cur_state;
  43         unsigned long next_target;
  44
  45         /*
  46          * We keep this instance the way it is by default.
  47          * Otherwise, we use the current state of the
  48          * cdev in use to determine the next_target.
  49          */
  50         cdev->ops->get_cur_state(cdev, &cur_state);
  51         next_target = instance->target;
  52         dev_dbg(&cdev->device, "cur_state=%ld\n", cur_state);
  53
  54         if (!instance->initialized) {
  55                 if (throttle) {
  56                         next_target = clamp((cur_state + 1), instance->lower, instance->upper);
  57                 } else {
  58                         next_target = THERMAL_NO_TARGET;
  59                 }
  60
  61                 return next_target;
  62         }
  63
  64         switch (trend) {
  65         case THERMAL_TREND_RAISING:
  66                 if (throttle) {
  67                         next_target = clamp((cur_state + 1), instance->lower, instance->upper);
  68                 }
  69                 break;
  70         case THERMAL_TREND_DROPPING:
  71                 if (cur_state <= instance->lower) {
  72                         if (!throttle)
  73                                 next_target = THERMAL_NO_TARGET;
  74                 } else {
  75                         if (!throttle) {
  76                                 next_target = clamp((cur_state - 1), instance->lower, instance->upper);
  77                         }
  78                 }
  79                 break;
  80         default:
  81                 break;
  82         }
  83
  84         return next_target;
  85 }
  86
  87 static void update_passive_instance(struct thermal_zone_device *tz,
  88                                 enum thermal_trip_type type, int value)
  89 {
  90         /*
  91          * If value is +1, activate a passive instance.
  92          * If value is -1, deactivate a passive instance.
  93          */
  94         if (type == THERMAL_TRIP_PASSIVE)
  95                 tz->passive += value;
  96 }
  97
  98 static void thermal_zone_trip_update(struct thermal_zone_device *tz, int trip)
  99 {
 100         int trip_temp;
 101         enum thermal_trip_type trip_type;
 102         enum thermal_trend trend;
 103         struct thermal_instance *instance;
 104         bool throttle = false;
 105         int old_target;
 106
 107         tz->ops->get_trip_temp(tz, trip, &trip_temp);
 108         tz->ops->get_trip_type(tz, trip, &trip_type);
 109
 110         trend = get_tz_trend(tz, trip);
 111
 112         if (tz->temperature >= trip_temp) {
 113                 throttle = true;
 114                 trace_thermal_zone_trip(tz, trip, trip_type);
 115         }
 116
 117         dev_dbg(&tz->device, "Trip%d[type=%d,temp=%d]:trend=%d,throttle=%d\n",
 118                                 trip, trip_type, trip_temp, trend, throttle);
 119
 120         mutex_lock(&tz->lock);
 121
 122         list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
 123                 if (instance->trip != trip)
 124                         continue;
 125
 126                 old_target = instance->target;
 127                 instance->target = get_target_state(instance, trend, throttle);
 128                 dev_dbg(&instance->cdev->device, "old_target=%d, target=%d\n",
 129                                         old_target, (int)instance->target);
 130
 131                 if (instance->initialized && old_target == instance->target)
 132                         continue;
 133
 134                 /* Activate a passive thermal instance */
 135                 if (old_target == THERMAL_NO_TARGET &&
 136                         instance->target != THERMAL_NO_TARGET)
 137                         update_passive_instance(tz, trip_type, 1);
 138                 /* Deactivate a passive thermal instance */
 139                 else if (old_target != THERMAL_NO_TARGET &&
 140                         instance->target == THERMAL_NO_TARGET)
 141                         update_passive_instance(tz, trip_type, -1);
 142
 143                 instance->initialized = true;
 144                 mutex_lock(&instance->cdev->lock);
 145                 instance->cdev->updated = false; /* cdev needs update */
 146                 mutex_unlock(&instance->cdev->lock);
 147         }
 148
 149         mutex_unlock(&tz->lock);
 150 }
 151
 152 /**
 153  * step_wise_throttle - throttles devices associated with the given zone
 154  * @tz: thermal_zone_device
 155  * @trip: trip point index
 156  *
 157  * Throttling Logic: This uses the trend of the thermal zone to throttle.
 158  * If the thermal zone is 'heating up' this throttles all the cooling
 159  * devices associated with the zone and its particular trip point, by one
 160  * step. If the zone is 'cooling down' it brings back the performance of
 161  * the devices by one step.
 162  */
 163 static int step_wise_throttle(struct thermal_zone_device *tz, int trip)
 164 {
 165         struct thermal_instance *instance;
 166
 167         thermal_zone_trip_update(tz, trip);
 168
 169         mutex_lock(&tz->lock);
 170
 171         list_for_each_entry(instance, &tz->thermal_instances, tz_node)
 172                 thermal_cdev_update(instance->cdev);
 173
 174         mutex_unlock(&tz->lock);
 175
 176         return 0;
 177 }
 178
 179 static struct thermal_governor thermal_gov_step_wise = {
 180         .name           = "step_wise",
 181         .throttle       = step_wise_throttle,
 182 };
 183 THERMAL_GOVERNOR_DECLARE(thermal_gov_step_wise);