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