drivers/thermal/gov_step_wise.c

0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /*
0003  *  step_wise.c - A step-by-step Thermal throttling governor
0004  *
0005  *  Copyright (C) 2012 Intel Corp
0006  *  Copyright (C) 2012 Durgadoss R <durgadoss.r@intel.com>
0007  *
0008  *  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
0009  *
0010  * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
0011  */
0012
0013 #include <linux/thermal.h>
0014 #include <linux/minmax.h>
0015 #include <trace/events/thermal.h>
0016
0017 #include "thermal_core.h"
0018
0019 /*
0020  * If the temperature is higher than a trip point,
0021  *    a. if the trend is THERMAL_TREND_RAISING, use higher cooling
0022  *       state for this trip point
0023  *    b. if the trend is THERMAL_TREND_DROPPING, do nothing
0024  *    c. if the trend is THERMAL_TREND_RAISE_FULL, use upper limit
0025  *       for this trip point
0026  *    d. if the trend is THERMAL_TREND_DROP_FULL, use lower limit
0027  *       for this trip point
0028  * If the temperature is lower than a trip point,
0029  *    a. if the trend is THERMAL_TREND_RAISING, do nothing
0030  *    b. if the trend is THERMAL_TREND_DROPPING, use lower cooling
0031  *       state for this trip point, if the cooling state already
0032  *       equals lower limit, deactivate the thermal instance
0033  *    c. if the trend is THERMAL_TREND_RAISE_FULL, do nothing
0034  *    d. if the trend is THERMAL_TREND_DROP_FULL, use lower limit,
0035  *       if the cooling state already equals lower limit,
0036  *       deactivate the thermal instance
0037  */
0038 static unsigned long get_target_state(struct thermal_instance *instance,
0039                 enum thermal_trend trend, bool throttle)
0040 {
0041     struct thermal_cooling_device *cdev = instance->cdev;
0042     unsigned long cur_state;
0043     unsigned long next_target;
0044
0045     /*
0046      * We keep this instance the way it is by default.
0047      * Otherwise, we use the current state of the
0048      * cdev in use to determine the next_target.
0049      */
0050     cdev->ops->get_cur_state(cdev, &cur_state);
0051     next_target = instance->target;
0052     dev_dbg(&cdev->device, "cur_state=%ld\n", cur_state);
0053
0054     if (!instance->initialized) {
0055         if (throttle) {
0056             next_target = clamp((cur_state + 1), instance->lower, instance->upper);
0057         } else {
0058             next_target = THERMAL_NO_TARGET;
0059         }
0060
0061         return next_target;
0062     }
0063
0064     switch (trend) {
0065     case THERMAL_TREND_RAISING:
0066         if (throttle) {
0067             next_target = clamp((cur_state + 1), instance->lower, instance->upper);
0068         }
0069         break;
0070     case THERMAL_TREND_DROPPING:
0071         if (cur_state <= instance->lower) {
0072             if (!throttle)
0073                 next_target = THERMAL_NO_TARGET;
0074         } else {
0075             if (!throttle) {
0076                 next_target = clamp((cur_state - 1), instance->lower, instance->upper);
0077             }
0078         }
0079         break;
0080     default:
0081         break;
0082     }
0083
0084     return next_target;
0085 }
0086
0087 static void update_passive_instance(struct thermal_zone_device *tz,
0088                 enum thermal_trip_type type, int value)
0089 {
0090     /*
0091      * If value is +1, activate a passive instance.
0092      * If value is -1, deactivate a passive instance.
0093      */
0094     if (type == THERMAL_TRIP_PASSIVE)
0095         tz->passive += value;
0096 }
0097
0098 static void thermal_zone_trip_update(struct thermal_zone_device *tz, int trip)
0099 {
0100     int trip_temp;
0101     enum thermal_trip_type trip_type;
0102     enum thermal_trend trend;
0103     struct thermal_instance *instance;
0104     bool throttle = false;
0105     int old_target;
0106
0107     tz->ops->get_trip_temp(tz, trip, &trip_temp);
0108     tz->ops->get_trip_type(tz, trip, &trip_type);
0109
0110     trend = get_tz_trend(tz, trip);
0111
0112     if (tz->temperature >= trip_temp) {
0113         throttle = true;
0114         trace_thermal_zone_trip(tz, trip, trip_type);
0115     }
0116
0117     dev_dbg(&tz->device, "Trip%d[type=%d,temp=%d]:trend=%d,throttle=%d\n",
0118                 trip, trip_type, trip_temp, trend, throttle);
0119
0120     mutex_lock(&tz->lock);
0121
0122     list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
0123         if (instance->trip != trip)
0124             continue;
0125
0126         old_target = instance->target;
0127         instance->target = get_target_state(instance, trend, throttle);
0128         dev_dbg(&instance->cdev->device, "old_target=%d, target=%d\n",
0129                     old_target, (int)instance->target);
0130
0131         if (instance->initialized && old_target == instance->target)
0132             continue;
0133
0134         /* Activate a passive thermal instance */
0135         if (old_target == THERMAL_NO_TARGET &&
0136             instance->target != THERMAL_NO_TARGET)
0137             update_passive_instance(tz, trip_type, 1);
0138         /* Deactivate a passive thermal instance */
0139         else if (old_target != THERMAL_NO_TARGET &&
0140             instance->target == THERMAL_NO_TARGET)
0141             update_passive_instance(tz, trip_type, -1);
0142
0143         instance->initialized = true;
0144         mutex_lock(&instance->cdev->lock);
0145         instance->cdev->updated = false; /* cdev needs update */
0146         mutex_unlock(&instance->cdev->lock);
0147     }
0148
0149     mutex_unlock(&tz->lock);
0150 }
0151
0152 /**
0153  * step_wise_throttle - throttles devices associated with the given zone
0154  * @tz: thermal_zone_device
0155  * @trip: trip point index
0156  *
0157  * Throttling Logic: This uses the trend of the thermal zone to throttle.
0158  * If the thermal zone is 'heating up' this throttles all the cooling
0159  * devices associated with the zone and its particular trip point, by one
0160  * step. If the zone is 'cooling down' it brings back the performance of
0161  * the devices by one step.
0162  */
0163 static int step_wise_throttle(struct thermal_zone_device *tz, int trip)
0164 {
0165     struct thermal_instance *instance;
0166
0167     thermal_zone_trip_update(tz, trip);
0168
0169     mutex_lock(&tz->lock);
0170
0171     list_for_each_entry(instance, &tz->thermal_instances, tz_node)
0172         thermal_cdev_update(instance->cdev);
0173
0174     mutex_unlock(&tz->lock);
0175
0176     return 0;
0177 }
0178
0179 static struct thermal_governor thermal_gov_step_wise = {
0180     .name       = "step_wise",
0181     .throttle   = step_wise_throttle,
0182 };
0183 THERMAL_GOVERNOR_DECLARE(thermal_gov_step_wise);