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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * step_wise.c - A step-by-step Thermal throttling governor4 *5 * Copyright (C) 2012 Intel Corp6 * 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 cooling22 * state for this trip point23 * b. if the trend is THERMAL_TREND_DROPPING, do nothing24 * If the temperature is lower than a trip point,25 * a. if the trend is THERMAL_TREND_RAISING, do nothing26 * b. if the trend is THERMAL_TREND_DROPPING, use lower cooling27 * state for this trip point, if the cooling state already28 * equals lower limit, deactivate the thermal instance29 */30static 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 36 /*37 * We keep this instance the way it is by default.38 * Otherwise, we use the current state of the39 * cdev in use to determine the next_target.40 */41 cdev->ops->get_cur_state(cdev, &cur_state);42 dev_dbg(&cdev->device, "cur_state=%ld\n", cur_state);43 44 if (!instance->initialized) {45 if (throttle)46 return clamp(cur_state + 1, instance->lower, instance->upper);47 48 return THERMAL_NO_TARGET;49 }50 51 if (throttle) {52 if (trend == THERMAL_TREND_RAISING)53 return clamp(cur_state + 1, instance->lower, instance->upper);54 } else if (trend == THERMAL_TREND_DROPPING) {55 if (cur_state <= instance->lower)56 return THERMAL_NO_TARGET;57 58 /*59 * If 'throttle' is false, no mitigation is necessary, so60 * request the lower state for this instance.61 */62 return instance->lower;63 }64 65 return instance->target;66}67 68static void thermal_zone_trip_update(struct thermal_zone_device *tz,69 const struct thermal_trip *trip,70 int trip_threshold)71{72 enum thermal_trend trend = get_tz_trend(tz, trip);73 int trip_id = thermal_zone_trip_id(tz, trip);74 struct thermal_instance *instance;75 bool throttle = false;76 77 if (tz->temperature >= trip_threshold) {78 throttle = true;79 trace_thermal_zone_trip(tz, trip_id, trip->type);80 }81 82 dev_dbg(&tz->device, "Trip%d[type=%d,temp=%d]:trend=%d,throttle=%d\n",83 trip_id, trip->type, trip_threshold, trend, throttle);84 85 list_for_each_entry(instance, &tz->thermal_instances, tz_node) {86 int old_target;87 88 if (instance->trip != trip)89 continue;90 91 old_target = instance->target;92 instance->target = get_target_state(instance, trend, throttle);93 94 dev_dbg(&instance->cdev->device, "old_target=%d, target=%ld\n",95 old_target, instance->target);96 97 if (instance->initialized && old_target == instance->target)98 continue;99 100 instance->initialized = true;101 102 mutex_lock(&instance->cdev->lock);103 instance->cdev->updated = false; /* cdev needs update */104 mutex_unlock(&instance->cdev->lock);105 }106}107 108static void step_wise_manage(struct thermal_zone_device *tz)109{110 const struct thermal_trip_desc *td;111 struct thermal_instance *instance;112 113 lockdep_assert_held(&tz->lock);114 115 /*116 * Throttling Logic: Use the trend of the thermal zone to throttle.117 * If the thermal zone is 'heating up', throttle all of the cooling118 * devices associated with each trip point by one step. If the zone119 * is 'cooling down', it brings back the performance of the devices120 * by one step.121 */122 for_each_trip_desc(tz, td) {123 const struct thermal_trip *trip = &td->trip;124 125 if (trip->temperature == THERMAL_TEMP_INVALID ||126 trip->type == THERMAL_TRIP_CRITICAL ||127 trip->type == THERMAL_TRIP_HOT)128 continue;129 130 thermal_zone_trip_update(tz, trip, td->threshold);131 }132 133 list_for_each_entry(instance, &tz->thermal_instances, tz_node)134 thermal_cdev_update(instance->cdev);135}136 137static struct thermal_governor thermal_gov_step_wise = {138 .name = "step_wise",139 .manage = step_wise_manage,140};141THERMAL_GOVERNOR_DECLARE(thermal_gov_step_wise);142