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 */
 38static 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
 87static 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
 98static 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	list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
121		if (instance->trip != trip)
122			continue;
123
124		old_target = instance->target;
125		instance->target = get_target_state(instance, trend, throttle);
126		dev_dbg(&instance->cdev->device, "old_target=%d, target=%d\n",
127					old_target, (int)instance->target);
128
129		if (instance->initialized && old_target == instance->target)
130			continue;
131
132		/* Activate a passive thermal instance */
133		if (old_target == THERMAL_NO_TARGET &&
134			instance->target != THERMAL_NO_TARGET)
135			update_passive_instance(tz, trip_type, 1);
136		/* Deactivate a passive thermal instance */
137		else if (old_target != THERMAL_NO_TARGET &&
138			instance->target == THERMAL_NO_TARGET)
139			update_passive_instance(tz, trip_type, -1);
140
141		instance->initialized = true;
142		mutex_lock(&instance->cdev->lock);
143		instance->cdev->updated = false; /* cdev needs update */
144		mutex_unlock(&instance->cdev->lock);
145	}
146}
147
148/**
149 * step_wise_throttle - throttles devices associated with the given zone
150 * @tz: thermal_zone_device
151 * @trip: trip point index
152 *
153 * Throttling Logic: This uses the trend of the thermal zone to throttle.
154 * If the thermal zone is 'heating up' this throttles all the cooling
155 * devices associated with the zone and its particular trip point, by one
156 * step. If the zone is 'cooling down' it brings back the performance of
157 * the devices by one step.
158 */
159static int step_wise_throttle(struct thermal_zone_device *tz, int trip)
160{
161	struct thermal_instance *instance;
162
163	lockdep_assert_held(&tz->lock);
164
165	thermal_zone_trip_update(tz, trip);
166
167	list_for_each_entry(instance, &tz->thermal_instances, tz_node)
168		thermal_cdev_update(instance->cdev);
169
170	return 0;
171}
172
173static struct thermal_governor thermal_gov_step_wise = {
174	.name		= "step_wise",
175	.throttle	= step_wise_throttle,
176};
177THERMAL_GOVERNOR_DECLARE(thermal_gov_step_wise);