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 <trace/events/thermal.h>
 15
 16#include "thermal_core.h"
 17
 18/*
 19 * If the temperature is higher than a trip point,
 20 *    a. if the trend is THERMAL_TREND_RAISING, use higher cooling
 21 *       state for this trip point
 22 *    b. if the trend is THERMAL_TREND_DROPPING, do nothing
 23 *    c. if the trend is THERMAL_TREND_RAISE_FULL, use upper limit
 24 *       for this trip point
 25 *    d. if the trend is THERMAL_TREND_DROP_FULL, use lower limit
 26 *       for this trip point
 27 * If the temperature is lower than a trip point,
 28 *    a. if the trend is THERMAL_TREND_RAISING, do nothing
 29 *    b. if the trend is THERMAL_TREND_DROPPING, use lower cooling
 30 *       state for this trip point, if the cooling state already
 31 *       equals lower limit, deactivate the thermal instance
 32 *    c. if the trend is THERMAL_TREND_RAISE_FULL, do nothing
 33 *    d. if the trend is THERMAL_TREND_DROP_FULL, use lower limit,
 34 *       if the cooling state already equals lower limit,
 35 *       deactivate the thermal instance
 36 */
 37static unsigned long get_target_state(struct thermal_instance *instance,
 38				enum thermal_trend trend, bool throttle)
 39{
 40	struct thermal_cooling_device *cdev = instance->cdev;
 41	unsigned long cur_state;
 42	unsigned long next_target;
 43
 44	/*
 45	 * We keep this instance the way it is by default.
 46	 * Otherwise, we use the current state of the
 47	 * cdev in use to determine the next_target.
 48	 */
 49	cdev->ops->get_cur_state(cdev, &cur_state);
 50	next_target = instance->target;
 51	dev_dbg(&cdev->device, "cur_state=%ld\n", cur_state);
 52
 53	if (!instance->initialized) {
 54		if (throttle) {
 55			next_target = (cur_state + 1) >= instance->upper ?
 56					instance->upper :
 57					((cur_state + 1) < instance->lower ?
 58					instance->lower : (cur_state + 1));
 59		} else {
 60			next_target = THERMAL_NO_TARGET;
 61		}
 62
 63		return next_target;
 64	}
 65
 66	switch (trend) {
 67	case THERMAL_TREND_RAISING:
 68		if (throttle) {
 69			next_target = cur_state < instance->upper ?
 70				    (cur_state + 1) : instance->upper;
 71			if (next_target < instance->lower)
 72				next_target = instance->lower;
 73		}
 74		break;
 75	case THERMAL_TREND_RAISE_FULL:
 76		if (throttle)
 77			next_target = instance->upper;
 78		break;
 79	case THERMAL_TREND_DROPPING:
 80		if (cur_state <= instance->lower) {
 81			if (!throttle)
 82				next_target = THERMAL_NO_TARGET;
 83		} else {
 84			if (!throttle) {
 85				next_target = cur_state - 1;
 86				if (next_target > instance->upper)
 87					next_target = instance->upper;
 88			}
 89		}
 90		break;
 91	case THERMAL_TREND_DROP_FULL:
 92		if (cur_state == instance->lower) {
 93			if (!throttle)
 94				next_target = THERMAL_NO_TARGET;
 95		} else
 96			next_target = instance->lower;
 97		break;
 98	default:
 99		break;
100	}
101
102	return next_target;
103}
104
105static void update_passive_instance(struct thermal_zone_device *tz,
106				enum thermal_trip_type type, int value)
107{
108	/*
109	 * If value is +1, activate a passive instance.
110	 * If value is -1, deactivate a passive instance.
111	 */
112	if (type == THERMAL_TRIP_PASSIVE || type == THERMAL_TRIPS_NONE)
113		tz->passive += value;
114}
115
116static void thermal_zone_trip_update(struct thermal_zone_device *tz, int trip)
117{
118	int trip_temp;
119	enum thermal_trip_type trip_type;
120	enum thermal_trend trend;
121	struct thermal_instance *instance;
122	bool throttle = false;
123	int old_target;
124
125	if (trip == THERMAL_TRIPS_NONE) {
126		trip_temp = tz->forced_passive;
127		trip_type = THERMAL_TRIPS_NONE;
128	} else {
129		tz->ops->get_trip_temp(tz, trip, &trip_temp);
130		tz->ops->get_trip_type(tz, trip, &trip_type);
131	}
132
133	trend = get_tz_trend(tz, trip);
134
135	if (tz->temperature >= trip_temp) {
136		throttle = true;
137		trace_thermal_zone_trip(tz, trip, trip_type);
138	}
139
140	dev_dbg(&tz->device, "Trip%d[type=%d,temp=%d]:trend=%d,throttle=%d\n",
141				trip, trip_type, trip_temp, trend, throttle);
142
143	mutex_lock(&tz->lock);
144
145	list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
146		if (instance->trip != trip)
147			continue;
148
149		old_target = instance->target;
150		instance->target = get_target_state(instance, trend, throttle);
151		dev_dbg(&instance->cdev->device, "old_target=%d, target=%d\n",
152					old_target, (int)instance->target);
153
154		if (instance->initialized && old_target == instance->target)
155			continue;
156
157		/* Activate a passive thermal instance */
158		if (old_target == THERMAL_NO_TARGET &&
159			instance->target != THERMAL_NO_TARGET)
160			update_passive_instance(tz, trip_type, 1);
161		/* Deactivate a passive thermal instance */
162		else if (old_target != THERMAL_NO_TARGET &&
163			instance->target == THERMAL_NO_TARGET)
164			update_passive_instance(tz, trip_type, -1);
165
166		instance->initialized = true;
167		mutex_lock(&instance->cdev->lock);
168		instance->cdev->updated = false; /* cdev needs update */
169		mutex_unlock(&instance->cdev->lock);
170	}
171
172	mutex_unlock(&tz->lock);
173}
174
175/**
176 * step_wise_throttle - throttles devices associated with the given zone
177 * @tz - thermal_zone_device
178 * @trip - trip point index
179 *
180 * Throttling Logic: This uses the trend of the thermal zone to throttle.
181 * If the thermal zone is 'heating up' this throttles all the cooling
182 * devices associated with the zone and its particular trip point, by one
183 * step. If the zone is 'cooling down' it brings back the performance of
184 * the devices by one step.
185 */
186static int step_wise_throttle(struct thermal_zone_device *tz, int trip)
187{
188	struct thermal_instance *instance;
189
190	thermal_zone_trip_update(tz, trip);
191
192	if (tz->forced_passive)
193		thermal_zone_trip_update(tz, THERMAL_TRIPS_NONE);
194
195	mutex_lock(&tz->lock);
196
197	list_for_each_entry(instance, &tz->thermal_instances, tz_node)
198		thermal_cdev_update(instance->cdev);
199
200	mutex_unlock(&tz->lock);
201
202	return 0;
203}
204
205static struct thermal_governor thermal_gov_step_wise = {
206	.name		= "step_wise",
207	.throttle	= step_wise_throttle,
208};
209THERMAL_GOVERNOR_DECLARE(thermal_gov_step_wise);