// SPDX-License-Identifier: GPL-2.0-only
/*
 *  step_wise.c - A step-by-step Thermal throttling governor
 *
 *  Copyright (C) 2012 Intel Corp
 *  Copyright (C) 2012 Durgadoss R <durgadoss.r@intel.com>
 *
 *  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 *
 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 */

#include <linux/thermal.h>
#include <linux/minmax.h>
#include "thermal_trace.h"

#include "thermal_core.h"

/*
 * If the temperature is higher than a trip point,
 *    a. if the trend is THERMAL_TREND_RAISING, use higher cooling
 *       state for this trip point
 *    b. if the trend is THERMAL_TREND_DROPPING, use a lower cooling state
 *       for this trip point, but keep the cooling state above the applicable
 *       minimum
 * If the temperature is lower than a trip point,
 *    a. if the trend is THERMAL_TREND_RAISING, do nothing
 *    b. if the trend is THERMAL_TREND_DROPPING, use the minimum applicable
 *       cooling state for this trip point, or if the cooling state already
 *       equals lower limit, deactivate the thermal instance
 */
static unsigned long get_target_state(struct thermal_instance *instance,
                                enum thermal_trend trend, bool throttle)
{
        struct thermal_cooling_device *cdev = instance->cdev;
        unsigned long cur_state;

        /*
         * We keep this instance the way it is by default.
         * Otherwise, we use the current state of the
         * cdev in use to determine the next_target.
         */
        cdev->ops->get_cur_state(cdev, &cur_state);
        dev_dbg(&cdev->device, "cur_state=%ld\n", cur_state);

        if (!instance->initialized) {
                if (throttle)
                        return clamp(cur_state + 1, instance->lower, instance->upper);

                return THERMAL_NO_TARGET;
        }

        if (throttle) {
                if (trend == THERMAL_TREND_RAISING)
                        return clamp(cur_state + 1, instance->lower, instance->upper);

                /*
                 * If the zone temperature is falling, the cooling level can
                 * be reduced, but it should still be above the lower state of
                 * the given thermal instance to pull the temperature further
                 * down.
                 */
                if (trend == THERMAL_TREND_DROPPING)
                        return clamp(cur_state - 1,
                                     min(instance->lower + 1, instance->upper),
                                     instance->upper);
        } else if (trend == THERMAL_TREND_DROPPING) {
                if (cur_state <= instance->lower)
                        return THERMAL_NO_TARGET;

                /*
                 * If 'throttle' is false, no mitigation is necessary, so
                 * request the lower state for this instance.
                 */
                return instance->lower;
        }

        return instance->target;
}

static void thermal_zone_trip_update(struct thermal_zone_device *tz,
                                     const struct thermal_trip_desc *td,
                                     int trip_threshold)
{
        bool throttle = tz->temperature >= trip_threshold;
        const struct thermal_trip *trip = &td->trip;
        enum thermal_trend trend = get_tz_trend(tz, trip);
        int trip_id = thermal_zone_trip_id(tz, trip);
        struct thermal_instance *instance;

        if (throttle)
                trace_thermal_zone_trip(tz, trip_id, trip->type);

        dev_dbg(&tz->device, "Trip%d[type=%d,temp=%d]:trend=%d,throttle=%d\n",
                trip_id, trip->type, trip_threshold, trend, throttle);

        list_for_each_entry(instance, &td->thermal_instances, trip_node) {
                int old_target;

                old_target = instance->target;
                instance->target = get_target_state(instance, trend, throttle);

                dev_dbg(&instance->cdev->device, "old_target=%d, target=%ld\n",
                        old_target, instance->target);

                if (instance->initialized && old_target == instance->target)
                        continue;

                instance->initialized = true;

                scoped_guard(cooling_dev, instance->cdev) {
                        instance->cdev->updated = false; /* cdev needs update */
                }
        }
}

static void step_wise_manage(struct thermal_zone_device *tz)
{
        const struct thermal_trip_desc *td;
        struct thermal_instance *instance;

        lockdep_assert_held(&tz->lock);

        /*
         * Throttling Logic: Use the trend of the thermal zone to throttle.
         * If the thermal zone is 'heating up', throttle all of the cooling
         * devices associated with each trip point by one step. If the zone
         * is 'cooling down', it brings back the performance of the devices
         * by one step.
         */
        for_each_trip_desc(tz, td) {
                const struct thermal_trip *trip = &td->trip;

                if (trip->temperature == THERMAL_TEMP_INVALID ||
                    trip->type == THERMAL_TRIP_CRITICAL ||
                    trip->type == THERMAL_TRIP_HOT)
                        continue;

                thermal_zone_trip_update(tz, td, td->threshold);
        }

        for_each_trip_desc(tz, td) {
                list_for_each_entry(instance, &td->thermal_instances, trip_node)
                        thermal_cdev_update(instance->cdev);
        }
}

static struct thermal_governor thermal_gov_step_wise = {
        .name   = "step_wise",
        .manage = step_wise_manage,
};
THERMAL_GOVERNOR_DECLARE(thermal_gov_step_wise);