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

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

#include "thermal_core.h"

static int get_trip_level(struct thermal_zone_device *tz)
{
        const struct thermal_trip_desc *level_td = NULL;
        const struct thermal_trip_desc *td;
        int trip_level = -1;

        for_each_trip_desc(tz, td) {
                if (td->threshold > tz->temperature)
                        continue;

                trip_level++;

                if (!level_td || td->threshold > level_td->threshold)
                        level_td = td;
        }

        /*  Bail out if the temperature is not greater than any trips. */
        if (trip_level < 0)
                return 0;

        trace_thermal_zone_trip(tz, thermal_zone_trip_id(tz, &level_td->trip),
                                level_td->trip.type);

        return trip_level;
}

/**
 * fair_share_throttle - throttles devices associated with the given zone
 * @tz: thermal_zone_device
 * @td: trip point descriptor
 * @trip_level: number of trips crossed by the zone temperature
 *
 * Throttling Logic: This uses three parameters to calculate the new
 * throttle state of the cooling devices associated with the given zone.
 *
 * Parameters used for Throttling:
 * P1. max_state: Maximum throttle state exposed by the cooling device.
 * P2. weight[i]/total_weight:
 *      How 'effective' the 'i'th device is, in cooling the given zone.
 * P3. trip_level/max_no_of_trips:
 *      This describes the extent to which the devices should be throttled.
 *      We do not want to throttle too much when we trip a lower temperature,
 *      whereas the throttling is at full swing if we trip critical levels.
 * new_state of cooling device = P3 * P2 * P1
 */
static void fair_share_throttle(struct thermal_zone_device *tz,
                                const struct thermal_trip_desc *td,
                                int trip_level)
{
        struct thermal_instance *instance;
        int total_weight = 0;
        int nr_instances = 0;

        list_for_each_entry(instance, &td->thermal_instances, trip_node) {
                total_weight += instance->weight;
                nr_instances++;
        }

        list_for_each_entry(instance, &td->thermal_instances, trip_node) {
                struct thermal_cooling_device *cdev = instance->cdev;
                u64 dividend;
                u32 divisor;

                dividend = trip_level;
                dividend *= cdev->max_state;
                divisor = tz->num_trips;
                if (total_weight) {
                        dividend *= instance->weight;
                        divisor *= total_weight;
                } else {
                        divisor *= nr_instances;
                }
                instance->target = div_u64(dividend, divisor);

                thermal_cdev_update_nocheck(cdev);
        }
}

static void fair_share_manage(struct thermal_zone_device *tz)
{
        int trip_level = get_trip_level(tz);
        const struct thermal_trip_desc *td;

        lockdep_assert_held(&tz->lock);

        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;

                fair_share_throttle(tz, td, trip_level);
        }
}

static struct thermal_governor thermal_gov_fair_share = {
        .name   = "fair_share",
        .manage = fair_share_manage,
};
THERMAL_GOVERNOR_DECLARE(thermal_gov_fair_share);