/*
 * Copyright (c) 2016, Mellanox Technologies. All rights reserved.
 *
 * This software is available to you under a choice of one of two
 * licenses.  You may choose to be licensed under the terms of the GNU
 * General Public License (GPL) Version 2, available from the file
 * COPYING in the main directory of this source tree, or the
 * OpenIB.org BSD license below:
 *
 *     Redistribution and use in source and binary forms, with or
 *     without modification, are permitted provided that the following
 *     conditions are met:
 *
 *      - Redistributions of source code must retain the above
 *        copyright notice, this list of conditions and the following
 *        disclaimer.
 *
 *      - Redistributions in binary form must reproduce the above
 *        copyright notice, this list of conditions and the following
 *        disclaimer in the documentation and/or other materials
 *        provided with the distribution.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

#include "en.h"

/* Adaptive moderation profiles */
#define MLX5E_AM_DEFAULT_RX_CQ_MODERATION_PKTS_FROM_EQE 256
#define MLX5E_RX_AM_DEF_PROFILE_CQE 1
#define MLX5E_RX_AM_DEF_PROFILE_EQE 1
#define MLX5E_PARAMS_AM_NUM_PROFILES 5

/* All profiles sizes must be MLX5E_PARAMS_AM_NUM_PROFILES */
#define MLX5_AM_EQE_PROFILES { \
        {1,   MLX5E_AM_DEFAULT_RX_CQ_MODERATION_PKTS_FROM_EQE}, \
        {8,   MLX5E_AM_DEFAULT_RX_CQ_MODERATION_PKTS_FROM_EQE}, \
        {64,  MLX5E_AM_DEFAULT_RX_CQ_MODERATION_PKTS_FROM_EQE}, \
        {128, MLX5E_AM_DEFAULT_RX_CQ_MODERATION_PKTS_FROM_EQE}, \
        {256, MLX5E_AM_DEFAULT_RX_CQ_MODERATION_PKTS_FROM_EQE}, \
}

#define MLX5_AM_CQE_PROFILES { \
        {2,  256},             \
        {8,  128},             \
        {16, 64},              \
        {32, 64},              \
        {64, 64}               \
}

static const struct mlx5e_cq_moder
profile[MLX5_CQ_PERIOD_NUM_MODES][MLX5E_PARAMS_AM_NUM_PROFILES] = {
        MLX5_AM_EQE_PROFILES,
        MLX5_AM_CQE_PROFILES,
};

static inline struct mlx5e_cq_moder mlx5e_am_get_profile(u8 cq_period_mode, int ix)
{
        return profile[cq_period_mode][ix];
}

struct mlx5e_cq_moder mlx5e_am_get_def_profile(u8 rx_cq_period_mode)
{
        int default_profile_ix;

        if (rx_cq_period_mode == MLX5_CQ_PERIOD_MODE_START_FROM_CQE)
                default_profile_ix = MLX5E_RX_AM_DEF_PROFILE_CQE;
        else /* MLX5_CQ_PERIOD_MODE_START_FROM_EQE */
                default_profile_ix = MLX5E_RX_AM_DEF_PROFILE_EQE;

        return profile[rx_cq_period_mode][default_profile_ix];
}

/* Adaptive moderation logic */
enum {
        MLX5E_AM_START_MEASURE,
        MLX5E_AM_MEASURE_IN_PROGRESS,
        MLX5E_AM_APPLY_NEW_PROFILE,
};

enum {
        MLX5E_AM_PARKING_ON_TOP,
        MLX5E_AM_PARKING_TIRED,
        MLX5E_AM_GOING_RIGHT,
        MLX5E_AM_GOING_LEFT,
};

enum {
        MLX5E_AM_STATS_WORSE,
        MLX5E_AM_STATS_SAME,
        MLX5E_AM_STATS_BETTER,
};

enum {
        MLX5E_AM_STEPPED,
        MLX5E_AM_TOO_TIRED,
        MLX5E_AM_ON_EDGE,
};

static bool mlx5e_am_on_top(struct mlx5e_rx_am *am)
{
        switch (am->tune_state) {
        case MLX5E_AM_PARKING_ON_TOP:
        case MLX5E_AM_PARKING_TIRED:
                return true;
        case MLX5E_AM_GOING_RIGHT:
                return (am->steps_left > 1) && (am->steps_right == 1);
        default: /* MLX5E_AM_GOING_LEFT */
                return (am->steps_right > 1) && (am->steps_left == 1);
        }
}

static void mlx5e_am_turn(struct mlx5e_rx_am *am)
{
        switch (am->tune_state) {
        case MLX5E_AM_PARKING_ON_TOP:
        case MLX5E_AM_PARKING_TIRED:
                break;
        case MLX5E_AM_GOING_RIGHT:
                am->tune_state = MLX5E_AM_GOING_LEFT;
                am->steps_left = 0;
                break;
        case MLX5E_AM_GOING_LEFT:
                am->tune_state = MLX5E_AM_GOING_RIGHT;
                am->steps_right = 0;
                break;
        }
}

static int mlx5e_am_step(struct mlx5e_rx_am *am)
{
        if (am->tired == (MLX5E_PARAMS_AM_NUM_PROFILES * 2))
                return MLX5E_AM_TOO_TIRED;

        switch (am->tune_state) {
        case MLX5E_AM_PARKING_ON_TOP:
        case MLX5E_AM_PARKING_TIRED:
                break;
        case MLX5E_AM_GOING_RIGHT:
                if (am->profile_ix == (MLX5E_PARAMS_AM_NUM_PROFILES - 1))
                        return MLX5E_AM_ON_EDGE;
                am->profile_ix++;
                am->steps_right++;
                break;
        case MLX5E_AM_GOING_LEFT:
                if (am->profile_ix == 0)
                        return MLX5E_AM_ON_EDGE;
                am->profile_ix--;
                am->steps_left++;
                break;
        }

        am->tired++;
        return MLX5E_AM_STEPPED;
}

static void mlx5e_am_park_on_top(struct mlx5e_rx_am *am)
{
        am->steps_right  = 0;
        am->steps_left   = 0;
        am->tired        = 0;
        am->tune_state   = MLX5E_AM_PARKING_ON_TOP;
}

static void mlx5e_am_park_tired(struct mlx5e_rx_am *am)
{
        am->steps_right  = 0;
        am->steps_left   = 0;
        am->tune_state   = MLX5E_AM_PARKING_TIRED;
}

static void mlx5e_am_exit_parking(struct mlx5e_rx_am *am)
{
        am->tune_state = am->profile_ix ? MLX5E_AM_GOING_LEFT :
                                          MLX5E_AM_GOING_RIGHT;
        mlx5e_am_step(am);
}

#define IS_SIGNIFICANT_DIFF(val, ref) \
        (((100 * abs((val) - (ref))) / (ref)) > 10) /* more than 10% difference */

static int mlx5e_am_stats_compare(struct mlx5e_rx_am_stats *curr,
                                  struct mlx5e_rx_am_stats *prev)
{
        if (!prev->bpms)
                return curr->bpms ? MLX5E_AM_STATS_BETTER :
                                    MLX5E_AM_STATS_SAME;

        if (IS_SIGNIFICANT_DIFF(curr->bpms, prev->bpms))
                return (curr->bpms > prev->bpms) ? MLX5E_AM_STATS_BETTER :
                                                   MLX5E_AM_STATS_WORSE;

        if (IS_SIGNIFICANT_DIFF(curr->ppms, prev->ppms))
                return (curr->ppms > prev->ppms) ? MLX5E_AM_STATS_BETTER :
                                                   MLX5E_AM_STATS_WORSE;

        if (IS_SIGNIFICANT_DIFF(curr->epms, prev->epms))
                return (curr->epms < prev->epms) ? MLX5E_AM_STATS_BETTER :
                                                   MLX5E_AM_STATS_WORSE;

        return MLX5E_AM_STATS_SAME;
}

static bool mlx5e_am_decision(struct mlx5e_rx_am_stats *curr_stats,
                              struct mlx5e_rx_am *am)
{
        int prev_state = am->tune_state;
        int prev_ix = am->profile_ix;
        int stats_res;
        int step_res;

        switch (am->tune_state) {
        case MLX5E_AM_PARKING_ON_TOP:
                stats_res = mlx5e_am_stats_compare(curr_stats, &am->prev_stats);
                if (stats_res != MLX5E_AM_STATS_SAME)
                        mlx5e_am_exit_parking(am);
                break;

        case MLX5E_AM_PARKING_TIRED:
                am->tired--;
                if (!am->tired)
                        mlx5e_am_exit_parking(am);
                break;

        case MLX5E_AM_GOING_RIGHT:
        case MLX5E_AM_GOING_LEFT:
                stats_res = mlx5e_am_stats_compare(curr_stats, &am->prev_stats);
                if (stats_res != MLX5E_AM_STATS_BETTER)
                        mlx5e_am_turn(am);

                if (mlx5e_am_on_top(am)) {
                        mlx5e_am_park_on_top(am);
                        break;
                }

                step_res = mlx5e_am_step(am);
                switch (step_res) {
                case MLX5E_AM_ON_EDGE:
                        mlx5e_am_park_on_top(am);
                        break;
                case MLX5E_AM_TOO_TIRED:
                        mlx5e_am_park_tired(am);
                        break;
                }

                break;
        }

        if ((prev_state     != MLX5E_AM_PARKING_ON_TOP) ||
            (am->tune_state != MLX5E_AM_PARKING_ON_TOP))
                am->prev_stats = *curr_stats;

        return am->profile_ix != prev_ix;
}

static void mlx5e_am_sample(struct mlx5e_rq *rq,
                            struct mlx5e_rx_am_sample *s)
{
        s->time      = ktime_get();
        s->pkt_ctr   = rq->stats.packets;
        s->byte_ctr  = rq->stats.bytes;
        s->event_ctr = rq->cq.event_ctr;
}

#define MLX5E_AM_NEVENTS 64
#define BITS_PER_TYPE(type) (sizeof(type) * BITS_PER_BYTE)
#define BIT_GAP(bits, end, start) ((((end) - (start)) + BIT_ULL(bits)) & (BIT_ULL(bits) - 1))

static void mlx5e_am_calc_stats(struct mlx5e_rx_am_sample *start,
                                struct mlx5e_rx_am_sample *end,
                                struct mlx5e_rx_am_stats *curr_stats)
{
        /* u32 holds up to 71 minutes, should be enough */
        u32 delta_us = ktime_us_delta(end->time, start->time);
        u32 npkts = BIT_GAP(BITS_PER_TYPE(u32), end->pkt_ctr, start->pkt_ctr);
        u32 nbytes = BIT_GAP(BITS_PER_TYPE(u32), end->byte_ctr,
                             start->byte_ctr);

        if (!delta_us)
                return;

        curr_stats->ppms = DIV_ROUND_UP(npkts * USEC_PER_MSEC, delta_us);
        curr_stats->bpms = DIV_ROUND_UP(nbytes * USEC_PER_MSEC, delta_us);
        curr_stats->epms = DIV_ROUND_UP(MLX5E_AM_NEVENTS * USEC_PER_MSEC,
                                        delta_us);
}

void mlx5e_rx_am_work(struct work_struct *work)
{
        struct mlx5e_rx_am *am = container_of(work, struct mlx5e_rx_am,
                                              work);
        struct mlx5e_rq *rq = container_of(am, struct mlx5e_rq, am);
        struct mlx5e_cq_moder cur_profile = profile[am->mode][am->profile_ix];

        mlx5_core_modify_cq_moderation(rq->mdev, &rq->cq.mcq,
                                       cur_profile.usec, cur_profile.pkts);

        am->state = MLX5E_AM_START_MEASURE;
}

void mlx5e_rx_am(struct mlx5e_rq *rq)
{
        struct mlx5e_rx_am *am = &rq->am;
        struct mlx5e_rx_am_sample end_sample;
        struct mlx5e_rx_am_stats curr_stats;
        u16 nevents;

        switch (am->state) {
        case MLX5E_AM_MEASURE_IN_PROGRESS:
                nevents = BIT_GAP(BITS_PER_TYPE(u16), rq->cq.event_ctr,
                                  am->start_sample.event_ctr);
                if (nevents < MLX5E_AM_NEVENTS)
                        break;
                mlx5e_am_sample(rq, &end_sample);
                mlx5e_am_calc_stats(&am->start_sample, &end_sample,
                                    &curr_stats);
                if (mlx5e_am_decision(&curr_stats, am)) {
                        am->state = MLX5E_AM_APPLY_NEW_PROFILE;
                        schedule_work(&am->work);
                        break;
                }
                /* fall through */
        case MLX5E_AM_START_MEASURE:
                mlx5e_am_sample(rq, &am->start_sample);
                am->state = MLX5E_AM_MEASURE_IN_PROGRESS;
                break;
        case MLX5E_AM_APPLY_NEW_PROFILE:
                break;
        }
}