/*-
 * SPDX-License-Identifier: BSD-2-Clause OR GPL-2.0
 *
 * Copyright (c) 2016, Mellanox Technologies. All rights reserved.
 * Copyright (c) 2017-2018, Broadcom Limited. 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.
 */

/* This file implements Dynamic Interrupt Moderation, DIM */

#ifndef _LINUXKPI_LINUX_NET_DIM_H
#define _LINUXKPI_LINUX_NET_DIM_H

#include <asm/types.h>

#include <linux/workqueue.h>
#include <linux/ktime.h>

struct net_dim_cq_moder {
        u16     usec;
        u16     pkts;
        u8      cq_period_mode;
};

struct net_dim_sample {
        ktime_t time;
        u32     pkt_ctr;
        u32     byte_ctr;
        u16     event_ctr;
};

struct net_dim_stats {
        int     ppms;                   /* packets per msec */
        int     bpms;                   /* bytes per msec */
        int     epms;                   /* events per msec */
};

struct net_dim {                        /* Adaptive Moderation */
        u8      state;
        struct net_dim_stats prev_stats;
        struct net_dim_sample start_sample;
        struct work_struct work;
        u16     event_ctr;
        u8      profile_ix;
        u8      mode;
        u8      tune_state;
        u8      steps_right;
        u8      steps_left;
        u8      tired;
};

enum {
        NET_DIM_CQ_PERIOD_MODE_START_FROM_EQE = 0x0,
        NET_DIM_CQ_PERIOD_MODE_START_FROM_CQE = 0x1,
        NET_DIM_CQ_PERIOD_NUM_MODES = 0x2,
        NET_DIM_CQ_PERIOD_MODE_DISABLED = 0xFF,
};

/* Adaptive moderation logic */
enum {
        NET_DIM_START_MEASURE,
        NET_DIM_MEASURE_IN_PROGRESS,
        NET_DIM_APPLY_NEW_PROFILE,
};

enum {
        NET_DIM_PARKING_ON_TOP,
        NET_DIM_PARKING_TIRED,
        NET_DIM_GOING_RIGHT,
        NET_DIM_GOING_LEFT,
};

enum {
        NET_DIM_STATS_WORSE,
        NET_DIM_STATS_SAME,
        NET_DIM_STATS_BETTER,
};

enum {
        NET_DIM_STEPPED,
        NET_DIM_TOO_TIRED,
        NET_DIM_ON_EDGE,
};

#define NET_DIM_PARAMS_NUM_PROFILES 5
/* Adaptive moderation profiles */
#define NET_DIM_DEFAULT_RX_CQ_MODERATION_PKTS_FROM_EQE 256
#define NET_DIM_DEF_PROFILE_CQE 1
#define NET_DIM_DEF_PROFILE_EQE 1

/* All profiles sizes must be NET_PARAMS_DIM_NUM_PROFILES */
#define NET_DIM_EQE_PROFILES { \
        {1,   NET_DIM_DEFAULT_RX_CQ_MODERATION_PKTS_FROM_EQE}, \
        {8,   NET_DIM_DEFAULT_RX_CQ_MODERATION_PKTS_FROM_EQE}, \
        {64,  NET_DIM_DEFAULT_RX_CQ_MODERATION_PKTS_FROM_EQE}, \
        {128, NET_DIM_DEFAULT_RX_CQ_MODERATION_PKTS_FROM_EQE}, \
        {256, NET_DIM_DEFAULT_RX_CQ_MODERATION_PKTS_FROM_EQE}, \
}

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

static const struct net_dim_cq_moder
        net_dim_profile[NET_DIM_CQ_PERIOD_NUM_MODES][NET_DIM_PARAMS_NUM_PROFILES] = {
        NET_DIM_EQE_PROFILES,
        NET_DIM_CQE_PROFILES,
};

static inline struct net_dim_cq_moder
net_dim_get_profile(u8 cq_period_mode,
    int ix)
{
        struct net_dim_cq_moder cq_moder;

        cq_moder = net_dim_profile[cq_period_mode][ix];
        cq_moder.cq_period_mode = cq_period_mode;
        return cq_moder;
}

static inline struct net_dim_cq_moder
net_dim_get_def_profile(u8 rx_cq_period_mode)
{
        int default_profile_ix;

        if (rx_cq_period_mode == NET_DIM_CQ_PERIOD_MODE_START_FROM_CQE)
                default_profile_ix = NET_DIM_DEF_PROFILE_CQE;
        else    /* NET_DIM_CQ_PERIOD_MODE_START_FROM_EQE */
                default_profile_ix = NET_DIM_DEF_PROFILE_EQE;

        return net_dim_get_profile(rx_cq_period_mode, default_profile_ix);
}

static inline bool
net_dim_on_top(struct net_dim *dim)
{
        switch (dim->tune_state) {
        case NET_DIM_PARKING_ON_TOP:
        case NET_DIM_PARKING_TIRED:
                return true;
        case NET_DIM_GOING_RIGHT:
                return (dim->steps_left > 1) && (dim->steps_right == 1);
        default:        /* NET_DIM_GOING_LEFT */
                return (dim->steps_right > 1) && (dim->steps_left == 1);
        }
}

static inline void
net_dim_turn(struct net_dim *dim)
{
        switch (dim->tune_state) {
        case NET_DIM_PARKING_ON_TOP:
        case NET_DIM_PARKING_TIRED:
                break;
        case NET_DIM_GOING_RIGHT:
                dim->tune_state = NET_DIM_GOING_LEFT;
                dim->steps_left = 0;
                break;
        case NET_DIM_GOING_LEFT:
                dim->tune_state = NET_DIM_GOING_RIGHT;
                dim->steps_right = 0;
                break;
        }
}

static inline int
net_dim_step(struct net_dim *dim)
{
        if (dim->tired == (NET_DIM_PARAMS_NUM_PROFILES * 2))
                return NET_DIM_TOO_TIRED;

        switch (dim->tune_state) {
        case NET_DIM_PARKING_ON_TOP:
        case NET_DIM_PARKING_TIRED:
                break;
        case NET_DIM_GOING_RIGHT:
                if (dim->profile_ix == (NET_DIM_PARAMS_NUM_PROFILES - 1))
                        return NET_DIM_ON_EDGE;
                dim->profile_ix++;
                dim->steps_right++;
                break;
        case NET_DIM_GOING_LEFT:
                if (dim->profile_ix == 0)
                        return NET_DIM_ON_EDGE;
                dim->profile_ix--;
                dim->steps_left++;
                break;
        }

        dim->tired++;
        return NET_DIM_STEPPED;
}

static inline void
net_dim_park_on_top(struct net_dim *dim)
{
        dim->steps_right = 0;
        dim->steps_left = 0;
        dim->tired = 0;
        dim->tune_state = NET_DIM_PARKING_ON_TOP;
}

static inline void
net_dim_park_tired(struct net_dim *dim)
{
        dim->steps_right = 0;
        dim->steps_left = 0;
        dim->tune_state = NET_DIM_PARKING_TIRED;
}

static inline void
net_dim_exit_parking(struct net_dim *dim)
{
        dim->tune_state = dim->profile_ix ? NET_DIM_GOING_LEFT :
        NET_DIM_GOING_RIGHT;
        net_dim_step(dim);
}

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

static inline int
net_dim_stats_compare(struct net_dim_stats *curr,
    struct net_dim_stats *prev)
{
        if (!prev->bpms)
                return curr->bpms ? NET_DIM_STATS_BETTER :
                NET_DIM_STATS_SAME;

        if (IS_SIGNIFICANT_DIFF(curr->bpms, prev->bpms))
                return (curr->bpms > prev->bpms) ? NET_DIM_STATS_BETTER :
                    NET_DIM_STATS_WORSE;

        if (!prev->ppms)
                return curr->ppms ? NET_DIM_STATS_BETTER :
                    NET_DIM_STATS_SAME;

        if (IS_SIGNIFICANT_DIFF(curr->ppms, prev->ppms))
                return (curr->ppms > prev->ppms) ? NET_DIM_STATS_BETTER :
                    NET_DIM_STATS_WORSE;

        if (!prev->epms)
                return NET_DIM_STATS_SAME;

        if (IS_SIGNIFICANT_DIFF(curr->epms, prev->epms))
                return (curr->epms < prev->epms) ? NET_DIM_STATS_BETTER :
                    NET_DIM_STATS_WORSE;

        return NET_DIM_STATS_SAME;
}

static inline bool
net_dim_decision(struct net_dim_stats *curr_stats,
    struct net_dim *dim)
{
        int prev_state = dim->tune_state;
        int prev_ix = dim->profile_ix;
        int stats_res;
        int step_res;

        switch (dim->tune_state) {
        case NET_DIM_PARKING_ON_TOP:
                stats_res = net_dim_stats_compare(curr_stats, &dim->prev_stats);
                if (stats_res != NET_DIM_STATS_SAME)
                        net_dim_exit_parking(dim);
                break;

        case NET_DIM_PARKING_TIRED:
                dim->tired--;
                if (!dim->tired)
                        net_dim_exit_parking(dim);
                break;

        case NET_DIM_GOING_RIGHT:
        case NET_DIM_GOING_LEFT:
                stats_res = net_dim_stats_compare(curr_stats, &dim->prev_stats);
                if (stats_res != NET_DIM_STATS_BETTER)
                        net_dim_turn(dim);

                if (net_dim_on_top(dim)) {
                        net_dim_park_on_top(dim);
                        break;
                }
                step_res = net_dim_step(dim);
                switch (step_res) {
                case NET_DIM_ON_EDGE:
                        net_dim_park_on_top(dim);
                        break;
                case NET_DIM_TOO_TIRED:
                        net_dim_park_tired(dim);
                        break;
                }

                break;
        }

        if ((prev_state != NET_DIM_PARKING_ON_TOP) ||
            (dim->tune_state != NET_DIM_PARKING_ON_TOP))
                dim->prev_stats = *curr_stats;

        return dim->profile_ix != prev_ix;
}

static inline void
net_dim_sample(u16 event_ctr,
    u64 packets,
    u64 bytes,
    struct net_dim_sample *s)
{
        s->time = ktime_get();
        s->pkt_ctr = packets;
        s->byte_ctr = bytes;
        s->event_ctr = event_ctr;
}

#define NET_DIM_NEVENTS 64
#define BIT_GAP(bits, end, start) ((((end) - (start)) + BIT_ULL(bits)) & (BIT_ULL(bits) - 1))

static inline void
net_dim_calc_stats(struct net_dim_sample *start,
    struct net_dim_sample *end,
    struct net_dim_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(NET_DIM_NEVENTS * USEC_PER_MSEC,
            delta_us);
}

static inline void
net_dim(struct net_dim *dim,
    u64 packets, u64 bytes)
{
        struct net_dim_stats curr_stats;
        struct net_dim_sample end_sample;
        u16 nevents;

        dim->event_ctr++;

        switch (dim->state) {
        case NET_DIM_MEASURE_IN_PROGRESS:
                nevents = BIT_GAP(BITS_PER_TYPE(u16),
                    dim->event_ctr,
                    dim->start_sample.event_ctr);
                if (nevents < NET_DIM_NEVENTS)
                        break;
                net_dim_sample(dim->event_ctr, packets, bytes, &end_sample);
                net_dim_calc_stats(&dim->start_sample, &end_sample,
                    &curr_stats);
                if (net_dim_decision(&curr_stats, dim)) {
                        dim->state = NET_DIM_APPLY_NEW_PROFILE;
                        schedule_work(&dim->work);
                        break;
                }
                /* FALLTHROUGH */
        case NET_DIM_START_MEASURE:
                net_dim_sample(dim->event_ctr, packets, bytes, &dim->start_sample);
                dim->state = NET_DIM_MEASURE_IN_PROGRESS;
                break;
        case NET_DIM_APPLY_NEW_PROFILE:
                break;
        default:
                break;
        }
}

#endif                                  /* _LINUXKPI_LINUX_NET_DIM_H */