/*      $NetBSD: athrate-onoe.c,v 1.16 2019/11/10 21:16:35 chs Exp $ */

/*-
 * Copyright (c) 2002-2005 Sam Leffler, Errno Consulting
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer,
 *    without modification.
 * 2. Redistributions in binary form must reproduce at minimum a disclaimer
 *    similar to the "NO WARRANTY" disclaimer below ("Disclaimer") and any
 *    redistribution must be conditioned upon including a substantially
 *    similar Disclaimer requirement for further binary redistribution.
 * 3. Neither the names of the above-listed copyright holders nor the names
 *    of any contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 *
 * Alternatively, this software may be distributed under the terms of the
 * GNU General Public License ("GPL") version 2 as published by the Free
 * Software Foundation.
 *
 * NO WARRANTY
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF NONINFRINGEMENT, MERCHANTIBILITY
 * AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
 * THE COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY,
 * OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER
 * IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
 * THE POSSIBILITY OF SUCH DAMAGES.
 */

#include <sys/cdefs.h>
#ifdef __FreeBSD__
__FBSDID("$FreeBSD: src/sys/dev/ath/ath_rate/onoe/onoe.c,v 1.10 2005/08/09 10:19:43 rwatson Exp $");
#endif
#ifdef __NetBSD__
__KERNEL_RCSID(0, "$NetBSD: athrate-onoe.c,v 1.16 2019/11/10 21:16:35 chs Exp $");
#endif

/*
 * Atsushi Onoe's rate control algorithm.
 */
#include "opt_inet.h"

#include <sys/param.h>
#include <sys/systm.h> 
#include <sys/sysctl.h>
#include <sys/kernel.h>
#include <sys/errno.h>
#include <sys/device.h>
#include <sys/bus.h>
#include <sys/socket.h>
 
#include <net/if.h>
#include <net/if_media.h>
#include <net/if_arp.h>
#include <net/if_ether.h>               /* XXX for ether_sprintf */

#include <net80211/ieee80211_var.h>

#include <net/bpf.h>

#ifdef INET
#include <netinet/in.h> 
#endif

#include "ah_desc.h"
#include <dev/ic/ath_netbsd.h>
#include <dev/ic/athvar.h>
#include <dev/ic/athrate-onoe.h>

#include <external/isc/atheros_hal/dist/ah.h>

#ifndef ONOE_DEBUG
#define ONOE_DEBUG
#endif

#ifdef ONOE_DEBUG
enum {
        ATH_DEBUG_RATE          = 0x00000010,   /* rate control */
};
#define DPRINTF(sc, _fmt, ...) do {                             \
        if (sc->sc_debug & ATH_DEBUG_RATE)                      \
                printf(_fmt, __VA_ARGS__);                      \
} while (0)
#else
#define DPRINTF(sc, _fmt, ...)
#endif

/*
 * Default parameters for the rate control algorithm.  These are
 * all tunable with sysctls.  The rate controller runs periodically
 * (each ath_rateinterval ms) analyzing transmit statistics for each
 * neighbor/station (when operating in station mode this is only the AP).
 * If transmits look to be working well over a sampling period then
 * it gives a "raise rate credit".  If transmits look to not be working
 * well than it deducts a credit.  If the credits cross a threshold then
 * the transmit rate is raised.  Various error conditions force the
 * the transmit rate to be dropped.
 *
 * The decision to issue/deduct a credit is based on the errors and
 * retries accumulated over the sampling period.  ath_rate_raise defines
 * the percent of retransmits for which a credit is issued/deducted.
 * ath_rate_raise_threshold defines the threshold on credits at which
 * the transmit rate is increased.
 *
 * XXX this algorithm is flawed.
 */
static  int ath_rateinterval = 1000;            /* rate ctl interval (ms)  */
static  int ath_rate_raise = 10;                /* add credit threshold */
static  int ath_rate_raise_threshold = 10;      /* rate ctl raise threshold */

static void     ath_ratectl(void *);
static void     ath_rate_update(struct ath_softc *, struct ieee80211_node *,
                        int rate);
static void     ath_rate_ctl_start(struct ath_softc *, struct ieee80211_node *);
static void     ath_rate_ctl(void *, struct ieee80211_node *);

void
ath_rate_node_init(struct ath_softc *sc, struct ath_node *an)
{
        /* NB: assumed to be zero'd by caller */
        ath_rate_update(sc, &an->an_node, 0);
}

void
ath_rate_node_cleanup(struct ath_softc *sc, struct ath_node *an)
{
}

void
ath_rate_findrate(struct ath_softc *sc, struct ath_node *an,
        int shortPreamble, size_t frameLen,
        u_int8_t *rix, int *try0, u_int8_t *txrate)
{
        struct onoe_node *on = ATH_NODE_ONOE(an);

        *rix = on->on_tx_rix0;
        *try0 = on->on_tx_try0;
        if (shortPreamble)
                *txrate = on->on_tx_rate0sp;
        else
                *txrate = on->on_tx_rate0;
}

void
ath_rate_setupxtxdesc(struct ath_softc *sc, struct ath_node *an,
        struct ath_desc *ds, int shortPreamble, u_int8_t rix)
{
        struct onoe_node *on = ATH_NODE_ONOE(an);

        ath_hal_setupxtxdesc(sc->sc_ah, ds
                , on->on_tx_rate1sp, 2  /* series 1 */
                , on->on_tx_rate2sp, 2  /* series 2 */
                , on->on_tx_rate3sp, 2  /* series 3 */
        );
}

void
ath_rate_tx_complete(struct ath_softc *sc, struct ath_node *an,
        const struct ath_desc *ds, const struct ath_desc *ds0)
{
        struct onoe_node *on = ATH_NODE_ONOE(an);

        if (ds->ds_txstat.ts_status == 0)
                on->on_tx_ok++;
        else
                on->on_tx_err++;
        on->on_tx_retr += ds->ds_txstat.ts_shortretry
                        + ds->ds_txstat.ts_longretry;
}

void
ath_rate_newassoc(struct ath_softc *sc, struct ath_node *an, int isnew)
{
        if (isnew)
                ath_rate_ctl_start(sc, &an->an_node);
}

static void
ath_rate_update(struct ath_softc *sc, struct ieee80211_node *ni, int rate)
{
        struct ath_node *an = ATH_NODE(ni);
        struct onoe_node *on = ATH_NODE_ONOE(an);
        const HAL_RATE_TABLE *rt = sc->sc_currates;
        u_int8_t rix;

        KASSERTMSG(rt != NULL, "no rate table, mode %u", sc->sc_curmode);

        DPRINTF(sc, "%s: set xmit rate for %s to %dM\n",
            __func__, ether_sprintf(ni->ni_macaddr),
            ni->ni_rates.rs_nrates > 0 ?
                (ni->ni_rates.rs_rates[rate] & IEEE80211_RATE_VAL) / 2 : 0);

        ni->ni_txrate = rate;
        /*
         * Before associating a node has no rate set setup
         * so we can't calculate any transmit codes to use.
         * This is ok since we should never be sending anything
         * but management frames and those always go at the
         * lowest hardware rate.
         */
        if (ni->ni_rates.rs_nrates == 0)
                goto done;
        on->on_tx_rix0 = sc->sc_rixmap[
                ni->ni_rates.rs_rates[rate] & IEEE80211_RATE_VAL];
        on->on_tx_rate0 = rt->info[on->on_tx_rix0].rateCode;
        
        on->on_tx_rate0sp = on->on_tx_rate0 |
                rt->info[on->on_tx_rix0].shortPreamble;
        if (sc->sc_mrretry) {
                /*
                 * Hardware supports multi-rate retry; setup two
                 * step-down retry rates and make the lowest rate
                 * be the ``last chance''.  We use 4, 2, 2, 2 tries
                 * respectively (4 is set here, the rest are fixed
                 * in the xmit routine).
                 */
                on->on_tx_try0 = 1 + 3;         /* 4 tries at rate 0 */
                if (--rate >= 0) {
                        rix = sc->sc_rixmap[
                                ni->ni_rates.rs_rates[rate]&IEEE80211_RATE_VAL];
                        on->on_tx_rate1 = rt->info[rix].rateCode;
                        on->on_tx_rate1sp = on->on_tx_rate1 |
                                rt->info[rix].shortPreamble;
                } else {
                        on->on_tx_rate1 = on->on_tx_rate1sp = 0;
                }
                if (--rate >= 0) {
                        rix = sc->sc_rixmap[
                                ni->ni_rates.rs_rates[rate]&IEEE80211_RATE_VAL];
                        on->on_tx_rate2 = rt->info[rix].rateCode;
                        on->on_tx_rate2sp = on->on_tx_rate2 |
                                rt->info[rix].shortPreamble;
                } else {
                        on->on_tx_rate2 = on->on_tx_rate2sp = 0;
                }
                if (rate > 0) {
                        /* NB: only do this if we didn't already do it above */
                        on->on_tx_rate3 = rt->info[0].rateCode;
                        on->on_tx_rate3sp =
                                on->on_tx_rate3 | rt->info[0].shortPreamble;
                } else {
                        on->on_tx_rate3 = on->on_tx_rate3sp = 0;
                }
        } else {
                on->on_tx_try0 = ATH_TXMAXTRY;  /* max tries at rate 0 */
                on->on_tx_rate1 = on->on_tx_rate1sp = 0;
                on->on_tx_rate2 = on->on_tx_rate2sp = 0;
                on->on_tx_rate3 = on->on_tx_rate3sp = 0;
        }
done:
        on->on_tx_ok = on->on_tx_err = on->on_tx_retr = on->on_tx_upper = 0;
}

/*
 * Set the starting transmit rate for a node.
 */
static void
ath_rate_ctl_start(struct ath_softc *sc, struct ieee80211_node *ni)
{
#define RATE(_ix)       (ni->ni_rates.rs_rates[(_ix)] & IEEE80211_RATE_VAL)
        struct ieee80211com *ic = &sc->sc_ic;
        int srate;

        KASSERTMSG(ni->ni_rates.rs_nrates > 0, "no rates");
        if (ic->ic_fixed_rate == IEEE80211_FIXED_RATE_NONE) {
                /*
                 * No fixed rate is requested. For 11b start with
                 * the highest negotiated rate; otherwise, for 11g
                 * and 11a, we start "in the middle" at 24Mb or 36Mb.
                 */
                srate = ni->ni_rates.rs_nrates - 1;
                if (sc->sc_curmode != IEEE80211_MODE_11B) {
                        /*
                         * Scan the negotiated rate set to find the
                         * closest rate.
                         */
                        /* NB: the rate set is assumed sorted */
                        for (; srate >= 0 && RATE(srate) > 72; srate--)
                                ;
                        KASSERTMSG(srate >= 0, "bogus rate set");
                }
        } else {
                /*
                 * A fixed rate is to be used; ic_fixed_rate is an
                 * index into the supported rate set.  Convert this
                 * to the index into the negotiated rate set for
                 * the node.  We know the rate is there because the
                 * rate set is checked when the station associates.
                 */
                const struct ieee80211_rateset *rs =
                        &ic->ic_sup_rates[ic->ic_curmode];
                int r = rs->rs_rates[ic->ic_fixed_rate] & IEEE80211_RATE_VAL;
                /* NB: the rate set is assumed sorted */
                srate = ni->ni_rates.rs_nrates - 1;
                for (; srate >= 0 && RATE(srate) != r; srate--)
                        ;
                KASSERTMSG(srate >= 0,
                        "fixed rate %d not in rate set", ic->ic_fixed_rate);
        }
        ath_rate_update(sc, ni, srate);
#undef RATE
}

static void
ath_rate_cb(void *arg, struct ieee80211_node *ni)
{
        struct ath_softc *sc = arg;

        ath_rate_update(sc, ni, 0);
}

/*
 * Reset the rate control state for each 802.11 state transition.
 */
void
ath_rate_newstate(struct ath_softc *sc, enum ieee80211_state state)
{
        struct onoe_softc *osc = (struct onoe_softc *) sc->sc_rc;
        struct ieee80211com *ic = &sc->sc_ic;
        struct ieee80211_node *ni;

        if (state == IEEE80211_S_INIT) {
                callout_stop(&osc->timer);
                return;
        }
        if (ic->ic_opmode == IEEE80211_M_STA) {
                /*
                 * Reset local xmit state; this is really only
                 * meaningful when operating in station mode.
                 */
                ni = ic->ic_bss;
                if (state == IEEE80211_S_RUN) {
                        ath_rate_ctl_start(sc, ni);
                } else {
                        ath_rate_update(sc, ni, 0);
                }
        } else {
                /*
                 * When operating as a station the node table holds
                 * the AP's that were discovered during scanning.
                 * For any other operating mode we want to reset the
                 * tx rate state of each node.
                 */
                ieee80211_iterate_nodes(&ic->ic_sta, ath_rate_cb, sc);
                ath_rate_update(sc, ic->ic_bss, 0);
        }
        if (ic->ic_fixed_rate == IEEE80211_FIXED_RATE_NONE &&
            state == IEEE80211_S_RUN) {
                int interval;
                /*
                 * Start the background rate control thread if we
                 * are not configured to use a fixed xmit rate.
                 */
                interval = ath_rateinterval;
                if (ic->ic_opmode == IEEE80211_M_STA)
                        interval /= 2;
                callout_reset(&osc->timer, (interval * hz) / 1000,
                        ath_ratectl, &sc->sc_if);
        }
}

/* 
 * Examine and potentially adjust the transmit rate.
 */
static void
ath_rate_ctl(void *arg, struct ieee80211_node *ni)
{
        struct ath_softc *sc = arg;
        struct onoe_node *on = ATH_NODE_ONOE(ATH_NODE(ni));
        struct ieee80211_rateset *rs = &ni->ni_rates;
        int dir = 0, nrate, enough;

        /*
         * Rate control
         * XXX: very primitive version.
         */
        enough = (on->on_tx_ok + on->on_tx_err >= 10);

        /* no packet reached -> down */
        if (on->on_tx_err > 0 && on->on_tx_ok == 0)
                dir = -1;

        /* all packets needs retry in average -> down */
        if (enough && on->on_tx_ok < on->on_tx_retr)
                dir = -1;

        /* no error and less than rate_raise% of packets need retry -> up */
        if (enough && on->on_tx_err == 0 &&
            on->on_tx_retr < (on->on_tx_ok * ath_rate_raise) / 100)
                dir = 1;

        DPRINTF(sc, "%s: ok %d err %d retr %d upper %d dir %d\n",
                ether_sprintf(ni->ni_macaddr),
                on->on_tx_ok, on->on_tx_err, on->on_tx_retr,
                on->on_tx_upper, dir);

        nrate = ni->ni_txrate;
        switch (dir) {
        case 0:
                if (enough && on->on_tx_upper > 0)
                        on->on_tx_upper--;
                break;
        case -1:
                if (nrate > 0) {
                        nrate--;
                        sc->sc_stats.ast_rate_drop++;
                }
                on->on_tx_upper = 0;
                break;
        case 1:
                /* raise rate if we hit rate_raise_threshold */
                if (++on->on_tx_upper < ath_rate_raise_threshold)
                        break;
                on->on_tx_upper = 0;
                if (nrate + 1 < rs->rs_nrates) {
                        nrate++;
                        sc->sc_stats.ast_rate_raise++;
                }
                break;
        }

        if (nrate != ni->ni_txrate) {
                DPRINTF(sc, "%s: %dM -> %dM (%d ok, %d err, %d retr)\n",
                    __func__,
                    (rs->rs_rates[ni->ni_txrate] & IEEE80211_RATE_VAL) / 2,
                    (rs->rs_rates[nrate] & IEEE80211_RATE_VAL) / 2,
                    on->on_tx_ok, on->on_tx_err, on->on_tx_retr);
                ath_rate_update(sc, ni, nrate);
        } else if (enough)
                on->on_tx_ok = on->on_tx_err = on->on_tx_retr = 0;
}

static void
ath_ratectl(void *arg)
{
        struct ifnet *ifp = arg;
        struct ath_softc *sc = ifp->if_softc;
        struct onoe_softc *osc = (struct onoe_softc *) sc->sc_rc;
        struct ieee80211com *ic = &sc->sc_ic;
        int interval;

        if (ifp->if_flags & IFF_RUNNING) {
                sc->sc_stats.ast_rate_calls++;

                if (ic->ic_opmode == IEEE80211_M_STA)
                        ath_rate_ctl(sc, ic->ic_bss);   /* NB: no reference */
                else
                        ieee80211_iterate_nodes(&ic->ic_sta, ath_rate_ctl, sc);
        }
        interval = ath_rateinterval;
        if (ic->ic_opmode == IEEE80211_M_STA)
                interval /= 2;
        callout_reset(&osc->timer, (interval * hz) / 1000,
                ath_ratectl, &sc->sc_if);
}

static void
ath_rate_sysctlattach(struct ath_softc *sc)
{
        struct sysctllog **clog = &sc->sc_sysctllog;
        const struct sysctlnode *cnode, *rnode;

        if ((rnode = ath_sysctl_treetop(NULL)) == NULL)
                return;

        SYSCTL_GLOBAL_INT(CTLFLAG_READWRITE, "rate_interval",
            "rate control: operation interval (ms)", rateinterval);
        /* XXX bounds check values */
        SYSCTL_GLOBAL_INT(CTLFLAG_READWRITE, "rate_raise",
            "rate control: retry threshold to credit rate raise (%%)",
            rate_raise);
        SYSCTL_GLOBAL_INT(CTLFLAG_READWRITE, "rate_raise_threshold",
            "rate control: # good periods before raising rate",
            rate_raise_threshold);
}

struct ath_ratectrl *
ath_rate_attach(struct ath_softc *sc)
{
        struct onoe_softc *osc;

        osc = malloc(sizeof(struct onoe_softc), M_DEVBUF, M_WAITOK|M_ZERO);
        osc->arc.arc_space = sizeof(struct onoe_node);
        callout_init(&osc->timer, 0);
        ath_rate_sysctlattach(sc);

        return &osc->arc;
}

void
ath_rate_detach(struct ath_ratectrl *arc)
{
        struct onoe_softc *osc = (struct onoe_softc *) arc;

        callout_stop(&osc->timer);
        free(osc, M_DEVBUF);
}