/*      $OpenBSD: ieee80211_amrr.c,v 1.1 2006/06/17 19:07:19 damien Exp $       */

/*-
 * Copyright (c) 2010 Rui Paulo <rpaulo@FreeBSD.org>
 * Copyright (c) 2006
 *      Damien Bergamini <damien.bergamini@free.fr>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");

/*-
 * Naive implementation of the Adaptive Multi Rate Retry algorithm:
 *
 * "IEEE 802.11 Rate Adaptation: A Practical Approach"
 *  Mathieu Lacage, Hossein Manshaei, Thierry Turletti
 *  INRIA Sophia - Projet Planete
 *  http://www-sop.inria.fr/rapports/sophia/RR-5208.html
 */
#include "opt_wlan.h"

#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <sys/module.h>
#include <sys/sbuf.h>
#include <sys/socket.h>
#include <sys/sysctl.h>

#include <net/if.h>
#include <net/if_var.h>
#include <net/if_media.h>
#include <net/ethernet.h>

#include <netproto/802_11/ieee80211_var.h>
#include <netproto/802_11/ieee80211_ht.h>
#include <netproto/802_11/ieee80211_amrr.h>
#include <netproto/802_11/ieee80211_ratectl.h>

#define is_success(amn) \
        ((amn)->amn_retrycnt < (amn)->amn_txcnt / 10)
#define is_failure(amn) \
        ((amn)->amn_retrycnt > (amn)->amn_txcnt / 3)
#define is_enough(amn)          \
        ((amn)->amn_txcnt > 10)

static void     amrr_setinterval(const struct ieee80211vap *, int);
static void     amrr_init(struct ieee80211vap *);
static void     amrr_deinit(struct ieee80211vap *);
static void     amrr_node_init(struct ieee80211_node *);
static void     amrr_node_deinit(struct ieee80211_node *);
static int      amrr_update(struct ieee80211_amrr *,
                        struct ieee80211_amrr_node *, struct ieee80211_node *);
static int      amrr_rate(struct ieee80211_node *, void *, uint32_t);
static void     amrr_tx_complete(const struct ieee80211vap *,
                        const struct ieee80211_node *, int, 
                        void *, void *);
static void     amrr_tx_update(const struct ieee80211vap *vap,
                        const struct ieee80211_node *, void *, void *, void *);
static void     amrr_sysctlattach(struct ieee80211vap *,
                        struct sysctl_ctx_list *, struct sysctl_oid *);
static void     amrr_node_stats(struct ieee80211_node *ni, struct sbuf *s);

/* number of references from net80211 layer */
static  int nrefs = 0;

static const struct ieee80211_ratectl amrr = {
        .ir_name        = "amrr",
        .ir_attach      = NULL,
        .ir_detach      = NULL,
        .ir_init        = amrr_init,
        .ir_deinit      = amrr_deinit,
        .ir_node_init   = amrr_node_init,
        .ir_node_deinit = amrr_node_deinit,
        .ir_rate        = amrr_rate,
        .ir_tx_complete = amrr_tx_complete,
        .ir_tx_update   = amrr_tx_update,
        .ir_setinterval = amrr_setinterval,
        .ir_node_stats  = amrr_node_stats,
};
IEEE80211_RATECTL_MODULE(amrr, 1);
IEEE80211_RATECTL_ALG(amrr, IEEE80211_RATECTL_AMRR, amrr);

static void
amrr_setinterval(const struct ieee80211vap *vap, int msecs)
{
        struct ieee80211_amrr *amrr = vap->iv_rs;
        int t;

        if (msecs < 100)
                msecs = 100;
        t = msecs_to_ticks(msecs);
        amrr->amrr_interval = (t < 1) ? 1 : t;
}

static void
amrr_init(struct ieee80211vap *vap)
{
        struct ieee80211_amrr *amrr;

        KASSERT(vap->iv_rs == NULL, ("%s called multiple times", __func__));

#if defined(__DragonFly__)
        amrr = vap->iv_rs = kmalloc(sizeof(struct ieee80211_amrr),
            M_80211_RATECTL, M_INTWAIT|M_ZERO);
#else
        amrr = vap->iv_rs = IEEE80211_MALLOC(sizeof(struct ieee80211_amrr),
            M_80211_RATECTL, IEEE80211_M_NOWAIT | IEEE80211_M_ZERO);
#endif
        if (amrr == NULL) {
                if_printf(vap->iv_ifp, "couldn't alloc ratectl structure\n");
                return;
        }
        amrr->amrr_min_success_threshold = IEEE80211_AMRR_MIN_SUCCESS_THRESHOLD;
        amrr->amrr_max_success_threshold = IEEE80211_AMRR_MAX_SUCCESS_THRESHOLD;
        amrr_setinterval(vap, 500 /* ms */);
        amrr_sysctlattach(vap, vap->iv_sysctl, vap->iv_oid);
}

static void
amrr_deinit(struct ieee80211vap *vap)
{
        IEEE80211_FREE(vap->iv_rs, M_80211_RATECTL);
}

/*
 * Return whether 11n rates are possible.
 *
 * Some 11n devices may return HT information but no HT rates.
 * Thus, we shouldn't treat them as an 11n node.
 */
static int
amrr_node_is_11n(struct ieee80211_node *ni)
{

        if (ni->ni_chan == NULL)
                return (0);
        if (ni->ni_chan == IEEE80211_CHAN_ANYC)
                return (0);
        if (IEEE80211_IS_CHAN_HT(ni->ni_chan) && ni->ni_htrates.rs_nrates == 0)
                return (0);
        return (IEEE80211_IS_CHAN_HT(ni->ni_chan));
}

static void
amrr_node_init(struct ieee80211_node *ni)
{
        const struct ieee80211_rateset *rs = NULL;
        struct ieee80211vap *vap = ni->ni_vap;
        struct ieee80211_amrr *amrr = vap->iv_rs;
        struct ieee80211_amrr_node *amn;
        uint8_t rate;

        if (ni->ni_rctls == NULL) {
#if defined(__DragonFly__)
                ni->ni_rctls = amn = kmalloc(sizeof(struct ieee80211_amrr_node),
                    M_80211_RATECTL, M_INTWAIT|M_ZERO);
#else
                ni->ni_rctls = amn = IEEE80211_MALLOC(sizeof(struct ieee80211_amrr_node),
                    M_80211_RATECTL, IEEE80211_M_NOWAIT | IEEE80211_M_ZERO);
#endif
                if (amn == NULL) {
                        if_printf(vap->iv_ifp, "couldn't alloc per-node ratectl "
                            "structure\n");
                        return;
                }
        } else
                amn = ni->ni_rctls;
        amn->amn_amrr = amrr;
        amn->amn_success = 0;
        amn->amn_recovery = 0;
        amn->amn_txcnt = amn->amn_retrycnt = 0;
        amn->amn_success_threshold = amrr->amrr_min_success_threshold;

        /* 11n or not? Pick the right rateset */
        if (amrr_node_is_11n(ni)) {
                /* XXX ew */
                IEEE80211_NOTE(ni->ni_vap, IEEE80211_MSG_RATECTL, ni,
                    "%s: 11n node", __func__);
                rs = (struct ieee80211_rateset *) &ni->ni_htrates;
        } else {
                IEEE80211_NOTE(ni->ni_vap, IEEE80211_MSG_RATECTL, ni,
                    "%s: non-11n node", __func__);
                rs = &ni->ni_rates;
        }

        /* Initial rate - lowest */
        rate = rs->rs_rates[0];

        /* XXX clear the basic rate flag if it's not 11n */
        if (! amrr_node_is_11n(ni))
                rate &= IEEE80211_RATE_VAL;

        /* pick initial rate from the rateset - HT or otherwise */
        /* Pick something low that's likely to succeed */
        for (amn->amn_rix = rs->rs_nrates - 1; amn->amn_rix > 0;
            amn->amn_rix--) {
                /* legacy - anything < 36mbit, stop searching */
                /* 11n - stop at MCS4 */
                if (amrr_node_is_11n(ni)) {
                        if ((rs->rs_rates[amn->amn_rix] & 0x1f) < 4)
                                break;
                } else if ((rs->rs_rates[amn->amn_rix] & IEEE80211_RATE_VAL) <= 72)
                        break;
        }
        rate = rs->rs_rates[amn->amn_rix] & IEEE80211_RATE_VAL;

        /* if the rate is an 11n rate, ensure the MCS bit is set */
        if (amrr_node_is_11n(ni))
                rate |= IEEE80211_RATE_MCS;

        /* Assign initial rate from the rateset */
        ni->ni_txrate = rate;
        amn->amn_ticks = ticks;

        IEEE80211_NOTE(ni->ni_vap, IEEE80211_MSG_RATECTL, ni,
            "AMRR: nrates=%d, initial rate %d",
            rs->rs_nrates,
            rate);
}

static void
amrr_node_deinit(struct ieee80211_node *ni)
{
        IEEE80211_FREE(ni->ni_rctls, M_80211_RATECTL);
}

static int
amrr_update(struct ieee80211_amrr *amrr, struct ieee80211_amrr_node *amn,
    struct ieee80211_node *ni)
{
        int rix = amn->amn_rix;
        const struct ieee80211_rateset *rs = NULL;

        KASSERT(is_enough(amn), ("txcnt %d", amn->amn_txcnt));

        /* 11n or not? Pick the right rateset */
        if (amrr_node_is_11n(ni)) {
                /* XXX ew */
                rs = (struct ieee80211_rateset *) &ni->ni_htrates;
        } else {
                rs = &ni->ni_rates;
        }

        IEEE80211_NOTE(ni->ni_vap, IEEE80211_MSG_RATECTL, ni,
            "AMRR: current rate %d, txcnt=%d, retrycnt=%d",
            rs->rs_rates[rix] & IEEE80211_RATE_VAL,
            amn->amn_txcnt,
            amn->amn_retrycnt);

        /*
         * XXX This is totally bogus for 11n, as although high MCS
         * rates for each stream may be failing, the next stream
         * should be checked.
         *
         * Eg, if MCS5 is ok but MCS6/7 isn't, and we can go up to
         * MCS23, we should skip 6/7 and try 8 onwards.
         */
        if (is_success(amn)) {
                amn->amn_success++;
                if (amn->amn_success >= amn->amn_success_threshold &&
                    rix + 1 < rs->rs_nrates) {
                        amn->amn_recovery = 1;
                        amn->amn_success = 0;
                        rix++;
                        IEEE80211_NOTE(ni->ni_vap, IEEE80211_MSG_RATECTL, ni,
                            "AMRR increasing rate %d (txcnt=%d retrycnt=%d)",
                            rs->rs_rates[rix] & IEEE80211_RATE_VAL,
                            amn->amn_txcnt, amn->amn_retrycnt);
                } else {
                        amn->amn_recovery = 0;
                }
        } else if (is_failure(amn)) {
                amn->amn_success = 0;
                if (rix > 0) {
                        if (amn->amn_recovery) {
                                amn->amn_success_threshold *= 2;
                                if (amn->amn_success_threshold >
                                    amrr->amrr_max_success_threshold)
                                        amn->amn_success_threshold =
                                            amrr->amrr_max_success_threshold;
                        } else {
                                amn->amn_success_threshold =
                                    amrr->amrr_min_success_threshold;
                        }
                        rix--;
                        IEEE80211_NOTE(ni->ni_vap, IEEE80211_MSG_RATECTL, ni,
                            "AMRR decreasing rate %d (txcnt=%d retrycnt=%d)",
                            rs->rs_rates[rix] & IEEE80211_RATE_VAL,
                            amn->amn_txcnt, amn->amn_retrycnt);
                }
                amn->amn_recovery = 0;
        }

        /* reset counters */
        amn->amn_txcnt = 0;
        amn->amn_retrycnt = 0;

        return rix;
}

/*
 * Return the rate index to use in sending a data frame.
 * Update our internal state if it's been long enough.
 * If the rate changes we also update ni_txrate to match.
 */
static int
amrr_rate(struct ieee80211_node *ni, void *arg __unused, uint32_t iarg __unused)
{
        struct ieee80211_amrr_node *amn = ni->ni_rctls;
        struct ieee80211_amrr *amrr = amn->amn_amrr;
        const struct ieee80211_rateset *rs = NULL;
        int rix;

        /* 11n or not? Pick the right rateset */
        if (amrr_node_is_11n(ni)) {
                /* XXX ew */
                rs = (struct ieee80211_rateset *) &ni->ni_htrates;
        } else {
                rs = &ni->ni_rates;
        }

        if (is_enough(amn) && (ticks - amn->amn_ticks) > amrr->amrr_interval) {
                rix = amrr_update(amrr, amn, ni);
                if (rix != amn->amn_rix) {
                        /* update public rate */
                        ni->ni_txrate = rs->rs_rates[rix];
                        /* XXX strip basic rate flag from txrate, if non-11n */
                        if (amrr_node_is_11n(ni))
                                ni->ni_txrate |= IEEE80211_RATE_MCS;
                        else
                                ni->ni_txrate &= IEEE80211_RATE_VAL;
                        amn->amn_rix = rix;
                }
                amn->amn_ticks = ticks;
        } else
                rix = amn->amn_rix;
        return rix;
}

/*
 * Update statistics with tx complete status.  Ok is non-zero
 * if the packet is known to be ACK'd.  Retries has the number
 * retransmissions (i.e. xmit attempts - 1).
 */
static void
amrr_tx_complete(const struct ieee80211vap *vap,
    const struct ieee80211_node *ni, int ok,
    void *arg1, void *arg2 __unused)
{
        struct ieee80211_amrr_node *amn = ni->ni_rctls;
        int retries = *(int *)arg1;

        amn->amn_txcnt++;
        if (ok)
                amn->amn_success++;
        amn->amn_retrycnt += retries;
}

/*
 * Set tx count/retry statistics explicitly.  Intended for
 * drivers that poll the device for statistics maintained
 * in the device.
 */
static void
amrr_tx_update(const struct ieee80211vap *vap, const struct ieee80211_node *ni,
    void *arg1, void *arg2, void *arg3)
{
        struct ieee80211_amrr_node *amn = ni->ni_rctls;
        int txcnt = *(int *)arg1, success = *(int *)arg2, retrycnt = *(int *)arg3;

        amn->amn_txcnt = txcnt;
        amn->amn_success = success;
        amn->amn_retrycnt = retrycnt;
}

static int
amrr_sysctl_interval(SYSCTL_HANDLER_ARGS)
{
        struct ieee80211vap *vap = arg1;
        struct ieee80211_amrr *amrr = vap->iv_rs;
        int msecs = ticks_to_msecs(amrr->amrr_interval);
        int error;

        error = sysctl_handle_int(oidp, &msecs, 0, req);
        if (error || !req->newptr)
                return error;
        amrr_setinterval(vap, msecs);
        return 0;
}

static void
amrr_sysctlattach(struct ieee80211vap *vap,
    struct sysctl_ctx_list *ctx, struct sysctl_oid *tree)
{
        struct ieee80211_amrr *amrr = vap->iv_rs;

        SYSCTL_ADD_PROC(ctx, SYSCTL_CHILDREN(tree), OID_AUTO,
            "amrr_rate_interval", CTLTYPE_INT | CTLFLAG_RW, vap,
            0, amrr_sysctl_interval, "I", "amrr operation interval (ms)");
        /* XXX bounds check values */
        SYSCTL_ADD_UINT(ctx, SYSCTL_CHILDREN(tree), OID_AUTO,
            "amrr_max_sucess_threshold", CTLFLAG_RW,
            &amrr->amrr_max_success_threshold, 0, "");
        SYSCTL_ADD_UINT(ctx, SYSCTL_CHILDREN(tree), OID_AUTO,
            "amrr_min_sucess_threshold", CTLFLAG_RW,
            &amrr->amrr_min_success_threshold, 0, "");
}

static void
amrr_node_stats(struct ieee80211_node *ni, struct sbuf *s)
{
        int rate;
        struct ieee80211_amrr_node *amn = ni->ni_rctls;
        struct ieee80211_rateset *rs;

        /* XXX TODO: check locking? */

        /* XXX TODO: this should be a method */
        if (amrr_node_is_11n(ni)) {
                rs = (struct ieee80211_rateset *) &ni->ni_htrates;
                rate = rs->rs_rates[amn->amn_rix] & IEEE80211_RATE_VAL;
                sbuf_printf(s, "rate: MCS %d\n", rate);
        } else {
                rs = &ni->ni_rates;
                rate = rs->rs_rates[amn->amn_rix] & IEEE80211_RATE_VAL;
                sbuf_printf(s, "rate: %d Mbit\n", rate / 2);
        }

        sbuf_printf(s, "ticks: %d\n", amn->amn_ticks);
        sbuf_printf(s, "txcnt: %u\n", amn->amn_txcnt);
        sbuf_printf(s, "success: %u\n", amn->amn_success);
        sbuf_printf(s, "success_threshold: %u\n", amn->amn_success_threshold);
        sbuf_printf(s, "recovery: %u\n", amn->amn_recovery);
        sbuf_printf(s, "retry_cnt: %u\n", amn->amn_retrycnt);
}