root/sys/net80211/ieee80211_ht.c 
/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2007-2008 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.
 * 2. 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, 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 DAMAGE.
 */

/*
 * IEEE 802.11n protocol support.
 */

#include "opt_inet.h"
#include "opt_wlan.h"

#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/libkern.h>
#include <sys/malloc.h>
#include <sys/systm.h> 
#include <sys/endian.h>

#include <sys/socket.h>

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

#include <net80211/ieee80211_var.h>
#include <net80211/ieee80211_action.h>
#include <net80211/ieee80211_input.h>

const struct ieee80211_mcs_rates ieee80211_htrates[IEEE80211_HTRATE_MAXSIZE] = {
        {  13,  14,   27,   30 },       /* MCS 0 */
        {  26,  29,   54,   60 },       /* MCS 1 */
        {  39,  43,   81,   90 },       /* MCS 2 */
        {  52,  58,  108,  120 },       /* MCS 3 */
        {  78,  87,  162,  180 },       /* MCS 4 */
        { 104, 116,  216,  240 },       /* MCS 5 */
        { 117, 130,  243,  270 },       /* MCS 6 */
        { 130, 144,  270,  300 },       /* MCS 7 */
        {  26,  29,   54,   60 },       /* MCS 8 */
        {  52,  58,  108,  120 },       /* MCS 9 */
        {  78,  87,  162,  180 },       /* MCS 10 */
        { 104, 116,  216,  240 },       /* MCS 11 */
        { 156, 173,  324,  360 },       /* MCS 12 */
        { 208, 231,  432,  480 },       /* MCS 13 */
        { 234, 260,  486,  540 },       /* MCS 14 */
        { 260, 289,  540,  600 },       /* MCS 15 */
        {  39,  43,   81,   90 },       /* MCS 16 */
        {  78,  87,  162,  180 },       /* MCS 17 */
        { 117, 130,  243,  270 },       /* MCS 18 */
        { 156, 173,  324,  360 },       /* MCS 19 */
        { 234, 260,  486,  540 },       /* MCS 20 */
        { 312, 347,  648,  720 },       /* MCS 21 */
        { 351, 390,  729,  810 },       /* MCS 22 */
        { 390, 433,  810,  900 },       /* MCS 23 */
        {  52,  58,  108,  120 },       /* MCS 24 */
        { 104, 116,  216,  240 },       /* MCS 25 */
        { 156, 173,  324,  360 },       /* MCS 26 */
        { 208, 231,  432,  480 },       /* MCS 27 */
        { 312, 347,  648,  720 },       /* MCS 28 */
        { 416, 462,  864,  960 },       /* MCS 29 */
        { 468, 520,  972, 1080 },       /* MCS 30 */
        { 520, 578, 1080, 1200 },       /* MCS 31 */
        {   0,   0,   12,   13 },       /* MCS 32 */
        {  78,  87,  162,  180 },       /* MCS 33 */
        { 104, 116,  216,  240 },       /* MCS 34 */
        { 130, 144,  270,  300 },       /* MCS 35 */
        { 117, 130,  243,  270 },       /* MCS 36 */
        { 156, 173,  324,  360 },       /* MCS 37 */
        { 195, 217,  405,  450 },       /* MCS 38 */
        { 104, 116,  216,  240 },       /* MCS 39 */
        { 130, 144,  270,  300 },       /* MCS 40 */
        { 130, 144,  270,  300 },       /* MCS 41 */
        { 156, 173,  324,  360 },       /* MCS 42 */
        { 182, 202,  378,  420 },       /* MCS 43 */
        { 182, 202,  378,  420 },       /* MCS 44 */
        { 208, 231,  432,  480 },       /* MCS 45 */
        { 156, 173,  324,  360 },       /* MCS 46 */
        { 195, 217,  405,  450 },       /* MCS 47 */
        { 195, 217,  405,  450 },       /* MCS 48 */
        { 234, 260,  486,  540 },       /* MCS 49 */
        { 273, 303,  567,  630 },       /* MCS 50 */
        { 273, 303,  567,  630 },       /* MCS 51 */
        { 312, 347,  648,  720 },       /* MCS 52 */
        { 130, 144,  270,  300 },       /* MCS 53 */
        { 156, 173,  324,  360 },       /* MCS 54 */
        { 182, 202,  378,  420 },       /* MCS 55 */
        { 156, 173,  324,  360 },       /* MCS 56 */
        { 182, 202,  378,  420 },       /* MCS 57 */
        { 208, 231,  432,  480 },       /* MCS 58 */
        { 234, 260,  486,  540 },       /* MCS 59 */
        { 208, 231,  432,  480 },       /* MCS 60 */
        { 234, 260,  486,  540 },       /* MCS 61 */
        { 260, 289,  540,  600 },       /* MCS 62 */
        { 260, 289,  540,  600 },       /* MCS 63 */
        { 286, 318,  594,  660 },       /* MCS 64 */
        { 195, 217,  405,  450 },       /* MCS 65 */
        { 234, 260,  486,  540 },       /* MCS 66 */
        { 273, 303,  567,  630 },       /* MCS 67 */
        { 234, 260,  486,  540 },       /* MCS 68 */
        { 273, 303,  567,  630 },       /* MCS 69 */
        { 312, 347,  648,  720 },       /* MCS 70 */
        { 351, 390,  729,  810 },       /* MCS 71 */
        { 312, 347,  648,  720 },       /* MCS 72 */
        { 351, 390,  729,  810 },       /* MCS 73 */
        { 390, 433,  810,  900 },       /* MCS 74 */
        { 390, 433,  810,  900 },       /* MCS 75 */
        { 429, 477,  891,  990 },       /* MCS 76 */
};

static  int ieee80211_ampdu_age = -1;   /* threshold for ampdu reorder q (ms) */
SYSCTL_PROC(_net_wlan, OID_AUTO, ampdu_age,
    CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT,
    &ieee80211_ampdu_age, 0, ieee80211_sysctl_msecs_ticks, "I",
    "AMPDU max reorder age (ms)");

static  int ieee80211_recv_bar_ena = 1;
SYSCTL_INT(_net_wlan, OID_AUTO, recv_bar, CTLFLAG_RW, &ieee80211_recv_bar_ena,
            0, "BAR frame processing (ena/dis)");

static  int ieee80211_addba_timeout = -1;/* timeout for ADDBA response */
SYSCTL_PROC(_net_wlan, OID_AUTO, addba_timeout,
    CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT,
    &ieee80211_addba_timeout, 0, ieee80211_sysctl_msecs_ticks, "I",
    "ADDBA request timeout (ms)");
static  int ieee80211_addba_backoff = -1;/* backoff after max ADDBA requests */
SYSCTL_PROC(_net_wlan, OID_AUTO, addba_backoff,
    CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT,
    &ieee80211_addba_backoff, 0, ieee80211_sysctl_msecs_ticks, "I",
    "ADDBA request backoff (ms)");
static  int ieee80211_addba_maxtries = 3;/* max ADDBA requests before backoff */
SYSCTL_INT(_net_wlan, OID_AUTO, addba_maxtries, CTLFLAG_RW,
        &ieee80211_addba_maxtries, 0, "max ADDBA requests sent before backoff");

static  int ieee80211_bar_timeout = -1; /* timeout waiting for BAR response */
static  int ieee80211_bar_maxtries = 50;/* max BAR requests before DELBA */

static  ieee80211_recv_action_func ht_recv_action_ba_addba_request;
static  ieee80211_recv_action_func ht_recv_action_ba_addba_response;
static  ieee80211_recv_action_func ht_recv_action_ba_delba;
static  ieee80211_recv_action_func ht_recv_action_ht_mimopwrsave;
static  ieee80211_recv_action_func ht_recv_action_ht_txchwidth;

static  ieee80211_send_action_func ht_send_action_ba_addba;
static  ieee80211_send_action_func ht_send_action_ba_delba;
static  ieee80211_send_action_func ht_send_action_ht_txchwidth;

static void
ieee80211_ht_init(void *dummy __unused)
{
        /*
         * Setup HT parameters that depends on the clock frequency.
         */
        ieee80211_ampdu_age = msecs_to_ticks(500);
        ieee80211_addba_timeout = msecs_to_ticks(250);
        ieee80211_addba_backoff = msecs_to_ticks(10*1000);
        ieee80211_bar_timeout = msecs_to_ticks(250);
        /*
         * Register action frame handlers.
         */
        ieee80211_recv_action_register(IEEE80211_ACTION_CAT_BA, 
            IEEE80211_ACTION_BA_ADDBA_REQUEST, ht_recv_action_ba_addba_request);
        ieee80211_recv_action_register(IEEE80211_ACTION_CAT_BA, 
            IEEE80211_ACTION_BA_ADDBA_RESPONSE, ht_recv_action_ba_addba_response);
        ieee80211_recv_action_register(IEEE80211_ACTION_CAT_BA, 
            IEEE80211_ACTION_BA_DELBA, ht_recv_action_ba_delba);
        ieee80211_recv_action_register(IEEE80211_ACTION_CAT_HT, 
            IEEE80211_ACTION_HT_MIMOPWRSAVE, ht_recv_action_ht_mimopwrsave);
        ieee80211_recv_action_register(IEEE80211_ACTION_CAT_HT, 
            IEEE80211_ACTION_HT_TXCHWIDTH, ht_recv_action_ht_txchwidth);

        ieee80211_send_action_register(IEEE80211_ACTION_CAT_BA, 
            IEEE80211_ACTION_BA_ADDBA_REQUEST, ht_send_action_ba_addba);
        ieee80211_send_action_register(IEEE80211_ACTION_CAT_BA, 
            IEEE80211_ACTION_BA_ADDBA_RESPONSE, ht_send_action_ba_addba);
        ieee80211_send_action_register(IEEE80211_ACTION_CAT_BA, 
            IEEE80211_ACTION_BA_DELBA, ht_send_action_ba_delba);
        ieee80211_send_action_register(IEEE80211_ACTION_CAT_HT, 
            IEEE80211_ACTION_HT_TXCHWIDTH, ht_send_action_ht_txchwidth);
}
SYSINIT(wlan_ht, SI_SUB_DRIVERS, SI_ORDER_FIRST, ieee80211_ht_init, NULL);

static int ieee80211_ampdu_enable(struct ieee80211_node *ni,
        struct ieee80211_tx_ampdu *tap);
static int ieee80211_addba_request(struct ieee80211_node *ni,
        struct ieee80211_tx_ampdu *tap,
        int dialogtoken, int baparamset, int batimeout);
static int ieee80211_addba_response(struct ieee80211_node *ni,
        struct ieee80211_tx_ampdu *tap,
        int code, int baparamset, int batimeout);
static void ieee80211_addba_stop(struct ieee80211_node *ni,
        struct ieee80211_tx_ampdu *tap);
static void null_addba_response_timeout(struct ieee80211_node *ni,
        struct ieee80211_tx_ampdu *tap);

static void ieee80211_bar_response(struct ieee80211_node *ni,
        struct ieee80211_tx_ampdu *tap, int status);
static void ampdu_tx_stop(struct ieee80211_tx_ampdu *tap);
static void bar_stop_timer(struct ieee80211_tx_ampdu *tap);
static int ampdu_rx_start(struct ieee80211_node *, struct ieee80211_rx_ampdu *,
        int baparamset, int batimeout, int baseqctl);
static void ampdu_rx_stop(struct ieee80211_node *, struct ieee80211_rx_ampdu *);

void
ieee80211_ht_attach(struct ieee80211com *ic)
{
        /* setup default aggregation policy */
        ic->ic_recv_action = ieee80211_recv_action;
        ic->ic_send_action = ieee80211_send_action;
        ic->ic_ampdu_enable = ieee80211_ampdu_enable;
        ic->ic_addba_request = ieee80211_addba_request;
        ic->ic_addba_response = ieee80211_addba_response;
        ic->ic_addba_response_timeout = null_addba_response_timeout;
        ic->ic_addba_stop = ieee80211_addba_stop;
        ic->ic_bar_response = ieee80211_bar_response;
        ic->ic_ampdu_rx_start = ampdu_rx_start;
        ic->ic_ampdu_rx_stop = ampdu_rx_stop;

        ic->ic_htprotmode = IEEE80211_PROT_RTSCTS;
        ic->ic_curhtprotmode = IEEE80211_HTINFO_OPMODE_PURE;
}

void
ieee80211_ht_detach(struct ieee80211com *ic)
{
}

void
ieee80211_ht_vattach(struct ieee80211vap *vap)
{

        /* driver can override defaults */
        vap->iv_ampdu_rxmax = IEEE80211_HTCAP_MAXRXAMPDU_8K;
        vap->iv_ampdu_density = IEEE80211_HTCAP_MPDUDENSITY_NA;
        vap->iv_ampdu_limit = vap->iv_ampdu_rxmax;
        vap->iv_amsdu_limit = vap->iv_htcaps & IEEE80211_HTCAP_MAXAMSDU;
        /* tx aggregation traffic thresholds */
        vap->iv_ampdu_mintraffic[WME_AC_BK] = 128;
        vap->iv_ampdu_mintraffic[WME_AC_BE] = 64;
        vap->iv_ampdu_mintraffic[WME_AC_VO] = 32;
        vap->iv_ampdu_mintraffic[WME_AC_VI] = 32;

        vap->iv_htprotmode = IEEE80211_PROT_RTSCTS;
        vap->iv_curhtprotmode = IEEE80211_HTINFO_OPMODE_PURE;

        if (vap->iv_htcaps & IEEE80211_HTC_HT) {
                /*
                 * Device is HT capable; enable all HT-related
                 * facilities by default.
                 * XXX these choices may be too aggressive.
                 */
                vap->iv_flags_ht |= IEEE80211_FHT_HT
                                 |  IEEE80211_FHT_HTCOMPAT
                                 ;
                if (vap->iv_htcaps & IEEE80211_HTCAP_SHORTGI20)
                        vap->iv_flags_ht |= IEEE80211_FHT_SHORTGI20;
                /* XXX infer from channel list? */
                if (vap->iv_htcaps & IEEE80211_HTCAP_CHWIDTH40) {
                        vap->iv_flags_ht |= IEEE80211_FHT_USEHT40;
                        if (vap->iv_htcaps & IEEE80211_HTCAP_SHORTGI40)
                                vap->iv_flags_ht |= IEEE80211_FHT_SHORTGI40;
                }
                /* enable RIFS if capable */
                if (vap->iv_htcaps & IEEE80211_HTC_RIFS)
                        vap->iv_flags_ht |= IEEE80211_FHT_RIFS;

                /* NB: A-MPDU and A-MSDU rx are mandated, these are tx only */
                vap->iv_flags_ht |= IEEE80211_FHT_AMPDU_RX;
                if (vap->iv_htcaps & IEEE80211_HTC_AMPDU)
                        vap->iv_flags_ht |= IEEE80211_FHT_AMPDU_TX;
                vap->iv_flags_ht |= IEEE80211_FHT_AMSDU_RX;
                if (vap->iv_htcaps & IEEE80211_HTC_AMSDU)
                        vap->iv_flags_ht |= IEEE80211_FHT_AMSDU_TX;

                if (vap->iv_htcaps & IEEE80211_HTCAP_TXSTBC)
                        vap->iv_flags_ht |= IEEE80211_FHT_STBC_TX;
                if (vap->iv_htcaps & IEEE80211_HTCAP_RXSTBC)
                        vap->iv_flags_ht |= IEEE80211_FHT_STBC_RX;

                if (vap->iv_htcaps & IEEE80211_HTCAP_LDPC)
                        vap->iv_flags_ht |= IEEE80211_FHT_LDPC_RX;
                if (vap->iv_htcaps & IEEE80211_HTC_TXLDPC)
                        vap->iv_flags_ht |= IEEE80211_FHT_LDPC_TX;
        }
        /* NB: disable default legacy WDS, too many issues right now */
        if (vap->iv_flags_ext & IEEE80211_FEXT_WDSLEGACY)
                vap->iv_flags_ht &= ~IEEE80211_FHT_HT;
}

void
ieee80211_ht_vdetach(struct ieee80211vap *vap)
{
}

static int
ht_getrate(struct ieee80211com *ic, int index, enum ieee80211_phymode mode,
    int ratetype)
{
        struct ieee80211_node_txrate tr;
        int mword, rate;

        tr = IEEE80211_NODE_TXRATE_INIT_HT(index);

        mword = ieee80211_rate2media(ic, &tr, mode);
        if (IFM_SUBTYPE(mword) != IFM_IEEE80211_MCS)
                return (0);
        switch (ratetype) {
        case 0:
                rate = ieee80211_htrates[index].ht20_rate_800ns;
                break;
        case 1:
                rate = ieee80211_htrates[index].ht20_rate_400ns;
                break;
        case 2:
                rate = ieee80211_htrates[index].ht40_rate_800ns;
                break;
        default:
                rate = ieee80211_htrates[index].ht40_rate_400ns;
                break;
        }
        return (rate);
}

static struct printranges {
        int     minmcs;
        int     maxmcs;
        int     txstream;
        int     ratetype;
        int     htcapflags;
} ranges[] = {
        {  0,  7, 1, 0, 0 },
        {  8, 15, 2, 0, 0 },
        { 16, 23, 3, 0, 0 },
        { 24, 31, 4, 0, 0 },
        { 32,  0, 1, 2, IEEE80211_HTC_TXMCS32 },
        { 33, 38, 2, 0, IEEE80211_HTC_TXUNEQUAL },
        { 39, 52, 3, 0, IEEE80211_HTC_TXUNEQUAL },
        { 53, 76, 4, 0, IEEE80211_HTC_TXUNEQUAL },
        {  0,  0, 0, 0, 0 },
};

static void
ht_rateprint(struct ieee80211com *ic, enum ieee80211_phymode mode, int ratetype)
{
        int minrate, maxrate;
        struct printranges *range;

        for (range = ranges; range->txstream != 0; range++) {
                if (ic->ic_txstream < range->txstream)
                        continue;
                if (range->htcapflags &&
                    (ic->ic_htcaps & range->htcapflags) == 0)
                        continue;
                if (ratetype < range->ratetype)
                        continue;
                minrate = ht_getrate(ic, range->minmcs, mode, ratetype);
                maxrate = ht_getrate(ic, range->maxmcs, mode, ratetype);
                if (range->maxmcs) {
                        ic_printf(ic, "MCS %d-%d: %d%sMbps - %d%sMbps\n",
                            range->minmcs, range->maxmcs,
                            minrate/2, ((minrate & 0x1) != 0 ? ".5" : ""),
                            maxrate/2, ((maxrate & 0x1) != 0 ? ".5" : ""));
                } else {
                        ic_printf(ic, "MCS %d: %d%sMbps\n", range->minmcs,
                            minrate/2, ((minrate & 0x1) != 0 ? ".5" : ""));
                }
        }
}

static void
ht_announce(struct ieee80211com *ic, enum ieee80211_phymode mode)
{
        const char *modestr = ieee80211_phymode_name[mode];

        ic_printf(ic, "%s MCS 20MHz\n", modestr);
        ht_rateprint(ic, mode, 0);
        if (ic->ic_htcaps & IEEE80211_HTCAP_SHORTGI20) {
                ic_printf(ic, "%s MCS 20MHz SGI\n", modestr);
                ht_rateprint(ic, mode, 1);
        }
        if (ic->ic_htcaps & IEEE80211_HTCAP_CHWIDTH40) {
                ic_printf(ic, "%s MCS 40MHz:\n", modestr);
                ht_rateprint(ic, mode, 2);
        }
        if ((ic->ic_htcaps & IEEE80211_HTCAP_CHWIDTH40) &&
            (ic->ic_htcaps & IEEE80211_HTCAP_SHORTGI40)) {
                ic_printf(ic, "%s MCS 40MHz SGI:\n", modestr);
                ht_rateprint(ic, mode, 3);
        }
}

void
ieee80211_ht_announce(struct ieee80211com *ic)
{

        if (isset(ic->ic_modecaps, IEEE80211_MODE_11NA) ||
            isset(ic->ic_modecaps, IEEE80211_MODE_11NG))
                ic_printf(ic, "%dT%dR\n", ic->ic_txstream, ic->ic_rxstream);
        if (isset(ic->ic_modecaps, IEEE80211_MODE_11NA))
                ht_announce(ic, IEEE80211_MODE_11NA);
        if (isset(ic->ic_modecaps, IEEE80211_MODE_11NG))
                ht_announce(ic, IEEE80211_MODE_11NG);
}

void
ieee80211_init_suphtrates(struct ieee80211com *ic)
{
#define ADDRATE(x)      do {                                            \
        htrateset->rs_rates[htrateset->rs_nrates] = x;                  \
        htrateset->rs_nrates++;                                         \
} while (0)
        struct ieee80211_htrateset *htrateset = &ic->ic_sup_htrates;
        int i;

        memset(htrateset, 0, sizeof(struct ieee80211_htrateset));
        for (i = 0; i < ic->ic_txstream * 8; i++)
                ADDRATE(i);
        if ((ic->ic_htcaps & IEEE80211_HTCAP_CHWIDTH40) &&
            (ic->ic_htcaps & IEEE80211_HTC_TXMCS32))
                ADDRATE(32);
        if (ic->ic_htcaps & IEEE80211_HTC_TXUNEQUAL) {
                if (ic->ic_txstream >= 2) {
                         for (i = 33; i <= 38; i++)
                                ADDRATE(i);
                }
                if (ic->ic_txstream >= 3) {
                        for (i = 39; i <= 52; i++)
                                ADDRATE(i);
                }
                if (ic->ic_txstream == 4) {
                        for (i = 53; i <= 76; i++)
                                ADDRATE(i);
                }
        }
#undef  ADDRATE
}

/*
 * Receive processing.
 */

/*
 * Decap the encapsulated A-MSDU frames and dispatch all but
 * the last for delivery.  The last frame is returned for 
 * delivery via the normal path.
 */
struct mbuf *
ieee80211_decap_amsdu(struct ieee80211_node *ni, struct mbuf *m)
{
        struct ieee80211vap *vap = ni->ni_vap;
        int framelen;
        struct mbuf *n;

        /* discard 802.3 header inserted by ieee80211_decap */
        m_adj(m, sizeof(struct ether_header));

        vap->iv_stats.is_amsdu_decap++;

        for (;;) {
                /*
                 * Decap the first frame, bust it apart from the
                 * remainder and deliver.  We leave the last frame
                 * delivery to the caller (for consistency with other
                 * code paths, could also do it here).
                 */
                m = ieee80211_decap1(m, &framelen);
                if (m == NULL) {
                        IEEE80211_DISCARD_MAC(vap, IEEE80211_MSG_ANY,
                            ni->ni_macaddr, "a-msdu", "%s", "decap failed");
                        vap->iv_stats.is_amsdu_tooshort++;
                        return NULL;
                }
                if (m->m_pkthdr.len == framelen)
                        break;
                n = m_split(m, framelen, IEEE80211_M_NOWAIT);
                if (n == NULL) {
                        IEEE80211_DISCARD_MAC(vap, IEEE80211_MSG_ANY,
                            ni->ni_macaddr, "a-msdu",
                            "%s", "unable to split encapsulated frames");
                        vap->iv_stats.is_amsdu_split++;
                        m_freem(m);                     /* NB: must reclaim */
                        return NULL;
                }
                vap->iv_deliver_data(vap, ni, m);

                /*
                 * Remove frame contents; each intermediate frame
                 * is required to be aligned to a 4-byte boundary.
                 */
                m = n;
                m_adj(m, roundup2(framelen, 4) - framelen);     /* padding */
        }
        return m;                               /* last delivered by caller */
}

static void
ampdu_rx_purge_slot(struct ieee80211_rx_ampdu *rap, int i)
{
        struct mbuf *m;

        /* Walk the queue, removing frames as appropriate */
        for (;;) {
                m = mbufq_dequeue(&rap->rxa_mq[i]);
                if (m == NULL)
                        break;
                rap->rxa_qbytes -= m->m_pkthdr.len;
                rap->rxa_qframes--;
                m_freem(m);
        }
}

/*
 * Add the given frame to the current RX reorder slot.
 *
 * For future offloaded A-MSDU handling where multiple frames with
 * the same sequence number show up here, this routine will append
 * those frames as long as they're appropriately tagged.
 */
static int
ampdu_rx_add_slot(struct ieee80211_rx_ampdu *rap, int off, int tid,
    ieee80211_seq rxseq,
    struct ieee80211_node *ni,
    struct mbuf *m,
    const struct ieee80211_rx_stats *rxs)
{
        const struct ieee80211_rx_stats *rxs_final = NULL;
        struct ieee80211vap *vap = ni->ni_vap;
        int toss_dup;
#define PROCESS         0       /* caller should process frame */
#define CONSUMED        1       /* frame consumed, caller does nothing */

        /*
         * Figure out if this is a duplicate frame for the given slot.
         *
         * We're assuming that the driver will hand us all the frames
         * for a given AMSDU decap pass and if we get /a/ frame
         * for an AMSDU decap then we'll get all of them.
         *
         * The tricksy bit is that we don't know when the /end/ of
         * the decap pass is, because we aren't tracking state here
         * per-slot to know that we've finished receiving the frame list.
         *
         * The driver sets RX_F_AMSDU and RX_F_AMSDU_MORE to tell us
         * what's going on; so ideally we'd just check the frame at the
         * end of the reassembly slot to see if its F_AMSDU w/ no F_AMSDU_MORE -
         * that means we've received the whole AMSDU decap pass.
         */

        /*
         * Get the rxs of the final mbuf in the slot, if one exists.
         */
        if (!mbufq_empty(&rap->rxa_mq[off])) {
                rxs_final = ieee80211_get_rx_params_ptr(mbufq_last(&rap->rxa_mq[off]));
        }

        /* Default to tossing the duplicate frame */
        toss_dup = 1;

        /*
         * Check to see if the final frame has F_AMSDU and F_AMSDU set, AND
         * this frame has F_AMSDU set (MORE or otherwise.)  That's a sign
         * that more can come.
         */

        if ((rxs != NULL) && (rxs_final != NULL) &&
            ieee80211_check_rxseq_amsdu(rxs) &&
            ieee80211_check_rxseq_amsdu(rxs_final)) {
                if (! ieee80211_check_rxseq_amsdu_more(rxs_final)) {
                        /*
                         * amsdu_more() returning 0 means "it's not the
                         * final frame" so we can append more
                         * frames here.
                         */
                        toss_dup = 0;
                }
        }

        /*
         * If the list is empty OR we have determined we can put more
         * driver decap'ed AMSDU frames in here, then insert.
         */
        if (mbufq_empty(&rap->rxa_mq[off]) || (toss_dup == 0)) {
                if (mbufq_enqueue(&rap->rxa_mq[off], m) != 0) {
                        IEEE80211_DISCARD_MAC(vap, IEEE80211_MSG_INPUT | IEEE80211_MSG_11N,
                            ni->ni_macaddr,
                            "a-mpdu queue fail",
                            "seqno %u tid %u BA win <%u:%u> off=%d, qlen=%d, maxqlen=%d",
                            rxseq, tid, rap->rxa_start,
                            IEEE80211_SEQ_ADD(rap->rxa_start, rap->rxa_wnd-1),
                            off,
                            mbufq_len(&rap->rxa_mq[off]),
                            rap->rxa_mq[off].mq_maxlen);
                        /* XXX error count */
                        m_freem(m);
                        return CONSUMED;
                }
                rap->rxa_qframes++;
                rap->rxa_qbytes += m->m_pkthdr.len;
                vap->iv_stats.is_ampdu_rx_reorder++;
                /*
                 * Statistics for AMSDU decap.
                 */
                if (rxs != NULL && ieee80211_check_rxseq_amsdu(rxs)) {
                        if (ieee80211_check_rxseq_amsdu_more(rxs)) {
                                /* more=1, AMSDU, end of batch */
                                IEEE80211_NODE_STAT(ni, rx_amsdu_more_end);
                        } else {
                                IEEE80211_NODE_STAT(ni, rx_amsdu_more);
                        }
                }
        } else {
                IEEE80211_DISCARD_MAC(vap,
                    IEEE80211_MSG_INPUT | IEEE80211_MSG_11N,
                    ni->ni_macaddr, "a-mpdu duplicate",
                    "seqno %u tid %u BA win <%u:%u>",
                    rxseq, tid, rap->rxa_start,
                    IEEE80211_SEQ_ADD(rap->rxa_start, rap->rxa_wnd-1));
                if (rxs != NULL) {
                        IEEE80211_DISCARD_MAC(vap,
                            IEEE80211_MSG_INPUT | IEEE80211_MSG_11N,
                            ni->ni_macaddr, "a-mpdu duplicate",
                            "seqno %d tid %u pktflags 0x%08x\n",
                            rxseq, tid, rxs->c_pktflags);
                }
                if (rxs_final != NULL) {
                        IEEE80211_DISCARD_MAC(vap,
                            IEEE80211_MSG_INPUT | IEEE80211_MSG_11N,
                            ni->ni_macaddr, "a-mpdu duplicate",
                            "final: pktflags 0x%08x\n",
                            rxs_final->c_pktflags);
                }
                vap->iv_stats.is_rx_dup++;
                IEEE80211_NODE_STAT(ni, rx_dup);
                m_freem(m);
        }
        return CONSUMED;
#undef  CONSUMED
#undef  PROCESS
}

/*
 * Purge all frames in the A-MPDU re-order queue.
 */
static void
ampdu_rx_purge(struct ieee80211_rx_ampdu *rap)
{
        int i;

        for (i = 0; i < rap->rxa_wnd; i++) {
                ampdu_rx_purge_slot(rap, i);
                if (rap->rxa_qframes == 0)
                        break;
        }
        KASSERT(rap->rxa_qbytes == 0 && rap->rxa_qframes == 0,
            ("lost %u data, %u frames on ampdu rx q",
            rap->rxa_qbytes, rap->rxa_qframes));
}

static void
ieee80211_ampdu_rx_init_rap(struct ieee80211_node *ni,
    struct ieee80211_rx_ampdu *rap)
{
        int i;

        /* XXX TODO: ensure the queues are empty */
        memset(rap, 0, sizeof(*rap));
        for (i = 0; i < IEEE80211_AGGR_BAWMAX; i++)
                mbufq_init(&rap->rxa_mq[i], 256);
}

/*
 * Start A-MPDU rx/re-order processing for the specified TID.
 */
static int
ampdu_rx_start(struct ieee80211_node *ni, struct ieee80211_rx_ampdu *rap,
        int baparamset, int batimeout, int baseqctl)
{
        struct ieee80211vap *vap = ni->ni_vap;
        int bufsiz = _IEEE80211_MASKSHIFT(baparamset, IEEE80211_BAPS_BUFSIZ);

        if (rap->rxa_flags & IEEE80211_AGGR_RUNNING) {
                /*
                 * AMPDU previously setup and not terminated with a DELBA,
                 * flush the reorder q's in case anything remains.
                 */
                ampdu_rx_purge(rap);
        }
        ieee80211_ampdu_rx_init_rap(ni, rap);
        rap->rxa_wnd = (bufsiz == 0) ?
            IEEE80211_AGGR_BAWMAX : min(bufsiz, IEEE80211_AGGR_BAWMAX);
        rap->rxa_start = _IEEE80211_MASKSHIFT(baseqctl, IEEE80211_BASEQ_START);
        rap->rxa_flags |=  IEEE80211_AGGR_RUNNING | IEEE80211_AGGR_XCHGPEND;

        /* XXX this should be a configuration flag */
        if ((vap->iv_htcaps & IEEE80211_HTC_RX_AMSDU_AMPDU) &&
            (_IEEE80211_MASKSHIFT(baparamset, IEEE80211_BAPS_AMSDU)))
                rap->rxa_flags |= IEEE80211_AGGR_AMSDU;
        else
                rap->rxa_flags &= ~IEEE80211_AGGR_AMSDU;

        return 0;
}

/*
 * Public function; manually setup the RX ampdu state.
 */
int
ieee80211_ampdu_rx_start_ext(struct ieee80211_node *ni, int tid, int seq, int baw)
{
        struct ieee80211_rx_ampdu *rap;

        /* XXX TODO: sanity check tid, seq, baw */

        rap = &ni->ni_rx_ampdu[tid];

        if (rap->rxa_flags & IEEE80211_AGGR_RUNNING) {
                /*
                 * AMPDU previously setup and not terminated with a DELBA,
                 * flush the reorder q's in case anything remains.
                 */
                ampdu_rx_purge(rap);
        }

        ieee80211_ampdu_rx_init_rap(ni, rap);

        rap->rxa_wnd = (baw== 0) ?
            IEEE80211_AGGR_BAWMAX : min(baw, IEEE80211_AGGR_BAWMAX);
        if (seq == -1) {
                /* Wait for the first RX frame, use that as BAW */
                rap->rxa_start = 0;
                rap->rxa_flags |= IEEE80211_AGGR_WAITRX;
        } else {
                rap->rxa_start = seq;
        }
        rap->rxa_flags |=  IEEE80211_AGGR_RUNNING | IEEE80211_AGGR_XCHGPEND;

        /* XXX TODO: no amsdu flag */

        IEEE80211_NOTE(ni->ni_vap, IEEE80211_MSG_11N, ni,
            "%s: tid=%d, start=%d, wnd=%d, flags=0x%08x",
            __func__,
            tid,
            seq,
            rap->rxa_wnd,
            rap->rxa_flags);

        return 0;
}

/*
 * Public function; manually stop the RX AMPDU state.
 */
void
ieee80211_ampdu_rx_stop_ext(struct ieee80211_node *ni, int tid)
{
        struct ieee80211_rx_ampdu *rap;

        /* XXX TODO: sanity check tid, seq, baw */
        rap = &ni->ni_rx_ampdu[tid];
        ampdu_rx_stop(ni, rap);
}

/*
 * Stop A-MPDU rx processing for the specified TID.
 */
static void
ampdu_rx_stop(struct ieee80211_node *ni, struct ieee80211_rx_ampdu *rap)
{

        ampdu_rx_purge(rap);
        rap->rxa_flags &= ~(IEEE80211_AGGR_RUNNING
            | IEEE80211_AGGR_XCHGPEND
            | IEEE80211_AGGR_WAITRX);
}

/*
 * Dispatch a frame from the A-MPDU reorder queue.  The
 * frame is fed back into ieee80211_input marked with an
 * M_AMPDU_MPDU flag so it doesn't come back to us (it also
 * permits ieee80211_input to optimize re-processing).
 */
static __inline void
ampdu_dispatch(struct ieee80211_node *ni, struct mbuf *m)
{
        m->m_flags |= M_AMPDU_MPDU;     /* bypass normal processing */
        /* NB: rssi and noise are ignored w/ M_AMPDU_MPDU set */
        (void) ieee80211_input(ni, m, 0, 0);
}

static int
ampdu_dispatch_slot(struct ieee80211_rx_ampdu *rap, struct ieee80211_node *ni,
    int i)
{
        struct mbuf *m;
        int n = 0;

        for (;;) {
                m = mbufq_dequeue(&rap->rxa_mq[i]);
                if (m == NULL)
                        break;
                n++;

                rap->rxa_qbytes -= m->m_pkthdr.len;
                rap->rxa_qframes--;

                ampdu_dispatch(ni, m);
        }
        return (n);
}

static void
ampdu_rx_moveup(struct ieee80211_rx_ampdu *rap, struct ieee80211_node *ni,
    int i, int winstart)
{
        struct ieee80211vap *vap = ni->ni_vap;

        /*
         * If frames remain, copy the mbuf pointers down so
         * they correspond to the offsets in the new window.
         */
        if (rap->rxa_qframes != 0) {
                int n = rap->rxa_qframes, j;
                for (j = i+1; j < rap->rxa_wnd; j++) {
                        /*
                         * Concat the list contents over, which will
                         * blank the source list for us.
                         */
                        if (mbufq_len(&rap->rxa_mq[j]) != 0) {
                                n = n - mbufq_len(&rap->rxa_mq[j]);
                                mbufq_concat(&rap->rxa_mq[j-i], &rap->rxa_mq[j]);
                                KASSERT(n >= 0, ("%s: n < 0 (%d)", __func__, n));
                                if (n == 0)
                                        break;
                        }
                }
                KASSERT(n == 0, ("%s: lost %d frames, qframes %d off %d "
                    "BA win <%d:%d> winstart %d",
                    __func__, n, rap->rxa_qframes, i, rap->rxa_start,
                    IEEE80211_SEQ_ADD(rap->rxa_start, rap->rxa_wnd-1),
                    winstart));
                vap->iv_stats.is_ampdu_rx_copy += rap->rxa_qframes;
        }
}

/*
 * Dispatch as many frames as possible from the re-order queue.
 * Frames will always be "at the front"; we process all frames
 * up to the first empty slot in the window.  On completion we
 * cleanup state if there are still pending frames in the current
 * BA window.  We assume the frame at slot 0 is already handled
 * by the caller; we always start at slot 1.
 */
static void
ampdu_rx_dispatch(struct ieee80211_rx_ampdu *rap, struct ieee80211_node *ni)
{
        struct ieee80211vap *vap = ni->ni_vap;
        int i, r, r2;

        /* flush run of frames */
        r2 = 0;
        for (i = 1; i < rap->rxa_wnd; i++) {
                r = ampdu_dispatch_slot(rap, ni, i);
                if (r == 0)
                        break;
                r2 += r;
        }

        /* move up frames */
        ampdu_rx_moveup(rap, ni, i, -1);

        /*
         * Adjust the start of the BA window to
         * reflect the frames just dispatched.
         */
        rap->rxa_start = IEEE80211_SEQ_ADD(rap->rxa_start, i);
        vap->iv_stats.is_ampdu_rx_oor += r2;

        IEEE80211_NOTE(ni->ni_vap, IEEE80211_MSG_11N, ni,
            "%s: moved slot up %d slots to start at %d (%d frames)",
            __func__,
            i,
            rap->rxa_start,
            r2);
}

/*
 * Dispatch all frames in the A-MPDU re-order queue.
 */
static void
ampdu_rx_flush(struct ieee80211_node *ni, struct ieee80211_rx_ampdu *rap)
{
        int i, r;

        for (i = 0; i < rap->rxa_wnd; i++) {
                r = ampdu_dispatch_slot(rap, ni, i);
                if (r == 0)
                        continue;
                ni->ni_vap->iv_stats.is_ampdu_rx_oor += r;

                IEEE80211_NOTE(ni->ni_vap, IEEE80211_MSG_11N, ni,
                    "%s: moved slot up %d slots to start at %d (%d frames)",
                    __func__,
                    1,
                    rap->rxa_start,
                    r);

                if (rap->rxa_qframes == 0)
                        break;
        }
}

/*
 * Dispatch all frames in the A-MPDU re-order queue
 * preceding the specified sequence number.  This logic
 * handles window moves due to a received MSDU or BAR.
 */
static void
ampdu_rx_flush_upto(struct ieee80211_node *ni,
        struct ieee80211_rx_ampdu *rap, ieee80211_seq winstart)
{
        struct ieee80211vap *vap = ni->ni_vap;
        ieee80211_seq seqno;
        int i, r;

        /*
         * Flush any complete MSDU's with a sequence number lower
         * than winstart.  Gaps may exist.  Note that we may actually
         * dispatch frames past winstart if a run continues; this is
         * an optimization that avoids having to do a separate pass
         * to dispatch frames after moving the BA window start.
         */
        seqno = rap->rxa_start;
        for (i = 0; i < rap->rxa_wnd; i++) {
                if ((r = mbufq_len(&rap->rxa_mq[i])) != 0) {
                        (void) ampdu_dispatch_slot(rap, ni, i);
                } else {
                        if (!IEEE80211_SEQ_BA_BEFORE(seqno, winstart))
                                break;
                }
                vap->iv_stats.is_ampdu_rx_oor += r;
                seqno = IEEE80211_SEQ_INC(seqno);

                IEEE80211_NOTE(ni->ni_vap, IEEE80211_MSG_11N, ni,
                    "%s: moved slot up %d slots to start at %d (%d frames)",
                    __func__,
                    1,
                    seqno,
                    r);
        }

        /*
         * If frames remain, copy the mbuf pointers down so
         * they correspond to the offsets in the new window.
         */
        ampdu_rx_moveup(rap, ni, i, winstart);

        /*
         * Move the start of the BA window; we use the
         * sequence number of the last MSDU that was
         * passed up the stack+1 or winstart if stopped on
         * a gap in the reorder buffer.
         */
        rap->rxa_start = seqno;
}

/*
 * Process a received QoS data frame for an HT station.  Handle
 * A-MPDU reordering: if this frame is received out of order
 * and falls within the BA window hold onto it.  Otherwise if
 * this frame completes a run, flush any pending frames.  We
 * return 1 if the frame is consumed.  A 0 is returned if
 * the frame should be processed normally by the caller.
 *
 * A-MSDU: handle hardware decap'ed A-MSDU frames that are
 * pretending to be MPDU's.  They're dispatched directly if
 * able; or attempted to put into the receive reordering slot.
 */
int
ieee80211_ampdu_reorder(struct ieee80211_node *ni, struct mbuf *m,
    const struct ieee80211_rx_stats *rxs)
{
#define PROCESS         0       /* caller should process frame */
#define CONSUMED        1       /* frame consumed, caller does nothing */
        struct ieee80211vap *vap = ni->ni_vap;
        struct ieee80211_qosframe *wh;
        struct ieee80211_rx_ampdu *rap;
        ieee80211_seq rxseq;
        uint8_t tid;
        int off;
        int amsdu = ieee80211_check_rxseq_amsdu(rxs);
        int amsdu_end = ieee80211_check_rxseq_amsdu_more(rxs);

        KASSERT((m->m_flags & (M_AMPDU | M_AMPDU_MPDU)) == M_AMPDU,
            ("!a-mpdu or already re-ordered, flags 0x%x", m->m_flags));
        KASSERT(ni->ni_flags & IEEE80211_NODE_HT, ("not an HT sta"));

        /* NB: m_len known to be sufficient */
        wh = mtod(m, struct ieee80211_qosframe *);
        if (!IEEE80211_IS_QOSDATA(wh)) {
                /*
                 * Not QoS data, shouldn't get here but just
                 * return it to the caller for processing.
                 */
                return PROCESS;
        }

        /*
         * 802.11-2012 9.3.2.10 - Duplicate detection and recovery.
         *
         * Multicast QoS data frames are checked against a different
         * counter, not the per-TID counter.
         */
        if (IEEE80211_IS_MULTICAST(wh->i_addr1))
                return PROCESS;

        tid = ieee80211_getqos(wh)[0];
        tid &= IEEE80211_QOS_TID;
        rap = &ni->ni_rx_ampdu[tid];
        if ((rap->rxa_flags & IEEE80211_AGGR_XCHGPEND) == 0) {
                /*
                 * No ADDBA request yet, don't touch.
                 */
                return PROCESS;
        }
        rxseq = le16toh(*(uint16_t *)wh->i_seq);
        if ((rxseq & IEEE80211_SEQ_FRAG_MASK) != 0) {
                /*
                 * Fragments are not allowed; toss.
                 */
                IEEE80211_DISCARD_MAC(vap,
                    IEEE80211_MSG_INPUT | IEEE80211_MSG_11N, ni->ni_macaddr,
                    "A-MPDU", "fragment, rxseq 0x%x tid %u%s", rxseq, tid,
                    wh->i_fc[1] & IEEE80211_FC1_RETRY ? " (retransmit)" : "");
                vap->iv_stats.is_ampdu_rx_drop++;
                IEEE80211_NODE_STAT(ni, rx_drop);
                m_freem(m);
                return CONSUMED;
        }
        rxseq >>= IEEE80211_SEQ_SEQ_SHIFT;
        rap->rxa_nframes++;

        /*
         * Handle waiting for the first frame to define the BAW.
         * Some firmware doesn't provide the RX of the starting point
         * of the BAW and we have to cope.
         */
        if (rap->rxa_flags & IEEE80211_AGGR_WAITRX) {
                rap->rxa_flags &= ~IEEE80211_AGGR_WAITRX;
                rap->rxa_start = rxseq;
        }
again:
        if (rxseq == rap->rxa_start) {
                /*
                 * First frame in window.
                 */
                if (rap->rxa_qframes != 0) {
                        /*
                         * Dispatch as many packets as we can.
                         */
                        KASSERT(mbufq_empty(&rap->rxa_mq[0]), ("unexpected dup"));
                        ampdu_dispatch(ni, m);
                        ampdu_rx_dispatch(rap, ni);
                        return CONSUMED;
                } else {
                        /*
                         * In order; advance window if needed and notify
                         * caller to dispatch directly.
                         */
                        if (amsdu) {
                                if (amsdu_end) {
                                        rap->rxa_start = IEEE80211_SEQ_INC(rxseq);
                                        IEEE80211_NODE_STAT(ni, rx_amsdu_more_end);
                                } else {
                                        IEEE80211_NODE_STAT(ni, rx_amsdu_more);
                                }
                        } else {
                                rap->rxa_start = IEEE80211_SEQ_INC(rxseq);
                        }
                        return PROCESS;
                }
        }
        /*
         * Frame is out of order; store if in the BA window.
         */
        /* calculate offset in BA window */
        off = IEEE80211_SEQ_SUB(rxseq, rap->rxa_start);
        if (off < rap->rxa_wnd) {
                /*
                 * Common case (hopefully): in the BA window.
                 * Sec 9.10.7.6.2 a) (p.137)
                 */

                /* 
                 * Check for frames sitting too long in the reorder queue.
                 * This should only ever happen if frames are not delivered
                 * without the sender otherwise notifying us (e.g. with a
                 * BAR to move the window).  Typically this happens because
                 * of vendor bugs that cause the sequence number to jump.
                 * When this happens we get a gap in the reorder queue that
                 * leaves frame sitting on the queue until they get pushed
                 * out due to window moves.  When the vendor does not send
                 * BAR this move only happens due to explicit packet sends
                 *
                 * NB: we only track the time of the oldest frame in the
                 * reorder q; this means that if we flush we might push
                 * frames that still "new"; if this happens then subsequent
                 * frames will result in BA window moves which cost something
                 * but is still better than a big throughput dip.
                 */
                if (rap->rxa_qframes != 0) {
                        /* XXX honor batimeout? */
                        if (ieee80211_time_after(ticks - rap->rxa_age,
                            ieee80211_ampdu_age)) {
                                /*
                                 * Too long since we received the first
                                 * frame; flush the reorder buffer.
                                 */
                                if (rap->rxa_qframes != 0) {
                                        vap->iv_stats.is_ampdu_rx_age +=
                                            rap->rxa_qframes;
                                        ampdu_rx_flush(ni, rap);
                                }
                                /*
                                 * Advance the window if needed and notify
                                 * the caller to dispatch directly.
                                 */
                                if (amsdu) {
                                        if (amsdu_end) {
                                                rap->rxa_start =
                                                    IEEE80211_SEQ_INC(rxseq);
                                                IEEE80211_NODE_STAT(ni,
                                                    rx_amsdu_more_end);
                                        } else {
                                                IEEE80211_NODE_STAT(ni,
                                                    rx_amsdu_more);
                                        }
                                } else {
                                        rap->rxa_start =
                                            IEEE80211_SEQ_INC(rxseq);
                                }
                                return PROCESS;
                        }
                } else {
                        /*
                         * First frame, start aging timer.
                         */
                        rap->rxa_age = ticks;
                }

                /* save packet - this consumes, no matter what */
                ampdu_rx_add_slot(rap, off, tid, rxseq, ni, m, rxs);
                return CONSUMED;
        }
        if (off < IEEE80211_SEQ_BA_RANGE) {
                /*
                 * Outside the BA window, but within range;
                 * flush the reorder q and move the window.
                 * Sec 9.10.7.6.2 b) (p.138)
                 */
                IEEE80211_NOTE(vap, IEEE80211_MSG_11N, ni,
                    "move BA win <%u:%u> (%u frames) rxseq %u tid %u",
                    rap->rxa_start,
                    IEEE80211_SEQ_ADD(rap->rxa_start, rap->rxa_wnd-1),
                    rap->rxa_qframes, rxseq, tid);
                vap->iv_stats.is_ampdu_rx_move++;

                /*
                 * The spec says to flush frames up to but not including:
                 *      WinStart_B = rxseq - rap->rxa_wnd + 1
                 * Then insert the frame or notify the caller to process
                 * it immediately.  We can safely do this by just starting
                 * over again because we know the frame will now be within
                 * the BA window.
                 */
                /* NB: rxa_wnd known to be >0 */
                ampdu_rx_flush_upto(ni, rap,
                    IEEE80211_SEQ_SUB(rxseq, rap->rxa_wnd-1));
                goto again;
        } else {
                /*
                 * Outside the BA window and out of range; toss.
                 * Sec 9.10.7.6.2 c) (p.138)
                 */
                IEEE80211_DISCARD_MAC(vap,
                    IEEE80211_MSG_INPUT | IEEE80211_MSG_11N, ni->ni_macaddr,
                    "MPDU", "BA win <%u:%u> (%u frames) rxseq %u tid %u%s",
                    rap->rxa_start,
                    IEEE80211_SEQ_ADD(rap->rxa_start, rap->rxa_wnd-1),
                    rap->rxa_qframes, rxseq, tid,
                    wh->i_fc[1] & IEEE80211_FC1_RETRY ? " (retransmit)" : "");
                vap->iv_stats.is_ampdu_rx_drop++;
                IEEE80211_NODE_STAT(ni, rx_drop);
                m_freem(m);
                return CONSUMED;
        }
#undef CONSUMED
#undef PROCESS
}

/*
 * Process a BAR ctl frame.  Dispatch all frames up to
 * the sequence number of the frame.  If this frame is
 * out of range it's discarded.
 */
void
ieee80211_recv_bar(struct ieee80211_node *ni, struct mbuf *m0)
{
        struct ieee80211vap *vap = ni->ni_vap;
        struct ieee80211_frame_bar *wh;
        struct ieee80211_rx_ampdu *rap;
        ieee80211_seq rxseq;
        int tid, off;

        if (!ieee80211_recv_bar_ena) {
#if 0
                IEEE80211_DISCARD_MAC(vap, IEEE80211_MSG_11N,
                    ni->ni_macaddr, "BAR", "%s", "processing disabled");
#endif
                vap->iv_stats.is_ampdu_bar_bad++;
                return;
        }
        wh = mtod(m0, struct ieee80211_frame_bar *);
        /* XXX check basic BAR */
        tid = _IEEE80211_MASKSHIFT(le16toh(wh->i_ctl), IEEE80211_BAR_TID);
        rap = &ni->ni_rx_ampdu[tid];
        if ((rap->rxa_flags & IEEE80211_AGGR_XCHGPEND) == 0) {
                /*
                 * No ADDBA request yet, don't touch.
                 */
                IEEE80211_DISCARD_MAC(vap,
                    IEEE80211_MSG_INPUT | IEEE80211_MSG_11N,
                    ni->ni_macaddr, "BAR", "no BA stream, tid %u", tid);
                vap->iv_stats.is_ampdu_bar_bad++;
                return;
        }
        vap->iv_stats.is_ampdu_bar_rx++;
        rxseq = le16toh(wh->i_seq) >> IEEE80211_SEQ_SEQ_SHIFT;
        if (rxseq == rap->rxa_start)
                return;
        /* calculate offset in BA window */
        off = IEEE80211_SEQ_SUB(rxseq, rap->rxa_start);
        if (off < IEEE80211_SEQ_BA_RANGE) {
                /*
                 * Flush the reorder q up to rxseq and move the window.
                 * Sec 9.10.7.6.3 a) (p.138)
                 */
                IEEE80211_NOTE(vap, IEEE80211_MSG_11N, ni,
                    "BAR moves BA win <%u:%u> (%u frames) rxseq %u tid %u",
                    rap->rxa_start,
                    IEEE80211_SEQ_ADD(rap->rxa_start, rap->rxa_wnd-1),
                    rap->rxa_qframes, rxseq, tid);
                vap->iv_stats.is_ampdu_bar_move++;

                ampdu_rx_flush_upto(ni, rap, rxseq);
                if (off >= rap->rxa_wnd) {
                        /*
                         * BAR specifies a window start to the right of BA
                         * window; we must move it explicitly since
                         * ampdu_rx_flush_upto will not.
                         */
                        rap->rxa_start = rxseq;
                }
        } else {
                /*
                 * Out of range; toss.
                 * Sec 9.10.7.6.3 b) (p.138)
                 */
                IEEE80211_DISCARD_MAC(vap,
                    IEEE80211_MSG_INPUT | IEEE80211_MSG_11N, ni->ni_macaddr,
                    "BAR", "BA win <%u:%u> (%u frames) rxseq %u tid %u%s",
                    rap->rxa_start,
                    IEEE80211_SEQ_ADD(rap->rxa_start, rap->rxa_wnd-1),
                    rap->rxa_qframes, rxseq, tid,
                    wh->i_fc[1] & IEEE80211_FC1_RETRY ? " (retransmit)" : "");
                vap->iv_stats.is_ampdu_bar_oow++;
                IEEE80211_NODE_STAT(ni, rx_drop);
        }
}

/*
 * Setup HT-specific state in a node.  Called only
 * when HT use is negotiated so we don't do extra
 * work for temporary and/or legacy sta's.
 */
void
ieee80211_ht_node_init(struct ieee80211_node *ni)
{
        struct ieee80211_tx_ampdu *tap;
        int tid;

        IEEE80211_NOTE(ni->ni_vap, IEEE80211_MSG_11N,
            ni,
            "%s: called (%p)",
            __func__,
            ni);

        if (ni->ni_flags & IEEE80211_NODE_HT) {
                /*
                 * Clean AMPDU state on re-associate.  This handles the case
                 * where a station leaves w/o notifying us and then returns
                 * before node is reaped for inactivity.
                 */
                IEEE80211_NOTE(ni->ni_vap, IEEE80211_MSG_11N,
                    ni,
                    "%s: calling cleanup (%p)",
                    __func__, ni);
                ieee80211_ht_node_cleanup(ni);
        }
        for (tid = 0; tid < WME_NUM_TID; tid++) {
                tap = &ni->ni_tx_ampdu[tid];
                tap->txa_tid = tid;
                tap->txa_ni = ni;
                ieee80211_txampdu_init_pps(tap);
                /* NB: further initialization deferred */
                ieee80211_ampdu_rx_init_rap(ni, &ni->ni_rx_ampdu[tid]);
        }
        ni->ni_flags |= IEEE80211_NODE_HT | IEEE80211_NODE_AMPDU |
            IEEE80211_NODE_AMSDU;
}

/*
 * Cleanup HT-specific state in a node.  Called only
 * when HT use has been marked.
 */
void
ieee80211_ht_node_cleanup(struct ieee80211_node *ni)
{
        struct ieee80211com *ic = ni->ni_ic;
        int i;

        IEEE80211_NOTE(ni->ni_vap, IEEE80211_MSG_11N,
            ni,
            "%s: called (%p)",
            __func__, ni);

        KASSERT(ni->ni_flags & IEEE80211_NODE_HT, ("not an HT node"));

        /* XXX optimize this */
        for (i = 0; i < WME_NUM_TID; i++) {
                struct ieee80211_tx_ampdu *tap = &ni->ni_tx_ampdu[i];
                if (tap->txa_flags & IEEE80211_AGGR_SETUP)
                        ampdu_tx_stop(tap);
        }
        for (i = 0; i < WME_NUM_TID; i++)
                ic->ic_ampdu_rx_stop(ni, &ni->ni_rx_ampdu[i]);

        ni->ni_htcap = 0;
        ni->ni_flags &= ~IEEE80211_NODE_HT_ALL;
}

/*
 * Age out HT resources for a station.
 */
void
ieee80211_ht_node_age(struct ieee80211_node *ni)
{
        struct ieee80211vap *vap = ni->ni_vap;
        uint8_t tid;

        KASSERT(ni->ni_flags & IEEE80211_NODE_HT, ("not an HT sta"));

        for (tid = 0; tid < WME_NUM_TID; tid++) {
                struct ieee80211_rx_ampdu *rap;

                rap = &ni->ni_rx_ampdu[tid];
                if ((rap->rxa_flags & IEEE80211_AGGR_XCHGPEND) == 0)
                        continue;
                if (rap->rxa_qframes == 0)
                        continue;
                /* 
                 * Check for frames sitting too long in the reorder queue.
                 * See above for more details on what's happening here.
                 */
                /* XXX honor batimeout? */
                if (ieee80211_time_after(ticks - rap->rxa_age,
                    ieee80211_ampdu_age)) {
                        /*
                         * Too long since we received the first
                         * frame; flush the reorder buffer.
                         */
                        vap->iv_stats.is_ampdu_rx_age += rap->rxa_qframes;
                        ampdu_rx_flush(ni, rap);
                }
        }
}

static struct ieee80211_channel *
findhtchan(struct ieee80211com *ic, struct ieee80211_channel *c, int htflags)
{
        return ieee80211_find_channel(ic, c->ic_freq,
            (c->ic_flags &~ IEEE80211_CHAN_HT) | htflags);
}

/*
 * Adjust a channel to be HT/non-HT according to the vap's configuration.
 */
struct ieee80211_channel *
ieee80211_ht_adjust_channel(struct ieee80211com *ic,
        struct ieee80211_channel *chan, int flags)
{
        struct ieee80211_channel *c;

        if (flags & IEEE80211_FHT_HT) {
                /* promote to HT if possible */
                if (flags & IEEE80211_FHT_USEHT40) {
                        if (!IEEE80211_IS_CHAN_HT40(chan)) {
                                /* NB: arbitrarily pick ht40+ over ht40- */
                                c = findhtchan(ic, chan, IEEE80211_CHAN_HT40U);
                                if (c == NULL)
                                        c = findhtchan(ic, chan,
                                                IEEE80211_CHAN_HT40D);
                                if (c == NULL)
                                        c = findhtchan(ic, chan,
                                                IEEE80211_CHAN_HT20);
                                if (c != NULL)
                                        chan = c;
                        }
                } else if (!IEEE80211_IS_CHAN_HT20(chan)) {
                        c = findhtchan(ic, chan, IEEE80211_CHAN_HT20);
                        if (c != NULL)
                                chan = c;
                }
        } else if (IEEE80211_IS_CHAN_HT(chan)) {
                /* demote to legacy, HT use is disabled */
                c = ieee80211_find_channel(ic, chan->ic_freq,
                    chan->ic_flags &~ IEEE80211_CHAN_HT);
                if (c != NULL)
                        chan = c;
        }
        return chan;
}

/*
 * Setup HT-specific state for a legacy WDS peer.
 */
void
ieee80211_ht_wds_init(struct ieee80211_node *ni)
{
        struct ieee80211vap *vap = ni->ni_vap;
        struct ieee80211_tx_ampdu *tap;
        int tid;

        KASSERT(vap->iv_flags_ht & IEEE80211_FHT_HT, ("no HT requested"));

        /* XXX check scan cache in case peer has an ap and we have info */
        /*
         * If setup with a legacy channel; locate an HT channel.
         * Otherwise if the inherited channel (from a companion
         * AP) is suitable use it so we use the same location
         * for the extension channel).
         */
        ni->ni_chan = ieee80211_ht_adjust_channel(ni->ni_ic,
            ni->ni_chan, ieee80211_htchanflags(ni->ni_chan));

        ni->ni_htcap = 0;
        if (vap->iv_flags_ht & IEEE80211_FHT_SHORTGI20)
                ni->ni_htcap |= IEEE80211_HTCAP_SHORTGI20;
        if (IEEE80211_IS_CHAN_HT40(ni->ni_chan)) {
                ni->ni_htcap |= IEEE80211_HTCAP_CHWIDTH40;
                ni->ni_chw = NET80211_STA_RX_BW_40;
                if (IEEE80211_IS_CHAN_HT40U(ni->ni_chan))
                        ni->ni_ht2ndchan = IEEE80211_HTINFO_2NDCHAN_ABOVE;
                else if (IEEE80211_IS_CHAN_HT40D(ni->ni_chan))
                        ni->ni_ht2ndchan = IEEE80211_HTINFO_2NDCHAN_BELOW;
                if (vap->iv_flags_ht & IEEE80211_FHT_SHORTGI40)
                        ni->ni_htcap |= IEEE80211_HTCAP_SHORTGI40;
        } else {
                ni->ni_chw = NET80211_STA_RX_BW_20;
                ni->ni_ht2ndchan = IEEE80211_HTINFO_2NDCHAN_NONE;
        }
        ni->ni_htctlchan = ni->ni_chan->ic_ieee;
        if (vap->iv_flags_ht & IEEE80211_FHT_RIFS)
                ni->ni_flags |= IEEE80211_NODE_RIFS;
        /* XXX does it make sense to enable SMPS? */

        ni->ni_htopmode = 0;            /* XXX need protection state */
        ni->ni_htstbc = 0;              /* XXX need info */

        for (tid = 0; tid < WME_NUM_TID; tid++) {
                tap = &ni->ni_tx_ampdu[tid];
                tap->txa_tid = tid;
                ieee80211_txampdu_init_pps(tap);
        }
        /* NB: AMPDU tx/rx governed by IEEE80211_FHT_AMPDU_{TX,RX} */
        ni->ni_flags |= IEEE80211_NODE_HT | IEEE80211_NODE_AMPDU |
            IEEE80211_NODE_AMSDU;
}

/*
 * Notify a VAP of a change in the HTINFO ie if it's a hostap VAP.
 *
 * This is to be called from the deferred HT protection update
 * task once the flags are updated.
 */
void
ieee80211_htinfo_notify(struct ieee80211vap *vap)
{

        IEEE80211_LOCK_ASSERT(vap->iv_ic);

        if (vap->iv_opmode != IEEE80211_M_HOSTAP)
                return;
        if (vap->iv_state != IEEE80211_S_RUN ||
            !IEEE80211_IS_CHAN_HT(vap->iv_bss->ni_chan))
                return;

        IEEE80211_NOTE(vap,
            IEEE80211_MSG_ASSOC | IEEE80211_MSG_11N,
            vap->iv_bss,
            "HT bss occupancy change: %d sta, %d ht, "
            "%d ht40%s, HT protmode now 0x%x"
            , vap->iv_sta_assoc
            , vap->iv_ht_sta_assoc
            , vap->iv_ht40_sta_assoc
            , (vap->iv_flags_ht & IEEE80211_FHT_NONHT_PR) ?
                 ", non-HT sta present" : ""
            , vap->iv_curhtprotmode);

        ieee80211_beacon_notify(vap, IEEE80211_BEACON_HTINFO);
}

/*
 * Calculate HT protection mode from current
 * state and handle updates.
 */
static void
htinfo_update(struct ieee80211vap *vap)
{
        struct ieee80211com *ic = vap->iv_ic;
        uint8_t protmode;

        if (vap->iv_sta_assoc != vap->iv_ht_sta_assoc) {
                protmode = IEEE80211_HTINFO_OPMODE_MIXED
                         | IEEE80211_HTINFO_NONHT_PRESENT;
        } else if (vap->iv_flags_ht & IEEE80211_FHT_NONHT_PR) {
                protmode = IEEE80211_HTINFO_OPMODE_PROTOPT
                         | IEEE80211_HTINFO_NONHT_PRESENT;
        } else if (ic->ic_bsschan != IEEE80211_CHAN_ANYC &&
            IEEE80211_IS_CHAN_HT40(ic->ic_bsschan) && 
            vap->iv_sta_assoc != vap->iv_ht40_sta_assoc) {
                protmode = IEEE80211_HTINFO_OPMODE_HT20PR;
        } else {
                protmode = IEEE80211_HTINFO_OPMODE_PURE;
        }
        if (protmode != vap->iv_curhtprotmode) {
                vap->iv_curhtprotmode = protmode;
                /* Update VAP with new protection mode */
                ieee80211_vap_update_ht_protmode(vap);
        }
}

/*
 * Handle an HT station joining a BSS.
 */
void
ieee80211_ht_node_join(struct ieee80211_node *ni)
{
        struct ieee80211vap *vap = ni->ni_vap;

        IEEE80211_LOCK_ASSERT(vap->iv_ic);

        if (ni->ni_flags & IEEE80211_NODE_HT) {
                vap->iv_ht_sta_assoc++;
                if (ni->ni_chw == NET80211_STA_RX_BW_40)
                        vap->iv_ht40_sta_assoc++;
        }
        htinfo_update(vap);
}

/*
 * Handle an HT station leaving a BSS.
 */
void
ieee80211_ht_node_leave(struct ieee80211_node *ni)
{
        struct ieee80211vap *vap = ni->ni_vap;

        IEEE80211_LOCK_ASSERT(vap->iv_ic);

        if (ni->ni_flags & IEEE80211_NODE_HT) {
                vap->iv_ht_sta_assoc--;
                if (ni->ni_chw == NET80211_STA_RX_BW_40)
                        vap->iv_ht40_sta_assoc--;
        }
        htinfo_update(vap);
}

/*
 * Public version of htinfo_update; used for processing
 * beacon frames from overlapping bss.
 *
 * Caller can specify either IEEE80211_HTINFO_OPMODE_MIXED
 * (on receipt of a beacon that advertises MIXED) or
 * IEEE80211_HTINFO_OPMODE_PROTOPT (on receipt of a beacon
 * from an overlapping legacy bss).  We treat MIXED with
 * a higher precedence than PROTOPT (i.e. we will not change
 * change PROTOPT -> MIXED; only MIXED -> PROTOPT).  This
 * corresponds to how we handle things in htinfo_update.
 *
 */
void
ieee80211_htprot_update(struct ieee80211vap *vap, int protmode)
{
        struct ieee80211com *ic = vap->iv_ic;
#define OPMODE(x)       _IEEE80211_SHIFTMASK(x, IEEE80211_HTINFO_OPMODE)
        IEEE80211_LOCK(ic);

        /* track non-HT station presence */
        KASSERT(protmode & IEEE80211_HTINFO_NONHT_PRESENT,
            ("protmode 0x%x", protmode));
        vap->iv_flags_ht |= IEEE80211_FHT_NONHT_PR;
        vap->iv_lastnonht = ticks;

        if (protmode != vap->iv_curhtprotmode &&
            (OPMODE(vap->iv_curhtprotmode) != IEEE80211_HTINFO_OPMODE_MIXED ||
             OPMODE(protmode) == IEEE80211_HTINFO_OPMODE_PROTOPT)) {
                vap->iv_curhtprotmode = protmode;
                /* Update VAP with new protection mode */
                ieee80211_vap_update_ht_protmode(vap);
        }
        IEEE80211_UNLOCK(ic);
#undef OPMODE
}

/*
 * Time out presence of an overlapping bss with non-HT
 * stations.  When operating in hostap mode we listen for
 * beacons from other stations and if we identify a non-HT
 * station is present we update the opmode field of the
 * HTINFO ie.  To identify when all non-HT stations are
 * gone we time out this condition.
 */
void
ieee80211_ht_timeout(struct ieee80211vap *vap)
{

        IEEE80211_LOCK_ASSERT(vap->iv_ic);

        if ((vap->iv_flags_ht & IEEE80211_FHT_NONHT_PR) &&
            ieee80211_time_after(ticks, vap->iv_lastnonht + IEEE80211_NONHT_PRESENT_AGE)) {
                IEEE80211_DPRINTF(vap, IEEE80211_MSG_11N,
                    "%s", "time out non-HT STA present on channel");
                vap->iv_flags_ht &= ~IEEE80211_FHT_NONHT_PR;
                htinfo_update(vap);
        }
}

/*
 * Process an 802.11n HT capabilities ie.
 */
void
ieee80211_parse_htcap(struct ieee80211_node *ni, const uint8_t *ie)
{
        if (ie[0] == IEEE80211_ELEMID_VENDOR) {
                /*
                 * Station used Vendor OUI ie to associate;
                 * mark the node so when we respond we'll use
                 * the Vendor OUI's and not the standard ie's.
                 */
                ni->ni_flags |= IEEE80211_NODE_HTCOMPAT;
                ie += 4;
        } else
                ni->ni_flags &= ~IEEE80211_NODE_HTCOMPAT;

        ni->ni_htcap = le16dec(ie +
                __offsetof(struct ieee80211_ie_htcap, hc_cap));
        ni->ni_htparam = ie[__offsetof(struct ieee80211_ie_htcap, hc_param)];
}

static void
htinfo_parse(struct ieee80211_node *ni,
        const struct ieee80211_ie_htinfo *htinfo)
{
        uint16_t w;

        ni->ni_htctlchan = htinfo->hi_ctrlchannel;
        ni->ni_ht2ndchan = _IEEE80211_SHIFTMASK(htinfo->hi_byte1,
            IEEE80211_HTINFO_2NDCHAN);
        w = le16dec(&htinfo->hi_byte2);
        ni->ni_htopmode = _IEEE80211_SHIFTMASK(w, IEEE80211_HTINFO_OPMODE);
        w = le16dec(&htinfo->hi_byte45);
        ni->ni_htstbc = _IEEE80211_SHIFTMASK(w, IEEE80211_HTINFO_BASIC_STBCMCS);
}

/*
 * Parse an 802.11n HT info ie and save useful information
 * to the node state.  Note this does not effect any state
 * changes such as for channel width change.
 */
void
ieee80211_parse_htinfo(struct ieee80211_node *ni, const uint8_t *ie)
{
        if (ie[0] == IEEE80211_ELEMID_VENDOR)
                ie += 4;
        htinfo_parse(ni, (const struct ieee80211_ie_htinfo *) ie);
}

/*
 * Handle 11n/11ac channel switch.
 *
 * Use the received HT/VHT ie's to identify the right channel to use.
 * If we cannot locate it in the channel table then fallback to
 * legacy operation.
 *
 * Note that we use this information to identify the node's
 * channel only; the caller is responsible for insuring any
 * required channel change is done (e.g. in sta mode when
 * parsing the contents of a beacon frame).
 */
static int
htinfo_update_chw(struct ieee80211_node *ni, int htflags, int vhtflags)
{
        struct ieee80211com *ic = ni->ni_ic;
        struct ieee80211_channel *c;
        int chanflags;
        int ret = 0;

        /*
         * First step - do HT/VHT only channel lookup based on operating mode
         * flags.  This involves masking out the VHT flags as well.
         * Otherwise we end up doing the full channel walk each time
         * we trigger this, which is expensive.
         */
        chanflags = (ni->ni_chan->ic_flags &~
            (IEEE80211_CHAN_HT | IEEE80211_CHAN_VHT)) | htflags | vhtflags;

        if (chanflags == ni->ni_chan->ic_flags)
                goto done;

        /*
         * If HT /or/ VHT flags have changed then check both.
         * We need to start by picking a HT channel anyway.
         */

        c = NULL;
        chanflags = (ni->ni_chan->ic_flags &~
            (IEEE80211_CHAN_HT | IEEE80211_CHAN_VHT)) | htflags;
        /* XXX not right for ht40- */
        c = ieee80211_find_channel(ic, ni->ni_chan->ic_freq, chanflags);
        if (c == NULL && (htflags & IEEE80211_CHAN_HT40)) {
                /*
                 * No HT40 channel entry in our table; fall back
                 * to HT20 operation.  This should not happen.
                 */
                c = findhtchan(ic, ni->ni_chan, IEEE80211_CHAN_HT20);
#if 0
                IEEE80211_NOTE(ni->ni_vap,
                    IEEE80211_MSG_ASSOC | IEEE80211_MSG_11N, ni,
                    "no HT40 channel (freq %u), falling back to HT20",
                    ni->ni_chan->ic_freq);
#endif
                /* XXX stat */
        }

        /* Nothing found - leave it alone; move onto VHT */
        if (c == NULL)
                c = ni->ni_chan;

        /*
         * If it's non-HT, then bail out now.
         */
        if (! IEEE80211_IS_CHAN_HT(c)) {
                IEEE80211_NOTE(ni->ni_vap,
                    IEEE80211_MSG_ASSOC | IEEE80211_MSG_11N, ni,
                    "not HT; skipping VHT check (%u/0x%x)",
                    c->ic_freq, c->ic_flags);
                goto done;
        }

        /*
         * Next step - look at the current VHT flags and determine
         * if we need to upgrade.  Mask out the VHT and HT flags since
         * the vhtflags field will already have the correct HT
         * flags to use.
         */
        if (IEEE80211_CONF_VHT(ic) && ni->ni_vhtcap != 0 && vhtflags != 0) {
                chanflags = (c->ic_flags
                    &~ (IEEE80211_CHAN_HT | IEEE80211_CHAN_VHT))
                    | vhtflags;
                IEEE80211_NOTE(ni->ni_vap,
                    IEEE80211_MSG_ASSOC | IEEE80211_MSG_11N,
                    ni,
                    "%s: VHT; chanwidth=0x%02x; vhtflags=0x%08x",
                    __func__, ni->ni_vht_chanwidth, vhtflags);

                IEEE80211_NOTE(ni->ni_vap,
                    IEEE80211_MSG_ASSOC | IEEE80211_MSG_11N,
                    ni,
                    "%s: VHT; trying lookup for %d/0x%08x",
                    __func__, c->ic_freq, chanflags);
                c = ieee80211_find_channel(ic, c->ic_freq, chanflags);
        }

        /* Finally, if it's changed */
        if (c != NULL && c != ni->ni_chan) {
                IEEE80211_NOTE(ni->ni_vap,
                    IEEE80211_MSG_ASSOC | IEEE80211_MSG_11N, ni,
                    "switch station to %s%d channel %u/0x%x",
                    IEEE80211_IS_CHAN_VHT(c) ? "VHT" : "HT",
                    IEEE80211_IS_CHAN_VHT80(c) ? 80 :
                      (IEEE80211_IS_CHAN_HT40(c) ? 40 : 20),
                    c->ic_freq, c->ic_flags);
                ni->ni_chan = c;
                ret = 1;
        }
        /* NB: caller responsible for forcing any channel change */

done:
        /* update node's (11n) tx channel width */
        ni->ni_chw = IEEE80211_IS_CHAN_HT40(ni->ni_chan) ?
            NET80211_STA_RX_BW_40 : NET80211_STA_RX_BW_20;
        return (ret);
}

/*
 * Update 11n MIMO PS state according to received htcap.
 */
static __inline int
htcap_update_mimo_ps(struct ieee80211_node *ni)
{
        uint16_t oflags = ni->ni_flags;

        switch (ni->ni_htcap & IEEE80211_HTCAP_SMPS) {
        case IEEE80211_HTCAP_SMPS_DYNAMIC:
                ni->ni_flags |= IEEE80211_NODE_MIMO_PS;
                ni->ni_flags |= IEEE80211_NODE_MIMO_RTS;
                break;
        case IEEE80211_HTCAP_SMPS_ENA:
                ni->ni_flags |= IEEE80211_NODE_MIMO_PS;
                ni->ni_flags &= ~IEEE80211_NODE_MIMO_RTS;
                break;
        case IEEE80211_HTCAP_SMPS_OFF:
        default:                /* disable on rx of reserved value */
                ni->ni_flags &= ~IEEE80211_NODE_MIMO_PS;
                ni->ni_flags &= ~IEEE80211_NODE_MIMO_RTS;
                break;
        }
        return (oflags ^ ni->ni_flags);
}

/*
 * Update short GI state according to received htcap
 * and local settings.
 */
static __inline void
htcap_update_shortgi(struct ieee80211_node *ni)
{
        struct ieee80211vap *vap = ni->ni_vap;

        ni->ni_flags &= ~(IEEE80211_NODE_SGI20|IEEE80211_NODE_SGI40);
        if ((ni->ni_htcap & IEEE80211_HTCAP_SHORTGI20) &&
            (vap->iv_flags_ht & IEEE80211_FHT_SHORTGI20))
                ni->ni_flags |= IEEE80211_NODE_SGI20;
        if ((ni->ni_htcap & IEEE80211_HTCAP_SHORTGI40) &&
            (vap->iv_flags_ht & IEEE80211_FHT_SHORTGI40))
                ni->ni_flags |= IEEE80211_NODE_SGI40;
}

/*
 * Update LDPC state according to received htcap
 * and local settings.
 */
static __inline void
htcap_update_ldpc(struct ieee80211_node *ni)
{
        struct ieee80211vap *vap = ni->ni_vap;

        if ((ni->ni_htcap & IEEE80211_HTCAP_LDPC) &&
            (vap->iv_flags_ht & IEEE80211_FHT_LDPC_TX))
                ni->ni_flags |= IEEE80211_NODE_LDPC;
}

/*
 * Parse and update HT-related state extracted from
 * the HT cap and info ie's.
 *
 * This is called from the STA management path and
 * the ieee80211_node_join() path.  It will take into
 * account the IEs discovered during scanning and
 * adjust things accordingly.
 */
void
ieee80211_ht_updateparams(struct ieee80211_node *ni,
        const uint8_t *htcapie, const uint8_t *htinfoie)
{
        struct ieee80211vap *vap = ni->ni_vap;
        const struct ieee80211_ie_htinfo *htinfo;

        ieee80211_parse_htcap(ni, htcapie);
        if (vap->iv_htcaps & IEEE80211_HTC_SMPS)
                htcap_update_mimo_ps(ni);
        htcap_update_shortgi(ni);
        htcap_update_ldpc(ni);

        if (htinfoie[0] == IEEE80211_ELEMID_VENDOR)
                htinfoie += 4;
        htinfo = (const struct ieee80211_ie_htinfo *) htinfoie;
        htinfo_parse(ni, htinfo);

        /*
         * Defer the node channel change; we need to now
         * update VHT parameters before we do it.
         */

        if ((htinfo->hi_byte1 & IEEE80211_HTINFO_RIFSMODE_PERM) &&
            (vap->iv_flags_ht & IEEE80211_FHT_RIFS))
                ni->ni_flags |= IEEE80211_NODE_RIFS;
        else
                ni->ni_flags &= ~IEEE80211_NODE_RIFS;
}

static uint32_t
ieee80211_vht_get_vhtflags(struct ieee80211_node *ni, uint32_t htflags)
{
#define _RETURN_CHAN_BITS(_cb)                                          \
do {                                                                    \
        if (0) IEEE80211_NOTE(ni->ni_vap, IEEE80211_MSG_11N, ni,        \
            "%s:%d: selected %b", __func__, __LINE__,                   \
            (_cb), IEEE80211_CHAN_BITS);                                \
        return (_cb);                                                   \
} while(0)
        struct ieee80211vap *vap;
        const struct ieee80211_ie_htinfo *htinfo;
        uint32_t vhtflags;
        bool can_vht160, can_vht80p80, can_vht80;
        bool ht40;

        vap = ni->ni_vap;

        /* If we do not support VHT or VHT is disabled just return. */
        if ((ni->ni_flags & IEEE80211_NODE_VHT) == 0 ||
            (vap->iv_vht_flags & IEEE80211_FVHT_VHT) == 0)
                _RETURN_CHAN_BITS(0);

        /*
         * TODO: should we bail out if there's no htinfo?
         * Or just treat it as if we can't do the HT20/HT40 check?
         */

        /*
         * The original code was based on
         * 802.11ac-2013, Table 8-183x-VHT Operation Information subfields.
         * 802.11-2020, Table 9-274-VHT Operation Information subfields
         * has IEEE80211_VHT_CHANWIDTH_160MHZ and
         * IEEE80211_VHT_CHANWIDTH_80P80MHZ deprecated.
         * For current logic see
         * 802.11-2020, 11.38.1 Basic VHT BSS functionality.
         */

        htinfo = (const struct ieee80211_ie_htinfo *)ni->ni_ies.htinfo_ie;
        if (htinfo != NULL)
                ht40 = ((htinfo->hi_byte1 & IEEE80211_HTINFO_TXWIDTH) ==
                    IEEE80211_HTINFO_TXWIDTH_2040);
        else
                ht40 = false;

        can_vht160 = can_vht80p80 = can_vht80 = false;

        /* 20 Mhz */
        if (!ht40) {
                /* Check for the full valid combination -- other fields be 0. */
                if (ni->ni_vht_chanwidth != IEEE80211_VHT_CHANWIDTH_USE_HT ||
                    ni->ni_vht_chan2 != 0)
                        IEEE80211_NOTE(ni->ni_vap, IEEE80211_MSG_11N, ni,
                            "%s: invalid VHT BSS bandwidth 0/%d/%d/%d",
                            __func__, ni->ni_vht_chanwidth,
                            ni->ni_vht_chan1, ni->ni_vht_chan2);

                _RETURN_CHAN_BITS(IEEE80211_CHAN_VHT20 | IEEE80211_CHAN_HT20);
        }

        vhtflags = 0;

        /* We know we can at least do 40Mhz, so mirror the HT40 flags. */
        if (htflags == IEEE80211_CHAN_HT40U)
                vhtflags |= IEEE80211_CHAN_HT40U;
        else if (htflags == IEEE80211_CHAN_HT40D)
                vhtflags |= IEEE80211_CHAN_HT40D;

        /* 40 MHz */
        if (ni->ni_vht_chanwidth == IEEE80211_VHT_CHANWIDTH_USE_HT) {
                if (ni->ni_vht_chan2 != 0)
                        IEEE80211_NOTE(ni->ni_vap, IEEE80211_MSG_11N, ni,
                            "%s: invalid VHT BSS bandwidth 1/%d/%d/%d",
                            __func__, ni->ni_vht_chanwidth,
                            ni->ni_vht_chan1, ni->ni_vht_chan2);

                if ((vap->iv_vht_flags & IEEE80211_FVHT_USEVHT40) != 0) {
                        if (htflags == IEEE80211_CHAN_HT40U)
                                _RETURN_CHAN_BITS(IEEE80211_CHAN_VHT40U | vhtflags);
                        if (htflags == IEEE80211_CHAN_HT40D)
                                _RETURN_CHAN_BITS(IEEE80211_CHAN_VHT40D | vhtflags);
                }

                /* If we get here VHT40 is not supported or disabled. */
                _RETURN_CHAN_BITS(IEEE80211_CHAN_VHT20 | IEEE80211_CHAN_HT20);
        }

        /* Deprecated check for 160. */
        if ((ni->ni_vht_chanwidth == IEEE80211_VHT_CHANWIDTH_160MHZ) &&
            IEEE80211_VHTCAP_SUPP_CHAN_WIDTH_IS_160MHZ(vap->iv_vht_cap.vht_cap_info) &&
            (vap->iv_vht_flags & IEEE80211_FVHT_USEVHT160) != 0)
                _RETURN_CHAN_BITS(IEEE80211_CHAN_VHT160 | vhtflags);

        /* Deprecated check for 80P80. */
        if ((ni->ni_vht_chanwidth == IEEE80211_VHT_CHANWIDTH_80P80MHZ) &&
            IEEE80211_VHTCAP_SUPP_CHAN_WIDTH_IS_160_80P80MHZ(vap->iv_vht_cap.vht_cap_info) &&
            (vap->iv_vht_flags & IEEE80211_FVHT_USEVHT80P80) != 0)
                _RETURN_CHAN_BITS(IEEE80211_CHAN_VHT80P80 | vhtflags);

        if (ni->ni_vht_chanwidth != IEEE80211_VHT_CHANWIDTH_80MHZ) {
                IEEE80211_NOTE(ni->ni_vap, IEEE80211_MSG_11N, ni,
                    "%s: invalid VHT BSS bandwidth %d/%d/%d", __func__,
                    ni->ni_vht_chanwidth, ni->ni_vht_chan2);

                _RETURN_CHAN_BITS(0);
        }

        /* CCFS1 > 0 and | CCFS1 - CCFS0 | = 8 */
        if (ni->ni_vht_chan2 > 0 && abs(ni->ni_vht_chan2 - ni->ni_vht_chan1) == 8)
                can_vht160 = can_vht80 = true;

        /* CCFS1 > 0 and | CCFS1 - CCFS0 | > 16 */
        if (ni->ni_vht_chan2 > 0 && abs(ni->ni_vht_chan2 - ni->ni_vht_chan1) > 16)
                can_vht80p80 = can_vht80 = true;

        /* CFFS1 == 0 */
        if (ni->ni_vht_chan2 == 0)
                can_vht80 = true;

        if (can_vht160 && (vap->iv_vht_flags & IEEE80211_FVHT_USEVHT160) != 0)
                _RETURN_CHAN_BITS(IEEE80211_CHAN_VHT160 | vhtflags);

        if (can_vht80p80 && (vap->iv_vht_flags & IEEE80211_FVHT_USEVHT80P80) != 0)
                _RETURN_CHAN_BITS(IEEE80211_CHAN_VHT80P80 | vhtflags);

        if (can_vht80 && (vap->iv_vht_flags & IEEE80211_FVHT_USEVHT80) != 0)
                _RETURN_CHAN_BITS(IEEE80211_CHAN_VHT80 | vhtflags);

        if (ht40 && (vap->iv_vht_flags & IEEE80211_FVHT_USEVHT40) != 0) {
                if (htflags == IEEE80211_CHAN_HT40U)
                        _RETURN_CHAN_BITS(IEEE80211_CHAN_VHT40U | vhtflags);
                if (htflags == IEEE80211_CHAN_HT40D)
                        _RETURN_CHAN_BITS(IEEE80211_CHAN_VHT40D | vhtflags);
        }

        /* Either we disabled support or got an invalid setting. */
        _RETURN_CHAN_BITS(IEEE80211_CHAN_VHT20 | IEEE80211_CHAN_HT20);
#undef _RETURN_CHAN_BITS
}

/*
 * Final part of updating the HT parameters.
 *
 * This is called from the STA management path and
 * the ieee80211_node_join() path.  It will take into
 * account the IEs discovered during scanning and
 * adjust things accordingly.
 *
 * This is done after a call to ieee80211_ht_updateparams()
 * because it (and the upcoming VHT version of updateparams)
 * needs to ensure everything is parsed before htinfo_update_chw()
 * is called - which will change the channel config for the
 * node for us.
 */
int
ieee80211_ht_updateparams_final(struct ieee80211_node *ni,
        const uint8_t *htcapie, const uint8_t *htinfoie)
{
        struct ieee80211vap *vap = ni->ni_vap;
        const struct ieee80211_ie_htinfo *htinfo;
        int htflags, vhtflags;
        int ret = 0;

        htinfo = (const struct ieee80211_ie_htinfo *) htinfoie;

        htflags = (vap->iv_flags_ht & IEEE80211_FHT_HT) ?
            IEEE80211_CHAN_HT20 : 0;

        /* NB: honor operating mode constraint */
        if ((htinfo->hi_byte1 & IEEE80211_HTINFO_TXWIDTH_2040) &&
            (vap->iv_flags_ht & IEEE80211_FHT_USEHT40)) {
                if (ni->ni_ht2ndchan == IEEE80211_HTINFO_2NDCHAN_ABOVE)
                        htflags = IEEE80211_CHAN_HT40U;
                else if (ni->ni_ht2ndchan == IEEE80211_HTINFO_2NDCHAN_BELOW)
                        htflags = IEEE80211_CHAN_HT40D;
        }

        /*
         * VHT flags - do much the same; check whether VHT is available
         * and if so, what our ideal channel use would be based on our
         * capabilities and the (pre-parsed) VHT info IE.
         */
        vhtflags = ieee80211_vht_get_vhtflags(ni, htflags);

        if (htinfo_update_chw(ni, htflags, vhtflags))
                ret = 1;

        return (ret);
}

/*
 * Parse and update HT-related state extracted from the HT cap ie
 * for a station joining an HT BSS.
 *
 * This is called from the hostap path for each station.
 */
void
ieee80211_ht_updatehtcap(struct ieee80211_node *ni, const uint8_t *htcapie)
{
        struct ieee80211vap *vap = ni->ni_vap;

        ieee80211_parse_htcap(ni, htcapie);
        if (vap->iv_htcaps & IEEE80211_HTC_SMPS)
                htcap_update_mimo_ps(ni);
        htcap_update_shortgi(ni);
        htcap_update_ldpc(ni);
}

/*
 * Called once HT and VHT capabilities are parsed in hostap mode -
 * this will adjust the channel configuration of the given node
 * based on the configuration and capabilities.
 */
void
ieee80211_ht_updatehtcap_final(struct ieee80211_node *ni)
{
        struct ieee80211vap *vap = ni->ni_vap;
        int htflags;
        int vhtflags;

        /* NB: honor operating mode constraint */
        /* XXX 40 MHz intolerant */
        htflags = (vap->iv_flags_ht & IEEE80211_FHT_HT) ?
            IEEE80211_CHAN_HT20 : 0;
        if ((ni->ni_htcap & IEEE80211_HTCAP_CHWIDTH40) &&
            (vap->iv_flags_ht & IEEE80211_FHT_USEHT40)) {
                if (IEEE80211_IS_CHAN_HT40U(vap->iv_bss->ni_chan))
                        htflags = IEEE80211_CHAN_HT40U;
                else if (IEEE80211_IS_CHAN_HT40D(vap->iv_bss->ni_chan))
                        htflags = IEEE80211_CHAN_HT40D;
        }
        /*
         * VHT flags - do much the same; check whether VHT is available
         * and if so, what our ideal channel use would be based on our
         * capabilities and the (pre-parsed) VHT info IE.
         */
        vhtflags = ieee80211_vht_get_vhtflags(ni, htflags);

        (void) htinfo_update_chw(ni, htflags, vhtflags);
}

/*
 * Install received HT rate set by parsing the HT cap ie.
 */
int
ieee80211_setup_htrates(struct ieee80211_node *ni, const uint8_t *ie, int flags)
{
        struct ieee80211com *ic = ni->ni_ic;
        struct ieee80211vap *vap = ni->ni_vap;
        const struct ieee80211_ie_htcap *htcap;
        struct ieee80211_htrateset *rs;
        int i, maxequalmcs, maxunequalmcs;

        maxequalmcs = ic->ic_txstream * 8 - 1;
        maxunequalmcs = 0;
        if (ic->ic_htcaps & IEEE80211_HTC_TXUNEQUAL) {
                if (ic->ic_txstream >= 2)
                        maxunequalmcs = 38;
                if (ic->ic_txstream >= 3)
                        maxunequalmcs = 52;
                if (ic->ic_txstream >= 4)
                        maxunequalmcs = 76;
        }

        rs = &ni->ni_htrates;
        memset(rs, 0, sizeof(*rs));
        if (ie != NULL) {
                if (ie[0] == IEEE80211_ELEMID_VENDOR)
                        ie += 4;
                htcap = (const struct ieee80211_ie_htcap *) ie;
                for (i = 0; i < IEEE80211_HTRATE_MAXSIZE; i++) {
                        if (isclr(htcap->hc_mcsset, i))
                                continue;
                        if (rs->rs_nrates == IEEE80211_HTRATE_MAXSIZE) {
                                IEEE80211_NOTE(vap,
                                    IEEE80211_MSG_XRATE | IEEE80211_MSG_11N, ni,
                                    "WARNING, HT rate set too large; only "
                                    "using %u rates", IEEE80211_HTRATE_MAXSIZE);
                                vap->iv_stats.is_rx_rstoobig++;
                                break;
                        }
                        if (i <= 31 && i > maxequalmcs)
                                continue;
                        if (i == 32 &&
                            (ic->ic_htcaps & IEEE80211_HTC_TXMCS32) == 0)
                                continue;
                        if (i > 32 && i > maxunequalmcs)
                                continue;
                        rs->rs_rates[rs->rs_nrates++] = i;
                }
        }
        return ieee80211_fix_rate(ni, (struct ieee80211_rateset *) rs, flags);
}

/*
 * Mark rates in a node's HT rate set as basic according
 * to the information in the supplied HT info ie.
 */
void
ieee80211_setup_basic_htrates(struct ieee80211_node *ni, const uint8_t *ie)
{
        const struct ieee80211_ie_htinfo *htinfo;
        struct ieee80211_htrateset *rs;
        int i, j;

        if (ie[0] == IEEE80211_ELEMID_VENDOR)
                ie += 4;
        htinfo = (const struct ieee80211_ie_htinfo *) ie;
        rs = &ni->ni_htrates;
        if (rs->rs_nrates == 0) {
                IEEE80211_NOTE(ni->ni_vap,
                    IEEE80211_MSG_XRATE | IEEE80211_MSG_11N, ni,
                    "%s", "WARNING, empty HT rate set");
                return;
        }
        for (i = 0; i < IEEE80211_HTRATE_MAXSIZE; i++) {
                if (isclr(htinfo->hi_basicmcsset, i))
                        continue;
                for (j = 0; j < rs->rs_nrates; j++)
                        if ((rs->rs_rates[j] & IEEE80211_RATE_VAL) == i)
                                rs->rs_rates[j] |= IEEE80211_RATE_BASIC;
        }
}

static void
ampdu_tx_setup(struct ieee80211_tx_ampdu *tap)
{
        callout_init(&tap->txa_timer, 1);
        tap->txa_flags |= IEEE80211_AGGR_SETUP;
        tap->txa_lastsample = ticks;
}

static void
ampdu_tx_stop(struct ieee80211_tx_ampdu *tap)
{
        struct ieee80211_node *ni = tap->txa_ni;
        struct ieee80211com *ic = ni->ni_ic;

        IEEE80211_NOTE(tap->txa_ni->ni_vap, IEEE80211_MSG_11N,
            tap->txa_ni,
            "%s: called",
            __func__);

        KASSERT(tap->txa_flags & IEEE80211_AGGR_SETUP,
            ("txa_flags 0x%x tid %d ac %d", tap->txa_flags, tap->txa_tid,
            TID_TO_WME_AC(tap->txa_tid)));

        /*
         * Stop BA stream if setup so driver has a chance
         * to reclaim any resources it might have allocated.
         */
        ic->ic_addba_stop(ni, tap);
        /*
         * Stop any pending BAR transmit.
         */
        bar_stop_timer(tap);

        /*
         * Reset packet estimate.
         */
        ieee80211_txampdu_init_pps(tap);

        /* NB: clearing NAK means we may re-send ADDBA */ 
        tap->txa_flags &= ~(IEEE80211_AGGR_SETUP | IEEE80211_AGGR_NAK);
}

/*
 * ADDBA response timeout.
 *
 * If software aggregation and per-TID queue management was done here,
 * that queue would be unpaused after the ADDBA timeout occurs.
 */
static void
addba_timeout(void *arg)
{
        struct ieee80211_tx_ampdu *tap = arg;
        struct ieee80211_node *ni = tap->txa_ni;
        struct ieee80211com *ic = ni->ni_ic;

        /* XXX ? */
        tap->txa_flags &= ~IEEE80211_AGGR_XCHGPEND;
        tap->txa_attempts++;
        ic->ic_addba_response_timeout(ni, tap);
}

static void
addba_start_timeout(struct ieee80211_tx_ampdu *tap)
{
        /* XXX use CALLOUT_PENDING instead? */
        callout_reset(&tap->txa_timer, ieee80211_addba_timeout,
            addba_timeout, tap);
        tap->txa_flags |= IEEE80211_AGGR_XCHGPEND;
        tap->txa_nextrequest = ticks + ieee80211_addba_timeout;
}

static void
addba_stop_timeout(struct ieee80211_tx_ampdu *tap)
{
        /* XXX use CALLOUT_PENDING instead? */
        if (tap->txa_flags & IEEE80211_AGGR_XCHGPEND) {
                callout_stop(&tap->txa_timer);
                tap->txa_flags &= ~IEEE80211_AGGR_XCHGPEND;
        }
}

static void
null_addba_response_timeout(struct ieee80211_node *ni,
    struct ieee80211_tx_ampdu *tap)
{
}

/*
 * Default method for requesting A-MPDU tx aggregation.
 * We setup the specified state block and start a timer
 * to wait for an ADDBA response frame.
 */
static int
ieee80211_addba_request(struct ieee80211_node *ni,
        struct ieee80211_tx_ampdu *tap,
        int dialogtoken, int baparamset, int batimeout)
{
        int bufsiz;

        /* XXX locking */
        tap->txa_token = dialogtoken;
        tap->txa_flags |= IEEE80211_AGGR_IMMEDIATE;
        bufsiz = _IEEE80211_MASKSHIFT(baparamset, IEEE80211_BAPS_BUFSIZ);
        tap->txa_wnd = (bufsiz == 0) ?
            IEEE80211_AGGR_BAWMAX : min(bufsiz, IEEE80211_AGGR_BAWMAX);
        addba_start_timeout(tap);
        return 1;
}

/*
 * Called by drivers that wish to request an ADDBA session be
 * setup.  This brings it up and starts the request timer.
 */
int
ieee80211_ampdu_tx_request_ext(struct ieee80211_node *ni, int tid)
{
        struct ieee80211_tx_ampdu *tap;

        if (tid < 0 || tid > 15)
                return (0);
        tap = &ni->ni_tx_ampdu[tid];

        /* XXX locking */
        if ((tap->txa_flags & IEEE80211_AGGR_SETUP) == 0) {
                /* do deferred setup of state */
                ampdu_tx_setup(tap);
        }
        /* XXX hack for not doing proper locking */
        tap->txa_flags &= ~IEEE80211_AGGR_NAK;
        addba_start_timeout(tap);
        return (1);
}

/*
 * Called by drivers that have marked a session as active.
 */
int
ieee80211_ampdu_tx_request_active_ext(struct ieee80211_node *ni, int tid,
    int status)
{
        struct ieee80211_tx_ampdu *tap;

        if (tid < 0 || tid > 15)
                return (0);
        tap = &ni->ni_tx_ampdu[tid];

        /* XXX locking */
        addba_stop_timeout(tap);
        if (status == 1) {
                tap->txa_flags |= IEEE80211_AGGR_RUNNING;
                tap->txa_attempts = 0;
        } else {
                /* mark tid so we don't try again */
                tap->txa_flags |= IEEE80211_AGGR_NAK;
        }
        return (1);
}

/*
 * Default method for processing an A-MPDU tx aggregation
 * response.  We shutdown any pending timer and update the
 * state block according to the reply.
 */
static int
ieee80211_addba_response(struct ieee80211_node *ni,
        struct ieee80211_tx_ampdu *tap,
        int status, int baparamset, int batimeout)
{
        struct ieee80211vap *vap = ni->ni_vap;
        int bufsiz;

        /* XXX locking */
        addba_stop_timeout(tap);
        if (status == IEEE80211_STATUS_SUCCESS) {
                bufsiz = _IEEE80211_MASKSHIFT(baparamset, IEEE80211_BAPS_BUFSIZ);
                /* XXX override our request? */
                tap->txa_wnd = (bufsiz == 0) ?
                    IEEE80211_AGGR_BAWMAX : min(bufsiz, IEEE80211_AGGR_BAWMAX);
#ifdef __notyet__
                tid = _IEEE80211_MASKSHIFT(baparamset, IEEE80211_BAPS_TID);
#endif
                tap->txa_flags |= IEEE80211_AGGR_RUNNING;
                tap->txa_attempts = 0;
                /* TODO: this should be a vap flag */
                if ((vap->iv_htcaps & IEEE80211_HTC_TX_AMSDU_AMPDU) &&
                    (ni->ni_flags & IEEE80211_NODE_AMSDU_TX) &&
                    (_IEEE80211_MASKSHIFT(baparamset, IEEE80211_BAPS_AMSDU)))
                        tap->txa_flags |= IEEE80211_AGGR_AMSDU;
                else
                        tap->txa_flags &= ~IEEE80211_AGGR_AMSDU;
        } else {
                /* mark tid so we don't try again */
                tap->txa_flags |= IEEE80211_AGGR_NAK;
        }
        return 1;
}

/*
 * Default method for stopping A-MPDU tx aggregation.
 * Any timer is cleared and we drain any pending frames.
 */
static void
ieee80211_addba_stop(struct ieee80211_node *ni, struct ieee80211_tx_ampdu *tap)
{
        /* XXX locking */
        addba_stop_timeout(tap);
        if (tap->txa_flags & IEEE80211_AGGR_RUNNING) {
                /* XXX clear aggregation queue */
                tap->txa_flags &= ~(IEEE80211_AGGR_RUNNING | IEEE80211_AGGR_AMSDU);
        }
        tap->txa_attempts = 0;
}

/*
 * Process a received action frame using the default aggregation
 * policy.  We intercept ADDBA-related frames and use them to
 * update our aggregation state.  All other frames are passed up
 * for processing by ieee80211_recv_action.
 */
static int
ht_recv_action_ba_addba_request(struct ieee80211_node *ni,
        const struct ieee80211_frame *wh,
        const uint8_t *frm, const uint8_t *efrm)
{
        struct ieee80211com *ic = ni->ni_ic;
        struct ieee80211vap *vap = ni->ni_vap;
        struct ieee80211_rx_ampdu *rap;
        uint8_t dialogtoken;
        uint16_t baparamset, batimeout, baseqctl;
        uint16_t args[5];
        int tid;

        dialogtoken = frm[2];
        baparamset = le16dec(frm+3);
        batimeout = le16dec(frm+5);
        baseqctl = le16dec(frm+7);

        tid = _IEEE80211_MASKSHIFT(baparamset, IEEE80211_BAPS_TID);

        IEEE80211_NOTE(vap, IEEE80211_MSG_ACTION | IEEE80211_MSG_11N, ni,
            "recv ADDBA request: dialogtoken %u baparamset 0x%x "
            "(tid %d bufsiz %d) batimeout %d baseqctl %d:%d amsdu %d",
            dialogtoken, baparamset,
            tid, _IEEE80211_MASKSHIFT(baparamset, IEEE80211_BAPS_BUFSIZ),
            batimeout,
            _IEEE80211_MASKSHIFT(baseqctl, IEEE80211_BASEQ_START),
            _IEEE80211_MASKSHIFT(baseqctl, IEEE80211_BASEQ_FRAG),
            _IEEE80211_MASKSHIFT(baparamset, IEEE80211_BAPS_AMSDU));

        rap = &ni->ni_rx_ampdu[tid];

        /* Send ADDBA response */
        args[0] = dialogtoken;
        /*
         * NB: We ack only if the sta associated with HT and
         * the ap is configured to do AMPDU rx (the latter
         * violates the 11n spec and is mostly for testing).
         */
        if ((ni->ni_flags & IEEE80211_NODE_AMPDU_RX) &&
            (vap->iv_flags_ht & IEEE80211_FHT_AMPDU_RX)) {
                /* XXX TODO: handle ampdu_rx_start failure */
                ic->ic_ampdu_rx_start(ni, rap,
                    baparamset, batimeout, baseqctl);

                args[1] = IEEE80211_STATUS_SUCCESS;
        } else {
                IEEE80211_NOTE(vap, IEEE80211_MSG_ACTION | IEEE80211_MSG_11N,
                    ni, "reject ADDBA request: %s",
                    ni->ni_flags & IEEE80211_NODE_AMPDU_RX ?
                       "administratively disabled" :
                       "not negotiated for station");
                vap->iv_stats.is_addba_reject++;
                args[1] = IEEE80211_STATUS_UNSPECIFIED;
        }
        /* XXX honor rap flags? */
        args[2] = IEEE80211_BAPS_POLICY_IMMEDIATE
                | _IEEE80211_SHIFTMASK(tid, IEEE80211_BAPS_TID)
                | _IEEE80211_SHIFTMASK(rap->rxa_wnd, IEEE80211_BAPS_BUFSIZ)
                ;

        /*
         * TODO: we're out of iv_flags_ht fields; once
         * this is extended we should make this configurable.
         */
        if ((baparamset & IEEE80211_BAPS_AMSDU) &&
            (ni->ni_flags & IEEE80211_NODE_AMSDU_RX) &&
            (vap->iv_htcaps & IEEE80211_HTC_RX_AMSDU_AMPDU))
                args[2] |= IEEE80211_BAPS_AMSDU;

        args[3] = 0;
        args[4] = 0;
        ic->ic_send_action(ni, IEEE80211_ACTION_CAT_BA,
                IEEE80211_ACTION_BA_ADDBA_RESPONSE, args);
        return 0;
}

static int
ht_recv_action_ba_addba_response(struct ieee80211_node *ni,
        const struct ieee80211_frame *wh,
        const uint8_t *frm, const uint8_t *efrm)
{
        struct ieee80211com *ic = ni->ni_ic;
        struct ieee80211vap *vap = ni->ni_vap;
        struct ieee80211_tx_ampdu *tap;
        uint8_t dialogtoken, policy;
        uint16_t baparamset, batimeout, code;
        int tid;
#ifdef IEEE80211_DEBUG
        int amsdu, bufsiz;
#endif

        dialogtoken = frm[2];
        code = le16dec(frm+3);
        baparamset = le16dec(frm+5);
        tid = _IEEE80211_MASKSHIFT(baparamset, IEEE80211_BAPS_TID);
#ifdef IEEE80211_DEBUG
        bufsiz = _IEEE80211_MASKSHIFT(baparamset, IEEE80211_BAPS_BUFSIZ);
        amsdu = !! _IEEE80211_MASKSHIFT(baparamset, IEEE80211_BAPS_AMSDU);
#endif
        policy = _IEEE80211_MASKSHIFT(baparamset, IEEE80211_BAPS_POLICY);
        batimeout = le16dec(frm+7);

        tap = &ni->ni_tx_ampdu[tid];
        if ((tap->txa_flags & IEEE80211_AGGR_XCHGPEND) == 0) {
                IEEE80211_DISCARD_MAC(vap,
                    IEEE80211_MSG_ACTION | IEEE80211_MSG_11N,
                    ni->ni_macaddr, "ADDBA response",
                    "no pending ADDBA, tid %d dialogtoken %u "
                    "code %d", tid, dialogtoken, code);
                vap->iv_stats.is_addba_norequest++;
                return 0;
        }
        if (dialogtoken != tap->txa_token) {
                IEEE80211_DISCARD_MAC(vap,
                    IEEE80211_MSG_ACTION | IEEE80211_MSG_11N,
                    ni->ni_macaddr, "ADDBA response",
                    "dialogtoken mismatch: waiting for %d, "
                    "received %d, tid %d code %d",
                    tap->txa_token, dialogtoken, tid, code);
                vap->iv_stats.is_addba_badtoken++;
                return 0;
        }
        /* NB: assumes IEEE80211_AGGR_IMMEDIATE is 1 */
        if (policy != (tap->txa_flags & IEEE80211_AGGR_IMMEDIATE)) {
                IEEE80211_DISCARD_MAC(vap,
                    IEEE80211_MSG_ACTION | IEEE80211_MSG_11N,
                    ni->ni_macaddr, "ADDBA response",
                    "policy mismatch: expecting %s, "
                    "received %s, tid %d code %d",
                    tap->txa_flags & IEEE80211_AGGR_IMMEDIATE,
                    policy, tid, code);
                vap->iv_stats.is_addba_badpolicy++;
                return 0;
        }
#if 0
        /* XXX we take MIN in ieee80211_addba_response */
        if (bufsiz > IEEE80211_AGGR_BAWMAX) {
                IEEE80211_DISCARD_MAC(vap,
                    IEEE80211_MSG_ACTION | IEEE80211_MSG_11N,
                    ni->ni_macaddr, "ADDBA response",
                    "BA window too large: max %d, "
                    "received %d, tid %d code %d",
                    bufsiz, IEEE80211_AGGR_BAWMAX, tid, code);
                vap->iv_stats.is_addba_badbawinsize++;
                return 0;
        }
#endif

        IEEE80211_NOTE(vap, IEEE80211_MSG_ACTION | IEEE80211_MSG_11N, ni,
            "recv ADDBA response: dialogtoken %u code %d "
            "baparamset 0x%x (tid %d bufsiz %d amsdu %d) batimeout %d",
            dialogtoken, code, baparamset, tid,
            bufsiz,
            amsdu,
            batimeout);
        ic->ic_addba_response(ni, tap, code, baparamset, batimeout);
        return 0;
}

static int
ht_recv_action_ba_delba(struct ieee80211_node *ni,
        const struct ieee80211_frame *wh,
        const uint8_t *frm, const uint8_t *efrm)
{
        struct ieee80211com *ic = ni->ni_ic;
        struct ieee80211_rx_ampdu *rap;
        struct ieee80211_tx_ampdu *tap;
        uint16_t baparamset;
#ifdef IEEE80211_DEBUG
        uint16_t code;
#endif
        int tid;

        baparamset = le16dec(frm+2);
#ifdef IEEE80211_DEBUG
        code = le16dec(frm+4);
#endif

        tid = _IEEE80211_MASKSHIFT(baparamset, IEEE80211_DELBAPS_TID);

        IEEE80211_NOTE(ni->ni_vap, IEEE80211_MSG_ACTION | IEEE80211_MSG_11N, ni,
            "recv DELBA: baparamset 0x%x (tid %d initiator %d) "
            "code %d", baparamset, tid,
            _IEEE80211_MASKSHIFT(baparamset, IEEE80211_DELBAPS_INIT), code);

        if ((baparamset & IEEE80211_DELBAPS_INIT) == 0) {
                tap = &ni->ni_tx_ampdu[tid];
                ic->ic_addba_stop(ni, tap);
        } else {
                rap = &ni->ni_rx_ampdu[tid];
                ic->ic_ampdu_rx_stop(ni, rap);
        }
        return 0;
}

/*
 * Handle the HT channel width action frame.
 *
 * 802.11-2020 9.6.11.2 (Notify Channel Width frame format).
 */
static int
ht_recv_action_ht_txchwidth(struct ieee80211_node *ni,
        const struct ieee80211_frame *wh __unused,
        const uint8_t *frm, const uint8_t *efrm __unused)
{
        int chw;

        /* If 20/40 is not supported the chw cannot change. */
        if ((ni->ni_htcap & IEEE80211_HTCAP_CHWIDTH40) == 0)
                return (0);

        /*
         * The supported values are either 0 (any supported width)
         * or 1 (HT20).  80, 160, etc MHz widths are not represented
         * here.
         */
        chw = (frm[2] == IEEE80211_A_HT_TXCHWIDTH_2040) ?
            NET80211_STA_RX_BW_40 : NET80211_STA_RX_BW_20;

        IEEE80211_NOTE(ni->ni_vap, IEEE80211_MSG_ACTION | IEEE80211_MSG_11N, ni,
            "%s: HT txchwidth, width %d%s (%s)", __func__,
            chw, ni->ni_chw != chw ? "*" : "", net80211_ni_chw_to_str(chw));
        if (chw != ni->ni_chw) {
                /* XXX does this need to change the ht40 station count? */
                ni->ni_chw = chw;
                /* XXX notify on change */
        }
        return 0;
}

static int
ht_recv_action_ht_mimopwrsave(struct ieee80211_node *ni,
        const struct ieee80211_frame *wh,
        const uint8_t *frm, const uint8_t *efrm)
{
        const struct ieee80211_action_ht_mimopowersave *mps =
            (const struct ieee80211_action_ht_mimopowersave *) frm;

        /* XXX check iv_htcaps */
        if (mps->am_control & IEEE80211_A_HT_MIMOPWRSAVE_ENA)
                ni->ni_flags |= IEEE80211_NODE_MIMO_PS;
        else
                ni->ni_flags &= ~IEEE80211_NODE_MIMO_PS;
        if (mps->am_control & IEEE80211_A_HT_MIMOPWRSAVE_MODE)
                ni->ni_flags |= IEEE80211_NODE_MIMO_RTS;
        else
                ni->ni_flags &= ~IEEE80211_NODE_MIMO_RTS;
        /* XXX notify on change */
        IEEE80211_NOTE(ni->ni_vap, IEEE80211_MSG_ACTION | IEEE80211_MSG_11N, ni,
            "%s: HT MIMO PS (%s%s)", __func__,
            (ni->ni_flags & IEEE80211_NODE_MIMO_PS) ?  "on" : "off",
            (ni->ni_flags & IEEE80211_NODE_MIMO_RTS) ?  "+rts" : ""
        );
        return 0;
}

/*
 * Transmit processing.
 */

/*
 * Check if A-MPDU should be requested/enabled for a stream.
 * We require a traffic rate above a per-AC threshold and we
 * also handle backoff from previous failed attempts.
 *
 * Drivers may override this method to bring in information
 * such as link state conditions in making the decision.
 */
static int
ieee80211_ampdu_enable(struct ieee80211_node *ni,
        struct ieee80211_tx_ampdu *tap)
{
        struct ieee80211vap *vap = ni->ni_vap;

        if (tap->txa_avgpps <
            vap->iv_ampdu_mintraffic[TID_TO_WME_AC(tap->txa_tid)])
                return 0;
        /* XXX check rssi? */
        if (tap->txa_attempts >= ieee80211_addba_maxtries &&
            ieee80211_time_after(ticks, tap->txa_nextrequest)) {
                /*
                 * Don't retry too often; txa_nextrequest is set
                 * to the minimum interval we'll retry after
                 * ieee80211_addba_maxtries failed attempts are made.
                 */
                return 0;
        }
        IEEE80211_NOTE(vap, IEEE80211_MSG_11N, ni,
            "enable AMPDU on tid %d (%s), avgpps %d pkts %d attempt %d",
            tap->txa_tid, ieee80211_wme_acnames[TID_TO_WME_AC(tap->txa_tid)],
            tap->txa_avgpps, tap->txa_pkts, tap->txa_attempts);
        return 1;
}

/**
 * @brief Request A-MPDU tx aggregation.
 *
 * Setup local state and issue an ADDBA request.  BA use will only happen after
 * the other end replies with ADDBA response.
 *
 * @param ni ieee80211_node update
 * @param tap tx_ampdu state
 * @returns 1 on success and 0 on error
 */
int
ieee80211_ampdu_request(struct ieee80211_node *ni,
        struct ieee80211_tx_ampdu *tap)
{
        struct ieee80211com *ic = ni->ni_ic;
        uint16_t args[5];
        int tid, dialogtoken, error;
        static int tokens = 0;  /* XXX */

        /* XXX locking */
        if ((tap->txa_flags & IEEE80211_AGGR_SETUP) == 0) {
                /* do deferred setup of state */
                ampdu_tx_setup(tap);
        }
        /* XXX hack for not doing proper locking */
        tap->txa_flags &= ~IEEE80211_AGGR_NAK;

        dialogtoken = (tokens+1) % 63;          /* XXX */
        tid = tap->txa_tid;

        /*
         * XXX TODO: This is racy with any other parallel TX going on. :(
         */
        tap->txa_start = ni->ni_txseqs[tid];

        args[0] = dialogtoken;
        args[1] = 0;    /* NB: status code not used */
        args[2] = IEEE80211_BAPS_POLICY_IMMEDIATE
                | _IEEE80211_SHIFTMASK(tid, IEEE80211_BAPS_TID)
                | _IEEE80211_SHIFTMASK(IEEE80211_AGGR_BAWMAX,
                    IEEE80211_BAPS_BUFSIZ)
                ;

        /* XXX TODO: this should be a flag, not iv_htcaps */
        if ((ni->ni_flags & IEEE80211_NODE_AMSDU_TX) &&
            (ni->ni_vap->iv_htcaps & IEEE80211_HTC_TX_AMSDU_AMPDU))
                args[2] |= IEEE80211_BAPS_AMSDU;

        args[3] = 0;    /* batimeout */
        /* NB: do first so there's no race against reply */
        if (!ic->ic_addba_request(ni, tap, dialogtoken, args[2], args[3])) {
                /* unable to setup state, don't make request */
                IEEE80211_NOTE(ni->ni_vap, IEEE80211_MSG_11N,
                    ni, "%s: could not setup BA stream for TID %d AC %d",
                    __func__, tap->txa_tid, TID_TO_WME_AC(tap->txa_tid));
                /* defer next try so we don't slam the driver with requests */
                tap->txa_attempts = ieee80211_addba_maxtries;
                /* NB: check in case driver wants to override */
                if (ieee80211_time_before_eq(tap->txa_nextrequest, ticks))
                        tap->txa_nextrequest = ticks + ieee80211_addba_backoff;
                return 0;
        }
        tokens = dialogtoken;                   /* allocate token */
        /* NB: after calling ic_addba_request so driver can set txa_start */
        args[4] = _IEEE80211_SHIFTMASK(tap->txa_start, IEEE80211_BASEQ_START)
                | _IEEE80211_SHIFTMASK(0, IEEE80211_BASEQ_FRAG)
                ;

        error = ic->ic_send_action(ni, IEEE80211_ACTION_CAT_BA,
                IEEE80211_ACTION_BA_ADDBA_REQUEST, args);
        /* Silly return of 1 for success here. */
        return (error == 0);
}

/*
 * Terminate an AMPDU tx stream.  State is reclaimed
 * and the peer notified with a DelBA Action frame.
 */
void
ieee80211_ampdu_stop(struct ieee80211_node *ni, struct ieee80211_tx_ampdu *tap,
        int reason)
{
        struct ieee80211com *ic = ni->ni_ic;
        struct ieee80211vap *vap = ni->ni_vap;
        uint16_t args[4];

        /* XXX locking */
        tap->txa_flags &= ~IEEE80211_AGGR_BARPEND;
        if (IEEE80211_AMPDU_RUNNING(tap)) {
                IEEE80211_NOTE(vap, IEEE80211_MSG_ACTION | IEEE80211_MSG_11N,
                    ni, "%s: stop BA stream for TID %d (reason: %d (%s))",
                    __func__, tap->txa_tid, reason,
                    ieee80211_reason_to_string(reason));
                vap->iv_stats.is_ampdu_stop++;

                ic->ic_addba_stop(ni, tap);
                args[0] = tap->txa_tid;
                args[1] = IEEE80211_DELBAPS_INIT;
                args[2] = reason;                       /* XXX reason code */
                ic->ic_send_action(ni, IEEE80211_ACTION_CAT_BA,
                        IEEE80211_ACTION_BA_DELBA, args);
        } else {
                IEEE80211_NOTE(vap, IEEE80211_MSG_ACTION | IEEE80211_MSG_11N,
                    ni, "%s: BA stream for TID %d not running "
                    "(reason: %d (%s))", __func__, tap->txa_tid, reason,
                    ieee80211_reason_to_string(reason));
                vap->iv_stats.is_ampdu_stop_failed++;
        }
}

/* XXX */
static void bar_start_timer(struct ieee80211_tx_ampdu *tap);

static void
bar_timeout(void *arg)
{
        struct ieee80211_tx_ampdu *tap = arg;
        struct ieee80211_node *ni = tap->txa_ni;

        KASSERT((tap->txa_flags & IEEE80211_AGGR_XCHGPEND) == 0,
            ("bar/addba collision, flags 0x%x", tap->txa_flags));

        IEEE80211_NOTE(ni->ni_vap, IEEE80211_MSG_11N,
            ni, "%s: tid %u flags 0x%x attempts %d", __func__,
            tap->txa_tid, tap->txa_flags, tap->txa_attempts);

        /* guard against race with bar_tx_complete */
        if ((tap->txa_flags & IEEE80211_AGGR_BARPEND) == 0)
                return;
        /* XXX ? */
        if (tap->txa_attempts >= ieee80211_bar_maxtries) {
                struct ieee80211com *ic = ni->ni_ic;

                ni->ni_vap->iv_stats.is_ampdu_bar_tx_fail++;
                /*
                 * If (at least) the last BAR TX timeout was due to
                 * an ieee80211_send_bar() failures, then we need
                 * to make sure we notify the driver that a BAR
                 * TX did occur and fail.  This gives the driver
                 * a chance to undo any queue pause that may
                 * have occurred.
                 */
                ic->ic_bar_response(ni, tap, 1);
                ieee80211_ampdu_stop(ni, tap, IEEE80211_REASON_TIMEOUT);
        } else {
                ni->ni_vap->iv_stats.is_ampdu_bar_tx_retry++;
                if (ieee80211_send_bar(ni, tap, tap->txa_seqpending) != 0) {
                        IEEE80211_NOTE(ni->ni_vap, IEEE80211_MSG_11N,
                            ni, "%s: failed to TX, starting timer\n",
                            __func__);
                        /*
                         * If ieee80211_send_bar() fails here, the
                         * timer may have stopped and/or the pending
                         * flag may be clear.  Because of this,
                         * fake the BARPEND and reset the timer.
                         * A retransmission attempt will then occur
                         * during the next timeout.
                         */
                        /* XXX locking */
                        tap->txa_flags |= IEEE80211_AGGR_BARPEND;
                        bar_start_timer(tap);
                }
        }
}

static void
bar_start_timer(struct ieee80211_tx_ampdu *tap)
{
        IEEE80211_NOTE(tap->txa_ni->ni_vap, IEEE80211_MSG_11N,
            tap->txa_ni,
            "%s: called",
            __func__);
        callout_reset(&tap->txa_timer, ieee80211_bar_timeout, bar_timeout, tap);
}

static void
bar_stop_timer(struct ieee80211_tx_ampdu *tap)
{
        IEEE80211_NOTE(tap->txa_ni->ni_vap, IEEE80211_MSG_11N,
            tap->txa_ni,
            "%s: called",
            __func__);
        callout_stop(&tap->txa_timer);
}

static void
bar_tx_complete(struct ieee80211_node *ni, void *arg, int status)
{
        struct ieee80211_tx_ampdu *tap = arg;

        IEEE80211_NOTE(ni->ni_vap, IEEE80211_MSG_11N,
            ni, "%s: tid %u flags 0x%x pending %d status %d",
            __func__, tap->txa_tid, tap->txa_flags,
            callout_pending(&tap->txa_timer), status);

        ni->ni_vap->iv_stats.is_ampdu_bar_tx++;
        /* XXX locking */
        if ((tap->txa_flags & IEEE80211_AGGR_BARPEND) &&
            callout_pending(&tap->txa_timer)) {
                struct ieee80211com *ic = ni->ni_ic;

                if (status == 0)                /* ACK'd */
                        bar_stop_timer(tap);
                ic->ic_bar_response(ni, tap, status);
                /* NB: just let timer expire so we pace requests */
        }
}

static void
ieee80211_bar_response(struct ieee80211_node *ni,
        struct ieee80211_tx_ampdu *tap, int status)
{

        IEEE80211_NOTE(tap->txa_ni->ni_vap, IEEE80211_MSG_11N,
            tap->txa_ni,
            "%s: called",
            __func__);
        if (status == 0) {              /* got ACK */
                IEEE80211_NOTE(ni->ni_vap, IEEE80211_MSG_11N,
                    ni, "BAR moves BA win <%u:%u> (%u frames) txseq %u tid %u",
                    tap->txa_start,
                    IEEE80211_SEQ_ADD(tap->txa_start, tap->txa_wnd-1),
                    tap->txa_qframes, tap->txa_seqpending,
                    tap->txa_tid);

                /* NB: timer already stopped in bar_tx_complete */
                tap->txa_start = tap->txa_seqpending;
                tap->txa_flags &= ~IEEE80211_AGGR_BARPEND;
        }
}

/*
 * Transmit a BAR frame to the specified node.  The
 * BAR contents are drawn from the supplied aggregation
 * state associated with the node.
 *
 * NB: we only handle immediate ACK w/ compressed bitmap.
 */
int
ieee80211_send_bar(struct ieee80211_node *ni,
        struct ieee80211_tx_ampdu *tap, ieee80211_seq seq)
{
#define senderr(_x, _v) do { vap->iv_stats._v++; ret = _x; goto bad; } while (0)
        struct ieee80211vap *vap = ni->ni_vap;
        struct ieee80211com *ic = ni->ni_ic;
        struct ieee80211_frame_bar *bar;
        struct mbuf *m;
        uint16_t barctl, barseqctl;
        uint8_t *frm;
        int tid, ret;

        IEEE80211_NOTE(tap->txa_ni->ni_vap, IEEE80211_MSG_11N,
            tap->txa_ni,
            "%s: called",
            __func__);

        if ((tap->txa_flags & IEEE80211_AGGR_RUNNING) == 0) {
                /* no ADDBA response, should not happen */
                /* XXX stat+msg */
                return EINVAL;
        }
        /* XXX locking */
        bar_stop_timer(tap);

        ieee80211_ref_node(ni);

        m = ieee80211_getmgtframe(&frm, ic->ic_headroom, sizeof(*bar));
        if (m == NULL)
                senderr(ENOMEM, is_tx_nobuf);

        if (!ieee80211_add_callback(m, bar_tx_complete, tap)) {
                m_freem(m);
                senderr(ENOMEM, is_tx_nobuf);   /* XXX */
                /* NOTREACHED */
        }

        bar = mtod(m, struct ieee80211_frame_bar *);
        bar->i_fc[0] = IEEE80211_FC0_VERSION_0 |
                IEEE80211_FC0_TYPE_CTL | IEEE80211_FC0_SUBTYPE_BAR;
        bar->i_fc[1] = 0;
        IEEE80211_ADDR_COPY(bar->i_ra, ni->ni_macaddr);
        IEEE80211_ADDR_COPY(bar->i_ta, vap->iv_myaddr);

        tid = tap->txa_tid;
        barctl  = (tap->txa_flags & IEEE80211_AGGR_IMMEDIATE ?
                        0 : IEEE80211_BAR_NOACK)
                | IEEE80211_BAR_COMP
                | _IEEE80211_SHIFTMASK(tid, IEEE80211_BAR_TID)
                ;
        barseqctl = _IEEE80211_SHIFTMASK(seq, IEEE80211_BAR_SEQ_START);
        /* NB: known to have proper alignment */
        bar->i_ctl = htole16(barctl);
        bar->i_seq = htole16(barseqctl);
        m->m_pkthdr.len = m->m_len = sizeof(struct ieee80211_frame_bar);

        M_WME_SETAC(m, WME_AC_VO);

        IEEE80211_NODE_STAT(ni, tx_mgmt);       /* XXX tx_ctl? */

        /* XXX locking */
        /* init/bump attempts counter */
        if ((tap->txa_flags & IEEE80211_AGGR_BARPEND) == 0)
                tap->txa_attempts = 1;
        else
                tap->txa_attempts++;
        tap->txa_seqpending = seq;
        tap->txa_flags |= IEEE80211_AGGR_BARPEND;

        IEEE80211_NOTE(vap, IEEE80211_MSG_DEBUG | IEEE80211_MSG_11N,
            ni, "send BAR: tid %u ctl 0x%x start %u (attempt %d)",
            tid, barctl, seq, tap->txa_attempts);

        /*
         * ic_raw_xmit will free the node reference
         * regardless of queue/TX success or failure.
         */
        IEEE80211_TX_LOCK(ic);
        ret = ieee80211_raw_output(vap, ni, m, NULL);
        IEEE80211_TX_UNLOCK(ic);
        if (ret != 0) {
                IEEE80211_NOTE(vap, IEEE80211_MSG_DEBUG | IEEE80211_MSG_11N,
                    ni, "send BAR: failed: (ret = %d)\n",
                    ret);
                /* xmit failed, clear state flag */
                tap->txa_flags &= ~IEEE80211_AGGR_BARPEND;
                vap->iv_stats.is_ampdu_bar_tx_fail++;
                return ret;
        }
        /* XXX hack against tx complete happening before timer is started */
        if (tap->txa_flags & IEEE80211_AGGR_BARPEND)
                bar_start_timer(tap);
        return 0;
bad:
        IEEE80211_NOTE(tap->txa_ni->ni_vap, IEEE80211_MSG_11N,
            tap->txa_ni,
            "%s: bad! ret=%d",
            __func__, ret);
        vap->iv_stats.is_ampdu_bar_tx_fail++;
        ieee80211_free_node(ni);
        return ret;
#undef senderr
}

static int
ht_action_output(struct ieee80211_node *ni, struct mbuf *m)
{
        struct ieee80211_bpf_params params;

        memset(&params, 0, sizeof(params));
        params.ibp_pri = WME_AC_VO;
        params.ibp_rate0 = ni->ni_txparms->mgmtrate;
        /* NB: we know all frames are unicast */
        params.ibp_try0 = ni->ni_txparms->maxretry;
        params.ibp_power = ni->ni_txpower;
        return ieee80211_mgmt_output(ni, m, IEEE80211_FC0_SUBTYPE_ACTION,
             &params);
}

#define ADDSHORT(frm, v) do {                   \
        frm[0] = (v) & 0xff;                    \
        frm[1] = (v) >> 8;                      \
        frm += 2;                               \
} while (0)

/*
 * Send an action management frame.  The arguments are stuff
 * into a frame without inspection; the caller is assumed to
 * prepare them carefully (e.g. based on the aggregation state).
 */
static int
ht_send_action_ba_addba(struct ieee80211_node *ni,
        int category, int action, void *arg0)
{
        struct ieee80211vap *vap = ni->ni_vap;
        struct ieee80211com *ic = ni->ni_ic;
        uint16_t *args = arg0;
        struct mbuf *m;
        uint8_t *frm;

        IEEE80211_NOTE(vap, IEEE80211_MSG_ACTION | IEEE80211_MSG_11N, ni,
            "send ADDBA %s: dialogtoken %d status %d "
            "baparamset 0x%x (tid %d amsdu %d) batimeout 0x%x baseqctl 0x%x",
            (action == IEEE80211_ACTION_BA_ADDBA_REQUEST) ?
                "request" : "response", args[0], args[1], args[2],
            _IEEE80211_MASKSHIFT(args[2], IEEE80211_BAPS_TID),
            _IEEE80211_MASKSHIFT(args[2], IEEE80211_BAPS_AMSDU),
            args[3], args[4]);

        IEEE80211_DPRINTF(vap, IEEE80211_MSG_NODE,
            "ieee80211_ref_node (%s:%u) %p<%s> refcnt %d\n", __func__, __LINE__,
            ni, ether_sprintf(ni->ni_macaddr), ieee80211_node_refcnt(ni)+1);
        ieee80211_ref_node(ni);

        m = ieee80211_getmgtframe(&frm,
            ic->ic_headroom + sizeof(struct ieee80211_frame),
            sizeof(uint16_t)    /* action+category */
            /* XXX may action payload */
            + sizeof(struct ieee80211_action_ba_addbaresponse)
        );
        if (m != NULL) {
                *frm++ = category;
                *frm++ = action;
                *frm++ = args[0];               /* dialog token */
                if (action == IEEE80211_ACTION_BA_ADDBA_RESPONSE)
                        ADDSHORT(frm, args[1]); /* status code */
                ADDSHORT(frm, args[2]);         /* baparamset */
                ADDSHORT(frm, args[3]);         /* batimeout */
                if (action == IEEE80211_ACTION_BA_ADDBA_REQUEST)
                        ADDSHORT(frm, args[4]); /* baseqctl */
                m->m_pkthdr.len = m->m_len = frm - mtod(m, uint8_t *);
                return ht_action_output(ni, m);
        } else {
                vap->iv_stats.is_tx_nobuf++;
                ieee80211_free_node(ni);
                return ENOMEM;
        }
}

static int
ht_send_action_ba_delba(struct ieee80211_node *ni,
        int category, int action, void *arg0)
{
        struct ieee80211vap *vap = ni->ni_vap;
        struct ieee80211com *ic = ni->ni_ic;
        uint16_t *args = arg0;
        struct mbuf *m;
        uint16_t baparamset;
        uint8_t *frm;

        baparamset = _IEEE80211_SHIFTMASK(args[0], IEEE80211_DELBAPS_TID)
                   | args[1]
                   ;
        IEEE80211_NOTE(vap, IEEE80211_MSG_ACTION | IEEE80211_MSG_11N, ni,
            "send DELBA action: tid %d, initiator %d reason %d (%s)",
            args[0], args[1], args[2], ieee80211_reason_to_string(args[2]));

        IEEE80211_DPRINTF(vap, IEEE80211_MSG_NODE,
            "ieee80211_ref_node (%s:%u) %p<%s> refcnt %d\n", __func__, __LINE__,
            ni, ether_sprintf(ni->ni_macaddr), ieee80211_node_refcnt(ni)+1);
        ieee80211_ref_node(ni);

        m = ieee80211_getmgtframe(&frm,
            ic->ic_headroom + sizeof(struct ieee80211_frame),
            sizeof(uint16_t)    /* action+category */
            /* XXX may action payload */
            + sizeof(struct ieee80211_action_ba_addbaresponse)
        );
        if (m != NULL) {
                *frm++ = category;
                *frm++ = action;
                ADDSHORT(frm, baparamset);
                ADDSHORT(frm, args[2]);         /* reason code */
                m->m_pkthdr.len = m->m_len = frm - mtod(m, uint8_t *);
                return ht_action_output(ni, m);
        } else {
                vap->iv_stats.is_tx_nobuf++;
                ieee80211_free_node(ni);
                return ENOMEM;
        }
}

static int
ht_send_action_ht_txchwidth(struct ieee80211_node *ni,
        int category, int action, void *arg0)
{
        struct ieee80211vap *vap = ni->ni_vap;
        struct ieee80211com *ic = ni->ni_ic;
        struct mbuf *m;
        uint8_t *frm;

        IEEE80211_NOTE(vap, IEEE80211_MSG_ACTION | IEEE80211_MSG_11N, ni,
            "send HT txchwidth: width %d",
            IEEE80211_IS_CHAN_HT40(ni->ni_chan) ? 40 : 20);

        IEEE80211_DPRINTF(vap, IEEE80211_MSG_NODE,
            "ieee80211_ref_node (%s:%u) %p<%s> refcnt %d\n", __func__, __LINE__,
            ni, ether_sprintf(ni->ni_macaddr), ieee80211_node_refcnt(ni)+1);
        ieee80211_ref_node(ni);

        m = ieee80211_getmgtframe(&frm,
            ic->ic_headroom + sizeof(struct ieee80211_frame),
            sizeof(uint16_t)    /* action+category */
            /* XXX may action payload */
            + sizeof(struct ieee80211_action_ba_addbaresponse)
        );
        if (m != NULL) {
                *frm++ = category;
                *frm++ = action;
                *frm++ = IEEE80211_IS_CHAN_HT40(ni->ni_chan) ? 
                        IEEE80211_A_HT_TXCHWIDTH_2040 :
                        IEEE80211_A_HT_TXCHWIDTH_20;
                m->m_pkthdr.len = m->m_len = frm - mtod(m, uint8_t *);
                return ht_action_output(ni, m);
        } else {
                vap->iv_stats.is_tx_nobuf++;
                ieee80211_free_node(ni);
                return ENOMEM;
        }
}
#undef ADDSHORT

/*
 * Construct the MCS bit mask for inclusion in an HT capabilities
 * information element.
 */
static void
ieee80211_set_mcsset(struct ieee80211com *ic, uint8_t *frm)
{
        int i;
        uint8_t txparams;

        KASSERT((ic->ic_rxstream > 0 && ic->ic_rxstream <= 4),
            ("ic_rxstream %d out of range", ic->ic_rxstream));
        KASSERT((ic->ic_txstream > 0 && ic->ic_txstream <= 4),
            ("ic_txstream %d out of range", ic->ic_txstream));

        for (i = 0; i < ic->ic_rxstream * 8; i++)
                setbit(frm, i);
        if ((ic->ic_htcaps & IEEE80211_HTCAP_CHWIDTH40) &&
            (ic->ic_htcaps & IEEE80211_HTC_RXMCS32))
                setbit(frm, 32);
        if (ic->ic_htcaps & IEEE80211_HTC_RXUNEQUAL) {
                if (ic->ic_rxstream >= 2) {
                        for (i = 33; i <= 38; i++)
                                setbit(frm, i);
                }
                if (ic->ic_rxstream >= 3) {
                        for (i = 39; i <= 52; i++)
                                setbit(frm, i);
                }
                if (ic->ic_rxstream >= 4) {
                        for (i = 53; i <= 76; i++)
                                setbit(frm, i);
                }
        }

        txparams = 0x1;                 /* TX MCS set defined */
        if (ic->ic_rxstream != ic->ic_txstream) {
                txparams |= 0x2;                /* TX RX MCS not equal */
                txparams |= (ic->ic_txstream - 1) << 2; /* num TX streams */
                if (ic->ic_htcaps & IEEE80211_HTC_TXUNEQUAL)
                        txparams |= 0x16;       /* TX unequal modulation sup */
        }

        frm[12] = txparams;
}

/*
 * Add body of an HTCAP information element.
 */
static uint8_t *
ieee80211_add_htcap_body(uint8_t *frm, struct ieee80211_node *ni)
{
#define ADDSHORT(frm, v) do {                   \
        frm[0] = (v) & 0xff;                    \
        frm[1] = (v) >> 8;                      \
        frm += 2;                               \
} while (0)
        struct ieee80211com *ic = ni->ni_ic;
        struct ieee80211vap *vap = ni->ni_vap;
        uint16_t caps, extcaps;
        int rxmax, density;

        /* HT capabilities */
        caps = vap->iv_htcaps & 0xffff;
        /*
         * Note channel width depends on whether we are operating as
         * a sta or not.  When operating as a sta we are generating
         * a request based on our desired configuration.  Otherwise
         * we are operational and the channel attributes identify
         * how we've been setup (which might be different if a fixed
         * channel is specified).
         */
        if (vap->iv_opmode == IEEE80211_M_STA) {
                /* override 20/40 use based on config */
                if (vap->iv_flags_ht & IEEE80211_FHT_USEHT40)
                        caps |= IEEE80211_HTCAP_CHWIDTH40;
                else
                        caps &= ~IEEE80211_HTCAP_CHWIDTH40;

                /* Start by using the advertised settings */
                rxmax = _IEEE80211_MASKSHIFT(ni->ni_htparam,
                    IEEE80211_HTCAP_MAXRXAMPDU);
                density = _IEEE80211_MASKSHIFT(ni->ni_htparam,
                    IEEE80211_HTCAP_MPDUDENSITY);

                IEEE80211_DPRINTF(vap, IEEE80211_MSG_11N,
                    "%s: advertised rxmax=%d, density=%d, vap rxmax=%d, density=%d\n",
                    __func__,
                    rxmax,
                    density,
                    vap->iv_ampdu_rxmax,
                    vap->iv_ampdu_density);

                /* Cap at VAP rxmax */
                if (rxmax > vap->iv_ampdu_rxmax)
                        rxmax = vap->iv_ampdu_rxmax;

                /*
                 * If the VAP ampdu density value greater, use that.
                 *
                 * (Larger density value == larger minimum gap between A-MPDU
                 * subframes.)
                 */
                if (vap->iv_ampdu_density > density)
                        density = vap->iv_ampdu_density;

                /*
                 * NB: Hardware might support HT40 on some but not all
                 * channels. We can't determine this earlier because only
                 * after association the channel is upgraded to HT based
                 * on the negotiated capabilities.
                 */
                if (ni->ni_chan != IEEE80211_CHAN_ANYC &&
                    findhtchan(ic, ni->ni_chan, IEEE80211_CHAN_HT40U) == NULL &&
                    findhtchan(ic, ni->ni_chan, IEEE80211_CHAN_HT40D) == NULL)
                        caps &= ~IEEE80211_HTCAP_CHWIDTH40;
        } else {
                /* override 20/40 use based on current channel */
                if (IEEE80211_IS_CHAN_HT40(ni->ni_chan))
                        caps |= IEEE80211_HTCAP_CHWIDTH40;
                else
                        caps &= ~IEEE80211_HTCAP_CHWIDTH40;

                /* XXX TODO should it start by using advertised settings? */
                rxmax = vap->iv_ampdu_rxmax;
                density = vap->iv_ampdu_density;
        }

        /* adjust short GI based on channel and config */
        if ((vap->iv_flags_ht & IEEE80211_FHT_SHORTGI20) == 0)
                caps &= ~IEEE80211_HTCAP_SHORTGI20;
        if ((vap->iv_flags_ht & IEEE80211_FHT_SHORTGI40) == 0 ||
            (caps & IEEE80211_HTCAP_CHWIDTH40) == 0)
                caps &= ~IEEE80211_HTCAP_SHORTGI40;

        /* adjust STBC based on receive capabilities */
        if ((vap->iv_flags_ht & IEEE80211_FHT_STBC_RX) == 0)
                caps &= ~IEEE80211_HTCAP_RXSTBC;

        /* adjust LDPC based on receive capabilites */
        if ((vap->iv_flags_ht & IEEE80211_FHT_LDPC_RX) == 0)
                caps &= ~IEEE80211_HTCAP_LDPC;

        ADDSHORT(frm, caps);

        /* HT parameters */
        *frm = _IEEE80211_SHIFTMASK(rxmax, IEEE80211_HTCAP_MAXRXAMPDU)
             | _IEEE80211_SHIFTMASK(density, IEEE80211_HTCAP_MPDUDENSITY)
             ;
        frm++;

        /* pre-zero remainder of ie */
        memset(frm, 0, sizeof(struct ieee80211_ie_htcap) - 
                __offsetof(struct ieee80211_ie_htcap, hc_mcsset));

        /* supported MCS set */
        /*
         * XXX: For sta mode the rate set should be restricted based
         * on the AP's capabilities, but ni_htrates isn't setup when
         * we're called to form an AssocReq frame so for now we're
         * restricted to the device capabilities.
         */
        ieee80211_set_mcsset(ni->ni_ic, frm);

        frm += __offsetof(struct ieee80211_ie_htcap, hc_extcap) -
                __offsetof(struct ieee80211_ie_htcap, hc_mcsset);

        /* HT extended capabilities */
        extcaps = vap->iv_htextcaps & 0xffff;

        ADDSHORT(frm, extcaps);

        frm += sizeof(struct ieee80211_ie_htcap) -
                __offsetof(struct ieee80211_ie_htcap, hc_txbf);

        return frm;
#undef ADDSHORT
}

/*
 * Add 802.11n HT capabilities information element
 */
uint8_t *
ieee80211_add_htcap(uint8_t *frm, struct ieee80211_node *ni)
{
        frm[0] = IEEE80211_ELEMID_HTCAP;
        frm[1] = sizeof(struct ieee80211_ie_htcap) - 2;
        return ieee80211_add_htcap_body(frm + 2, ni);
}

/*
 * Non-associated probe request - add HT capabilities based on
 * the current channel configuration.
 */
static uint8_t *
ieee80211_add_htcap_body_ch(uint8_t *frm, struct ieee80211vap *vap,
    struct ieee80211_channel *c)
{
#define ADDSHORT(frm, v) do {                   \
        frm[0] = (v) & 0xff;                    \
        frm[1] = (v) >> 8;                      \
        frm += 2;                               \
} while (0)
        struct ieee80211com *ic = vap->iv_ic;
        uint16_t caps, extcaps;
        int rxmax, density;

        /* HT capabilities */
        caps = vap->iv_htcaps & 0xffff;

        /*
         * We don't use this in STA mode; only in IBSS mode.
         * So in IBSS mode we base our HTCAP flags on the
         * given channel.
         */

        /* override 20/40 use based on current channel */
        if (IEEE80211_IS_CHAN_HT40(c))
                caps |= IEEE80211_HTCAP_CHWIDTH40;
        else
                caps &= ~IEEE80211_HTCAP_CHWIDTH40;

        /* Use the currently configured values */
        rxmax = vap->iv_ampdu_rxmax;
        density = vap->iv_ampdu_density;

        /* adjust short GI based on channel and config */
        if ((vap->iv_flags_ht & IEEE80211_FHT_SHORTGI20) == 0)
                caps &= ~IEEE80211_HTCAP_SHORTGI20;
        if ((vap->iv_flags_ht & IEEE80211_FHT_SHORTGI40) == 0 ||
            (caps & IEEE80211_HTCAP_CHWIDTH40) == 0)
                caps &= ~IEEE80211_HTCAP_SHORTGI40;
        ADDSHORT(frm, caps);

        /* HT parameters */
        *frm = _IEEE80211_SHIFTMASK(rxmax, IEEE80211_HTCAP_MAXRXAMPDU)
             | _IEEE80211_SHIFTMASK(density, IEEE80211_HTCAP_MPDUDENSITY)
             ;
        frm++;

        /* pre-zero remainder of ie */
        memset(frm, 0, sizeof(struct ieee80211_ie_htcap) - 
                __offsetof(struct ieee80211_ie_htcap, hc_mcsset));

        /* supported MCS set */
        /*
         * XXX: For sta mode the rate set should be restricted based
         * on the AP's capabilities, but ni_htrates isn't setup when
         * we're called to form an AssocReq frame so for now we're
         * restricted to the device capabilities.
         */
        ieee80211_set_mcsset(ic, frm);

        frm += __offsetof(struct ieee80211_ie_htcap, hc_extcap) -
                __offsetof(struct ieee80211_ie_htcap, hc_mcsset);

        /* HT extended capabilities */
        extcaps = vap->iv_htextcaps & 0xffff;

        ADDSHORT(frm, extcaps);

        frm += sizeof(struct ieee80211_ie_htcap) -
                __offsetof(struct ieee80211_ie_htcap, hc_txbf);

        return frm;
#undef ADDSHORT
}

/*
 * Add 802.11n HT capabilities information element
 */
uint8_t *
ieee80211_add_htcap_ch(uint8_t *frm, struct ieee80211vap *vap,
    struct ieee80211_channel *c)
{
        frm[0] = IEEE80211_ELEMID_HTCAP;
        frm[1] = sizeof(struct ieee80211_ie_htcap) - 2;
        return ieee80211_add_htcap_body_ch(frm + 2, vap, c);
}

/*
 * Add Broadcom OUI wrapped standard HTCAP ie; this is
 * used for compatibility w/ pre-draft implementations.
 */
uint8_t *
ieee80211_add_htcap_vendor(uint8_t *frm, struct ieee80211_node *ni)
{
        frm[0] = IEEE80211_ELEMID_VENDOR;
        frm[1] = 4 + sizeof(struct ieee80211_ie_htcap) - 2;
        frm[2] = (BCM_OUI >> 0) & 0xff;
        frm[3] = (BCM_OUI >> 8) & 0xff;
        frm[4] = (BCM_OUI >> 16) & 0xff;
        frm[5] = BCM_OUI_HTCAP;
        return ieee80211_add_htcap_body(frm + 6, ni);
}

/*
 * Construct the MCS bit mask of basic rates
 * for inclusion in an HT information element.
 */
static void
ieee80211_set_basic_htrates(uint8_t *frm, const struct ieee80211_htrateset *rs)
{
        int i;

        for (i = 0; i < rs->rs_nrates; i++) {
                int r = rs->rs_rates[i] & IEEE80211_RATE_VAL;
                if ((rs->rs_rates[i] & IEEE80211_RATE_BASIC) &&
                    r < IEEE80211_HTRATE_MAXSIZE) {
                        /* NB: this assumes a particular implementation */
                        setbit(frm, r);
                }
        }
}

/*
 * Update the HTINFO ie for a beacon frame.
 */
void
ieee80211_ht_update_beacon(struct ieee80211vap *vap,
        struct ieee80211_beacon_offsets *bo)
{
#define PROTMODE        (IEEE80211_HTINFO_OPMODE|IEEE80211_HTINFO_NONHT_PRESENT)
        struct ieee80211_node *ni;
        const struct ieee80211_channel *bsschan;
        struct ieee80211com *ic = vap->iv_ic;
        struct ieee80211_ie_htinfo *ht =
           (struct ieee80211_ie_htinfo *) bo->bo_htinfo;

        ni = ieee80211_ref_node(vap->iv_bss);
        bsschan = ni->ni_chan;

        /* XXX only update on channel change */
        ht->hi_ctrlchannel = ieee80211_chan2ieee(ic, bsschan);
        if (vap->iv_flags_ht & IEEE80211_FHT_RIFS)
                ht->hi_byte1 = IEEE80211_HTINFO_RIFSMODE_PERM;
        else
                ht->hi_byte1 = IEEE80211_HTINFO_RIFSMODE_PROH;
        if (IEEE80211_IS_CHAN_HT40U(bsschan))
                ht->hi_byte1 |= IEEE80211_HTINFO_2NDCHAN_ABOVE;
        else if (IEEE80211_IS_CHAN_HT40D(bsschan))
                ht->hi_byte1 |= IEEE80211_HTINFO_2NDCHAN_BELOW;
        else
                ht->hi_byte1 |= IEEE80211_HTINFO_2NDCHAN_NONE;
        if (IEEE80211_IS_CHAN_HT40(bsschan))
                ht->hi_byte1 |= IEEE80211_HTINFO_TXWIDTH_2040;

        /* protection mode */
        /*
         * XXX TODO: this uses the global flag, not the per-VAP flag.
         * Eventually (once the protection modes are done per-channel
         * rather than per-VAP) we can flip this over to be per-VAP but
         * using the channel protection mode.
         */
        ht->hi_byte2 = (ht->hi_byte2 &~ PROTMODE) | ic->ic_curhtprotmode;

        ieee80211_free_node(ni);

        /* XXX propagate to vendor ie's */
#undef PROTMODE
}

/*
 * Add body of an HTINFO information element.
 *
 * NB: We don't use struct ieee80211_ie_htinfo because we can
 * be called to fillin both a standard ie and a compat ie that
 * has a vendor OUI at the front.
 */
static uint8_t *
ieee80211_add_htinfo_body(uint8_t *frm, struct ieee80211_node *ni)
{
        struct ieee80211vap *vap = ni->ni_vap;
        struct ieee80211com *ic = ni->ni_ic;

        /* pre-zero remainder of ie */
        memset(frm, 0, sizeof(struct ieee80211_ie_htinfo) - 2);

        /* primary/control channel center */
        *frm++ = ieee80211_chan2ieee(ic, ni->ni_chan);

        if (vap->iv_flags_ht & IEEE80211_FHT_RIFS)
                frm[0] = IEEE80211_HTINFO_RIFSMODE_PERM;
        else
                frm[0] = IEEE80211_HTINFO_RIFSMODE_PROH;
        if (IEEE80211_IS_CHAN_HT40U(ni->ni_chan))
                frm[0] |= IEEE80211_HTINFO_2NDCHAN_ABOVE;
        else if (IEEE80211_IS_CHAN_HT40D(ni->ni_chan))
                frm[0] |= IEEE80211_HTINFO_2NDCHAN_BELOW;
        else
                frm[0] |= IEEE80211_HTINFO_2NDCHAN_NONE;
        if (IEEE80211_IS_CHAN_HT40(ni->ni_chan))
                frm[0] |= IEEE80211_HTINFO_TXWIDTH_2040;

        /*
         * Add current protection mode.  Unlike for beacons,
         * this will respect the per-VAP flags.
         */
        frm[1] = vap->iv_curhtprotmode;

        frm += 5;

        /* basic MCS set */
        ieee80211_set_basic_htrates(frm, &ni->ni_htrates);
        frm += sizeof(struct ieee80211_ie_htinfo) -
                __offsetof(struct ieee80211_ie_htinfo, hi_basicmcsset);
        return frm;
}

/*
 * Add 802.11n HT information element.
 */
uint8_t *
ieee80211_add_htinfo(uint8_t *frm, struct ieee80211_node *ni)
{
        frm[0] = IEEE80211_ELEMID_HTINFO;
        frm[1] = sizeof(struct ieee80211_ie_htinfo) - 2;
        return ieee80211_add_htinfo_body(frm + 2, ni);
}

/*
 * Add Broadcom OUI wrapped standard HTINFO ie; this is
 * used for compatibility w/ pre-draft implementations.
 */
uint8_t *
ieee80211_add_htinfo_vendor(uint8_t *frm, struct ieee80211_node *ni)
{
        frm[0] = IEEE80211_ELEMID_VENDOR;
        frm[1] = 4 + sizeof(struct ieee80211_ie_htinfo) - 2;
        frm[2] = (BCM_OUI >> 0) & 0xff;
        frm[3] = (BCM_OUI >> 8) & 0xff;
        frm[4] = (BCM_OUI >> 16) & 0xff;
        frm[5] = BCM_OUI_HTINFO;
        return ieee80211_add_htinfo_body(frm + 6, ni);
}

/*
 * Get the HT density for the given 802.11n node.
 *
 * Take into account the density advertised from the peer.
 * Larger values are longer A-MPDU density spacing values, and
 * we want to obey them per station if we get them.
 */
int
ieee80211_ht_get_node_ampdu_density(const struct ieee80211_node *ni)
{
        struct ieee80211vap *vap;
        int peer_mpdudensity;

        vap = ni->ni_vap;
        peer_mpdudensity =
            _IEEE80211_MASKSHIFT(ni->ni_htparam, IEEE80211_HTCAP_MPDUDENSITY);
        if (vap->iv_ampdu_density > peer_mpdudensity)
                peer_mpdudensity = vap->iv_ampdu_density;
        return (peer_mpdudensity);
}

/*
 * Get the transmit A-MPDU limit for the given 802.11n node.
 *
 * Take into account the limit advertised from the peer.
 * Smaller values indicate smaller maximum A-MPDU sizes, and
 * should be used when forming an A-MPDU to the given peer.
 */
int
ieee80211_ht_get_node_ampdu_limit(const struct ieee80211_node *ni)
{
        struct ieee80211vap *vap;
        int peer_mpdulimit;

        vap = ni->ni_vap;
        peer_mpdulimit =
            _IEEE80211_MASKSHIFT(ni->ni_htparam, IEEE80211_HTCAP_MAXRXAMPDU);

        return (MIN(vap->iv_ampdu_limit, peer_mpdulimit));
}

/*
 * Return true if short-GI is available when transmitting to
 * the given node at 20MHz.
 *
 * Ensure it's configured and available in the VAP / driver as
 * well as the node.
 */
bool
ieee80211_ht_check_tx_shortgi_20(const struct ieee80211_node *ni)
{
        const struct ieee80211vap *vap;
        const struct ieee80211com *ic;

        if (! ieee80211_ht_check_tx_ht(ni))
                return (false);

        vap = ni->ni_vap;
        ic = ni->ni_ic;

        return ((ic->ic_htcaps & IEEE80211_HTCAP_SHORTGI20) &&
            (ni->ni_htcap & IEEE80211_HTCAP_SHORTGI20) &&
            (vap->iv_flags_ht & IEEE80211_FHT_SHORTGI20));
}

/*
 * Return true if short-GI is available when transmitting to
 * the given node at 40MHz.
 *
 * Ensure it's configured and available in the VAP / driver as
 * well as the node and BSS.
 */
bool
ieee80211_ht_check_tx_shortgi_40(const struct ieee80211_node *ni)
{
        const struct ieee80211vap *vap;
        const struct ieee80211com *ic;

        if (! ieee80211_ht_check_tx_ht40(ni))
                return (false);

        vap = ni->ni_vap;
        ic = ni->ni_ic;

        return ((ic->ic_htcaps & IEEE80211_HTCAP_SHORTGI40) &&
            (ni->ni_htcap & IEEE80211_HTCAP_SHORTGI40) &&
            (vap->iv_flags_ht & IEEE80211_FHT_SHORTGI40));
}

/*
 * Return true if HT rates can be used for the given node.
 *
 * There are some situations seen in the wild, wild past where
 * HT APs would announce HT but no HT rates.
 */
bool
ieee80211_ht_check_tx_ht(const struct ieee80211_node *ni)
{
        const struct ieee80211vap *vap;
        const struct ieee80211_channel *bss_chan;

        if (ni == NULL || ni->ni_chan == IEEE80211_CHAN_ANYC ||
            ni->ni_vap == NULL || ni->ni_vap->iv_bss == NULL)
                return (false);

        vap = ni->ni_vap;
        bss_chan = vap->iv_bss->ni_chan;

        if (bss_chan == IEEE80211_CHAN_ANYC)
                return (false);

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

/*
 * Return true if HT40 rates can be transmitted to the given node.
 *
 * This verifies that the BSS is HT40 capable and the current
 * node channel width is 40MHz.
 */
bool
ieee80211_ht_check_tx_ht40(const struct ieee80211_node *ni)
{
        struct ieee80211vap *vap;
        struct ieee80211_channel *bss_chan;

        if (! ieee80211_ht_check_tx_ht(ni))
                return (false);

        vap = ni->ni_vap;
        bss_chan = vap->iv_bss->ni_chan;

        return (IEEE80211_IS_CHAN_HT40(bss_chan) &&
            IEEE80211_IS_CHAN_HT40(ni->ni_chan) &&
            (ni->ni_chw == NET80211_STA_RX_BW_40));
}