/*
 * Copyright (c) 2008-2011 Atheros Communications Inc.
 *
 * Permission to use, copy, modify, and/or distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <linux/dma-mapping.h>
#include "ath9k.h"
#include "ar9003_mac.h"

#define BITS_PER_BYTE           8
#define OFDM_PLCP_BITS          22
#define HT_RC_2_STREAMS(_rc)    ((((_rc) & 0x78) >> 3) + 1)
#define L_STF                   8
#define L_LTF                   8
#define L_SIG                   4
#define HT_SIG                  8
#define HT_STF                  4
#define HT_LTF(_ns)             (4 * (_ns))
#define SYMBOL_TIME(_ns)        ((_ns) << 2) /* ns * 4 us */
#define SYMBOL_TIME_HALFGI(_ns) (((_ns) * 18 + 4) / 5)  /* ns * 3.6 us */
#define TIME_SYMBOLS(t)         ((t) >> 2)
#define TIME_SYMBOLS_HALFGI(t)  (((t) * 5 - 4) / 18)
#define NUM_SYMBOLS_PER_USEC(_usec) (_usec >> 2)
#define NUM_SYMBOLS_PER_USEC_HALFGI(_usec) (((_usec*5)-4)/18)


static u16 bits_per_symbol[][2] = {
        /* 20MHz 40MHz */
        {    26,   54 },     /*  0: BPSK */
        {    52,  108 },     /*  1: QPSK 1/2 */
        {    78,  162 },     /*  2: QPSK 3/4 */
        {   104,  216 },     /*  3: 16-QAM 1/2 */
        {   156,  324 },     /*  4: 16-QAM 3/4 */
        {   208,  432 },     /*  5: 64-QAM 2/3 */
        {   234,  486 },     /*  6: 64-QAM 3/4 */
        {   260,  540 },     /*  7: 64-QAM 5/6 */
};

#define IS_HT_RATE(_rate)     ((_rate) & 0x80)

static void ath_tx_send_normal(struct ath_softc *sc, struct ath_txq *txq,
                               struct ath_atx_tid *tid, struct sk_buff *skb);
static void ath_tx_complete(struct ath_softc *sc, struct sk_buff *skb,
                            int tx_flags, struct ath_txq *txq);
static void ath_tx_complete_buf(struct ath_softc *sc, struct ath_buf *bf,
                                struct ath_txq *txq, struct list_head *bf_q,
                                struct ath_tx_status *ts, int txok);
static void ath_tx_txqaddbuf(struct ath_softc *sc, struct ath_txq *txq,
                             struct list_head *head, bool internal);
static void ath_tx_rc_status(struct ath_softc *sc, struct ath_buf *bf,
                             struct ath_tx_status *ts, int nframes, int nbad,
                             int txok);
static void ath_tx_update_baw(struct ath_softc *sc, struct ath_atx_tid *tid,
                              int seqno);
static struct ath_buf *ath_tx_setup_buffer(struct ath_softc *sc,
                                           struct ath_txq *txq,
                                           struct ath_atx_tid *tid,
                                           struct sk_buff *skb);

enum {
        MCS_HT20,
        MCS_HT20_SGI,
        MCS_HT40,
        MCS_HT40_SGI,
};

/*********************/
/* Aggregation logic */
/*********************/

void ath_txq_lock(struct ath_softc *sc, struct ath_txq *txq)
        __acquires(&txq->axq_lock)
{
        spin_lock_bh(&txq->axq_lock);
}

void ath_txq_unlock(struct ath_softc *sc, struct ath_txq *txq)
        __releases(&txq->axq_lock)
{
        spin_unlock_bh(&txq->axq_lock);
}

void ath_txq_unlock_complete(struct ath_softc *sc, struct ath_txq *txq)
        __releases(&txq->axq_lock)
{
        struct sk_buff_head q;
        struct sk_buff *skb;

        __skb_queue_head_init(&q);
        skb_queue_splice_init(&txq->complete_q, &q);
        spin_unlock_bh(&txq->axq_lock);

        while ((skb = __skb_dequeue(&q)))
                ieee80211_tx_status(sc->hw, skb);
}

static void ath_tx_queue_tid(struct ath_txq *txq, struct ath_atx_tid *tid)
{
        struct ath_atx_ac *ac = tid->ac;

        if (tid->paused)
                return;

        if (tid->sched)
                return;

        tid->sched = true;
        list_add_tail(&tid->list, &ac->tid_q);

        if (ac->sched)
                return;

        ac->sched = true;
        list_add_tail(&ac->list, &txq->axq_acq);
}

static struct ath_frame_info *get_frame_info(struct sk_buff *skb)
{
        struct ieee80211_tx_info *tx_info = IEEE80211_SKB_CB(skb);
        BUILD_BUG_ON(sizeof(struct ath_frame_info) >
                     sizeof(tx_info->rate_driver_data));
        return (struct ath_frame_info *) &tx_info->rate_driver_data[0];
}

static void ath_send_bar(struct ath_atx_tid *tid, u16 seqno)
{
        if (!tid->an->sta)
                return;

        ieee80211_send_bar(tid->an->vif, tid->an->sta->addr, tid->tidno,
                           seqno << IEEE80211_SEQ_SEQ_SHIFT);
}

static void ath_set_rates(struct ieee80211_vif *vif, struct ieee80211_sta *sta,
                          struct ath_buf *bf)
{
        ieee80211_get_tx_rates(vif, sta, bf->bf_mpdu, bf->rates,
                               ARRAY_SIZE(bf->rates));
}

static void ath_txq_skb_done(struct ath_softc *sc, struct ath_txq *txq,
                             struct sk_buff *skb)
{
        int q;

        q = skb_get_queue_mapping(skb);
        if (txq == sc->tx.uapsdq)
                txq = sc->tx.txq_map[q];

        if (txq != sc->tx.txq_map[q])
                return;

        if (WARN_ON(--txq->pending_frames < 0))
                txq->pending_frames = 0;

        if (txq->stopped &&
            txq->pending_frames < sc->tx.txq_max_pending[q]) {
                ieee80211_wake_queue(sc->hw, q);
                txq->stopped = false;
        }
}

static struct ath_atx_tid *
ath_get_skb_tid(struct ath_softc *sc, struct ath_node *an, struct sk_buff *skb)
{
        struct ieee80211_hdr *hdr;
        u8 tidno = 0;

        hdr = (struct ieee80211_hdr *) skb->data;
        if (ieee80211_is_data_qos(hdr->frame_control))
                tidno = ieee80211_get_qos_ctl(hdr)[0];

        tidno &= IEEE80211_QOS_CTL_TID_MASK;
        return ATH_AN_2_TID(an, tidno);
}

static bool ath_tid_has_buffered(struct ath_atx_tid *tid)
{
        return !skb_queue_empty(&tid->buf_q) || !skb_queue_empty(&tid->retry_q);
}

static struct sk_buff *ath_tid_dequeue(struct ath_atx_tid *tid)
{
        struct sk_buff *skb;

        skb = __skb_dequeue(&tid->retry_q);
        if (!skb)
                skb = __skb_dequeue(&tid->buf_q);

        return skb;
}

/*
 * ath_tx_tid_change_state:
 * - clears a-mpdu flag of previous session
 * - force sequence number allocation to fix next BlockAck Window
 */
static void
ath_tx_tid_change_state(struct ath_softc *sc, struct ath_atx_tid *tid)
{
        struct ath_txq *txq = tid->ac->txq;
        struct ieee80211_tx_info *tx_info;
        struct sk_buff *skb, *tskb;
        struct ath_buf *bf;
        struct ath_frame_info *fi;

        skb_queue_walk_safe(&tid->buf_q, skb, tskb) {
                fi = get_frame_info(skb);
                bf = fi->bf;

                tx_info = IEEE80211_SKB_CB(skb);
                tx_info->flags &= ~IEEE80211_TX_CTL_AMPDU;

                if (bf)
                        continue;

                bf = ath_tx_setup_buffer(sc, txq, tid, skb);
                if (!bf) {
                        __skb_unlink(skb, &tid->buf_q);
                        ath_txq_skb_done(sc, txq, skb);
                        ieee80211_free_txskb(sc->hw, skb);
                        continue;
                }
        }

}

static void ath_tx_flush_tid(struct ath_softc *sc, struct ath_atx_tid *tid)
{
        struct ath_txq *txq = tid->ac->txq;
        struct sk_buff *skb;
        struct ath_buf *bf;
        struct list_head bf_head;
        struct ath_tx_status ts;
        struct ath_frame_info *fi;
        bool sendbar = false;

        INIT_LIST_HEAD(&bf_head);

        memset(&ts, 0, sizeof(ts));

        while ((skb = __skb_dequeue(&tid->retry_q))) {
                fi = get_frame_info(skb);
                bf = fi->bf;
                if (!bf) {
                        ath_txq_skb_done(sc, txq, skb);
                        ieee80211_free_txskb(sc->hw, skb);
                        continue;
                }

                if (fi->baw_tracked) {
                        ath_tx_update_baw(sc, tid, bf->bf_state.seqno);
                        sendbar = true;
                }

                list_add_tail(&bf->list, &bf_head);
                ath_tx_complete_buf(sc, bf, txq, &bf_head, &ts, 0);
        }

        if (sendbar) {
                ath_txq_unlock(sc, txq);
                ath_send_bar(tid, tid->seq_start);
                ath_txq_lock(sc, txq);
        }
}

static void ath_tx_update_baw(struct ath_softc *sc, struct ath_atx_tid *tid,
                              int seqno)
{
        int index, cindex;

        index  = ATH_BA_INDEX(tid->seq_start, seqno);
        cindex = (tid->baw_head + index) & (ATH_TID_MAX_BUFS - 1);

        __clear_bit(cindex, tid->tx_buf);

        while (tid->baw_head != tid->baw_tail && !test_bit(tid->baw_head, tid->tx_buf)) {
                INCR(tid->seq_start, IEEE80211_SEQ_MAX);
                INCR(tid->baw_head, ATH_TID_MAX_BUFS);
                if (tid->bar_index >= 0)
                        tid->bar_index--;
        }
}

static void ath_tx_addto_baw(struct ath_softc *sc, struct ath_atx_tid *tid,
                             struct ath_buf *bf)
{
        struct ath_frame_info *fi = get_frame_info(bf->bf_mpdu);
        u16 seqno = bf->bf_state.seqno;
        int index, cindex;

        index  = ATH_BA_INDEX(tid->seq_start, seqno);
        cindex = (tid->baw_head + index) & (ATH_TID_MAX_BUFS - 1);
        __set_bit(cindex, tid->tx_buf);
        fi->baw_tracked = 1;

        if (index >= ((tid->baw_tail - tid->baw_head) &
                (ATH_TID_MAX_BUFS - 1))) {
                tid->baw_tail = cindex;
                INCR(tid->baw_tail, ATH_TID_MAX_BUFS);
        }
}

static void ath_tid_drain(struct ath_softc *sc, struct ath_txq *txq,
                          struct ath_atx_tid *tid)

{
        struct sk_buff *skb;
        struct ath_buf *bf;
        struct list_head bf_head;
        struct ath_tx_status ts;
        struct ath_frame_info *fi;

        memset(&ts, 0, sizeof(ts));
        INIT_LIST_HEAD(&bf_head);

        while ((skb = ath_tid_dequeue(tid))) {
                fi = get_frame_info(skb);
                bf = fi->bf;

                if (!bf) {
                        ath_tx_complete(sc, skb, ATH_TX_ERROR, txq);
                        continue;
                }

                list_add_tail(&bf->list, &bf_head);
                ath_tx_complete_buf(sc, bf, txq, &bf_head, &ts, 0);
        }
}

static void ath_tx_set_retry(struct ath_softc *sc, struct ath_txq *txq,
                             struct sk_buff *skb, int count)
{
        struct ath_frame_info *fi = get_frame_info(skb);
        struct ath_buf *bf = fi->bf;
        struct ieee80211_hdr *hdr;
        int prev = fi->retries;

        TX_STAT_INC(txq->axq_qnum, a_retries);
        fi->retries += count;

        if (prev > 0)
                return;

        hdr = (struct ieee80211_hdr *)skb->data;
        hdr->frame_control |= cpu_to_le16(IEEE80211_FCTL_RETRY);
        dma_sync_single_for_device(sc->dev, bf->bf_buf_addr,
                sizeof(*hdr), DMA_TO_DEVICE);
}

static struct ath_buf *ath_tx_get_buffer(struct ath_softc *sc)
{
        struct ath_buf *bf = NULL;

        spin_lock_bh(&sc->tx.txbuflock);

        if (unlikely(list_empty(&sc->tx.txbuf))) {
                spin_unlock_bh(&sc->tx.txbuflock);
                return NULL;
        }

        bf = list_first_entry(&sc->tx.txbuf, struct ath_buf, list);
        list_del(&bf->list);

        spin_unlock_bh(&sc->tx.txbuflock);

        return bf;
}

static void ath_tx_return_buffer(struct ath_softc *sc, struct ath_buf *bf)
{
        spin_lock_bh(&sc->tx.txbuflock);
        list_add_tail(&bf->list, &sc->tx.txbuf);
        spin_unlock_bh(&sc->tx.txbuflock);
}

static struct ath_buf* ath_clone_txbuf(struct ath_softc *sc, struct ath_buf *bf)
{
        struct ath_buf *tbf;

        tbf = ath_tx_get_buffer(sc);
        if (WARN_ON(!tbf))
                return NULL;

        ATH_TXBUF_RESET(tbf);

        tbf->bf_mpdu = bf->bf_mpdu;
        tbf->bf_buf_addr = bf->bf_buf_addr;
        memcpy(tbf->bf_desc, bf->bf_desc, sc->sc_ah->caps.tx_desc_len);
        tbf->bf_state = bf->bf_state;
        tbf->bf_state.stale = false;

        return tbf;
}

static void ath_tx_count_frames(struct ath_softc *sc, struct ath_buf *bf,
                                struct ath_tx_status *ts, int txok,
                                int *nframes, int *nbad)
{
        struct ath_frame_info *fi;
        u16 seq_st = 0;
        u32 ba[WME_BA_BMP_SIZE >> 5];
        int ba_index;
        int isaggr = 0;

        *nbad = 0;
        *nframes = 0;

        isaggr = bf_isaggr(bf);
        if (isaggr) {
                seq_st = ts->ts_seqnum;
                memcpy(ba, &ts->ba_low, WME_BA_BMP_SIZE >> 3);
        }

        while (bf) {
                fi = get_frame_info(bf->bf_mpdu);
                ba_index = ATH_BA_INDEX(seq_st, bf->bf_state.seqno);

                (*nframes)++;
                if (!txok || (isaggr && !ATH_BA_ISSET(ba, ba_index)))
                        (*nbad)++;

                bf = bf->bf_next;
        }
}


static void ath_tx_complete_aggr(struct ath_softc *sc, struct ath_txq *txq,
                                 struct ath_buf *bf, struct list_head *bf_q,
                                 struct ath_tx_status *ts, int txok)
{
        struct ath_node *an = NULL;
        struct sk_buff *skb;
        struct ieee80211_sta *sta;
        struct ieee80211_hw *hw = sc->hw;
        struct ieee80211_hdr *hdr;
        struct ieee80211_tx_info *tx_info;
        struct ath_atx_tid *tid = NULL;
        struct ath_buf *bf_next, *bf_last = bf->bf_lastbf;
        struct list_head bf_head;
        struct sk_buff_head bf_pending;
        u16 seq_st = 0, acked_cnt = 0, txfail_cnt = 0, seq_first;
        u32 ba[WME_BA_BMP_SIZE >> 5];
        int isaggr, txfail, txpending, sendbar = 0, needreset = 0, nbad = 0;
        bool rc_update = true, isba;
        struct ieee80211_tx_rate rates[4];
        struct ath_frame_info *fi;
        int nframes;
        bool flush = !!(ts->ts_status & ATH9K_TX_FLUSH);
        int i, retries;
        int bar_index = -1;

        skb = bf->bf_mpdu;
        hdr = (struct ieee80211_hdr *)skb->data;

        tx_info = IEEE80211_SKB_CB(skb);

        memcpy(rates, bf->rates, sizeof(rates));

        retries = ts->ts_longretry + 1;
        for (i = 0; i < ts->ts_rateindex; i++)
                retries += rates[i].count;

        rcu_read_lock();

        sta = ieee80211_find_sta_by_ifaddr(hw, hdr->addr1, hdr->addr2);
        if (!sta) {
                rcu_read_unlock();

                INIT_LIST_HEAD(&bf_head);
                while (bf) {
                        bf_next = bf->bf_next;

                        if (!bf->bf_state.stale || bf_next != NULL)
                                list_move_tail(&bf->list, &bf_head);

                        ath_tx_complete_buf(sc, bf, txq, &bf_head, ts, 0);

                        bf = bf_next;
                }
                return;
        }

        an = (struct ath_node *)sta->drv_priv;
        tid = ath_get_skb_tid(sc, an, skb);
        seq_first = tid->seq_start;
        isba = ts->ts_flags & ATH9K_TX_BA;

        /*
         * The hardware occasionally sends a tx status for the wrong TID.
         * In this case, the BA status cannot be considered valid and all
         * subframes need to be retransmitted
         *
         * Only BlockAcks have a TID and therefore normal Acks cannot be
         * checked
         */
        if (isba && tid->tidno != ts->tid)
                txok = false;

        isaggr = bf_isaggr(bf);
        memset(ba, 0, WME_BA_BMP_SIZE >> 3);

        if (isaggr && txok) {
                if (ts->ts_flags & ATH9K_TX_BA) {
                        seq_st = ts->ts_seqnum;
                        memcpy(ba, &ts->ba_low, WME_BA_BMP_SIZE >> 3);
                } else {
                        /*
                         * AR5416 can become deaf/mute when BA
                         * issue happens. Chip needs to be reset.
                         * But AP code may have sychronization issues
                         * when perform internal reset in this routine.
                         * Only enable reset in STA mode for now.
                         */
                        if (sc->sc_ah->opmode == NL80211_IFTYPE_STATION)
                                needreset = 1;
                }
        }

        __skb_queue_head_init(&bf_pending);

        ath_tx_count_frames(sc, bf, ts, txok, &nframes, &nbad);
        while (bf) {
                u16 seqno = bf->bf_state.seqno;

                txfail = txpending = sendbar = 0;
                bf_next = bf->bf_next;

                skb = bf->bf_mpdu;
                tx_info = IEEE80211_SKB_CB(skb);
                fi = get_frame_info(skb);

                if (!BAW_WITHIN(tid->seq_start, tid->baw_size, seqno) ||
                    !tid->active) {
                        /*
                         * Outside of the current BlockAck window,
                         * maybe part of a previous session
                         */
                        txfail = 1;
                } else if (ATH_BA_ISSET(ba, ATH_BA_INDEX(seq_st, seqno))) {
                        /* transmit completion, subframe is
                         * acked by block ack */
                        acked_cnt++;
                } else if (!isaggr && txok) {
                        /* transmit completion */
                        acked_cnt++;
                } else if (flush) {
                        txpending = 1;
                } else if (fi->retries < ATH_MAX_SW_RETRIES) {
                        if (txok || !an->sleeping)
                                ath_tx_set_retry(sc, txq, bf->bf_mpdu,
                                                 retries);

                        txpending = 1;
                } else {
                        txfail = 1;
                        txfail_cnt++;
                        bar_index = max_t(int, bar_index,
                                ATH_BA_INDEX(seq_first, seqno));
                }

                /*
                 * Make sure the last desc is reclaimed if it
                 * not a holding desc.
                 */
                INIT_LIST_HEAD(&bf_head);
                if (bf_next != NULL || !bf_last->bf_state.stale)
                        list_move_tail(&bf->list, &bf_head);

                if (!txpending) {
                        /*
                         * complete the acked-ones/xretried ones; update
                         * block-ack window
                         */
                        ath_tx_update_baw(sc, tid, seqno);

                        if (rc_update && (acked_cnt == 1 || txfail_cnt == 1)) {
                                memcpy(tx_info->control.rates, rates, sizeof(rates));
                                ath_tx_rc_status(sc, bf, ts, nframes, nbad, txok);
                                rc_update = false;
                        }

                        ath_tx_complete_buf(sc, bf, txq, &bf_head, ts,
                                !txfail);
                } else {
                        if (tx_info->flags & IEEE80211_TX_STATUS_EOSP) {
                                tx_info->flags &= ~IEEE80211_TX_STATUS_EOSP;
                                ieee80211_sta_eosp(sta);
                        }
                        /* retry the un-acked ones */
                        if (bf->bf_next == NULL && bf_last->bf_state.stale) {
                                struct ath_buf *tbf;

                                tbf = ath_clone_txbuf(sc, bf_last);
                                /*
                                 * Update tx baw and complete the
                                 * frame with failed status if we
                                 * run out of tx buf.
                                 */
                                if (!tbf) {
                                        ath_tx_update_baw(sc, tid, seqno);

                                        ath_tx_complete_buf(sc, bf, txq,
                                                            &bf_head, ts, 0);
                                        bar_index = max_t(int, bar_index,
                                                ATH_BA_INDEX(seq_first, seqno));
                                        break;
                                }

                                fi->bf = tbf;
                        }

                        /*
                         * Put this buffer to the temporary pending
                         * queue to retain ordering
                         */
                        __skb_queue_tail(&bf_pending, skb);
                }

                bf = bf_next;
        }

        /* prepend un-acked frames to the beginning of the pending frame queue */
        if (!skb_queue_empty(&bf_pending)) {
                if (an->sleeping)
                        ieee80211_sta_set_buffered(sta, tid->tidno, true);

                skb_queue_splice_tail(&bf_pending, &tid->retry_q);
                if (!an->sleeping) {
                        ath_tx_queue_tid(txq, tid);

                        if (ts->ts_status & (ATH9K_TXERR_FILT | ATH9K_TXERR_XRETRY))
                                tid->ac->clear_ps_filter = true;
                }
        }

        if (bar_index >= 0) {
                u16 bar_seq = ATH_BA_INDEX2SEQ(seq_first, bar_index);

                if (BAW_WITHIN(tid->seq_start, tid->baw_size, bar_seq))
                        tid->bar_index = ATH_BA_INDEX(tid->seq_start, bar_seq);

                ath_txq_unlock(sc, txq);
                ath_send_bar(tid, ATH_BA_INDEX2SEQ(seq_first, bar_index + 1));
                ath_txq_lock(sc, txq);
        }

        rcu_read_unlock();

        if (needreset)
                ath9k_queue_reset(sc, RESET_TYPE_TX_ERROR);
}

static bool bf_is_ampdu_not_probing(struct ath_buf *bf)
{
    struct ieee80211_tx_info *info = IEEE80211_SKB_CB(bf->bf_mpdu);
    return bf_isampdu(bf) && !(info->flags & IEEE80211_TX_CTL_RATE_CTRL_PROBE);
}

static void ath_tx_process_buffer(struct ath_softc *sc, struct ath_txq *txq,
                                  struct ath_tx_status *ts, struct ath_buf *bf,
                                  struct list_head *bf_head)
{
        struct ieee80211_tx_info *info;
        bool txok, flush;

        txok = !(ts->ts_status & ATH9K_TXERR_MASK);
        flush = !!(ts->ts_status & ATH9K_TX_FLUSH);
        txq->axq_tx_inprogress = false;

        txq->axq_depth--;
        if (bf_is_ampdu_not_probing(bf))
                txq->axq_ampdu_depth--;

        if (!bf_isampdu(bf)) {
                if (!flush) {
                        info = IEEE80211_SKB_CB(bf->bf_mpdu);
                        memcpy(info->control.rates, bf->rates,
                               sizeof(info->control.rates));
                        ath_tx_rc_status(sc, bf, ts, 1, txok ? 0 : 1, txok);
                }
                ath_tx_complete_buf(sc, bf, txq, bf_head, ts, txok);
        } else
                ath_tx_complete_aggr(sc, txq, bf, bf_head, ts, txok);

        if (!flush)
                ath_txq_schedule(sc, txq);
}

static bool ath_lookup_legacy(struct ath_buf *bf)
{
        struct sk_buff *skb;
        struct ieee80211_tx_info *tx_info;
        struct ieee80211_tx_rate *rates;
        int i;

        skb = bf->bf_mpdu;
        tx_info = IEEE80211_SKB_CB(skb);
        rates = tx_info->control.rates;

        for (i = 0; i < 4; i++) {
                if (!rates[i].count || rates[i].idx < 0)
                        break;

                if (!(rates[i].flags & IEEE80211_TX_RC_MCS))
                        return true;
        }

        return false;
}

static u32 ath_lookup_rate(struct ath_softc *sc, struct ath_buf *bf,
                           struct ath_atx_tid *tid)
{
        struct sk_buff *skb;
        struct ieee80211_tx_info *tx_info;
        struct ieee80211_tx_rate *rates;
        u32 max_4ms_framelen, frmlen;
        u16 aggr_limit, bt_aggr_limit, legacy = 0;
        int q = tid->ac->txq->mac80211_qnum;
        int i;

        skb = bf->bf_mpdu;
        tx_info = IEEE80211_SKB_CB(skb);
        rates = bf->rates;

        /*
         * Find the lowest frame length among the rate series that will have a
         * 4ms (or TXOP limited) transmit duration.
         */
        max_4ms_framelen = ATH_AMPDU_LIMIT_MAX;

        for (i = 0; i < 4; i++) {
                int modeidx;

                if (!rates[i].count)
                        continue;

                if (!(rates[i].flags & IEEE80211_TX_RC_MCS)) {
                        legacy = 1;
                        break;
                }

                if (rates[i].flags & IEEE80211_TX_RC_40_MHZ_WIDTH)
                        modeidx = MCS_HT40;
                else
                        modeidx = MCS_HT20;

                if (rates[i].flags & IEEE80211_TX_RC_SHORT_GI)
                        modeidx++;

                frmlen = sc->tx.max_aggr_framelen[q][modeidx][rates[i].idx];
                max_4ms_framelen = min(max_4ms_framelen, frmlen);
        }

        /*
         * limit aggregate size by the minimum rate if rate selected is
         * not a probe rate, if rate selected is a probe rate then
         * avoid aggregation of this packet.
         */
        if (tx_info->flags & IEEE80211_TX_CTL_RATE_CTRL_PROBE || legacy)
                return 0;

        aggr_limit = min(max_4ms_framelen, (u32)ATH_AMPDU_LIMIT_MAX);

        /*
         * Override the default aggregation limit for BTCOEX.
         */
        bt_aggr_limit = ath9k_btcoex_aggr_limit(sc, max_4ms_framelen);
        if (bt_aggr_limit)
                aggr_limit = bt_aggr_limit;

        /*
         * h/w can accept aggregates up to 16 bit lengths (65535).
         * The IE, however can hold up to 65536, which shows up here
         * as zero. Ignore 65536 since we  are constrained by hw.
         */
        if (tid->an->maxampdu)
                aggr_limit = min(aggr_limit, tid->an->maxampdu);

        return aggr_limit;
}

/*
 * Returns the number of delimiters to be added to
 * meet the minimum required mpdudensity.
 */
static int ath_compute_num_delims(struct ath_softc *sc, struct ath_atx_tid *tid,
                                  struct ath_buf *bf, u16 frmlen,
                                  bool first_subfrm)
{
#define FIRST_DESC_NDELIMS 60
        u32 nsymbits, nsymbols;
        u16 minlen;
        u8 flags, rix;
        int width, streams, half_gi, ndelim, mindelim;
        struct ath_frame_info *fi = get_frame_info(bf->bf_mpdu);

        /* Select standard number of delimiters based on frame length alone */
        ndelim = ATH_AGGR_GET_NDELIM(frmlen);

        /*
         * If encryption enabled, hardware requires some more padding between
         * subframes.
         * TODO - this could be improved to be dependent on the rate.
         *      The hardware can keep up at lower rates, but not higher rates
         */
        if ((fi->keyix != ATH9K_TXKEYIX_INVALID) &&
            !(sc->sc_ah->caps.hw_caps & ATH9K_HW_CAP_EDMA))
                ndelim += ATH_AGGR_ENCRYPTDELIM;

        /*
         * Add delimiter when using RTS/CTS with aggregation
         * and non enterprise AR9003 card
         */
        if (first_subfrm && !AR_SREV_9580_10_OR_LATER(sc->sc_ah) &&
            (sc->sc_ah->ent_mode & AR_ENT_OTP_MIN_PKT_SIZE_DISABLE))
                ndelim = max(ndelim, FIRST_DESC_NDELIMS);

        /*
         * Convert desired mpdu density from microeconds to bytes based
         * on highest rate in rate series (i.e. first rate) to determine
         * required minimum length for subframe. Take into account
         * whether high rate is 20 or 40Mhz and half or full GI.
         *
         * If there is no mpdu density restriction, no further calculation
         * is needed.
         */

        if (tid->an->mpdudensity == 0)
                return ndelim;

        rix = bf->rates[0].idx;
        flags = bf->rates[0].flags;
        width = (flags & IEEE80211_TX_RC_40_MHZ_WIDTH) ? 1 : 0;
        half_gi = (flags & IEEE80211_TX_RC_SHORT_GI) ? 1 : 0;

        if (half_gi)
                nsymbols = NUM_SYMBOLS_PER_USEC_HALFGI(tid->an->mpdudensity);
        else
                nsymbols = NUM_SYMBOLS_PER_USEC(tid->an->mpdudensity);

        if (nsymbols == 0)
                nsymbols = 1;

        streams = HT_RC_2_STREAMS(rix);
        nsymbits = bits_per_symbol[rix % 8][width] * streams;
        minlen = (nsymbols * nsymbits) / BITS_PER_BYTE;

        if (frmlen < minlen) {
                mindelim = (minlen - frmlen) / ATH_AGGR_DELIM_SZ;
                ndelim = max(mindelim, ndelim);
        }

        return ndelim;
}

static struct ath_buf *
ath_tx_get_tid_subframe(struct ath_softc *sc, struct ath_txq *txq,
                        struct ath_atx_tid *tid, struct sk_buff_head **q)
{
        struct ieee80211_tx_info *tx_info;
        struct ath_frame_info *fi;
        struct sk_buff *skb;
        struct ath_buf *bf;
        u16 seqno;

        while (1) {
                *q = &tid->retry_q;
                if (skb_queue_empty(*q))
                        *q = &tid->buf_q;

                skb = skb_peek(*q);
                if (!skb)
                        break;

                fi = get_frame_info(skb);
                bf = fi->bf;
                if (!fi->bf)
                        bf = ath_tx_setup_buffer(sc, txq, tid, skb);
                else
                        bf->bf_state.stale = false;

                if (!bf) {
                        __skb_unlink(skb, *q);
                        ath_txq_skb_done(sc, txq, skb);
                        ieee80211_free_txskb(sc->hw, skb);
                        continue;
                }

                bf->bf_next = NULL;
                bf->bf_lastbf = bf;

                tx_info = IEEE80211_SKB_CB(skb);
                tx_info->flags &= ~IEEE80211_TX_CTL_CLEAR_PS_FILT;
                if (!(tx_info->flags & IEEE80211_TX_CTL_AMPDU)) {
                        bf->bf_state.bf_type = 0;
                        return bf;
                }

                bf->bf_state.bf_type = BUF_AMPDU | BUF_AGGR;
                seqno = bf->bf_state.seqno;

                /* do not step over block-ack window */
                if (!BAW_WITHIN(tid->seq_start, tid->baw_size, seqno))
                        break;

                if (tid->bar_index > ATH_BA_INDEX(tid->seq_start, seqno)) {
                        struct ath_tx_status ts = {};
                        struct list_head bf_head;

                        INIT_LIST_HEAD(&bf_head);
                        list_add(&bf->list, &bf_head);
                        __skb_unlink(skb, *q);
                        ath_tx_update_baw(sc, tid, seqno);
                        ath_tx_complete_buf(sc, bf, txq, &bf_head, &ts, 0);
                        continue;
                }

                return bf;
        }

        return NULL;
}

static bool
ath_tx_form_aggr(struct ath_softc *sc, struct ath_txq *txq,
                 struct ath_atx_tid *tid, struct list_head *bf_q,
                 struct ath_buf *bf_first, struct sk_buff_head *tid_q,
                 int *aggr_len)
{
#define PADBYTES(_len) ((4 - ((_len) % 4)) % 4)
        struct ath_buf *bf = bf_first, *bf_prev = NULL;
        int nframes = 0, ndelim;
        u16 aggr_limit = 0, al = 0, bpad = 0,
            al_delta, h_baw = tid->baw_size / 2;
        struct ieee80211_tx_info *tx_info;
        struct ath_frame_info *fi;
        struct sk_buff *skb;
        bool closed = false;

        bf = bf_first;
        aggr_limit = ath_lookup_rate(sc, bf, tid);

        do {
                skb = bf->bf_mpdu;
                fi = get_frame_info(skb);

                /* do not exceed aggregation limit */
                al_delta = ATH_AGGR_DELIM_SZ + fi->framelen;
                if (nframes) {
                        if (aggr_limit < al + bpad + al_delta ||
                            ath_lookup_legacy(bf) || nframes >= h_baw)
                                break;

                        tx_info = IEEE80211_SKB_CB(bf->bf_mpdu);
                        if ((tx_info->flags & IEEE80211_TX_CTL_RATE_CTRL_PROBE) ||
                            !(tx_info->flags & IEEE80211_TX_CTL_AMPDU))
                                break;
                }

                /* add padding for previous frame to aggregation length */
                al += bpad + al_delta;

                /*
                 * Get the delimiters needed to meet the MPDU
                 * density for this node.
                 */
                ndelim = ath_compute_num_delims(sc, tid, bf_first, fi->framelen,
                                                !nframes);
                bpad = PADBYTES(al_delta) + (ndelim << 2);

                nframes++;
                bf->bf_next = NULL;

                /* link buffers of this frame to the aggregate */
                if (!fi->baw_tracked)
                        ath_tx_addto_baw(sc, tid, bf);
                bf->bf_state.ndelim = ndelim;

                __skb_unlink(skb, tid_q);
                list_add_tail(&bf->list, bf_q);
                if (bf_prev)
                        bf_prev->bf_next = bf;

                bf_prev = bf;

                bf = ath_tx_get_tid_subframe(sc, txq, tid, &tid_q);
                if (!bf) {

                        closed = true;
                        break;
                }
        } while (ath_tid_has_buffered(tid));

        bf = bf_first;
        bf->bf_lastbf = bf_prev;

        if (bf == bf_prev) {
                al = get_frame_info(bf->bf_mpdu)->framelen;
                bf->bf_state.bf_type = BUF_AMPDU;
        } else {
                TX_STAT_INC(txq->axq_qnum, a_aggr);
        }

        *aggr_len = al;

        return closed;
#undef PADBYTES
}

/*
 * rix - rate index
 * pktlen - total bytes (delims + data + fcs + pads + pad delims)
 * width  - 0 for 20 MHz, 1 for 40 MHz
 * half_gi - to use 4us v/s 3.6 us for symbol time
 */
static u32 ath_pkt_duration(struct ath_softc *sc, u8 rix, int pktlen,
                            int width, int half_gi, bool shortPreamble)
{
        u32 nbits, nsymbits, duration, nsymbols;
        int streams;

        /* find number of symbols: PLCP + data */
        streams = HT_RC_2_STREAMS(rix);
        nbits = (pktlen << 3) + OFDM_PLCP_BITS;
        nsymbits = bits_per_symbol[rix % 8][width] * streams;
        nsymbols = (nbits + nsymbits - 1) / nsymbits;

        if (!half_gi)
                duration = SYMBOL_TIME(nsymbols);
        else
                duration = SYMBOL_TIME_HALFGI(nsymbols);

        /* addup duration for legacy/ht training and signal fields */
        duration += L_STF + L_LTF + L_SIG + HT_SIG + HT_STF + HT_LTF(streams);

        return duration;
}

static int ath_max_framelen(int usec, int mcs, bool ht40, bool sgi)
{
        int streams = HT_RC_2_STREAMS(mcs);
        int symbols, bits;
        int bytes = 0;

        symbols = sgi ? TIME_SYMBOLS_HALFGI(usec) : TIME_SYMBOLS(usec);
        bits = symbols * bits_per_symbol[mcs % 8][ht40] * streams;
        bits -= OFDM_PLCP_BITS;
        bytes = bits / 8;
        bytes -= L_STF + L_LTF + L_SIG + HT_SIG + HT_STF + HT_LTF(streams);
        if (bytes > 65532)
                bytes = 65532;

        return bytes;
}

void ath_update_max_aggr_framelen(struct ath_softc *sc, int queue, int txop)
{
        u16 *cur_ht20, *cur_ht20_sgi, *cur_ht40, *cur_ht40_sgi;
        int mcs;

        /* 4ms is the default (and maximum) duration */
        if (!txop || txop > 4096)
                txop = 4096;

        cur_ht20 = sc->tx.max_aggr_framelen[queue][MCS_HT20];
        cur_ht20_sgi = sc->tx.max_aggr_framelen[queue][MCS_HT20_SGI];
        cur_ht40 = sc->tx.max_aggr_framelen[queue][MCS_HT40];
        cur_ht40_sgi = sc->tx.max_aggr_framelen[queue][MCS_HT40_SGI];
        for (mcs = 0; mcs < 32; mcs++) {
                cur_ht20[mcs] = ath_max_framelen(txop, mcs, false, false);
                cur_ht20_sgi[mcs] = ath_max_framelen(txop, mcs, false, true);
                cur_ht40[mcs] = ath_max_framelen(txop, mcs, true, false);
                cur_ht40_sgi[mcs] = ath_max_framelen(txop, mcs, true, true);
        }
}

static void ath_buf_set_rate(struct ath_softc *sc, struct ath_buf *bf,
                             struct ath_tx_info *info, int len, bool rts)
{
        struct ath_hw *ah = sc->sc_ah;
        struct sk_buff *skb;
        struct ieee80211_tx_info *tx_info;
        struct ieee80211_tx_rate *rates;
        const struct ieee80211_rate *rate;
        struct ieee80211_hdr *hdr;
        struct ath_frame_info *fi = get_frame_info(bf->bf_mpdu);
        u32 rts_thresh = sc->hw->wiphy->rts_threshold;
        int i;
        u8 rix = 0;

        skb = bf->bf_mpdu;
        tx_info = IEEE80211_SKB_CB(skb);
        rates = bf->rates;
        hdr = (struct ieee80211_hdr *)skb->data;

        /* set dur_update_en for l-sig computation except for PS-Poll frames */
        info->dur_update = !ieee80211_is_pspoll(hdr->frame_control);
        info->rtscts_rate = fi->rtscts_rate;

        for (i = 0; i < ARRAY_SIZE(bf->rates); i++) {
                bool is_40, is_sgi, is_sp;
                int phy;

                if (!rates[i].count || (rates[i].idx < 0))
                        continue;

                rix = rates[i].idx;
                info->rates[i].Tries = rates[i].count;

                /*
                 * Handle RTS threshold for unaggregated HT frames.
                 */
                if (bf_isampdu(bf) && !bf_isaggr(bf) &&
                    (rates[i].flags & IEEE80211_TX_RC_MCS) &&
                    unlikely(rts_thresh != (u32) -1)) {
                        if (!rts_thresh || (len > rts_thresh))
                                rts = true;
                }

                if (rts || rates[i].flags & IEEE80211_TX_RC_USE_RTS_CTS) {
                        info->rates[i].RateFlags |= ATH9K_RATESERIES_RTS_CTS;
                        info->flags |= ATH9K_TXDESC_RTSENA;
                } else if (rates[i].flags & IEEE80211_TX_RC_USE_CTS_PROTECT) {
                        info->rates[i].RateFlags |= ATH9K_RATESERIES_RTS_CTS;
                        info->flags |= ATH9K_TXDESC_CTSENA;
                }

                if (rates[i].flags & IEEE80211_TX_RC_40_MHZ_WIDTH)
                        info->rates[i].RateFlags |= ATH9K_RATESERIES_2040;
                if (rates[i].flags & IEEE80211_TX_RC_SHORT_GI)
                        info->rates[i].RateFlags |= ATH9K_RATESERIES_HALFGI;

                is_sgi = !!(rates[i].flags & IEEE80211_TX_RC_SHORT_GI);
                is_40 = !!(rates[i].flags & IEEE80211_TX_RC_40_MHZ_WIDTH);
                is_sp = !!(rates[i].flags & IEEE80211_TX_RC_USE_SHORT_PREAMBLE);

                if (rates[i].flags & IEEE80211_TX_RC_MCS) {
                        /* MCS rates */
                        info->rates[i].Rate = rix | 0x80;
                        info->rates[i].ChSel = ath_txchainmask_reduction(sc,
                                        ah->txchainmask, info->rates[i].Rate);
                        info->rates[i].PktDuration = ath_pkt_duration(sc, rix, len,
                                 is_40, is_sgi, is_sp);
                        if (rix < 8 && (tx_info->flags & IEEE80211_TX_CTL_STBC))
                                info->rates[i].RateFlags |= ATH9K_RATESERIES_STBC;
                        continue;
                }

                /* legacy rates */
                rate = &sc->sbands[tx_info->band].bitrates[rates[i].idx];
                if ((tx_info->band == IEEE80211_BAND_2GHZ) &&
                    !(rate->flags & IEEE80211_RATE_ERP_G))
                        phy = WLAN_RC_PHY_CCK;
                else
                        phy = WLAN_RC_PHY_OFDM;

                info->rates[i].Rate = rate->hw_value;
                if (rate->hw_value_short) {
                        if (rates[i].flags & IEEE80211_TX_RC_USE_SHORT_PREAMBLE)
                                info->rates[i].Rate |= rate->hw_value_short;
                } else {
                        is_sp = false;
                }

                if (bf->bf_state.bfs_paprd)
                        info->rates[i].ChSel = ah->txchainmask;
                else
                        info->rates[i].ChSel = ath_txchainmask_reduction(sc,
                                        ah->txchainmask, info->rates[i].Rate);

                info->rates[i].PktDuration = ath9k_hw_computetxtime(sc->sc_ah,
                        phy, rate->bitrate * 100, len, rix, is_sp);
        }

        /* For AR5416 - RTS cannot be followed by a frame larger than 8K */
        if (bf_isaggr(bf) && (len > sc->sc_ah->caps.rts_aggr_limit))
                info->flags &= ~ATH9K_TXDESC_RTSENA;

        /* ATH9K_TXDESC_RTSENA and ATH9K_TXDESC_CTSENA are mutually exclusive. */
        if (info->flags & ATH9K_TXDESC_RTSENA)
                info->flags &= ~ATH9K_TXDESC_CTSENA;
}

static enum ath9k_pkt_type get_hw_packet_type(struct sk_buff *skb)
{
        struct ieee80211_hdr *hdr;
        enum ath9k_pkt_type htype;
        __le16 fc;

        hdr = (struct ieee80211_hdr *)skb->data;
        fc = hdr->frame_control;

        if (ieee80211_is_beacon(fc))
                htype = ATH9K_PKT_TYPE_BEACON;
        else if (ieee80211_is_probe_resp(fc))
                htype = ATH9K_PKT_TYPE_PROBE_RESP;
        else if (ieee80211_is_atim(fc))
                htype = ATH9K_PKT_TYPE_ATIM;
        else if (ieee80211_is_pspoll(fc))
                htype = ATH9K_PKT_TYPE_PSPOLL;
        else
                htype = ATH9K_PKT_TYPE_NORMAL;

        return htype;
}

static void ath_tx_fill_desc(struct ath_softc *sc, struct ath_buf *bf,
                             struct ath_txq *txq, int len)
{
        struct ath_hw *ah = sc->sc_ah;
        struct ath_buf *bf_first = NULL;
        struct ath_tx_info info;
        u32 rts_thresh = sc->hw->wiphy->rts_threshold;
        bool rts = false;

        memset(&info, 0, sizeof(info));
        info.is_first = true;
        info.is_last = true;
        info.txpower = MAX_RATE_POWER;
        info.qcu = txq->axq_qnum;

        while (bf) {
                struct sk_buff *skb = bf->bf_mpdu;
                struct ieee80211_tx_info *tx_info = IEEE80211_SKB_CB(skb);
                struct ath_frame_info *fi = get_frame_info(skb);
                bool aggr = !!(bf->bf_state.bf_type & BUF_AGGR);

                info.type = get_hw_packet_type(skb);
                if (bf->bf_next)
                        info.link = bf->bf_next->bf_daddr;
                else
                        info.link = 0;

                if (!bf_first) {
                        bf_first = bf;

                        info.flags = ATH9K_TXDESC_INTREQ;
                        if ((tx_info->flags & IEEE80211_TX_CTL_CLEAR_PS_FILT) ||
                            txq == sc->tx.uapsdq)
                                info.flags |= ATH9K_TXDESC_CLRDMASK;

                        if (tx_info->flags & IEEE80211_TX_CTL_NO_ACK)
                                info.flags |= ATH9K_TXDESC_NOACK;
                        if (tx_info->flags & IEEE80211_TX_CTL_LDPC)
                                info.flags |= ATH9K_TXDESC_LDPC;

                        if (bf->bf_state.bfs_paprd)
                                info.flags |= (u32) bf->bf_state.bfs_paprd <<
                                              ATH9K_TXDESC_PAPRD_S;

                        /*
                         * mac80211 doesn't handle RTS threshold for HT because
                         * the decision has to be taken based on AMPDU length
                         * and aggregation is done entirely inside ath9k.
                         * Set the RTS/CTS flag for the first subframe based
                         * on the threshold.
                         */
                        if (aggr && (bf == bf_first) &&
                            unlikely(rts_thresh != (u32) -1)) {
                                /*
                                 * "len" is the size of the entire AMPDU.
                                 */
                                if (!rts_thresh || (len > rts_thresh))
                                        rts = true;
                        }
                        ath_buf_set_rate(sc, bf, &info, len, rts);
                }

                info.buf_addr[0] = bf->bf_buf_addr;
                info.buf_len[0] = skb->len;
                info.pkt_len = fi->framelen;
                info.keyix = fi->keyix;
                info.keytype = fi->keytype;

                if (aggr) {
                        if (bf == bf_first)
                                info.aggr = AGGR_BUF_FIRST;
                        else if (bf == bf_first->bf_lastbf)
                                info.aggr = AGGR_BUF_LAST;
                        else
                                info.aggr = AGGR_BUF_MIDDLE;

                        info.ndelim = bf->bf_state.ndelim;
                        info.aggr_len = len;
                }

                if (bf == bf_first->bf_lastbf)
                        bf_first = NULL;

                ath9k_hw_set_txdesc(ah, bf->bf_desc, &info);
                bf = bf->bf_next;
        }
}

static void
ath_tx_form_burst(struct ath_softc *sc, struct ath_txq *txq,
                  struct ath_atx_tid *tid, struct list_head *bf_q,
                  struct ath_buf *bf_first, struct sk_buff_head *tid_q)
{
        struct ath_buf *bf = bf_first, *bf_prev = NULL;
        struct sk_buff *skb;
        int nframes = 0;

        do {
                struct ieee80211_tx_info *tx_info;
                skb = bf->bf_mpdu;

                nframes++;
                __skb_unlink(skb, tid_q);
                list_add_tail(&bf->list, bf_q);
                if (bf_prev)
                        bf_prev->bf_next = bf;
                bf_prev = bf;

                if (nframes >= 2)
                        break;

                bf = ath_tx_get_tid_subframe(sc, txq, tid, &tid_q);
                if (!bf)
                        break;

                tx_info = IEEE80211_SKB_CB(bf->bf_mpdu);
                if (tx_info->flags & IEEE80211_TX_CTL_AMPDU)
                        break;

                ath_set_rates(tid->an->vif, tid->an->sta, bf);
        } while (1);
}

static bool ath_tx_sched_aggr(struct ath_softc *sc, struct ath_txq *txq,
                              struct ath_atx_tid *tid, bool *stop)
{
        struct ath_buf *bf;
        struct ieee80211_tx_info *tx_info;
        struct sk_buff_head *tid_q;
        struct list_head bf_q;
        int aggr_len = 0;
        bool aggr, last = true;

        if (!ath_tid_has_buffered(tid))
                return false;

        INIT_LIST_HEAD(&bf_q);

        bf = ath_tx_get_tid_subframe(sc, txq, tid, &tid_q);
        if (!bf)
                return false;

        tx_info = IEEE80211_SKB_CB(bf->bf_mpdu);
        aggr = !!(tx_info->flags & IEEE80211_TX_CTL_AMPDU);
        if ((aggr && txq->axq_ampdu_depth >= ATH_AGGR_MIN_QDEPTH) ||
                (!aggr && txq->axq_depth >= ATH_NON_AGGR_MIN_QDEPTH)) {
                *stop = true;
                return false;
        }

        ath_set_rates(tid->an->vif, tid->an->sta, bf);
        if (aggr)
                last = ath_tx_form_aggr(sc, txq, tid, &bf_q, bf,
                                        tid_q, &aggr_len);
        else
                ath_tx_form_burst(sc, txq, tid, &bf_q, bf, tid_q);

        if (list_empty(&bf_q))
                return false;

        if (tid->ac->clear_ps_filter || tid->an->no_ps_filter) {
                tid->ac->clear_ps_filter = false;
                tx_info->flags |= IEEE80211_TX_CTL_CLEAR_PS_FILT;
        }

        ath_tx_fill_desc(sc, bf, txq, aggr_len);
        ath_tx_txqaddbuf(sc, txq, &bf_q, false);
        return true;
}

int ath_tx_aggr_start(struct ath_softc *sc, struct ieee80211_sta *sta,
                      u16 tid, u16 *ssn)
{
        struct ath_atx_tid *txtid;
        struct ath_txq *txq;
        struct ath_node *an;
        u8 density;

        an = (struct ath_node *)sta->drv_priv;
        txtid = ATH_AN_2_TID(an, tid);
        txq = txtid->ac->txq;

        ath_txq_lock(sc, txq);

        /* update ampdu factor/density, they may have changed. This may happen
         * in HT IBSS when a beacon with HT-info is received after the station
         * has already been added.
         */
        if (sta->ht_cap.ht_supported) {
                an->maxampdu = 1 << (IEEE80211_HT_MAX_AMPDU_FACTOR +
                                     sta->ht_cap.ampdu_factor);
                density = ath9k_parse_mpdudensity(sta->ht_cap.ampdu_density);
                an->mpdudensity = density;
        }

        /* force sequence number allocation for pending frames */
        ath_tx_tid_change_state(sc, txtid);

        txtid->active = true;
        txtid->paused = true;
        *ssn = txtid->seq_start = txtid->seq_next;
        txtid->bar_index = -1;

        memset(txtid->tx_buf, 0, sizeof(txtid->tx_buf));
        txtid->baw_head = txtid->baw_tail = 0;

        ath_txq_unlock_complete(sc, txq);

        return 0;
}

void ath_tx_aggr_stop(struct ath_softc *sc, struct ieee80211_sta *sta, u16 tid)
{
        struct ath_node *an = (struct ath_node *)sta->drv_priv;
        struct ath_atx_tid *txtid = ATH_AN_2_TID(an, tid);
        struct ath_txq *txq = txtid->ac->txq;

        ath_txq_lock(sc, txq);
        txtid->active = false;
        txtid->paused = false;
        ath_tx_flush_tid(sc, txtid);
        ath_tx_tid_change_state(sc, txtid);
        ath_txq_unlock_complete(sc, txq);
}

void ath_tx_aggr_sleep(struct ieee80211_sta *sta, struct ath_softc *sc,
                       struct ath_node *an)
{
        struct ath_atx_tid *tid;
        struct ath_atx_ac *ac;
        struct ath_txq *txq;
        bool buffered;
        int tidno;

        for (tidno = 0, tid = &an->tid[tidno];
             tidno < IEEE80211_NUM_TIDS; tidno++, tid++) {

                if (!tid->sched)
                        continue;

                ac = tid->ac;
                txq = ac->txq;

                ath_txq_lock(sc, txq);

                buffered = ath_tid_has_buffered(tid);

                tid->sched = false;
                list_del(&tid->list);

                if (ac->sched) {
                        ac->sched = false;
                        list_del(&ac->list);
                }

                ath_txq_unlock(sc, txq);

                ieee80211_sta_set_buffered(sta, tidno, buffered);
        }
}

void ath_tx_aggr_wakeup(struct ath_softc *sc, struct ath_node *an)
{
        struct ath_atx_tid *tid;
        struct ath_atx_ac *ac;
        struct ath_txq *txq;
        int tidno;

        for (tidno = 0, tid = &an->tid[tidno];
             tidno < IEEE80211_NUM_TIDS; tidno++, tid++) {

                ac = tid->ac;
                txq = ac->txq;

                ath_txq_lock(sc, txq);
                ac->clear_ps_filter = true;

                if (!tid->paused && ath_tid_has_buffered(tid)) {
                        ath_tx_queue_tid(txq, tid);
                        ath_txq_schedule(sc, txq);
                }

                ath_txq_unlock_complete(sc, txq);
        }
}

void ath_tx_aggr_resume(struct ath_softc *sc, struct ieee80211_sta *sta,
                        u16 tidno)
{
        struct ath_atx_tid *tid;
        struct ath_node *an;
        struct ath_txq *txq;

        an = (struct ath_node *)sta->drv_priv;
        tid = ATH_AN_2_TID(an, tidno);
        txq = tid->ac->txq;

        ath_txq_lock(sc, txq);

        tid->baw_size = IEEE80211_MIN_AMPDU_BUF << sta->ht_cap.ampdu_factor;
        tid->paused = false;

        if (ath_tid_has_buffered(tid)) {
                ath_tx_queue_tid(txq, tid);
                ath_txq_schedule(sc, txq);
        }

        ath_txq_unlock_complete(sc, txq);
}

void ath9k_release_buffered_frames(struct ieee80211_hw *hw,
                                   struct ieee80211_sta *sta,
                                   u16 tids, int nframes,
                                   enum ieee80211_frame_release_type reason,
                                   bool more_data)
{
        struct ath_softc *sc = hw->priv;
        struct ath_node *an = (struct ath_node *)sta->drv_priv;
        struct ath_txq *txq = sc->tx.uapsdq;
        struct ieee80211_tx_info *info;
        struct list_head bf_q;
        struct ath_buf *bf_tail = NULL, *bf;
        struct sk_buff_head *tid_q;
        int sent = 0;
        int i;

        INIT_LIST_HEAD(&bf_q);
        for (i = 0; tids && nframes; i++, tids >>= 1) {
                struct ath_atx_tid *tid;

                if (!(tids & 1))
                        continue;

                tid = ATH_AN_2_TID(an, i);
                if (tid->paused)
                        continue;

                ath_txq_lock(sc, tid->ac->txq);
                while (nframes > 0) {
                        bf = ath_tx_get_tid_subframe(sc, sc->tx.uapsdq, tid, &tid_q);
                        if (!bf)
                                break;

                        __skb_unlink(bf->bf_mpdu, tid_q);
                        list_add_tail(&bf->list, &bf_q);
                        ath_set_rates(tid->an->vif, tid->an->sta, bf);
                        if (bf_isampdu(bf)) {
                                ath_tx_addto_baw(sc, tid, bf);
                                bf->bf_state.bf_type &= ~BUF_AGGR;
                        }
                        if (bf_tail)
                                bf_tail->bf_next = bf;

                        bf_tail = bf;
                        nframes--;
                        sent++;
                        TX_STAT_INC(txq->axq_qnum, a_queued_hw);

                        if (an->sta && !ath_tid_has_buffered(tid))
                                ieee80211_sta_set_buffered(an->sta, i, false);
                }
                ath_txq_unlock_complete(sc, tid->ac->txq);
        }

        if (list_empty(&bf_q))
                return;

        info = IEEE80211_SKB_CB(bf_tail->bf_mpdu);
        info->flags |= IEEE80211_TX_STATUS_EOSP;

        bf = list_first_entry(&bf_q, struct ath_buf, list);
        ath_txq_lock(sc, txq);
        ath_tx_fill_desc(sc, bf, txq, 0);
        ath_tx_txqaddbuf(sc, txq, &bf_q, false);
        ath_txq_unlock(sc, txq);
}

/********************/
/* Queue Management */
/********************/

struct ath_txq *ath_txq_setup(struct ath_softc *sc, int qtype, int subtype)
{
        struct ath_hw *ah = sc->sc_ah;
        struct ath9k_tx_queue_info qi;
        static const int subtype_txq_to_hwq[] = {
                [IEEE80211_AC_BE] = ATH_TXQ_AC_BE,
                [IEEE80211_AC_BK] = ATH_TXQ_AC_BK,
                [IEEE80211_AC_VI] = ATH_TXQ_AC_VI,
                [IEEE80211_AC_VO] = ATH_TXQ_AC_VO,
        };
        int axq_qnum, i;

        memset(&qi, 0, sizeof(qi));
        qi.tqi_subtype = subtype_txq_to_hwq[subtype];
        qi.tqi_aifs = ATH9K_TXQ_USEDEFAULT;
        qi.tqi_cwmin = ATH9K_TXQ_USEDEFAULT;
        qi.tqi_cwmax = ATH9K_TXQ_USEDEFAULT;
        qi.tqi_physCompBuf = 0;

        /*
         * Enable interrupts only for EOL and DESC conditions.
         * We mark tx descriptors to receive a DESC interrupt
         * when a tx queue gets deep; otherwise waiting for the
         * EOL to reap descriptors.  Note that this is done to
         * reduce interrupt load and this only defers reaping
         * descriptors, never transmitting frames.  Aside from
         * reducing interrupts this also permits more concurrency.
         * The only potential downside is if the tx queue backs
         * up in which case the top half of the kernel may backup
         * due to a lack of tx descriptors.
         *
         * The UAPSD queue is an exception, since we take a desc-
         * based intr on the EOSP frames.
         */
        if (ah->caps.hw_caps & ATH9K_HW_CAP_EDMA) {
                qi.tqi_qflags = TXQ_FLAG_TXINT_ENABLE;
        } else {
                if (qtype == ATH9K_TX_QUEUE_UAPSD)
                        qi.tqi_qflags = TXQ_FLAG_TXDESCINT_ENABLE;
                else
                        qi.tqi_qflags = TXQ_FLAG_TXEOLINT_ENABLE |
                                        TXQ_FLAG_TXDESCINT_ENABLE;
        }
        axq_qnum = ath9k_hw_setuptxqueue(ah, qtype, &qi);
        if (axq_qnum == -1) {
                /*
                 * NB: don't print a message, this happens
                 * normally on parts with too few tx queues
                 */
                return NULL;
        }
        if (!ATH_TXQ_SETUP(sc, axq_qnum)) {
                struct ath_txq *txq = &sc->tx.txq[axq_qnum];

                txq->axq_qnum = axq_qnum;
                txq->mac80211_qnum = -1;
                txq->axq_link = NULL;
                __skb_queue_head_init(&txq->complete_q);
                INIT_LIST_HEAD(&txq->axq_q);
                INIT_LIST_HEAD(&txq->axq_acq);
                spin_lock_init(&txq->axq_lock);
                txq->axq_depth = 0;
                txq->axq_ampdu_depth = 0;
                txq->axq_tx_inprogress = false;
                sc->tx.txqsetup |= 1<<axq_qnum;

                txq->txq_headidx = txq->txq_tailidx = 0;
                for (i = 0; i < ATH_TXFIFO_DEPTH; i++)
                        INIT_LIST_HEAD(&txq->txq_fifo[i]);
        }
        return &sc->tx.txq[axq_qnum];
}

int ath_txq_update(struct ath_softc *sc, int qnum,
                   struct ath9k_tx_queue_info *qinfo)
{
        struct ath_hw *ah = sc->sc_ah;
        int error = 0;
        struct ath9k_tx_queue_info qi;

        BUG_ON(sc->tx.txq[qnum].axq_qnum != qnum);

        ath9k_hw_get_txq_props(ah, qnum, &qi);
        qi.tqi_aifs = qinfo->tqi_aifs;
        qi.tqi_cwmin = qinfo->tqi_cwmin;
        qi.tqi_cwmax = qinfo->tqi_cwmax;
        qi.tqi_burstTime = qinfo->tqi_burstTime;
        qi.tqi_readyTime = qinfo->tqi_readyTime;

        if (!ath9k_hw_set_txq_props(ah, qnum, &qi)) {
                ath_err(ath9k_hw_common(sc->sc_ah),
                        "Unable to update hardware queue %u!\n", qnum);
                error = -EIO;
        } else {
                ath9k_hw_resettxqueue(ah, qnum);
        }

        return error;
}

int ath_cabq_update(struct ath_softc *sc)
{
        struct ath9k_tx_queue_info qi;
        struct ath_beacon_config *cur_conf = &sc->cur_beacon_conf;
        int qnum = sc->beacon.cabq->axq_qnum;

        ath9k_hw_get_txq_props(sc->sc_ah, qnum, &qi);
        /*
         * Ensure the readytime % is within the bounds.
         */
        if (sc->config.cabqReadytime < ATH9K_READY_TIME_LO_BOUND)
                sc->config.cabqReadytime = ATH9K_READY_TIME_LO_BOUND;
        else if (sc->config.cabqReadytime > ATH9K_READY_TIME_HI_BOUND)
                sc->config.cabqReadytime = ATH9K_READY_TIME_HI_BOUND;

        qi.tqi_readyTime = (cur_conf->beacon_interval *
                            sc->config.cabqReadytime) / 100;
        ath_txq_update(sc, qnum, &qi);

        return 0;
}

static void ath_drain_txq_list(struct ath_softc *sc, struct ath_txq *txq,
                               struct list_head *list)
{
        struct ath_buf *bf, *lastbf;
        struct list_head bf_head;
        struct ath_tx_status ts;

        memset(&ts, 0, sizeof(ts));
        ts.ts_status = ATH9K_TX_FLUSH;
        INIT_LIST_HEAD(&bf_head);

        while (!list_empty(list)) {
                bf = list_first_entry(list, struct ath_buf, list);

                if (bf->bf_state.stale) {
                        list_del(&bf->list);

                        ath_tx_return_buffer(sc, bf);
                        continue;
                }

                lastbf = bf->bf_lastbf;
                list_cut_position(&bf_head, list, &lastbf->list);
                ath_tx_process_buffer(sc, txq, &ts, bf, &bf_head);
        }
}

/*
 * Drain a given TX queue (could be Beacon or Data)
 *
 * This assumes output has been stopped and
 * we do not need to block ath_tx_tasklet.
 */
void ath_draintxq(struct ath_softc *sc, struct ath_txq *txq)
{
        ath_txq_lock(sc, txq);

        if (sc->sc_ah->caps.hw_caps & ATH9K_HW_CAP_EDMA) {
                int idx = txq->txq_tailidx;

                while (!list_empty(&txq->txq_fifo[idx])) {
                        ath_drain_txq_list(sc, txq, &txq->txq_fifo[idx]);

                        INCR(idx, ATH_TXFIFO_DEPTH);
                }
                txq->txq_tailidx = idx;
        }

        txq->axq_link = NULL;
        txq->axq_tx_inprogress = false;
        ath_drain_txq_list(sc, txq, &txq->axq_q);

        ath_txq_unlock_complete(sc, txq);
}

bool ath_drain_all_txq(struct ath_softc *sc)
{
        struct ath_hw *ah = sc->sc_ah;
        struct ath_common *common = ath9k_hw_common(sc->sc_ah);
        struct ath_txq *txq;
        int i;
        u32 npend = 0;

        if (test_bit(SC_OP_INVALID, &sc->sc_flags))
                return true;

        ath9k_hw_abort_tx_dma(ah);

        /* Check if any queue remains active */
        for (i = 0; i < ATH9K_NUM_TX_QUEUES; i++) {
                if (!ATH_TXQ_SETUP(sc, i))
                        continue;

                if (ath9k_hw_numtxpending(ah, sc->tx.txq[i].axq_qnum))
                        npend |= BIT(i);
        }

        if (npend)
                ath_err(common, "Failed to stop TX DMA, queues=0x%03x!\n", npend);

        for (i = 0; i < ATH9K_NUM_TX_QUEUES; i++) {
                if (!ATH_TXQ_SETUP(sc, i))
                        continue;

                /*
                 * The caller will resume queues with ieee80211_wake_queues.
                 * Mark the queue as not stopped to prevent ath_tx_complete
                 * from waking the queue too early.
                 */
                txq = &sc->tx.txq[i];
                txq->stopped = false;
                ath_draintxq(sc, txq);
        }

        return !npend;
}

void ath_tx_cleanupq(struct ath_softc *sc, struct ath_txq *txq)
{
        ath9k_hw_releasetxqueue(sc->sc_ah, txq->axq_qnum);
        sc->tx.txqsetup &= ~(1<<txq->axq_qnum);
}

/* For each axq_acq entry, for each tid, try to schedule packets
 * for transmit until ampdu_depth has reached min Q depth.
 */
void ath_txq_schedule(struct ath_softc *sc, struct ath_txq *txq)
{
        struct ath_atx_ac *ac, *last_ac;
        struct ath_atx_tid *tid, *last_tid;
        bool sent = false;

        if (test_bit(SC_OP_HW_RESET, &sc->sc_flags) ||
            list_empty(&txq->axq_acq))
                return;

        rcu_read_lock();

        last_ac = list_entry(txq->axq_acq.prev, struct ath_atx_ac, list);
        while (!list_empty(&txq->axq_acq)) {
                bool stop = false;

                ac = list_first_entry(&txq->axq_acq, struct ath_atx_ac, list);
                last_tid = list_entry(ac->tid_q.prev, struct ath_atx_tid, list);
                list_del(&ac->list);
                ac->sched = false;

                while (!list_empty(&ac->tid_q)) {

                        tid = list_first_entry(&ac->tid_q, struct ath_atx_tid,
                                               list);
                        list_del(&tid->list);
                        tid->sched = false;

                        if (tid->paused)
                                continue;

                        if (ath_tx_sched_aggr(sc, txq, tid, &stop))
                                sent = true;

                        /*
                         * add tid to round-robin queue if more frames
                         * are pending for the tid
                         */
                        if (ath_tid_has_buffered(tid))
                                ath_tx_queue_tid(txq, tid);

                        if (stop || tid == last_tid)
                                break;
                }

                if (!list_empty(&ac->tid_q) && !ac->sched) {
                        ac->sched = true;
                        list_add_tail(&ac->list, &txq->axq_acq);
                }

                if (stop)
                        break;

                if (ac == last_ac) {
                        if (!sent)
                                break;

                        sent = false;
                        last_ac = list_entry(txq->axq_acq.prev,
                                             struct ath_atx_ac, list);
                }
        }

        rcu_read_unlock();
}

/***********/
/* TX, DMA */
/***********/

/*
 * Insert a chain of ath_buf (descriptors) on a txq and
 * assume the descriptors are already chained together by caller.
 */
static void ath_tx_txqaddbuf(struct ath_softc *sc, struct ath_txq *txq,
                             struct list_head *head, bool internal)
{
        struct ath_hw *ah = sc->sc_ah;
        struct ath_common *common = ath9k_hw_common(ah);
        struct ath_buf *bf, *bf_last;
        bool puttxbuf = false;
        bool edma;

        /*
         * Insert the frame on the outbound list and
         * pass it on to the hardware.
         */

        if (list_empty(head))
                return;

        edma = !!(ah->caps.hw_caps & ATH9K_HW_CAP_EDMA);
        bf = list_first_entry(head, struct ath_buf, list);
        bf_last = list_entry(head->prev, struct ath_buf, list);

        ath_dbg(common, QUEUE, "qnum: %d, txq depth: %d\n",
                txq->axq_qnum, txq->axq_depth);

        if (edma && list_empty(&txq->txq_fifo[txq->txq_headidx])) {
                list_splice_tail_init(head, &txq->txq_fifo[txq->txq_headidx]);
                INCR(txq->txq_headidx, ATH_TXFIFO_DEPTH);
                puttxbuf = true;
        } else {
                list_splice_tail_init(head, &txq->axq_q);

                if (txq->axq_link) {
                        ath9k_hw_set_desc_link(ah, txq->axq_link, bf->bf_daddr);
                        ath_dbg(common, XMIT, "link[%u] (%p)=%llx (%p)\n",
                                txq->axq_qnum, txq->axq_link,
                                ito64(bf->bf_daddr), bf->bf_desc);
                } else if (!edma)
                        puttxbuf = true;

                txq->axq_link = bf_last->bf_desc;
        }

        if (puttxbuf) {
                TX_STAT_INC(txq->axq_qnum, puttxbuf);
                ath9k_hw_puttxbuf(ah, txq->axq_qnum, bf->bf_daddr);
                ath_dbg(common, XMIT, "TXDP[%u] = %llx (%p)\n",
                        txq->axq_qnum, ito64(bf->bf_daddr), bf->bf_desc);
        }

        if (!edma) {
                TX_STAT_INC(txq->axq_qnum, txstart);
                ath9k_hw_txstart(ah, txq->axq_qnum);
        }

        if (!internal) {
                while (bf) {
                        txq->axq_depth++;
                        if (bf_is_ampdu_not_probing(bf))
                                txq->axq_ampdu_depth++;

                        bf_last = bf->bf_lastbf;
                        bf = bf_last->bf_next;
                        bf_last->bf_next = NULL;
                }
        }
}

static void ath_tx_send_normal(struct ath_softc *sc, struct ath_txq *txq,
                               struct ath_atx_tid *tid, struct sk_buff *skb)
{
        struct ieee80211_tx_info *tx_info = IEEE80211_SKB_CB(skb);
        struct ath_frame_info *fi = get_frame_info(skb);
        struct list_head bf_head;
        struct ath_buf *bf = fi->bf;

        INIT_LIST_HEAD(&bf_head);
        list_add_tail(&bf->list, &bf_head);
        bf->bf_state.bf_type = 0;
        if (tid && (tx_info->flags & IEEE80211_TX_CTL_AMPDU)) {
                bf->bf_state.bf_type = BUF_AMPDU;
                ath_tx_addto_baw(sc, tid, bf);
        }

        bf->bf_next = NULL;
        bf->bf_lastbf = bf;
        ath_tx_fill_desc(sc, bf, txq, fi->framelen);
        ath_tx_txqaddbuf(sc, txq, &bf_head, false);
        TX_STAT_INC(txq->axq_qnum, queued);
}

static void setup_frame_info(struct ieee80211_hw *hw,
                             struct ieee80211_sta *sta,
                             struct sk_buff *skb,
                             int framelen)
{
        struct ieee80211_tx_info *tx_info = IEEE80211_SKB_CB(skb);
        struct ieee80211_key_conf *hw_key = tx_info->control.hw_key;
        struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
        const struct ieee80211_rate *rate;

        struct ath_frame_info *fi = get_frame_info(skb);
        struct ath_node *an = NULL;
        enum ath9k_key_type keytype;
        bool short_preamble = false;

        /*
         * We check if Short Preamble is needed for the CTS rate by
         * checking the BSS's global flag.
         * But for the rate series, IEEE80211_TX_RC_USE_SHORT_PREAMBLE is used.
         */
        if (tx_info->control.vif &&
            tx_info->control.vif->bss_conf.use_short_preamble)
                short_preamble = true;

        rate = ieee80211_get_rts_cts_rate(hw, tx_info);
        keytype = ath9k_cmn_get_hw_crypto_keytype(skb);

        if (sta)
                an = (struct ath_node *) sta->drv_priv;

        memset(fi, 0, sizeof(*fi));
        if (hw_key)
                fi->keyix = hw_key->hw_key_idx;
        else if (an && ieee80211_is_data(hdr->frame_control) && an->ps_key > 0)
                fi->keyix = an->ps_key;
        else
                fi->keyix = ATH9K_TXKEYIX_INVALID;
        fi->keytype = keytype;
        fi->framelen = framelen;
        fi->rtscts_rate = rate->hw_value;
        if (short_preamble)
                fi->rtscts_rate |= rate->hw_value_short;
}

u8 ath_txchainmask_reduction(struct ath_softc *sc, u8 chainmask, u32 rate)
{
        struct ath_hw *ah = sc->sc_ah;
        struct ath9k_channel *curchan = ah->curchan;

        if ((ah->caps.hw_caps & ATH9K_HW_CAP_APM) &&
            (curchan->channelFlags & CHANNEL_5GHZ) &&
            (chainmask == 0x7) && (rate < 0x90))
                return 0x3;
        else if (AR_SREV_9462(ah) && ath9k_hw_btcoex_is_enabled(ah) &&
                 IS_CCK_RATE(rate))
                return 0x2;
        else
                return chainmask;
}

/*
 * Assign a descriptor (and sequence number if necessary,
 * and map buffer for DMA. Frees skb on error
 */
static struct ath_buf *ath_tx_setup_buffer(struct ath_softc *sc,
                                           struct ath_txq *txq,
                                           struct ath_atx_tid *tid,
                                           struct sk_buff *skb)
{
        struct ath_common *common = ath9k_hw_common(sc->sc_ah);
        struct ath_frame_info *fi = get_frame_info(skb);
        struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
        struct ath_buf *bf;
        int fragno;
        u16 seqno;

        bf = ath_tx_get_buffer(sc);
        if (!bf) {
                ath_dbg(common, XMIT, "TX buffers are full\n");
                return NULL;
        }

        ATH_TXBUF_RESET(bf);

        if (tid) {
                fragno = le16_to_cpu(hdr->seq_ctrl) & IEEE80211_SCTL_FRAG;
                seqno = tid->seq_next;
                hdr->seq_ctrl = cpu_to_le16(tid->seq_next << IEEE80211_SEQ_SEQ_SHIFT);

                if (fragno)
                        hdr->seq_ctrl |= cpu_to_le16(fragno);

                if (!ieee80211_has_morefrags(hdr->frame_control))
                        INCR(tid->seq_next, IEEE80211_SEQ_MAX);

                bf->bf_state.seqno = seqno;
        }

        bf->bf_mpdu = skb;

        bf->bf_buf_addr = dma_map_single(sc->dev, skb->data,
                                         skb->len, DMA_TO_DEVICE);
        if (unlikely(dma_mapping_error(sc->dev, bf->bf_buf_addr))) {
                bf->bf_mpdu = NULL;
                bf->bf_buf_addr = 0;
                ath_err(ath9k_hw_common(sc->sc_ah),
                        "dma_mapping_error() on TX\n");
                ath_tx_return_buffer(sc, bf);
                return NULL;
        }

        fi->bf = bf;

        return bf;
}

static int ath_tx_prepare(struct ieee80211_hw *hw, struct sk_buff *skb,
                          struct ath_tx_control *txctl)
{
        struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
        struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
        struct ieee80211_sta *sta = txctl->sta;
        struct ieee80211_vif *vif = info->control.vif;
        struct ath_vif *avp;
        struct ath_softc *sc = hw->priv;
        int frmlen = skb->len + FCS_LEN;
        int padpos, padsize;

        /* NOTE:  sta can be NULL according to net/mac80211.h */
        if (sta)
                txctl->an = (struct ath_node *)sta->drv_priv;
        else if (vif && ieee80211_is_data(hdr->frame_control)) {
                avp = (void *)vif->drv_priv;
                txctl->an = &avp->mcast_node;
        }

        if (info->control.hw_key)
                frmlen += info->control.hw_key->icv_len;

        /*
         * As a temporary workaround, assign seq# here; this will likely need
         * to be cleaned up to work better with Beacon transmission and virtual
         * BSSes.
         */
        if (info->flags & IEEE80211_TX_CTL_ASSIGN_SEQ) {
                if (info->flags & IEEE80211_TX_CTL_FIRST_FRAGMENT)
                        sc->tx.seq_no += 0x10;
                hdr->seq_ctrl &= cpu_to_le16(IEEE80211_SCTL_FRAG);
                hdr->seq_ctrl |= cpu_to_le16(sc->tx.seq_no);
        }

        if ((vif && vif->type != NL80211_IFTYPE_AP &&
                    vif->type != NL80211_IFTYPE_AP_VLAN) ||
            !ieee80211_is_data(hdr->frame_control))
                info->flags |= IEEE80211_TX_CTL_CLEAR_PS_FILT;

        /* Add the padding after the header if this is not already done */
        padpos = ieee80211_hdrlen(hdr->frame_control);
        padsize = padpos & 3;
        if (padsize && skb->len > padpos) {
                if (skb_headroom(skb) < padsize)
                        return -ENOMEM;

                skb_push(skb, padsize);
                memmove(skb->data, skb->data + padsize, padpos);
        }

        setup_frame_info(hw, sta, skb, frmlen);
        return 0;
}


/* Upon failure caller should free skb */
int ath_tx_start(struct ieee80211_hw *hw, struct sk_buff *skb,
                 struct ath_tx_control *txctl)
{
        struct ieee80211_hdr *hdr;
        struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
        struct ieee80211_sta *sta = txctl->sta;
        struct ieee80211_vif *vif = info->control.vif;
        struct ath_softc *sc = hw->priv;
        struct ath_txq *txq = txctl->txq;
        struct ath_atx_tid *tid = NULL;
        struct ath_buf *bf;
        int q;
        int ret;

        ret = ath_tx_prepare(hw, skb, txctl);
        if (ret)
            return ret;

        hdr = (struct ieee80211_hdr *) skb->data;
        /*
         * At this point, the vif, hw_key and sta pointers in the tx control
         * info are no longer valid (overwritten by the ath_frame_info data.
         */

        q = skb_get_queue_mapping(skb);

        ath_txq_lock(sc, txq);
        if (txq == sc->tx.txq_map[q] &&
            ++txq->pending_frames > sc->tx.txq_max_pending[q] &&
            !txq->stopped) {
                ieee80211_stop_queue(sc->hw, q);
                txq->stopped = true;
        }

        if (info->flags & IEEE80211_TX_CTL_PS_RESPONSE) {
                ath_txq_unlock(sc, txq);
                txq = sc->tx.uapsdq;
                ath_txq_lock(sc, txq);
        } else if (txctl->an &&
                   ieee80211_is_data_present(hdr->frame_control)) {
                tid = ath_get_skb_tid(sc, txctl->an, skb);

                WARN_ON(tid->ac->txq != txctl->txq);

                if (info->flags & IEEE80211_TX_CTL_CLEAR_PS_FILT)
                        tid->ac->clear_ps_filter = true;

                /*
                 * Add this frame to software queue for scheduling later
                 * for aggregation.
                 */
                TX_STAT_INC(txq->axq_qnum, a_queued_sw);
                __skb_queue_tail(&tid->buf_q, skb);
                if (!txctl->an->sleeping)
                        ath_tx_queue_tid(txq, tid);

                ath_txq_schedule(sc, txq);
                goto out;
        }

        bf = ath_tx_setup_buffer(sc, txq, tid, skb);
        if (!bf) {
                ath_txq_skb_done(sc, txq, skb);
                if (txctl->paprd)
                        dev_kfree_skb_any(skb);
                else
                        ieee80211_free_txskb(sc->hw, skb);
                goto out;
        }

        bf->bf_state.bfs_paprd = txctl->paprd;

        if (txctl->paprd)
                bf->bf_state.bfs_paprd_timestamp = jiffies;

        ath_set_rates(vif, sta, bf);
        ath_tx_send_normal(sc, txq, tid, skb);

out:
        ath_txq_unlock(sc, txq);

        return 0;
}

void ath_tx_cabq(struct ieee80211_hw *hw, struct ieee80211_vif *vif,
                 struct sk_buff *skb)
{
        struct ath_softc *sc = hw->priv;
        struct ath_tx_control txctl = {
                .txq = sc->beacon.cabq
        };
        struct ath_tx_info info = {};
        struct ieee80211_hdr *hdr;
        struct ath_buf *bf_tail = NULL;
        struct ath_buf *bf;
        LIST_HEAD(bf_q);
        int duration = 0;
        int max_duration;

        max_duration =
                sc->cur_beacon_conf.beacon_interval * 1000 *
                sc->cur_beacon_conf.dtim_period / ATH_BCBUF;

        do {
                struct ath_frame_info *fi = get_frame_info(skb);

                if (ath_tx_prepare(hw, skb, &txctl))
                        break;

                bf = ath_tx_setup_buffer(sc, txctl.txq, NULL, skb);
                if (!bf)
                        break;

                bf->bf_lastbf = bf;
                ath_set_rates(vif, NULL, bf);
                ath_buf_set_rate(sc, bf, &info, fi->framelen, false);
                duration += info.rates[0].PktDuration;
                if (bf_tail)
                        bf_tail->bf_next = bf;

                list_add_tail(&bf->list, &bf_q);
                bf_tail = bf;
                skb = NULL;

                if (duration > max_duration)
                        break;

                skb = ieee80211_get_buffered_bc(hw, vif);
        } while(skb);

        if (skb)
                ieee80211_free_txskb(hw, skb);

        if (list_empty(&bf_q))
                return;

        bf = list_first_entry(&bf_q, struct ath_buf, list);
        hdr = (struct ieee80211_hdr *) bf->bf_mpdu->data;

        if (hdr->frame_control & IEEE80211_FCTL_MOREDATA) {
                hdr->frame_control &= ~IEEE80211_FCTL_MOREDATA;
                dma_sync_single_for_device(sc->dev, bf->bf_buf_addr,
                        sizeof(*hdr), DMA_TO_DEVICE);
        }

        ath_txq_lock(sc, txctl.txq);
        ath_tx_fill_desc(sc, bf, txctl.txq, 0);
        ath_tx_txqaddbuf(sc, txctl.txq, &bf_q, false);
        TX_STAT_INC(txctl.txq->axq_qnum, queued);
        ath_txq_unlock(sc, txctl.txq);
}

/*****************/
/* TX Completion */
/*****************/

static void ath_tx_complete(struct ath_softc *sc, struct sk_buff *skb,
                            int tx_flags, struct ath_txq *txq)
{
        struct ieee80211_tx_info *tx_info = IEEE80211_SKB_CB(skb);
        struct ath_common *common = ath9k_hw_common(sc->sc_ah);
        struct ieee80211_hdr * hdr = (struct ieee80211_hdr *)skb->data;
        int padpos, padsize;
        unsigned long flags;

        ath_dbg(common, XMIT, "TX complete: skb: %p\n", skb);

        if (sc->sc_ah->caldata)
                sc->sc_ah->caldata->paprd_packet_sent = true;

        if (!(tx_flags & ATH_TX_ERROR))
                /* Frame was ACKed */
                tx_info->flags |= IEEE80211_TX_STAT_ACK;

        padpos = ieee80211_hdrlen(hdr->frame_control);
        padsize = padpos & 3;
        if (padsize && skb->len>padpos+padsize) {
                /*
                 * Remove MAC header padding before giving the frame back to
                 * mac80211.
                 */
                memmove(skb->data + padsize, skb->data, padpos);
                skb_pull(skb, padsize);
        }

        spin_lock_irqsave(&sc->sc_pm_lock, flags);
        if ((sc->ps_flags & PS_WAIT_FOR_TX_ACK) && !txq->axq_depth) {
                sc->ps_flags &= ~PS_WAIT_FOR_TX_ACK;
                ath_dbg(common, PS,
                        "Going back to sleep after having received TX status (0x%lx)\n",
                        sc->ps_flags & (PS_WAIT_FOR_BEACON |
                                        PS_WAIT_FOR_CAB |
                                        PS_WAIT_FOR_PSPOLL_DATA |
                                        PS_WAIT_FOR_TX_ACK));
        }
        spin_unlock_irqrestore(&sc->sc_pm_lock, flags);

        __skb_queue_tail(&txq->complete_q, skb);
        ath_txq_skb_done(sc, txq, skb);
}

static void ath_tx_complete_buf(struct ath_softc *sc, struct ath_buf *bf,
                                struct ath_txq *txq, struct list_head *bf_q,
                                struct ath_tx_status *ts, int txok)
{
        struct sk_buff *skb = bf->bf_mpdu;
        struct ieee80211_tx_info *tx_info = IEEE80211_SKB_CB(skb);
        unsigned long flags;
        int tx_flags = 0;

        if (!txok)
                tx_flags |= ATH_TX_ERROR;

        if (ts->ts_status & ATH9K_TXERR_FILT)
                tx_info->flags |= IEEE80211_TX_STAT_TX_FILTERED;

        dma_unmap_single(sc->dev, bf->bf_buf_addr, skb->len, DMA_TO_DEVICE);
        bf->bf_buf_addr = 0;

        if (bf->bf_state.bfs_paprd) {
                if (time_after(jiffies,
                                bf->bf_state.bfs_paprd_timestamp +
                                msecs_to_jiffies(ATH_PAPRD_TIMEOUT)))
                        dev_kfree_skb_any(skb);
                else
                        complete(&sc->paprd_complete);
        } else {
                ath_debug_stat_tx(sc, bf, ts, txq, tx_flags);
                ath_tx_complete(sc, skb, tx_flags, txq);
        }
        /* At this point, skb (bf->bf_mpdu) is consumed...make sure we don't
         * accidentally reference it later.
         */
        bf->bf_mpdu = NULL;

        /*
         * Return the list of ath_buf of this mpdu to free queue
         */
        spin_lock_irqsave(&sc->tx.txbuflock, flags);
        list_splice_tail_init(bf_q, &sc->tx.txbuf);
        spin_unlock_irqrestore(&sc->tx.txbuflock, flags);
}

static void ath_tx_rc_status(struct ath_softc *sc, struct ath_buf *bf,
                             struct ath_tx_status *ts, int nframes, int nbad,
                             int txok)
{
        struct sk_buff *skb = bf->bf_mpdu;
        struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
        struct ieee80211_tx_info *tx_info = IEEE80211_SKB_CB(skb);
        struct ieee80211_hw *hw = sc->hw;
        struct ath_hw *ah = sc->sc_ah;
        u8 i, tx_rateindex;

        if (txok)
                tx_info->status.ack_signal = ts->ts_rssi;

        tx_rateindex = ts->ts_rateindex;
        WARN_ON(tx_rateindex >= hw->max_rates);

        if (tx_info->flags & IEEE80211_TX_CTL_AMPDU) {
                tx_info->flags |= IEEE80211_TX_STAT_AMPDU;

                BUG_ON(nbad > nframes);
        }
        tx_info->status.ampdu_len = nframes;
        tx_info->status.ampdu_ack_len = nframes - nbad;

        if ((ts->ts_status & ATH9K_TXERR_FILT) == 0 &&
            (tx_info->flags & IEEE80211_TX_CTL_NO_ACK) == 0) {
                /*
                 * If an underrun error is seen assume it as an excessive
                 * retry only if max frame trigger level has been reached
                 * (2 KB for single stream, and 4 KB for dual stream).
                 * Adjust the long retry as if the frame was tried
                 * hw->max_rate_tries times to affect how rate control updates
                 * PER for the failed rate.
                 * In case of congestion on the bus penalizing this type of
                 * underruns should help hardware actually transmit new frames
                 * successfully by eventually preferring slower rates.
                 * This itself should also alleviate congestion on the bus.
                 */
                if (unlikely(ts->ts_flags & (ATH9K_TX_DATA_UNDERRUN |
                                             ATH9K_TX_DELIM_UNDERRUN)) &&
                    ieee80211_is_data(hdr->frame_control) &&
                    ah->tx_trig_level >= sc->sc_ah->config.max_txtrig_level)
                        tx_info->status.rates[tx_rateindex].count =
                                hw->max_rate_tries;
        }

        for (i = tx_rateindex + 1; i < hw->max_rates; i++) {
                tx_info->status.rates[i].count = 0;
                tx_info->status.rates[i].idx = -1;
        }

        tx_info->status.rates[tx_rateindex].count = ts->ts_longretry + 1;
}

static void ath_tx_processq(struct ath_softc *sc, struct ath_txq *txq)
{
        struct ath_hw *ah = sc->sc_ah;
        struct ath_common *common = ath9k_hw_common(ah);
        struct ath_buf *bf, *lastbf, *bf_held = NULL;
        struct list_head bf_head;
        struct ath_desc *ds;
        struct ath_tx_status ts;
        int status;

        ath_dbg(common, QUEUE, "tx queue %d (%x), link %p\n",
                txq->axq_qnum, ath9k_hw_gettxbuf(sc->sc_ah, txq->axq_qnum),
                txq->axq_link);

        ath_txq_lock(sc, txq);
        for (;;) {
                if (test_bit(SC_OP_HW_RESET, &sc->sc_flags))
                        break;

                if (list_empty(&txq->axq_q)) {
                        txq->axq_link = NULL;
                        ath_txq_schedule(sc, txq);
                        break;
                }
                bf = list_first_entry(&txq->axq_q, struct ath_buf, list);

                /*
                 * There is a race condition that a BH gets scheduled
                 * after sw writes TxE and before hw re-load the last
                 * descriptor to get the newly chained one.
                 * Software must keep the last DONE descriptor as a
                 * holding descriptor - software does so by marking
                 * it with the STALE flag.
                 */
                bf_held = NULL;
                if (bf->bf_state.stale) {
                        bf_held = bf;
                        if (list_is_last(&bf_held->list, &txq->axq_q))
                                break;

                        bf = list_entry(bf_held->list.next, struct ath_buf,
                                        list);
                }

                lastbf = bf->bf_lastbf;
                ds = lastbf->bf_desc;

                memset(&ts, 0, sizeof(ts));
                status = ath9k_hw_txprocdesc(ah, ds, &ts);
                if (status == -EINPROGRESS)
                        break;

                TX_STAT_INC(txq->axq_qnum, txprocdesc);

                /*
                 * Remove ath_buf's of the same transmit unit from txq,
                 * however leave the last descriptor back as the holding
                 * descriptor for hw.
                 */
                lastbf->bf_state.stale = true;
                INIT_LIST_HEAD(&bf_head);
                if (!list_is_singular(&lastbf->list))
                        list_cut_position(&bf_head,
                                &txq->axq_q, lastbf->list.prev);

                if (bf_held) {
                        list_del(&bf_held->list);
                        ath_tx_return_buffer(sc, bf_held);
                }

                ath_tx_process_buffer(sc, txq, &ts, bf, &bf_head);
        }
        ath_txq_unlock_complete(sc, txq);
}

void ath_tx_tasklet(struct ath_softc *sc)
{
        struct ath_hw *ah = sc->sc_ah;
        u32 qcumask = ((1 << ATH9K_NUM_TX_QUEUES) - 1) & ah->intr_txqs;
        int i;

        for (i = 0; i < ATH9K_NUM_TX_QUEUES; i++) {
                if (ATH_TXQ_SETUP(sc, i) && (qcumask & (1 << i)))
                        ath_tx_processq(sc, &sc->tx.txq[i]);
        }
}

void ath_tx_edma_tasklet(struct ath_softc *sc)
{
        struct ath_tx_status ts;
        struct ath_common *common = ath9k_hw_common(sc->sc_ah);
        struct ath_hw *ah = sc->sc_ah;
        struct ath_txq *txq;
        struct ath_buf *bf, *lastbf;
        struct list_head bf_head;
        struct list_head *fifo_list;
        int status;

        for (;;) {
                if (test_bit(SC_OP_HW_RESET, &sc->sc_flags))
                        break;

                status = ath9k_hw_txprocdesc(ah, NULL, (void *)&ts);
                if (status == -EINPROGRESS)
                        break;
                if (status == -EIO) {
                        ath_dbg(common, XMIT, "Error processing tx status\n");
                        break;
                }

                /* Process beacon completions separately */
                if (ts.qid == sc->beacon.beaconq) {
                        sc->beacon.tx_processed = true;
                        sc->beacon.tx_last = !(ts.ts_status & ATH9K_TXERR_MASK);

                        ath9k_csa_is_finished(sc);
                        continue;
                }

                txq = &sc->tx.txq[ts.qid];

                ath_txq_lock(sc, txq);

                TX_STAT_INC(txq->axq_qnum, txprocdesc);

                fifo_list = &txq->txq_fifo[txq->txq_tailidx];
                if (list_empty(fifo_list)) {
                        ath_txq_unlock(sc, txq);
                        return;
                }

                bf = list_first_entry(fifo_list, struct ath_buf, list);
                if (bf->bf_state.stale) {
                        list_del(&bf->list);
                        ath_tx_return_buffer(sc, bf);
                        bf = list_first_entry(fifo_list, struct ath_buf, list);
                }

                lastbf = bf->bf_lastbf;

                INIT_LIST_HEAD(&bf_head);
                if (list_is_last(&lastbf->list, fifo_list)) {
                        list_splice_tail_init(fifo_list, &bf_head);
                        INCR(txq->txq_tailidx, ATH_TXFIFO_DEPTH);

                        if (!list_empty(&txq->axq_q)) {
                                struct list_head bf_q;

                                INIT_LIST_HEAD(&bf_q);
                                txq->axq_link = NULL;
                                list_splice_tail_init(&txq->axq_q, &bf_q);
                                ath_tx_txqaddbuf(sc, txq, &bf_q, true);
                        }
                } else {
                        lastbf->bf_state.stale = true;
                        if (bf != lastbf)
                                list_cut_position(&bf_head, fifo_list,
                                                  lastbf->list.prev);
                }

                ath_tx_process_buffer(sc, txq, &ts, bf, &bf_head);
                ath_txq_unlock_complete(sc, txq);
        }
}

/*****************/
/* Init, Cleanup */
/*****************/

static int ath_txstatus_setup(struct ath_softc *sc, int size)
{
        struct ath_descdma *dd = &sc->txsdma;
        u8 txs_len = sc->sc_ah->caps.txs_len;

        dd->dd_desc_len = size * txs_len;
        dd->dd_desc = dmam_alloc_coherent(sc->dev, dd->dd_desc_len,
                                          &dd->dd_desc_paddr, GFP_KERNEL);
        if (!dd->dd_desc)
                return -ENOMEM;

        return 0;
}

static int ath_tx_edma_init(struct ath_softc *sc)
{
        int err;

        err = ath_txstatus_setup(sc, ATH_TXSTATUS_RING_SIZE);
        if (!err)
                ath9k_hw_setup_statusring(sc->sc_ah, sc->txsdma.dd_desc,
                                          sc->txsdma.dd_desc_paddr,
                                          ATH_TXSTATUS_RING_SIZE);

        return err;
}

int ath_tx_init(struct ath_softc *sc, int nbufs)
{
        struct ath_common *common = ath9k_hw_common(sc->sc_ah);
        int error = 0;

        spin_lock_init(&sc->tx.txbuflock);

        error = ath_descdma_setup(sc, &sc->tx.txdma, &sc->tx.txbuf,
                                  "tx", nbufs, 1, 1);
        if (error != 0) {
                ath_err(common,
                        "Failed to allocate tx descriptors: %d\n", error);
                return error;
        }

        error = ath_descdma_setup(sc, &sc->beacon.bdma, &sc->beacon.bbuf,
                                  "beacon", ATH_BCBUF, 1, 1);
        if (error != 0) {
                ath_err(common,
                        "Failed to allocate beacon descriptors: %d\n", error);
                return error;
        }

        INIT_DELAYED_WORK(&sc->tx_complete_work, ath_tx_complete_poll_work);

        if (sc->sc_ah->caps.hw_caps & ATH9K_HW_CAP_EDMA)
                error = ath_tx_edma_init(sc);

        return error;
}

void ath_tx_node_init(struct ath_softc *sc, struct ath_node *an)
{
        struct ath_atx_tid *tid;
        struct ath_atx_ac *ac;
        int tidno, acno;

        for (tidno = 0, tid = &an->tid[tidno];
             tidno < IEEE80211_NUM_TIDS;
             tidno++, tid++) {
                tid->an        = an;
                tid->tidno     = tidno;
                tid->seq_start = tid->seq_next = 0;
                tid->baw_size  = WME_MAX_BA;
                tid->baw_head  = tid->baw_tail = 0;
                tid->sched     = false;
                tid->paused    = false;
                tid->active        = false;
                __skb_queue_head_init(&tid->buf_q);
                __skb_queue_head_init(&tid->retry_q);
                acno = TID_TO_WME_AC(tidno);
                tid->ac = &an->ac[acno];
        }

        for (acno = 0, ac = &an->ac[acno];
             acno < IEEE80211_NUM_ACS; acno++, ac++) {
                ac->sched    = false;
                ac->clear_ps_filter = true;
                ac->txq = sc->tx.txq_map[acno];
                INIT_LIST_HEAD(&ac->tid_q);
        }
}

void ath_tx_node_cleanup(struct ath_softc *sc, struct ath_node *an)
{
        struct ath_atx_ac *ac;
        struct ath_atx_tid *tid;
        struct ath_txq *txq;
        int tidno;

        for (tidno = 0, tid = &an->tid[tidno];
             tidno < IEEE80211_NUM_TIDS; tidno++, tid++) {

                ac = tid->ac;
                txq = ac->txq;

                ath_txq_lock(sc, txq);

                if (tid->sched) {
                        list_del(&tid->list);
                        tid->sched = false;
                }

                if (ac->sched) {
                        list_del(&ac->list);
                        tid->ac->sched = false;
                }

                ath_tid_drain(sc, txq, tid);
                tid->active = false;

                ath_txq_unlock(sc, txq);
        }
}