ath9k: RX Filter cleanup

[linux-2.6/libata-dev.git] / drivers / net / wireless / ath9k / recv.c

/*
 * Copyright (c) 2008 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.
 */

/*
 * Implementation of receive path.
 */

#include "core.h"

/*
 * Setup and link descriptors.
 *
 * 11N: we can no longer afford to self link the last descriptor.
 * MAC acknowledges BA status as long as it copies frames to host
 * buffer (or rx fifo). This can incorrectly acknowledge packets
 * to a sender if last desc is self-linked.
 *
 * NOTE: Caller should hold the rxbuf lock.
 */

static void ath_rx_buf_link(struct ath_softc *sc, struct ath_buf *bf)
{
        struct ath_hal *ah = sc->sc_ah;
        struct ath_desc *ds;
        struct sk_buff *skb;

        ATH_RXBUF_RESET(bf);

        ds = bf->bf_desc;
        ds->ds_link = 0;    /* link to null */
        ds->ds_data = bf->bf_buf_addr;

        /* XXX For RADAR?
         * virtual addr of the beginning of the buffer. */
        skb = bf->bf_mpdu;
        ASSERT(skb != NULL);
        ds->ds_vdata = skb->data;

        /* setup rx descriptors */
        ath9k_hw_setuprxdesc(ah,
                             ds,
                             skb_tailroom(skb),   /* buffer size */
                             0);

        if (sc->sc_rxlink == NULL)
                ath9k_hw_putrxbuf(ah, bf->bf_daddr);
        else
                *sc->sc_rxlink = bf->bf_daddr;

        sc->sc_rxlink = &ds->ds_link;
        ath9k_hw_rxena(ah);
}

/* Process received BAR frame */

static int ath_bar_rx(struct ath_softc *sc,
                      struct ath_node *an,
                      struct sk_buff *skb)
{
        struct ieee80211_bar *bar;
        struct ath_arx_tid *rxtid;
        struct sk_buff *tskb;
        struct ath_recv_status *rx_status;
        int tidno, index, cindex;
        u16 seqno;

        /* look at BAR contents  */

        bar = (struct ieee80211_bar *)skb->data;
        tidno = (le16_to_cpu(bar->control) & IEEE80211_BAR_CTL_TID_M)
                >> IEEE80211_BAR_CTL_TID_S;
        seqno = le16_to_cpu(bar->start_seq_num) >> IEEE80211_SEQ_SEQ_SHIFT;

        /* process BAR - indicate all pending RX frames till the BAR seqno */

        rxtid = &an->an_aggr.rx.tid[tidno];

        spin_lock_bh(&rxtid->tidlock);

        /* get relative index */

        index = ATH_BA_INDEX(rxtid->seq_next, seqno);

        /* drop BAR if old sequence (index is too large) */

        if ((index > rxtid->baw_size) &&
            (index > (IEEE80211_SEQ_MAX - (rxtid->baw_size << 2))))
                /* discard frame, ieee layer may not treat frame as a dup */
                goto unlock_and_free;

        /* complete receive processing for all pending frames upto BAR seqno */

        cindex = (rxtid->baw_head + index) & (ATH_TID_MAX_BUFS - 1);
        while ((rxtid->baw_head != rxtid->baw_tail) &&
               (rxtid->baw_head != cindex)) {
                tskb = rxtid->rxbuf[rxtid->baw_head].rx_wbuf;
                rx_status = &rxtid->rxbuf[rxtid->baw_head].rx_status;
                rxtid->rxbuf[rxtid->baw_head].rx_wbuf = NULL;

                if (tskb != NULL)
                        ath_rx_subframe(an, tskb, rx_status);

                INCR(rxtid->baw_head, ATH_TID_MAX_BUFS);
                INCR(rxtid->seq_next, IEEE80211_SEQ_MAX);
        }

        /* ... and indicate rest of the frames in-order */

        while (rxtid->baw_head != rxtid->baw_tail &&
               rxtid->rxbuf[rxtid->baw_head].rx_wbuf != NULL) {
                tskb = rxtid->rxbuf[rxtid->baw_head].rx_wbuf;
                rx_status = &rxtid->rxbuf[rxtid->baw_head].rx_status;
                rxtid->rxbuf[rxtid->baw_head].rx_wbuf = NULL;

                ath_rx_subframe(an, tskb, rx_status);

                INCR(rxtid->baw_head, ATH_TID_MAX_BUFS);
                INCR(rxtid->seq_next, IEEE80211_SEQ_MAX);
        }

unlock_and_free:
        spin_unlock_bh(&rxtid->tidlock);
        /* free bar itself */
        dev_kfree_skb(skb);
        return IEEE80211_FTYPE_CTL;
}

/* Function to handle a subframe of aggregation when HT is enabled */

static int ath_ampdu_input(struct ath_softc *sc,
                           struct ath_node *an,
                           struct sk_buff *skb,
                           struct ath_recv_status *rx_status)
{
        struct ieee80211_hdr *hdr;
        struct ath_arx_tid *rxtid;
        struct ath_rxbuf *rxbuf;
        u8 type, subtype;
        u16 rxseq;
        int tid = 0, index, cindex, rxdiff;
        __le16 fc;
        u8 *qc;

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

        /* collect stats of frames with non-zero version */

        if ((le16_to_cpu(hdr->frame_control) & IEEE80211_FCTL_VERS) != 0) {
                dev_kfree_skb(skb);
                return -1;
        }

        type = le16_to_cpu(hdr->frame_control) & IEEE80211_FCTL_FTYPE;
        subtype = le16_to_cpu(hdr->frame_control) & IEEE80211_FCTL_STYPE;

        if (ieee80211_is_back_req(fc))
                return ath_bar_rx(sc, an, skb);

        /* special aggregate processing only for qos unicast data frames */

        if (!ieee80211_is_data(fc) ||
            !ieee80211_is_data_qos(fc) ||
            is_multicast_ether_addr(hdr->addr1))
                return ath_rx_subframe(an, skb, rx_status);

        /* lookup rx tid state */

        if (ieee80211_is_data_qos(fc)) {
                qc = ieee80211_get_qos_ctl(hdr);
                tid = qc[0] & 0xf;
        }

        if (sc->sc_opmode == ATH9K_M_STA) {
                /* Drop the frame not belonging to me. */
                if (memcmp(hdr->addr1, sc->sc_myaddr, ETH_ALEN)) {
                        dev_kfree_skb(skb);
                        return -1;
                }
        }

        rxtid = &an->an_aggr.rx.tid[tid];

        spin_lock(&rxtid->tidlock);

        rxdiff = (rxtid->baw_tail - rxtid->baw_head) &
                (ATH_TID_MAX_BUFS - 1);

        /*
         * If the ADDBA exchange has not been completed by the source,
         * process via legacy path (i.e. no reordering buffer is needed)
         */
        if (!rxtid->addba_exchangecomplete) {
                spin_unlock(&rxtid->tidlock);
                return ath_rx_subframe(an, skb, rx_status);
        }

        /* extract sequence number from recvd frame */

        rxseq = le16_to_cpu(hdr->seq_ctrl) >> IEEE80211_SEQ_SEQ_SHIFT;

        if (rxtid->seq_reset) {
                rxtid->seq_reset = 0;
                rxtid->seq_next = rxseq;
        }

        index = ATH_BA_INDEX(rxtid->seq_next, rxseq);

        /* drop frame if old sequence (index is too large) */

        if (index > (IEEE80211_SEQ_MAX - (rxtid->baw_size << 2))) {
                /* discard frame, ieee layer may not treat frame as a dup */
                spin_unlock(&rxtid->tidlock);
                dev_kfree_skb(skb);
                return IEEE80211_FTYPE_DATA;
        }

        /* sequence number is beyond block-ack window */

        if (index >= rxtid->baw_size) {

                /* complete receive processing for all pending frames */

                while (index >= rxtid->baw_size) {

                        rxbuf = rxtid->rxbuf + rxtid->baw_head;

                        if (rxbuf->rx_wbuf != NULL) {
                                ath_rx_subframe(an, rxbuf->rx_wbuf,
                                                &rxbuf->rx_status);
                                rxbuf->rx_wbuf = NULL;
                        }

                        INCR(rxtid->baw_head, ATH_TID_MAX_BUFS);
                        INCR(rxtid->seq_next, IEEE80211_SEQ_MAX);

                        index--;
                }
        }

        /* add buffer to the recv ba window */

        cindex = (rxtid->baw_head + index) & (ATH_TID_MAX_BUFS - 1);
        rxbuf = rxtid->rxbuf + cindex;

        if (rxbuf->rx_wbuf != NULL) {
                spin_unlock(&rxtid->tidlock);
                /* duplicate frame */
                dev_kfree_skb(skb);
                return IEEE80211_FTYPE_DATA;
        }

        rxbuf->rx_wbuf = skb;
        rxbuf->rx_time = get_timestamp();
        rxbuf->rx_status = *rx_status;

        /* advance tail if sequence received is newer
         * than any received so far */

        if (index >= rxdiff) {
                rxtid->baw_tail = cindex;
                INCR(rxtid->baw_tail, ATH_TID_MAX_BUFS);
        }

        /* indicate all in-order received frames */

        while (rxtid->baw_head != rxtid->baw_tail) {
                rxbuf = rxtid->rxbuf + rxtid->baw_head;
                if (!rxbuf->rx_wbuf)
                        break;

                ath_rx_subframe(an, rxbuf->rx_wbuf, &rxbuf->rx_status);
                rxbuf->rx_wbuf = NULL;

                INCR(rxtid->baw_head, ATH_TID_MAX_BUFS);
                INCR(rxtid->seq_next, IEEE80211_SEQ_MAX);
        }

        /*
         * start a timer to flush all received frames if there are pending
         * receive frames
         */
        if (rxtid->baw_head != rxtid->baw_tail)
                mod_timer(&rxtid->timer, ATH_RX_TIMEOUT);
        else
                del_timer_sync(&rxtid->timer);

        spin_unlock(&rxtid->tidlock);
        return IEEE80211_FTYPE_DATA;
}

/* Timer to flush all received sub-frames */

static void ath_rx_timer(unsigned long data)
{
        struct ath_arx_tid *rxtid = (struct ath_arx_tid *)data;
        struct ath_node *an = rxtid->an;
        struct ath_rxbuf *rxbuf;
        int nosched;

        spin_lock_bh(&rxtid->tidlock);
        while (rxtid->baw_head != rxtid->baw_tail) {
                rxbuf = rxtid->rxbuf + rxtid->baw_head;
                if (!rxbuf->rx_wbuf) {
                        INCR(rxtid->baw_head, ATH_TID_MAX_BUFS);
                        INCR(rxtid->seq_next, IEEE80211_SEQ_MAX);
                        continue;
                }

                /*
                 * Stop if the next one is a very recent frame.
                 *
                 * Call get_timestamp in every iteration to protect against the
                 * case in which a new frame is received while we are executing
                 * this function. Using a timestamp obtained before entering
                 * the loop could lead to a very large time interval
                 * (a negative value typecast to unsigned), breaking the
                 * function's logic.
                 */
                if ((get_timestamp() - rxbuf->rx_time) <
                        (ATH_RX_TIMEOUT * HZ / 1000))
                        break;

                ath_rx_subframe(an, rxbuf->rx_wbuf,
                                &rxbuf->rx_status);
                rxbuf->rx_wbuf = NULL;

                INCR(rxtid->baw_head, ATH_TID_MAX_BUFS);
                INCR(rxtid->seq_next, IEEE80211_SEQ_MAX);
        }

        /*
         * start a timer to flush all received frames if there are pending
         * receive frames
         */
        if (rxtid->baw_head != rxtid->baw_tail)
                nosched = 0;
        else
                nosched = 1; /* no need to re-arm the timer again */

        spin_unlock_bh(&rxtid->tidlock);
}

/* Free all pending sub-frames in the re-ordering buffer */

static void ath_rx_flush_tid(struct ath_softc *sc,
        struct ath_arx_tid *rxtid, int drop)
{
        struct ath_rxbuf *rxbuf;

        spin_lock_bh(&rxtid->tidlock);
        while (rxtid->baw_head != rxtid->baw_tail) {
                rxbuf = rxtid->rxbuf + rxtid->baw_head;
                if (!rxbuf->rx_wbuf) {
                        INCR(rxtid->baw_head, ATH_TID_MAX_BUFS);
                        INCR(rxtid->seq_next, IEEE80211_SEQ_MAX);
                        continue;
                }

                if (drop)
                        dev_kfree_skb(rxbuf->rx_wbuf);
                else
                        ath_rx_subframe(rxtid->an,
                                        rxbuf->rx_wbuf,
                                        &rxbuf->rx_status);

                rxbuf->rx_wbuf = NULL;

                INCR(rxtid->baw_head, ATH_TID_MAX_BUFS);
                INCR(rxtid->seq_next, IEEE80211_SEQ_MAX);
        }
        spin_unlock_bh(&rxtid->tidlock);
}

static struct sk_buff *ath_rxbuf_alloc(struct ath_softc *sc,
        u32 len)
{
        struct sk_buff *skb;
        u32 off;

        /*
         * Cache-line-align.  This is important (for the
         * 5210 at least) as not doing so causes bogus data
         * in rx'd frames.
         */

        skb = dev_alloc_skb(len + sc->sc_cachelsz - 1);
        if (skb != NULL) {
                off = ((unsigned long) skb->data) % sc->sc_cachelsz;
                if (off != 0)
                        skb_reserve(skb, sc->sc_cachelsz - off);
        } else {
                DPRINTF(sc, ATH_DBG_FATAL,
                        "%s: skbuff alloc of size %u failed\n",
                        __func__, len);
                return NULL;
        }

        return skb;
}

static void ath_rx_requeue(struct ath_softc *sc, struct sk_buff *skb)
{
        struct ath_buf *bf = ATH_RX_CONTEXT(skb)->ctx_rxbuf;

        ASSERT(bf != NULL);

        spin_lock_bh(&sc->sc_rxbuflock);
        if (bf->bf_status & ATH_BUFSTATUS_STALE) {
                /*
                 * This buffer is still held for hw acess.
                 * Mark it as free to be re-queued it later.
                 */
                bf->bf_status |= ATH_BUFSTATUS_FREE;
        } else {
                /* XXX: we probably never enter here, remove after
                 * verification */
                list_add_tail(&bf->list, &sc->sc_rxbuf);
                ath_rx_buf_link(sc, bf);
        }
        spin_unlock_bh(&sc->sc_rxbuflock);
}

/*
 * The skb indicated to upper stack won't be returned to us.
 * So we have to allocate a new one and queue it by ourselves.
 */
static int ath_rx_indicate(struct ath_softc *sc,
                           struct sk_buff *skb,
                           struct ath_recv_status *status,
                           u16 keyix)
{
        struct ath_buf *bf = ATH_RX_CONTEXT(skb)->ctx_rxbuf;
        struct sk_buff *nskb;
        int type;

        /* indicate frame to the stack, which will free the old skb. */
        type = ath__rx_indicate(sc, skb, status, keyix);

        /* allocate a new skb and queue it to for H/W processing */
        nskb = ath_rxbuf_alloc(sc, sc->sc_rxbufsize);
        if (nskb != NULL) {
                bf->bf_mpdu = nskb;
                bf->bf_buf_addr = ath_skb_map_single(sc,
                        nskb,
                        PCI_DMA_FROMDEVICE,
                        /* XXX: Remove get_dma_mem_context() */
                        get_dma_mem_context(bf, bf_dmacontext));
                ATH_RX_CONTEXT(nskb)->ctx_rxbuf = bf;

                /* queue the new wbuf to H/W */
                ath_rx_requeue(sc, nskb);
        }

        return type;
}

static void ath_opmode_init(struct ath_softc *sc)
{
        struct ath_hal *ah = sc->sc_ah;
        u32 rfilt, mfilt[2];

        /* configure rx filter */
        rfilt = ath_calcrxfilter(sc);
        ath9k_hw_setrxfilter(ah, rfilt);

        /* configure bssid mask */
        if (ah->ah_caps.hw_caps & ATH9K_HW_CAP_BSSIDMASK)
                ath9k_hw_setbssidmask(ah, sc->sc_bssidmask);

        /* configure operational mode */
        ath9k_hw_setopmode(ah);

        /* Handle any link-level address change. */
        ath9k_hw_setmac(ah, sc->sc_myaddr);

        /* calculate and install multicast filter */
        mfilt[0] = mfilt[1] = ~0;

        ath9k_hw_setmcastfilter(ah, mfilt[0], mfilt[1]);
        DPRINTF(sc, ATH_DBG_CONFIG ,
                "%s: RX filter 0x%x, MC filter %08x:%08x\n",
                __func__, rfilt, mfilt[0], mfilt[1]);
}

int ath_rx_init(struct ath_softc *sc, int nbufs)
{
        struct sk_buff *skb;
        struct ath_buf *bf;
        int error = 0;

        do {
                spin_lock_init(&sc->sc_rxflushlock);
                sc->sc_rxflush = 0;
                spin_lock_init(&sc->sc_rxbuflock);

                /*
                 * Cisco's VPN software requires that drivers be able to
                 * receive encapsulated frames that are larger than the MTU.
                 * Since we can't be sure how large a frame we'll get, setup
                 * to handle the larges on possible.
                 */
                sc->sc_rxbufsize = roundup(IEEE80211_MAX_MPDU_LEN,
                                           min(sc->sc_cachelsz,
                                               (u16)64));

                DPRINTF(sc, ATH_DBG_CONFIG, "%s: cachelsz %u rxbufsize %u\n",
                        __func__, sc->sc_cachelsz, sc->sc_rxbufsize);

                /* Initialize rx descriptors */

                error = ath_descdma_setup(sc, &sc->sc_rxdma, &sc->sc_rxbuf,
                                          "rx", nbufs, 1);
                if (error != 0) {
                        DPRINTF(sc, ATH_DBG_FATAL,
                                "%s: failed to allocate rx descriptors: %d\n",
                                __func__, error);
                        break;
                }

                /* Pre-allocate a wbuf for each rx buffer */

                list_for_each_entry(bf, &sc->sc_rxbuf, list) {
                        skb = ath_rxbuf_alloc(sc, sc->sc_rxbufsize);
                        if (skb == NULL) {
                                error = -ENOMEM;
                                break;
                        }

                        bf->bf_mpdu = skb;
                        bf->bf_buf_addr =
                                ath_skb_map_single(sc, skb, PCI_DMA_FROMDEVICE,
                                       get_dma_mem_context(bf, bf_dmacontext));
                        ATH_RX_CONTEXT(skb)->ctx_rxbuf = bf;
                }
                sc->sc_rxlink = NULL;

        } while (0);

        if (error)
                ath_rx_cleanup(sc);

        return error;
}

/* Reclaim all rx queue resources */

void ath_rx_cleanup(struct ath_softc *sc)
{
        struct sk_buff *skb;
        struct ath_buf *bf;

        list_for_each_entry(bf, &sc->sc_rxbuf, list) {
                skb = bf->bf_mpdu;
                if (skb)
                        dev_kfree_skb(skb);
        }

        /* cleanup rx descriptors */

        if (sc->sc_rxdma.dd_desc_len != 0)
                ath_descdma_cleanup(sc, &sc->sc_rxdma, &sc->sc_rxbuf);
}

/*
 * Calculate the receive filter according to the
 * operating mode and state:
 *
 * o always accept unicast, broadcast, and multicast traffic
 * o maintain current state of phy error reception (the hal
 *   may enable phy error frames for noise immunity work)
 * o probe request frames are accepted only when operating in
 *   hostap, adhoc, or monitor modes
 * o enable promiscuous mode according to the interface state
 * o accept beacons:
 *   - when operating in adhoc mode so the 802.11 layer creates
 *     node table entries for peers,
 *   - when operating in station mode for collecting rssi data when
 *     the station is otherwise quiet, or
 *   - when operating as a repeater so we see repeater-sta beacons
 *   - when scanning
 */

u32 ath_calcrxfilter(struct ath_softc *sc)
{
#define RX_FILTER_PRESERVE (ATH9K_RX_FILTER_PHYERR | ATH9K_RX_FILTER_PHYRADAR)

        u32 rfilt;

        rfilt = (ath9k_hw_getrxfilter(sc->sc_ah) & RX_FILTER_PRESERVE)
                | ATH9K_RX_FILTER_UCAST | ATH9K_RX_FILTER_BCAST
                | ATH9K_RX_FILTER_MCAST;

        /* If not a STA, enable processing of Probe Requests */
        if (sc->sc_opmode != ATH9K_M_STA)
                rfilt |= ATH9K_RX_FILTER_PROBEREQ;

        /* Can't set HOSTAP into promiscous mode */
        if (((sc->sc_opmode != ATH9K_M_HOSTAP) &&
             (sc->rx_filter & FIF_PROMISC_IN_BSS)) ||
            (sc->sc_opmode == ATH9K_M_MONITOR)) {
                rfilt |= ATH9K_RX_FILTER_PROM;
                /* ??? To prevent from sending ACK */
                rfilt &= ~ATH9K_RX_FILTER_UCAST;
        }

        if (((sc->sc_opmode == ATH9K_M_STA) &&
             (sc->rx_filter & FIF_BCN_PRBRESP_PROMISC)) ||
            (sc->sc_opmode == ATH9K_M_IBSS))
                rfilt |= ATH9K_RX_FILTER_BEACON;

        /* If in HOSTAP mode, want to enable reception of PSPOLL frames
           & beacon frames */
        if (sc->sc_opmode == ATH9K_M_HOSTAP)
                rfilt |= (ATH9K_RX_FILTER_BEACON | ATH9K_RX_FILTER_PSPOLL);
        return rfilt;

#undef RX_FILTER_PRESERVE
}

/* Enable the receive h/w following a reset. */

int ath_startrecv(struct ath_softc *sc)
{
        struct ath_hal *ah = sc->sc_ah;
        struct ath_buf *bf, *tbf;

        spin_lock_bh(&sc->sc_rxbuflock);
        if (list_empty(&sc->sc_rxbuf))
                goto start_recv;

        sc->sc_rxlink = NULL;
        list_for_each_entry_safe(bf, tbf, &sc->sc_rxbuf, list) {
                if (bf->bf_status & ATH_BUFSTATUS_STALE) {
                        /* restarting h/w, no need for holding descriptors */
                        bf->bf_status &= ~ATH_BUFSTATUS_STALE;
                        /*
                         * Upper layer may not be done with the frame yet so
                         * we can't just re-queue it to hardware. Remove it
                         * from h/w queue. It'll be re-queued when upper layer
                         * returns the frame and ath_rx_requeue_mpdu is called.
                         */
                        if (!(bf->bf_status & ATH_BUFSTATUS_FREE)) {
                                list_del(&bf->list);
                                continue;
                        }
                }
                /* chain descriptors */
                ath_rx_buf_link(sc, bf);
        }

        /* We could have deleted elements so the list may be empty now */
        if (list_empty(&sc->sc_rxbuf))
                goto start_recv;

        bf = list_first_entry(&sc->sc_rxbuf, struct ath_buf, list);
        ath9k_hw_putrxbuf(ah, bf->bf_daddr);
        ath9k_hw_rxena(ah);      /* enable recv descriptors */

start_recv:
        spin_unlock_bh(&sc->sc_rxbuflock);
        ath_opmode_init(sc);        /* set filters, etc. */
        ath9k_hw_startpcureceive(ah);   /* re-enable PCU/DMA engine */
        return 0;
}

/* Disable the receive h/w in preparation for a reset. */

bool ath_stoprecv(struct ath_softc *sc)
{
        struct ath_hal *ah = sc->sc_ah;
        u64 tsf;
        bool stopped;

        ath9k_hw_stoppcurecv(ah);       /* disable PCU */
        ath9k_hw_setrxfilter(ah, 0);    /* clear recv filter */
        stopped = ath9k_hw_stopdmarecv(ah);     /* disable DMA engine */
        mdelay(3);                      /* 3ms is long enough for 1 frame */
        tsf = ath9k_hw_gettsf64(ah);
        sc->sc_rxlink = NULL;           /* just in case */
        return stopped;
}

/* Flush receive queue */

void ath_flushrecv(struct ath_softc *sc)
{
        /*
         * ath_rx_tasklet may be used to handle rx interrupt and flush receive
         * queue at the same time. Use a lock to serialize the access of rx
         * queue.
         * ath_rx_tasklet cannot hold the spinlock while indicating packets.
         * Instead, do not claim the spinlock but check for a flush in
         * progress (see references to sc_rxflush)
         */
        spin_lock_bh(&sc->sc_rxflushlock);
        sc->sc_rxflush = 1;

        ath_rx_tasklet(sc, 1);

        sc->sc_rxflush = 0;
        spin_unlock_bh(&sc->sc_rxflushlock);
}

/* Process an individual frame */

int ath_rx_input(struct ath_softc *sc,
                 struct ath_node *an,
                 int is_ampdu,
                 struct sk_buff *skb,
                 struct ath_recv_status *rx_status,
                 enum ATH_RX_TYPE *status)
{
        if (is_ampdu && sc->sc_rxaggr) {
                *status = ATH_RX_CONSUMED;
                return ath_ampdu_input(sc, an, skb, rx_status);
        } else {
                *status = ATH_RX_NON_CONSUMED;
                return -1;
        }
}

/* Process receive queue, as well as LED, etc. */

int ath_rx_tasklet(struct ath_softc *sc, int flush)
{
#define PA2DESC(_sc, _pa)                                               \
        ((struct ath_desc *)((caddr_t)(_sc)->sc_rxdma.dd_desc +         \
                             ((_pa) - (_sc)->sc_rxdma.dd_desc_paddr)))

        struct ath_buf *bf, *bf_held = NULL;
        struct ath_desc *ds;
        struct ieee80211_hdr *hdr;
        struct sk_buff *skb = NULL;
        struct ath_recv_status rx_status;
        struct ath_hal *ah = sc->sc_ah;
        int type, rx_processed = 0;
        u32 phyerr;
        u8 chainreset = 0;
        int retval;
        __le16 fc;

        do {
                /* If handling rx interrupt and flush is in progress => exit */
                if (sc->sc_rxflush && (flush == 0))
                        break;

                spin_lock_bh(&sc->sc_rxbuflock);
                if (list_empty(&sc->sc_rxbuf)) {
                        sc->sc_rxlink = NULL;
                        spin_unlock_bh(&sc->sc_rxbuflock);
                        break;
                }

                bf = list_first_entry(&sc->sc_rxbuf, struct ath_buf, list);

                /*
                 * There is a race condition that BH gets scheduled after sw
                 * writes RxE 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.
                 */
                if (bf->bf_status & ATH_BUFSTATUS_STALE) {
                        bf_held = bf;
                        if (list_is_last(&bf_held->list, &sc->sc_rxbuf)) {
                                /*
                                 * The holding descriptor is the last
                                 * descriptor in queue. It's safe to
                                 * remove the last holding descriptor
                                 * in BH context.
                                 */
                                list_del(&bf_held->list);
                                bf_held->bf_status &= ~ATH_BUFSTATUS_STALE;
                                sc->sc_rxlink = NULL;

                                if (bf_held->bf_status & ATH_BUFSTATUS_FREE) {
                                        list_add_tail(&bf_held->list,
                                                &sc->sc_rxbuf);
                                        ath_rx_buf_link(sc, bf_held);
                                }
                                spin_unlock_bh(&sc->sc_rxbuflock);
                                break;
                        }
                        bf = list_entry(bf->list.next, struct ath_buf, list);
                }

                ds = bf->bf_desc;
                ++rx_processed;

                /*
                 * Must provide the virtual address of the current
                 * descriptor, the physical address, and the virtual
                 * address of the next descriptor in the h/w chain.
                 * This allows the HAL to look ahead to see if the
                 * hardware is done with a descriptor by checking the
                 * done bit in the following descriptor and the address
                 * of the current descriptor the DMA engine is working
                 * on.  All this is necessary because of our use of
                 * a self-linked list to avoid rx overruns.
                 */
                retval = ath9k_hw_rxprocdesc(ah,
                                             ds,
                                             bf->bf_daddr,
                                             PA2DESC(sc, ds->ds_link),
                                             0);
                if (retval == -EINPROGRESS) {
                        struct ath_buf *tbf;
                        struct ath_desc *tds;

                        if (list_is_last(&bf->list, &sc->sc_rxbuf)) {
                                spin_unlock_bh(&sc->sc_rxbuflock);
                                break;
                        }

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

                        /*
                         * On some hardware the descriptor status words could
                         * get corrupted, including the done bit. Because of
                         * this, check if the next descriptor's done bit is
                         * set or not.
                         *
                         * If the next descriptor's done bit is set, the current
                         * descriptor has been corrupted. Force s/w to discard
                         * this descriptor and continue...
                         */

                        tds = tbf->bf_desc;
                        retval = ath9k_hw_rxprocdesc(ah,
                                tds, tbf->bf_daddr,
                                PA2DESC(sc, tds->ds_link), 0);
                        if (retval == -EINPROGRESS) {
                                spin_unlock_bh(&sc->sc_rxbuflock);
                                break;
                        }
                }

                /* XXX: we do not support frames spanning
                 * multiple descriptors */
                bf->bf_status |= ATH_BUFSTATUS_DONE;

                skb = bf->bf_mpdu;
                if (skb == NULL) {              /* XXX ??? can this happen */
                        spin_unlock_bh(&sc->sc_rxbuflock);
                        continue;
                }
                /*
                 * Now we know it's a completed frame, we can indicate the
                 * frame. Remove the previous holding descriptor and leave
                 * this one in the queue as the new holding descriptor.
                 */
                if (bf_held) {
                        list_del(&bf_held->list);
                        bf_held->bf_status &= ~ATH_BUFSTATUS_STALE;
                        if (bf_held->bf_status & ATH_BUFSTATUS_FREE) {
                                list_add_tail(&bf_held->list, &sc->sc_rxbuf);
                                /* try to requeue this descriptor */
                                ath_rx_buf_link(sc, bf_held);
                        }
                }

                bf->bf_status |= ATH_BUFSTATUS_STALE;
                bf_held = bf;
                /*
                 * Release the lock here in case ieee80211_input() return
                 * the frame immediately by calling ath_rx_mpdu_requeue().
                 */
                spin_unlock_bh(&sc->sc_rxbuflock);

                if (flush) {
                        /*
                         * If we're asked to flush receive queue, directly
                         * chain it back at the queue without processing it.
                         */
                        goto rx_next;
                }

                hdr = (struct ieee80211_hdr *)skb->data;
                fc = hdr->frame_control;
                memzero(&rx_status, sizeof(struct ath_recv_status));

                if (ds->ds_rxstat.rs_more) {
                        /*
                         * Frame spans multiple descriptors; this
                         * cannot happen yet as we don't support
                         * jumbograms.  If not in monitor mode,
                         * discard the frame.
                         */
#ifndef ERROR_FRAMES
                        /*
                         * Enable this if you want to see
                         * error frames in Monitor mode.
                         */
                        if (sc->sc_opmode != ATH9K_M_MONITOR)
                                goto rx_next;
#endif
                        /* fall thru for monitor mode handling... */
                } else if (ds->ds_rxstat.rs_status != 0) {
                        if (ds->ds_rxstat.rs_status & ATH9K_RXERR_CRC)
                                rx_status.flags |= ATH_RX_FCS_ERROR;
                        if (ds->ds_rxstat.rs_status & ATH9K_RXERR_PHY) {
                                phyerr = ds->ds_rxstat.rs_phyerr & 0x1f;
                                goto rx_next;
                        }

                        if (ds->ds_rxstat.rs_status & ATH9K_RXERR_DECRYPT) {
                                /*
                                 * Decrypt error. We only mark packet status
                                 * here and always push up the frame up to let
                                 * mac80211 handle the actual error case, be
                                 * it no decryption key or real decryption
                                 * error. This let us keep statistics there.
                                 */
                                rx_status.flags |= ATH_RX_DECRYPT_ERROR;
                        } else if (ds->ds_rxstat.rs_status & ATH9K_RXERR_MIC) {
                                /*
                                 * Demic error. We only mark frame status here
                                 * and always push up the frame up to let
                                 * mac80211 handle the actual error case. This
                                 * let us keep statistics there. Hardware may
                                 * post a false-positive MIC error.
                                 */
                                if (ieee80211_is_ctl(fc))
                                        /*
                                         * Sometimes, we get invalid
                                         * MIC failures on valid control frames.
                                         * Remove these mic errors.
                                         */
                                        ds->ds_rxstat.rs_status &=
                                                ~ATH9K_RXERR_MIC;
                                else
                                        rx_status.flags |= ATH_RX_MIC_ERROR;
                        }
                        /*
                         * Reject error frames with the exception of
                         * decryption and MIC failures. For monitor mode,
                         * we also ignore the CRC error.
                         */
                        if (sc->sc_opmode == ATH9K_M_MONITOR) {
                                if (ds->ds_rxstat.rs_status &
                                    ~(ATH9K_RXERR_DECRYPT | ATH9K_RXERR_MIC |
                                        ATH9K_RXERR_CRC))
                                        goto rx_next;
                        } else {
                                if (ds->ds_rxstat.rs_status &
                                    ~(ATH9K_RXERR_DECRYPT | ATH9K_RXERR_MIC)) {
                                        goto rx_next;
                                }
                        }
                }
                /*
                 * The status portion of the descriptor could get corrupted.
                 */
                if (sc->sc_rxbufsize < ds->ds_rxstat.rs_datalen)
                        goto rx_next;
                /*
                 * Sync and unmap the frame.  At this point we're
                 * committed to passing the sk_buff somewhere so
                 * clear buf_skb; this means a new sk_buff must be
                 * allocated when the rx descriptor is setup again
                 * to receive another frame.
                 */
                skb_put(skb, ds->ds_rxstat.rs_datalen);
                skb->protocol = cpu_to_be16(ETH_P_CONTROL);
                rx_status.tsf = ath_extend_tsf(sc, ds->ds_rxstat.rs_tstamp);
                rx_status.rateieee =
                        sc->sc_hwmap[ds->ds_rxstat.rs_rate].ieeerate;
                rx_status.rateKbps =
                        sc->sc_hwmap[ds->ds_rxstat.rs_rate].rateKbps;
                rx_status.ratecode = ds->ds_rxstat.rs_rate;

                /* HT rate */
                if (rx_status.ratecode & 0x80) {
                        /* TODO - add table to avoid division */
                        if (ds->ds_rxstat.rs_flags & ATH9K_RX_2040) {
                                rx_status.flags |= ATH_RX_40MHZ;
                                rx_status.rateKbps =
                                        (rx_status.rateKbps * 27) / 13;
                        }
                        if (ds->ds_rxstat.rs_flags & ATH9K_RX_GI)
                                rx_status.rateKbps =
                                        (rx_status.rateKbps * 10) / 9;
                        else
                                rx_status.flags |= ATH_RX_SHORT_GI;
                }

                /* sc->sc_noise_floor is only available when the station
                   attaches to an AP, so we use a default value
                   if we are not yet attached. */

                /* XXX we should use either sc->sc_noise_floor or
                 * ath_hal_getChanNoise(ah, &sc->sc_curchan)
                 * to calculate the noise floor.
                 * However, the value returned by ath_hal_getChanNoise
                 * seems to be incorrect (-31dBm on the last test),
                 * so we will use a hard-coded value until we
                 * figure out what is going on.
                 */
                rx_status.abs_rssi =
                        ds->ds_rxstat.rs_rssi + ATH_DEFAULT_NOISE_FLOOR;

                pci_dma_sync_single_for_cpu(sc->pdev,
                                            bf->bf_buf_addr,
                                            skb_tailroom(skb),
                                            PCI_DMA_FROMDEVICE);
                pci_unmap_single(sc->pdev,
                                 bf->bf_buf_addr,
                                 sc->sc_rxbufsize,
                                 PCI_DMA_FROMDEVICE);

                /* XXX: Ah! make me more readable, use a helper */
                if (ah->ah_caps.hw_caps & ATH9K_HW_CAP_HT) {
                        if (ds->ds_rxstat.rs_moreaggr == 0) {
                                rx_status.rssictl[0] =
                                        ds->ds_rxstat.rs_rssi_ctl0;
                                rx_status.rssictl[1] =
                                        ds->ds_rxstat.rs_rssi_ctl1;
                                rx_status.rssictl[2] =
                                        ds->ds_rxstat.rs_rssi_ctl2;
                                rx_status.rssi = ds->ds_rxstat.rs_rssi;
                                if (ds->ds_rxstat.rs_flags & ATH9K_RX_2040) {
                                        rx_status.rssiextn[0] =
                                                ds->ds_rxstat.rs_rssi_ext0;
                                        rx_status.rssiextn[1] =
                                                ds->ds_rxstat.rs_rssi_ext1;
                                        rx_status.rssiextn[2] =
                                                ds->ds_rxstat.rs_rssi_ext2;
                                        rx_status.flags |=
                                                ATH_RX_RSSI_EXTN_VALID;
                                }
                                rx_status.flags |= ATH_RX_RSSI_VALID |
                                        ATH_RX_CHAIN_RSSI_VALID;
                        }
                } else {
                        /*
                         * Need to insert the "combined" rssi into the
                         * status structure for upper layer processing
                         */
                        rx_status.rssi = ds->ds_rxstat.rs_rssi;
                        rx_status.flags |= ATH_RX_RSSI_VALID;
                }

                /* Pass frames up to the stack. */

                type = ath_rx_indicate(sc, skb,
                        &rx_status, ds->ds_rxstat.rs_keyix);

                /*
                 * change the default rx antenna if rx diversity chooses the
                 * other antenna 3 times in a row.
                 */
                if (sc->sc_defant != ds->ds_rxstat.rs_antenna) {
                        if (++sc->sc_rxotherant >= 3)
                                ath_setdefantenna(sc,
                                                ds->ds_rxstat.rs_antenna);
                } else {
                        sc->sc_rxotherant = 0;
                }

#ifdef CONFIG_SLOW_ANT_DIV
                if ((rx_status.flags & ATH_RX_RSSI_VALID) &&
                    ieee80211_is_beacon(fc)) {
                        ath_slow_ant_div(&sc->sc_antdiv, hdr, &ds->ds_rxstat);
                }
#endif
                /*
                 * For frames successfully indicated, the buffer will be
                 * returned to us by upper layers by calling
                 * ath_rx_mpdu_requeue, either synchronusly or asynchronously.
                 * So we don't want to do it here in this loop.
                 */
                continue;

rx_next:
                bf->bf_status |= ATH_BUFSTATUS_FREE;
        } while (TRUE);

        if (chainreset) {
                DPRINTF(sc, ATH_DBG_CONFIG,
                        "%s: Reset rx chain mask. "
                        "Do internal reset\n", __func__);
                ASSERT(flush == 0);
                ath_reset(sc, false);
        }

        return 0;
#undef PA2DESC
}

/* Process ADDBA request in per-TID data structure */

int ath_rx_aggr_start(struct ath_softc *sc,
                      const u8 *addr,
                      u16 tid,
                      u16 *ssn)
{
        struct ath_arx_tid *rxtid;
        struct ath_node *an;
        struct ieee80211_hw *hw = sc->hw;
        struct ieee80211_supported_band *sband;
        u16 buffersize = 0;

        spin_lock_bh(&sc->node_lock);
        an = ath_node_find(sc, (u8 *) addr);
        spin_unlock_bh(&sc->node_lock);

        if (!an) {
                DPRINTF(sc, ATH_DBG_AGGR,
                        "%s: Node not found to initialize RX aggregation\n",
                        __func__);
                return -1;
        }

        sband = hw->wiphy->bands[hw->conf.channel->band];
        buffersize = IEEE80211_MIN_AMPDU_BUF <<
                sband->ht_info.ampdu_factor; /* FIXME */

        rxtid = &an->an_aggr.rx.tid[tid];

        spin_lock_bh(&rxtid->tidlock);
        if (sc->sc_rxaggr) {
                /* Allow aggregation reception
                 * Adjust rx BA window size. Peer might indicate a
                 * zero buffer size for a _dont_care_ condition.
                 */
                if (buffersize)
                        rxtid->baw_size = min(buffersize, rxtid->baw_size);

                /* set rx sequence number */
                rxtid->seq_next = *ssn;

                /* Allocate the receive buffers for this TID */
                DPRINTF(sc, ATH_DBG_AGGR,
                        "%s: Allcating rxbuffer for TID %d\n", __func__, tid);

                if (rxtid->rxbuf == NULL) {
                        /*
                        * If the rxbuff is not NULL at this point, we *probably*
                        * already allocated the buffer on a previous ADDBA,
                        * and this is a subsequent ADDBA that got through.
                        * Don't allocate, but use the value in the pointer,
                        * we zero it out when we de-allocate.
                        */
                        rxtid->rxbuf = kmalloc(ATH_TID_MAX_BUFS *
                                sizeof(struct ath_rxbuf), GFP_ATOMIC);
                }
                if (rxtid->rxbuf == NULL) {
                        DPRINTF(sc, ATH_DBG_AGGR,
                                "%s: Unable to allocate RX buffer, "
                                "refusing ADDBA\n", __func__);
                } else {
                        /* Ensure the memory is zeroed out (all internal
                         * pointers are null) */
                        memzero(rxtid->rxbuf, ATH_TID_MAX_BUFS *
                                sizeof(struct ath_rxbuf));
                        DPRINTF(sc, ATH_DBG_AGGR,
                                "%s: Allocated @%p\n", __func__, rxtid->rxbuf);

                        /* Allow aggregation reception */
                        rxtid->addba_exchangecomplete = 1;
                }
        }
        spin_unlock_bh(&rxtid->tidlock);

        return 0;
}

/* Process DELBA */

int ath_rx_aggr_stop(struct ath_softc *sc,
                     const u8 *addr,
                     u16 tid)
{
        struct ath_node *an;

        spin_lock_bh(&sc->node_lock);
        an = ath_node_find(sc, (u8 *) addr);
        spin_unlock_bh(&sc->node_lock);

        if (!an) {
                DPRINTF(sc, ATH_DBG_AGGR,
                        "%s: RX aggr stop for non-existent node\n", __func__);
                return -1;
        }

        ath_rx_aggr_teardown(sc, an, tid);
        return 0;
}

/* Rx aggregation tear down */

void ath_rx_aggr_teardown(struct ath_softc *sc,
        struct ath_node *an, u8 tid)
{
        struct ath_arx_tid *rxtid = &an->an_aggr.rx.tid[tid];

        if (!rxtid->addba_exchangecomplete)
                return;

        del_timer_sync(&rxtid->timer);
        ath_rx_flush_tid(sc, rxtid, 0);
        rxtid->addba_exchangecomplete = 0;

        /* De-allocate the receive buffer array allocated when addba started */

        if (rxtid->rxbuf) {
                DPRINTF(sc, ATH_DBG_AGGR,
                        "%s: Deallocating TID %d rxbuff @%p\n",
                        __func__, tid, rxtid->rxbuf);
                kfree(rxtid->rxbuf);

                /* Set pointer to null to avoid reuse*/
                rxtid->rxbuf = NULL;
        }
}

/* Initialize per-node receive state */

void ath_rx_node_init(struct ath_softc *sc, struct ath_node *an)
{
        if (sc->sc_rxaggr) {
                struct ath_arx_tid *rxtid;
                int tidno;

                /* Init per tid rx state */
                for (tidno = 0, rxtid = &an->an_aggr.rx.tid[tidno];
                                tidno < WME_NUM_TID;
                                tidno++, rxtid++) {
                        rxtid->an        = an;
                        rxtid->seq_reset = 1;
                        rxtid->seq_next  = 0;
                        rxtid->baw_size  = WME_MAX_BA;
                        rxtid->baw_head  = rxtid->baw_tail = 0;

                        /*
                         * Ensure the buffer pointer is null at this point
                         * (needs to be allocated when addba is received)
                        */

                        rxtid->rxbuf     = NULL;
                        setup_timer(&rxtid->timer, ath_rx_timer,
                                (unsigned long)rxtid);
                        spin_lock_init(&rxtid->tidlock);

                        /* ADDBA state */
                        rxtid->addba_exchangecomplete = 0;
                }
        }
}

void ath_rx_node_cleanup(struct ath_softc *sc, struct ath_node *an)
{
        if (sc->sc_rxaggr) {
                struct ath_arx_tid *rxtid;
                int tidno, i;

                /* Init per tid rx state */
                for (tidno = 0, rxtid = &an->an_aggr.rx.tid[tidno];
                                tidno < WME_NUM_TID;
                                tidno++, rxtid++) {

                        if (!rxtid->addba_exchangecomplete)
                                continue;

                        /* must cancel timer first */
                        del_timer_sync(&rxtid->timer);

                        /* drop any pending sub-frames */
                        ath_rx_flush_tid(sc, rxtid, 1);

                        for (i = 0; i < ATH_TID_MAX_BUFS; i++)
                                ASSERT(rxtid->rxbuf[i].rx_wbuf == NULL);

                        rxtid->addba_exchangecomplete = 0;
                }
        }

}

/* Cleanup per-node receive state */

void ath_rx_node_free(struct ath_softc *sc, struct ath_node *an)
{
        ath_rx_node_cleanup(sc, an);
}

dma_addr_t ath_skb_map_single(struct ath_softc *sc,
                              struct sk_buff *skb,
                              int direction,
                              dma_addr_t *pa)
{
        /*
         * NB: do NOT use skb->len, which is 0 on initialization.
         * Use skb's entire data area instead.
         */
        *pa = pci_map_single(sc->pdev, skb->data,
                skb_end_pointer(skb) - skb->head, direction);
        return *pa;
}

void ath_skb_unmap_single(struct ath_softc *sc,
                          struct sk_buff *skb,
                          int direction,
                          dma_addr_t *pa)
{
        /* Unmap skb's entire data area */
        pci_unmap_single(sc->pdev, *pa,
                skb_end_pointer(skb) - skb->head, direction);
}