/*
 * 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"

#define FUDGE 2

static void ath9k_reset_beacon_status(struct ath_softc *sc)
{
        sc->beacon.tx_processed = false;
        sc->beacon.tx_last = false;
}

/*
 *  This function will modify certain transmit queue properties depending on
 *  the operating mode of the station (AP or AdHoc).  Parameters are AIFS
 *  settings and channel width min/max
*/
static void ath9k_beaconq_config(struct ath_softc *sc)
{
        struct ath_hw *ah = sc->sc_ah;
        struct ath_common *common = ath9k_hw_common(ah);
        struct ath9k_tx_queue_info qi, qi_be;
        struct ath_txq *txq;

        ath9k_hw_get_txq_props(ah, sc->beacon.beaconq, &qi);

        if (sc->sc_ah->opmode == NL80211_IFTYPE_AP ||
            sc->sc_ah->opmode == NL80211_IFTYPE_MESH_POINT) {
                /* Always burst out beacon and CAB traffic. */
                qi.tqi_aifs = 1;
                qi.tqi_cwmin = 0;
                qi.tqi_cwmax = 0;
        } else {
                /* Adhoc mode; important thing is to use 2x cwmin. */
                txq = sc->tx.txq_map[IEEE80211_AC_BE];
                ath9k_hw_get_txq_props(ah, txq->axq_qnum, &qi_be);
                qi.tqi_aifs = qi_be.tqi_aifs;
                if (ah->slottime == ATH9K_SLOT_TIME_20)
                        qi.tqi_cwmin = 2*qi_be.tqi_cwmin;
                else
                        qi.tqi_cwmin = 4*qi_be.tqi_cwmin;
                qi.tqi_cwmax = qi_be.tqi_cwmax;
        }

        if (!ath9k_hw_set_txq_props(ah, sc->beacon.beaconq, &qi)) {
                ath_err(common, "Unable to update h/w beacon queue parameters\n");
        } else {
                ath9k_hw_resettxqueue(ah, sc->beacon.beaconq);
        }
}

/*
 *  Associates the beacon frame buffer with a transmit descriptor.  Will set
 *  up rate codes, and channel flags. Beacons are always sent out at the
 *  lowest rate, and are not retried.
*/
static void ath9k_beacon_setup(struct ath_softc *sc, struct ieee80211_vif *vif,
                             struct ath_buf *bf, int rateidx)
{
        struct sk_buff *skb = bf->bf_mpdu;
        struct ath_hw *ah = sc->sc_ah;
        struct ath_common *common = ath9k_hw_common(ah);
        struct ath_tx_info info;
        struct ieee80211_supported_band *sband;
        u8 chainmask = ah->txchainmask;
        u8 rate = 0;

        sband = &sc->sbands[common->hw->conf.chandef.chan->band];
        rate = sband->bitrates[rateidx].hw_value;
        if (vif->bss_conf.use_short_preamble)
                rate |= sband->bitrates[rateidx].hw_value_short;

        memset(&info, 0, sizeof(info));
        info.pkt_len = skb->len + FCS_LEN;
        info.type = ATH9K_PKT_TYPE_BEACON;
        info.txpower = MAX_RATE_POWER;
        info.keyix = ATH9K_TXKEYIX_INVALID;
        info.keytype = ATH9K_KEY_TYPE_CLEAR;
        info.flags = ATH9K_TXDESC_NOACK | ATH9K_TXDESC_CLRDMASK;

        info.buf_addr[0] = bf->bf_buf_addr;
        info.buf_len[0] = roundup(skb->len, 4);

        info.is_first = true;
        info.is_last = true;

        info.qcu = sc->beacon.beaconq;

        info.rates[0].Tries = 1;
        info.rates[0].Rate = rate;
        info.rates[0].ChSel = ath_txchainmask_reduction(sc, chainmask, rate);

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

static struct ath_buf *ath9k_beacon_generate(struct ieee80211_hw *hw,
                                             struct ieee80211_vif *vif)
{
        struct ath_softc *sc = hw->priv;
        struct ath_common *common = ath9k_hw_common(sc->sc_ah);
        struct ath_buf *bf;
        struct ath_vif *avp = (void *)vif->drv_priv;
        struct sk_buff *skb;
        struct ath_txq *cabq = sc->beacon.cabq;
        struct ieee80211_tx_info *info;
        struct ieee80211_mgmt *mgmt_hdr;
        int cabq_depth;

        if (avp->av_bcbuf == NULL)
                return NULL;

        bf = avp->av_bcbuf;
        skb = bf->bf_mpdu;
        if (skb) {
                dma_unmap_single(sc->dev, bf->bf_buf_addr,
                                 skb->len, DMA_TO_DEVICE);
                dev_kfree_skb_any(skb);
                bf->bf_buf_addr = 0;
                bf->bf_mpdu = NULL;
        }

        skb = ieee80211_beacon_get(hw, vif);
        if (skb == NULL)
                return NULL;

        bf->bf_mpdu = skb;

        mgmt_hdr = (struct ieee80211_mgmt *)skb->data;
        mgmt_hdr->u.beacon.timestamp = avp->tsf_adjust;

        info = IEEE80211_SKB_CB(skb);
        if (info->flags & IEEE80211_TX_CTL_ASSIGN_SEQ) {
                /*
                 * TODO: make sure the seq# gets assigned properly (vs. other
                 * TX frames)
                 */
                struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
                sc->tx.seq_no += 0x10;
                hdr->seq_ctrl &= cpu_to_le16(IEEE80211_SCTL_FRAG);
                hdr->seq_ctrl |= cpu_to_le16(sc->tx.seq_no);
        }

        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))) {
                dev_kfree_skb_any(skb);
                bf->bf_mpdu = NULL;
                bf->bf_buf_addr = 0;
                ath_err(common, "dma_mapping_error on beaconing\n");
                return NULL;
        }

        skb = ieee80211_get_buffered_bc(hw, vif);

        /*
         * if the CABQ traffic from previous DTIM is pending and the current
         *  beacon is also a DTIM.
         *  1) if there is only one vif let the cab traffic continue.
         *  2) if there are more than one vif and we are using staggered
         *     beacons, then drain the cabq by dropping all the frames in
         *     the cabq so that the current vifs cab traffic can be scheduled.
         */
        spin_lock_bh(&cabq->axq_lock);
        cabq_depth = cabq->axq_depth;
        spin_unlock_bh(&cabq->axq_lock);

        if (skb && cabq_depth) {
                if (sc->nvifs > 1) {
                        ath_dbg(common, BEACON,
                                "Flushing previous cabq traffic\n");
                        ath_draintxq(sc, cabq);
                }
        }

        ath9k_beacon_setup(sc, vif, bf, info->control.rates[0].idx);

        if (skb)
                ath_tx_cabq(hw, vif, skb);

        return bf;
}

void ath9k_beacon_assign_slot(struct ath_softc *sc, struct ieee80211_vif *vif)
{
        struct ath_common *common = ath9k_hw_common(sc->sc_ah);
        struct ath_vif *avp = (void *)vif->drv_priv;
        int slot;

        avp->av_bcbuf = list_first_entry(&sc->beacon.bbuf, struct ath_buf, list);
        list_del(&avp->av_bcbuf->list);

        for (slot = 0; slot < ATH_BCBUF; slot++) {
                if (sc->beacon.bslot[slot] == NULL) {
                        avp->av_bslot = slot;
                        break;
                }
        }

        sc->beacon.bslot[avp->av_bslot] = vif;
        sc->nbcnvifs++;

        ath_dbg(common, CONFIG, "Added interface at beacon slot: %d\n",
                avp->av_bslot);
}

void ath9k_beacon_remove_slot(struct ath_softc *sc, struct ieee80211_vif *vif)
{
        struct ath_common *common = ath9k_hw_common(sc->sc_ah);
        struct ath_vif *avp = (void *)vif->drv_priv;
        struct ath_buf *bf = avp->av_bcbuf;

        ath_dbg(common, CONFIG, "Removing interface at beacon slot: %d\n",
                avp->av_bslot);

        tasklet_disable(&sc->bcon_tasklet);

        if (bf && bf->bf_mpdu) {
                struct sk_buff *skb = bf->bf_mpdu;
                dma_unmap_single(sc->dev, bf->bf_buf_addr,
                                 skb->len, DMA_TO_DEVICE);
                dev_kfree_skb_any(skb);
                bf->bf_mpdu = NULL;
                bf->bf_buf_addr = 0;
        }

        avp->av_bcbuf = NULL;
        sc->beacon.bslot[avp->av_bslot] = NULL;
        sc->nbcnvifs--;
        list_add_tail(&bf->list, &sc->beacon.bbuf);

        tasklet_enable(&sc->bcon_tasklet);
}

static int ath9k_beacon_choose_slot(struct ath_softc *sc)
{
        struct ath_common *common = ath9k_hw_common(sc->sc_ah);
        struct ath_beacon_config *cur_conf = &sc->cur_beacon_conf;
        u16 intval;
        u32 tsftu;
        u64 tsf;
        int slot;

        if (sc->sc_ah->opmode != NL80211_IFTYPE_AP &&
            sc->sc_ah->opmode != NL80211_IFTYPE_MESH_POINT) {
                ath_dbg(common, BEACON, "slot 0, tsf: %llu\n",
                        ath9k_hw_gettsf64(sc->sc_ah));
                return 0;
        }

        intval = cur_conf->beacon_interval ? : ATH_DEFAULT_BINTVAL;
        tsf = ath9k_hw_gettsf64(sc->sc_ah);
        tsf += TU_TO_USEC(sc->sc_ah->config.sw_beacon_response_time);
        tsftu = TSF_TO_TU((tsf * ATH_BCBUF) >>32, tsf * ATH_BCBUF);
        slot = (tsftu % (intval * ATH_BCBUF)) / intval;

        ath_dbg(common, BEACON, "slot: %d tsf: %llu tsftu: %u\n",
                slot, tsf, tsftu / ATH_BCBUF);

        return slot;
}

void ath9k_set_tsfadjust(struct ath_softc *sc, struct ieee80211_vif *vif)
{
        struct ath_common *common = ath9k_hw_common(sc->sc_ah);
        struct ath_beacon_config *cur_conf = &sc->cur_beacon_conf;
        struct ath_vif *avp = (void *)vif->drv_priv;
        u64 tsfadjust;

        if (avp->av_bslot == 0)
                return;

        tsfadjust = cur_conf->beacon_interval * avp->av_bslot / ATH_BCBUF;
        avp->tsf_adjust = cpu_to_le64(TU_TO_USEC(tsfadjust));

        ath_dbg(common, CONFIG, "tsfadjust is: %llu for bslot: %d\n",
                (unsigned long long)tsfadjust, avp->av_bslot);
}

void ath9k_beacon_tasklet(unsigned long data)
{
        struct ath_softc *sc = (struct ath_softc *)data;
        struct ath_hw *ah = sc->sc_ah;
        struct ath_common *common = ath9k_hw_common(ah);
        struct ath_buf *bf = NULL;
        struct ieee80211_vif *vif;
        bool edma = !!(ah->caps.hw_caps & ATH9K_HW_CAP_EDMA);
        int slot;

        if (test_bit(SC_OP_HW_RESET, &sc->sc_flags)) {
                ath_dbg(common, RESET,
                        "reset work is pending, skip beaconing now\n");
                return;
        }

        /*
         * Check if the previous beacon has gone out.  If
         * not don't try to post another, skip this period
         * and wait for the next.  Missed beacons indicate
         * a problem and should not occur.  If we miss too
         * many consecutive beacons reset the device.
         */
        if (ath9k_hw_numtxpending(ah, sc->beacon.beaconq) != 0) {
                sc->beacon.bmisscnt++;

                if (!ath9k_hw_check_alive(ah))
                        ieee80211_queue_work(sc->hw, &sc->hw_check_work);

                if (sc->beacon.bmisscnt < BSTUCK_THRESH * sc->nbcnvifs) {
                        ath_dbg(common, BSTUCK,
                                "missed %u consecutive beacons\n",
                                sc->beacon.bmisscnt);
                        ath9k_hw_stop_dma_queue(ah, sc->beacon.beaconq);
                        if (sc->beacon.bmisscnt > 3)
                                ath9k_hw_bstuck_nfcal(ah);
                } else if (sc->beacon.bmisscnt >= BSTUCK_THRESH) {
                        ath_dbg(common, BSTUCK, "beacon is officially stuck\n");
                        sc->beacon.bmisscnt = 0;
                        ath9k_queue_reset(sc, RESET_TYPE_BEACON_STUCK);
                }

                return;
        }

        slot = ath9k_beacon_choose_slot(sc);
        vif = sc->beacon.bslot[slot];

        if (!vif || !vif->bss_conf.enable_beacon)
                return;

        bf = ath9k_beacon_generate(sc->hw, vif);

        if (sc->beacon.bmisscnt != 0) {
                ath_dbg(common, BSTUCK, "resume beacon xmit after %u misses\n",
                        sc->beacon.bmisscnt);
                sc->beacon.bmisscnt = 0;
        }

        /*
         * Handle slot time change when a non-ERP station joins/leaves
         * an 11g network.  The 802.11 layer notifies us via callback,
         * we mark updateslot, then wait one beacon before effecting
         * the change.  This gives associated stations at least one
         * beacon interval to note the state change.
         *
         * NB: The slot time change state machine is clocked according
         *     to whether we are bursting or staggering beacons.  We
         *     recognize the request to update and record the current
         *     slot then don't transition until that slot is reached
         *     again.  If we miss a beacon for that slot then we'll be
         *     slow to transition but we'll be sure at least one beacon
         *     interval has passed.  When bursting slot is always left
         *     set to ATH_BCBUF so this check is a noop.
         */
        if (sc->beacon.updateslot == UPDATE) {
                sc->beacon.updateslot = COMMIT;
                sc->beacon.slotupdate = slot;
        } else if (sc->beacon.updateslot == COMMIT &&
                   sc->beacon.slotupdate == slot) {
                ah->slottime = sc->beacon.slottime;
                ath9k_hw_init_global_settings(ah);
                sc->beacon.updateslot = OK;
        }

        if (bf) {
                ath9k_reset_beacon_status(sc);

                ath_dbg(common, BEACON,
                        "Transmitting beacon for slot: %d\n", slot);

                /* NB: cabq traffic should already be queued and primed */
                ath9k_hw_puttxbuf(ah, sc->beacon.beaconq, bf->bf_daddr);

                if (!edma)
                        ath9k_hw_txstart(ah, sc->beacon.beaconq);
        }
}

/*
 * Both nexttbtt and intval have to be in usecs.
 */
static void ath9k_beacon_init(struct ath_softc *sc, u32 nexttbtt,
                              u32 intval, bool reset_tsf)
{
        struct ath_hw *ah = sc->sc_ah;

        ath9k_hw_disable_interrupts(ah);
        if (reset_tsf)
                ath9k_hw_reset_tsf(ah);
        ath9k_beaconq_config(sc);
        ath9k_hw_beaconinit(ah, nexttbtt, intval);
        sc->beacon.bmisscnt = 0;
        ath9k_hw_set_interrupts(ah);
        ath9k_hw_enable_interrupts(ah);
}

/*
 * For multi-bss ap support beacons are either staggered evenly over N slots or
 * burst together.  For the former arrange for the SWBA to be delivered for each
 * slot. Slots that are not occupied will generate nothing.
 */
static void ath9k_beacon_config_ap(struct ath_softc *sc,
                                   struct ath_beacon_config *conf)
{
        struct ath_hw *ah = sc->sc_ah;
        struct ath_common *common = ath9k_hw_common(ah);
        u32 nexttbtt, intval;

        /* NB: the beacon interval is kept internally in TU's */
        intval = TU_TO_USEC(conf->beacon_interval);
        intval /= ATH_BCBUF;
        nexttbtt = intval;

        if (conf->enable_beacon)
                ah->imask |= ATH9K_INT_SWBA;
        else
                ah->imask &= ~ATH9K_INT_SWBA;

        ath_dbg(common, BEACON,
                "AP (%s) nexttbtt: %u intval: %u conf_intval: %u\n",
                (conf->enable_beacon) ? "Enable" : "Disable",
                nexttbtt, intval, conf->beacon_interval);

        ath9k_beacon_init(sc, nexttbtt, intval, true);
}

/*
 * This sets up the beacon timers according to the timestamp of the last
 * received beacon and the current TSF, configures PCF and DTIM
 * handling, programs the sleep registers so the hardware will wakeup in
 * time to receive beacons, and configures the beacon miss handling so
 * we'll receive a BMISS interrupt when we stop seeing beacons from the AP
 * we've associated with.
 */
static void ath9k_beacon_config_sta(struct ath_softc *sc,
                                    struct ath_beacon_config *conf)
{
        struct ath_hw *ah = sc->sc_ah;
        struct ath_common *common = ath9k_hw_common(ah);
        struct ath9k_beacon_state bs;
        int dtimperiod, dtimcount, sleepduration;
        int cfpperiod, cfpcount;
        u32 nexttbtt = 0, intval, tsftu;
        u64 tsf;
        int num_beacons, offset, dtim_dec_count, cfp_dec_count;

        /* No need to configure beacon if we are not associated */
        if (!test_bit(SC_OP_PRIM_STA_VIF, &sc->sc_flags)) {
                ath_dbg(common, BEACON,
                        "STA is not yet associated..skipping beacon config\n");
                return;
        }

        memset(&bs, 0, sizeof(bs));
        intval = conf->beacon_interval;

        /*
         * Setup dtim and cfp parameters according to
         * last beacon we received (which may be none).
         */
        dtimperiod = conf->dtim_period;
        dtimcount = conf->dtim_count;
        if (dtimcount >= dtimperiod)    /* NB: sanity check */
                dtimcount = 0;
        cfpperiod = 1;                  /* NB: no PCF support yet */
        cfpcount = 0;

        sleepduration = conf->listen_interval * intval;

        /*
         * Pull nexttbtt forward to reflect the current
         * TSF and calculate dtim+cfp state for the result.
         */
        tsf = ath9k_hw_gettsf64(ah);
        tsftu = TSF_TO_TU(tsf>>32, tsf) + FUDGE;

        num_beacons = tsftu / intval + 1;
        offset = tsftu % intval;
        nexttbtt = tsftu - offset;
        if (offset)
                nexttbtt += intval;

        /* DTIM Beacon every dtimperiod Beacon */
        dtim_dec_count = num_beacons % dtimperiod;
        /* CFP every cfpperiod DTIM Beacon */
        cfp_dec_count = (num_beacons / dtimperiod) % cfpperiod;
        if (dtim_dec_count)
                cfp_dec_count++;

        dtimcount -= dtim_dec_count;
        if (dtimcount < 0)
                dtimcount += dtimperiod;

        cfpcount -= cfp_dec_count;
        if (cfpcount < 0)
                cfpcount += cfpperiod;

        bs.bs_intval = intval;
        bs.bs_nexttbtt = nexttbtt;
        bs.bs_dtimperiod = dtimperiod*intval;
        bs.bs_nextdtim = bs.bs_nexttbtt + dtimcount*intval;
        bs.bs_cfpperiod = cfpperiod*bs.bs_dtimperiod;
        bs.bs_cfpnext = bs.bs_nextdtim + cfpcount*bs.bs_dtimperiod;
        bs.bs_cfpmaxduration = 0;

        /*
         * Calculate the number of consecutive beacons to miss* before taking
         * a BMISS interrupt. The configuration is specified in TU so we only
         * need calculate based on the beacon interval.  Note that we clamp the
         * result to at most 15 beacons.
         */
        if (sleepduration > intval) {
                bs.bs_bmissthreshold = conf->listen_interval *
                        ATH_DEFAULT_BMISS_LIMIT / 2;
        } else {
                bs.bs_bmissthreshold = DIV_ROUND_UP(conf->bmiss_timeout, intval);
                if (bs.bs_bmissthreshold > 15)
                        bs.bs_bmissthreshold = 15;
                else if (bs.bs_bmissthreshold <= 0)
                        bs.bs_bmissthreshold = 1;
        }

        /*
         * Calculate sleep duration. The configuration is given in ms.
         * We ensure a multiple of the beacon period is used. Also, if the sleep
         * duration is greater than the DTIM period then it makes senses
         * to make it a multiple of that.
         *
         * XXX fixed at 100ms
         */

        bs.bs_sleepduration = roundup(IEEE80211_MS_TO_TU(100), sleepduration);
        if (bs.bs_sleepduration > bs.bs_dtimperiod)
                bs.bs_sleepduration = bs.bs_dtimperiod;

        /* TSF out of range threshold fixed at 1 second */
        bs.bs_tsfoor_threshold = ATH9K_TSFOOR_THRESHOLD;

        ath_dbg(common, BEACON, "tsf: %llu tsftu: %u\n", tsf, tsftu);
        ath_dbg(common, BEACON,
                "bmiss: %u sleep: %u cfp-period: %u maxdur: %u next: %u\n",
                bs.bs_bmissthreshold, bs.bs_sleepduration,
                bs.bs_cfpperiod, bs.bs_cfpmaxduration, bs.bs_cfpnext);

        /* Set the computed STA beacon timers */

        ath9k_hw_disable_interrupts(ah);
        ath9k_hw_set_sta_beacon_timers(ah, &bs);
        ah->imask |= ATH9K_INT_BMISS;

        ath9k_hw_set_interrupts(ah);
        ath9k_hw_enable_interrupts(ah);
}

static void ath9k_beacon_config_adhoc(struct ath_softc *sc,
                                      struct ath_beacon_config *conf)
{
        struct ath_hw *ah = sc->sc_ah;
        struct ath_common *common = ath9k_hw_common(ah);
        u32 intval, nexttbtt;

        ath9k_reset_beacon_status(sc);

        intval = TU_TO_USEC(conf->beacon_interval);

        if (conf->ibss_creator) {
                nexttbtt = intval;
        } else {
                u32 tbtt, offset, tsftu;
                u64 tsf;

                /*
                 * Pull nexttbtt forward to reflect the current
                 * sync'd TSF.
                 */
                tsf = ath9k_hw_gettsf64(ah);
                tsftu = TSF_TO_TU(tsf >> 32, tsf) + FUDGE;
                offset = tsftu % conf->beacon_interval;
                tbtt = tsftu - offset;
                if (offset)
                        tbtt += conf->beacon_interval;

                nexttbtt = TU_TO_USEC(tbtt);
        }

        if (conf->enable_beacon)
                ah->imask |= ATH9K_INT_SWBA;
        else
                ah->imask &= ~ATH9K_INT_SWBA;

        ath_dbg(common, BEACON,
                "IBSS (%s) nexttbtt: %u intval: %u conf_intval: %u\n",
                (conf->enable_beacon) ? "Enable" : "Disable",
                nexttbtt, intval, conf->beacon_interval);

        ath9k_beacon_init(sc, nexttbtt, intval, conf->ibss_creator);

        /*
         * Set the global 'beacon has been configured' flag for the
         * joiner case in IBSS mode.
         */
        if (!conf->ibss_creator && conf->enable_beacon)
                set_bit(SC_OP_BEACONS, &sc->sc_flags);
}

bool ath9k_allow_beacon_config(struct ath_softc *sc, struct ieee80211_vif *vif)
{
        struct ath_common *common = ath9k_hw_common(sc->sc_ah);
        struct ath_vif *avp = (void *)vif->drv_priv;

        if (sc->sc_ah->opmode == NL80211_IFTYPE_AP) {
                if ((vif->type != NL80211_IFTYPE_AP) ||
                    (sc->nbcnvifs > 1)) {
                        ath_dbg(common, CONFIG,
                                "An AP interface is already present !\n");
                        return false;
                }
        }

        if (sc->sc_ah->opmode == NL80211_IFTYPE_STATION) {
                if ((vif->type == NL80211_IFTYPE_STATION) &&
                    test_bit(SC_OP_BEACONS, &sc->sc_flags) &&
                    !avp->primary_sta_vif) {
                        ath_dbg(common, CONFIG,
                                "Beacon already configured for a station interface\n");
                        return false;
                }
        }

        return true;
}

static void ath9k_cache_beacon_config(struct ath_softc *sc,
                                      struct ieee80211_bss_conf *bss_conf)
{
        struct ath_common *common = ath9k_hw_common(sc->sc_ah);
        struct ath_beacon_config *cur_conf = &sc->cur_beacon_conf;

        ath_dbg(common, BEACON,
                "Caching beacon data for BSS: %pM\n", bss_conf->bssid);

        cur_conf->beacon_interval = bss_conf->beacon_int;
        cur_conf->dtim_period = bss_conf->dtim_period;
        cur_conf->listen_interval = 1;
        cur_conf->dtim_count = 1;
        cur_conf->ibss_creator = bss_conf->ibss_creator;
        cur_conf->bmiss_timeout =
                ATH_DEFAULT_BMISS_LIMIT * cur_conf->beacon_interval;

        /*
         * It looks like mac80211 may end up using beacon interval of zero in
         * some cases (at least for mesh point). Avoid getting into an
         * infinite loop by using a bit safer value instead. To be safe,
         * do sanity check on beacon interval for all operating modes.
         */
        if (cur_conf->beacon_interval == 0)
                cur_conf->beacon_interval = 100;

        /*
         * We don't parse dtim period from mac80211 during the driver
         * initialization as it breaks association with hidden-ssid
         * AP and it causes latency in roaming
         */
        if (cur_conf->dtim_period == 0)
                cur_conf->dtim_period = 1;

}

void ath9k_beacon_config(struct ath_softc *sc, struct ieee80211_vif *vif,
                         u32 changed)
{
        struct ieee80211_bss_conf *bss_conf = &vif->bss_conf;
        struct ath_beacon_config *cur_conf = &sc->cur_beacon_conf;
        unsigned long flags;
        bool skip_beacon = false;

        if (sc->sc_ah->opmode == NL80211_IFTYPE_STATION) {
                ath9k_cache_beacon_config(sc, bss_conf);
                ath9k_set_beacon(sc);
                set_bit(SC_OP_BEACONS, &sc->sc_flags);
                return;

        }

        /*
         * Take care of multiple interfaces when
         * enabling/disabling SWBA.
         */
        if (changed & BSS_CHANGED_BEACON_ENABLED) {
                if (!bss_conf->enable_beacon &&
                    (sc->nbcnvifs <= 1)) {
                        cur_conf->enable_beacon = false;
                } else if (bss_conf->enable_beacon) {
                        cur_conf->enable_beacon = true;
                        ath9k_cache_beacon_config(sc, bss_conf);
                }
        }

        /*
         * Configure the HW beacon registers only when we have a valid
         * beacon interval.
         */
        if (cur_conf->beacon_interval) {
                /*
                 * If we are joining an existing IBSS network, start beaconing
                 * only after a TSF-sync has taken place. Ensure that this
                 * happens by setting the appropriate flags.
                 */
                if ((changed & BSS_CHANGED_IBSS) && !bss_conf->ibss_creator &&
                    bss_conf->enable_beacon) {
                        spin_lock_irqsave(&sc->sc_pm_lock, flags);
                        sc->ps_flags |= PS_BEACON_SYNC | PS_WAIT_FOR_BEACON;
                        spin_unlock_irqrestore(&sc->sc_pm_lock, flags);
                        skip_beacon = true;
                } else {
                        ath9k_set_beacon(sc);
                }

                /*
                 * Do not set the SC_OP_BEACONS flag for IBSS joiner mode
                 * here, it is done in ath9k_beacon_config_adhoc().
                 */
                if (cur_conf->enable_beacon && !skip_beacon)
                        set_bit(SC_OP_BEACONS, &sc->sc_flags);
                else
                        clear_bit(SC_OP_BEACONS, &sc->sc_flags);
        }
}

void ath9k_set_beacon(struct ath_softc *sc)
{
        struct ath_common *common = ath9k_hw_common(sc->sc_ah);
        struct ath_beacon_config *cur_conf = &sc->cur_beacon_conf;

        switch (sc->sc_ah->opmode) {
        case NL80211_IFTYPE_AP:
        case NL80211_IFTYPE_MESH_POINT:
                ath9k_beacon_config_ap(sc, cur_conf);
                break;
        case NL80211_IFTYPE_ADHOC:
                ath9k_beacon_config_adhoc(sc, cur_conf);
                break;
        case NL80211_IFTYPE_STATION:
                ath9k_beacon_config_sta(sc, cur_conf);
                break;
        default:
                ath_dbg(common, CONFIG, "Unsupported beaconing mode\n");
                return;
        }
}