/*
 * 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 == 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 i, rate = 0;

        sband = &common->sbands[sc->cur_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;
        for (i = 0; i < 4; i++)
                info.txpower[i] = 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);

        ath_assign_seq(common, skb);

        /* Always assign NOA attr when MCC enabled */
        if (ath9k_is_chanctx_enabled())
                ath9k_beacon_add_noa(sc, avp, 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))) {
                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->cur_chan->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;

        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;
        list_add_tail(&bf->list, &sc->beacon.bbuf);

        tasklet_enable(&sc->bcon_tasklet);
}

void ath9k_beacon_ensure_primary_slot(struct ath_softc *sc)
{
        struct ath_common *common = ath9k_hw_common(sc->sc_ah);
        struct ieee80211_vif *vif;
        struct ath_vif *avp;
        s64 tsfadjust;
        u32 offset;
        int first_slot = ATH_BCBUF;
        int slot;

        tasklet_disable_in_atomic(&sc->bcon_tasklet);

        /* Find first taken slot. */
        for (slot = 0; slot < ATH_BCBUF; slot++) {
                if (sc->beacon.bslot[slot]) {
                        first_slot = slot;
                        break;
                }
        }
        if (first_slot == 0)
                goto out;

        /* Re-enumarate all slots, moving them forward. */
        for (slot = 0; slot < ATH_BCBUF; slot++) {
                if (slot + first_slot < ATH_BCBUF) {
                        vif = sc->beacon.bslot[slot + first_slot];
                        sc->beacon.bslot[slot] = vif;

                        if (vif) {
                                avp = (void *)vif->drv_priv;
                                avp->av_bslot = slot;
                        }
                } else {
                        sc->beacon.bslot[slot] = NULL;
                }
        }

        vif = sc->beacon.bslot[0];
        if (WARN_ON(!vif))
                goto out;

        /* Get the tsf_adjust value for the new first slot. */
        avp = (void *)vif->drv_priv;
        tsfadjust = le64_to_cpu(avp->tsf_adjust);

        ath_dbg(common, CONFIG,
                "Adjusting global TSF after beacon slot reassignment: %lld\n",
                (signed long long)tsfadjust);

        /* Modify TSF as required and update the HW. */
        avp->chanctx->tsf_val += tsfadjust;
        if (sc->cur_chan == avp->chanctx) {
                offset = ath9k_hw_get_tsf_offset(&avp->chanctx->tsf_ts, NULL);
                ath9k_hw_settsf64(sc->sc_ah, avp->chanctx->tsf_val + offset);
        }

        /* The slots tsf_adjust will be updated by ath9k_beacon_config later. */

out:
        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_chan->beacon;
        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;
}

static void ath9k_set_tsfadjust(struct ath_softc *sc,
                                struct ath_beacon_config *cur_conf)
{
        struct ath_common *common = ath9k_hw_common(sc->sc_ah);
        s64 tsfadjust;
        int slot;

        for (slot = 0; slot < ATH_BCBUF; slot++) {
                struct ath_vif *avp;

                if (!sc->beacon.bslot[slot])
                        continue;

                avp = (void *)sc->beacon.bslot[slot]->drv_priv;

                /* tsf_adjust is added to the TSF value. We send out the
                 * beacon late, so need to adjust the TSF starting point to be
                 * later in time (i.e. the theoretical first beacon has a TSF
                 * of 0 after correction).
                 */
                tsfadjust = cur_conf->beacon_interval * avp->av_bslot;
                tsfadjust = -TU_TO_USEC(tsfadjust) / ATH_BCBUF;
                avp->tsf_adjust = cpu_to_le64(tsfadjust);

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

bool ath9k_csa_is_finished(struct ath_softc *sc, struct ieee80211_vif *vif)
{
        if (!vif || !vif->csa_active)
                return false;

        if (!ieee80211_beacon_cntdwn_is_complete(vif))
                return false;

        ieee80211_csa_finish(vif);
        return true;
}

static void ath9k_csa_update_vif(void *data, u8 *mac, struct ieee80211_vif *vif)
{
        struct ath_softc *sc = data;
        ath9k_csa_is_finished(sc, vif);
}

void ath9k_csa_update(struct ath_softc *sc)
{
        ieee80211_iterate_active_interfaces_atomic(sc->hw,
                                                   IEEE80211_IFACE_ITER_NORMAL,
                                                   ath9k_csa_update_vif, sc);
}

void ath9k_beacon_tasklet(struct tasklet_struct *t)
{
        struct ath_softc *sc = from_tasklet(sc, t, bcon_tasklet);
        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(ATH_OP_HW_RESET, &common->op_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++;

                ath9k_hw_check_nav(ah);

                /*
                 * If the previous beacon has not been transmitted
                 * and a MAC/BB hang has been identified, return
                 * here because a chip reset would have been
                 * initiated.
                 */
                if (!ath_hw_check(sc))
                        return;

                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];

        /* EDMA devices check that in the tx completion function. */
        if (!edma) {
                if (ath9k_is_chanctx_enabled()) {
                        ath_chanctx_beacon_sent_ev(sc,
                                          ATH_CHANCTX_EVENT_BEACON_SENT);
                }

                if (ath9k_csa_is_finished(sc, vif))
                        return;
        }

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

        if (ath9k_is_chanctx_enabled()) {
                ath_chanctx_event(sc, vif, ATH_CHANCTX_EVENT_BEACON_PREPARE);
        }

        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)
{
        struct ath_hw *ah = sc->sc_ah;

        ath9k_hw_disable_interrupts(ah);
        ath9k_beaconq_config(sc);
        ath9k_hw_beaconinit(ah, nexttbtt, intval);
        ah->imask |= ATH9K_INT_SWBA;
        sc->beacon.bmisscnt = 0;
        ath9k_hw_set_interrupts(ah);
        ath9k_hw_enable_interrupts(ah);
}

static void ath9k_beacon_stop(struct ath_softc *sc)
{
        ath9k_hw_disable_interrupts(sc->sc_ah);
        sc->sc_ah->imask &= ~(ATH9K_INT_SWBA | ATH9K_INT_BMISS);
        sc->beacon.bmisscnt = 0;
        ath9k_hw_set_interrupts(sc->sc_ah);
        ath9k_hw_enable_interrupts(sc->sc_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;

        ath9k_cmn_beacon_config_ap(ah, conf, ATH_BCBUF);
        ath9k_beacon_init(sc, conf->nexttbtt, conf->intval);
}

static void ath9k_beacon_config_sta(struct ath_hw *ah,
                                    struct ath_beacon_config *conf)
{
        struct ath9k_beacon_state bs;

        if (ath9k_cmn_beacon_config_sta(ah, conf, &bs) == -EPERM)
                return;

        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);

        ath9k_reset_beacon_status(sc);

        ath9k_cmn_beacon_config_adhoc(ah, conf);

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

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

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

        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->dtim_count = 1;
        cur_conf->ibss_creator = bss_conf->ibss_creator;

        /*
         * 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;

        cur_conf->bmiss_timeout =
                ATH_DEFAULT_BMISS_LIMIT * cur_conf->beacon_interval;

        /*
         * 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;

        ath9k_set_tsfadjust(sc, cur_conf);
}

void ath9k_beacon_config(struct ath_softc *sc, struct ieee80211_vif *main_vif,
                         bool beacons)
{
        struct ath_hw *ah = sc->sc_ah;
        struct ath_common *common = ath9k_hw_common(ah);
        struct ath_vif *avp;
        struct ath_chanctx *ctx;
        struct ath_beacon_config *cur_conf;
        unsigned long flags;
        bool enabled;
        bool skip_beacon = false;

        if (!beacons) {
                clear_bit(ATH_OP_BEACONS, &common->op_flags);
                ath9k_beacon_stop(sc);
                return;
        }

        if (WARN_ON(!main_vif))
                return;

        avp = (void *)main_vif->drv_priv;
        ctx = avp->chanctx;
        cur_conf = &ctx->beacon;
        enabled = cur_conf->enable_beacon;
        cur_conf->enable_beacon = beacons;

        if (sc->sc_ah->opmode == NL80211_IFTYPE_STATION) {
                ath9k_cache_beacon_config(sc, ctx, &main_vif->bss_conf);

                ath9k_set_beacon(sc);
                set_bit(ATH_OP_BEACONS, &common->op_flags);
                return;
        }

        /* Update the beacon configuration. */
        ath9k_cache_beacon_config(sc, ctx, &main_vif->bss_conf);

        /*
         * Configure the HW beacon registers only when we have a valid
         * beacon interval.
         */
        if (cur_conf->beacon_interval) {
                /* Special case to sync the TSF when joining an existing IBSS.
                 * This is only done if no AP interface is active.
                 * Note that mac80211 always resets the TSF when creating a new
                 * IBSS interface.
                 */
                if (sc->sc_ah->opmode == NL80211_IFTYPE_ADHOC &&
                    !enabled && beacons && !main_vif->bss_conf.ibss_creator) {
                        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;
                }

                /*
                 * Do not set the ATH_OP_BEACONS flag for IBSS joiner mode
                 * here, it is done in ath9k_beacon_config_adhoc().
                 */
                if (beacons && !skip_beacon) {
                        set_bit(ATH_OP_BEACONS, &common->op_flags);
                        ath9k_set_beacon(sc);
                } else {
                        clear_bit(ATH_OP_BEACONS, &common->op_flags);
                        ath9k_beacon_stop(sc);
                }
        } else {
                clear_bit(ATH_OP_BEACONS, &common->op_flags);
                ath9k_beacon_stop(sc);
        }
}

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_chan->beacon;

        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->sc_ah, cur_conf);
                break;
        default:
                ath_dbg(common, CONFIG, "Unsupported beaconing mode\n");
                return;
        }
}