beacon.c

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/*
 * 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) {
        /* 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[WME_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.channel->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 void ath9k_tx_cabq(struct ieee80211_hw *hw, struct sk_buff *skb)
{
    struct ath_softc *sc = hw->priv;
    struct ath_common *common = ath9k_hw_common(sc->sc_ah);
    struct ath_tx_control txctl;

    memset(&txctl, 0, sizeof(struct ath_tx_control));
    txctl.txq = sc->beacon.cabq;

    ath_dbg(common, XMIT, "transmitting CABQ packet, skb: %p\n", skb);

    if (ath_tx_start(hw, skb, &txctl) != 0) {
        ath_dbg(common, XMIT, "CABQ TX failed\n");
        ieee80211_free_txskb(hw, skb);
    }
}

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;
    }

    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, false);
        }
    }

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

    while (skb) {
        ath9k_tx_cabq(hw, skb);
        skb = ieee80211_get_buffered_bc(hw, vif);
    }

    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) {
        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);
    WARN_ON(!bf);

    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);
    }
}

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_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 nexttbtt: %u intval: %u conf_intval: %u\n",
        nexttbtt, intval, conf->beacon_interval);

    ath9k_beacon_init(sc, nexttbtt, intval);
}

/*
 * 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);
    nexttbtt = intval;

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

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

    ath9k_beacon_init(sc, nexttbtt, intval);
}

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->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;

    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);
    } else {
        /*
         * 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);
            }
        }

        if (cur_conf->beacon_interval) {
            ath9k_set_beacon(sc);

            if (cur_conf->enable_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:
        ath9k_beacon_config_ap(sc, cur_conf);
        break;
    case NL80211_IFTYPE_ADHOC:
    case NL80211_IFTYPE_MESH_POINT:
        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;
    }
}