[deliverable/linux.git] / drivers / net / wireless / ath / ath9k / beacon.c

/*
 * Copyright (c) 2008-2009 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 "ath9k.h"

#define FUDGE 2

/*
 *  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 int ath_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;

        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. */
                qi.tqi_aifs = sc->beacon.beacon_qi.tqi_aifs;
                qi.tqi_cwmin = 2*sc->beacon.beacon_qi.tqi_cwmin;
                qi.tqi_cwmax = sc->beacon.beacon_qi.tqi_cwmax;
        }

        if (!ath9k_hw_set_txq_props(ah, sc->beacon.beaconq, &qi)) {
                ath_print(common, ATH_DBG_FATAL,
                          "Unable to update h/w beacon queue parameters\n");
                return 0;
        } else {
                ath9k_hw_resettxqueue(ah, sc->beacon.beaconq);
                return 1;
        }
}

/*
 *  Associates the beacon frame buffer with a transmit descriptor.  Will set
 *  up all required antenna switch parameters, rate codes, and channel flags.
 *  Beacons are always sent out at the lowest rate, and are not retried.
*/
static void ath_beacon_setup(struct ath_softc *sc, struct ath_vif *avp,
                             struct ath_buf *bf)
{
        struct sk_buff *skb = bf->bf_mpdu;
        struct ath_hw *ah = sc->sc_ah;
        struct ath_desc *ds;
        struct ath9k_11n_rate_series series[4];
        const struct ath_rate_table *rt;
        int flags, antenna, ctsrate = 0, ctsduration = 0;
        u8 rate;

        ds = bf->bf_desc;
        flags = ATH9K_TXDESC_NOACK;

        if (((sc->sc_ah->opmode == NL80211_IFTYPE_ADHOC) ||
             (sc->sc_ah->opmode == NL80211_IFTYPE_MESH_POINT)) &&
            (ah->caps.hw_caps & ATH9K_HW_CAP_VEOL)) {
                ds->ds_link = bf->bf_daddr; /* self-linked */
                flags |= ATH9K_TXDESC_VEOL;
                /* Let hardware handle antenna switching. */
                antenna = 0;
        } else {
                ds->ds_link = 0;
                /*
                 * Switch antenna every beacon.
                 * Should only switch every beacon period, not for every SWBA
                 * XXX assumes two antennae
                 */
                antenna = ((sc->beacon.ast_be_xmit / sc->nbcnvifs) & 1 ? 2 : 1);
        }

        ds->ds_data = bf->bf_buf_addr;

        rt = sc->cur_rate_table;
        rate = rt->info[0].ratecode;
        if (sc->sc_flags & SC_OP_PREAMBLE_SHORT)
                rate |= rt->info[0].short_preamble;

        ath9k_hw_set11n_txdesc(ah, ds, skb->len + FCS_LEN,
                               ATH9K_PKT_TYPE_BEACON,
                               MAX_RATE_POWER,
                               ATH9K_TXKEYIX_INVALID,
                               ATH9K_KEY_TYPE_CLEAR,
                               flags);

        /* NB: beacon's BufLen must be a multiple of 4 bytes */
        ath9k_hw_filltxdesc(ah, ds, roundup(skb->len, 4),
                            true, true, ds);

        memset(series, 0, sizeof(struct ath9k_11n_rate_series) * 4);
        series[0].Tries = 1;
        series[0].Rate = rate;
        series[0].ChSel = sc->tx_chainmask;
        series[0].RateFlags = (ctsrate) ? ATH9K_RATESERIES_RTS_CTS : 0;
        ath9k_hw_set11n_ratescenario(ah, ds, ds, 0, ctsrate, ctsduration,
                                     series, 4, 0);
}

static struct ath_buf *ath_beacon_generate(struct ieee80211_hw *hw,
                                           struct ieee80211_vif *vif)
{
        struct ath_wiphy *aphy = hw->priv;
        struct ath_softc *sc = aphy->sc;
        struct ath_common *common = ath9k_hw_common(sc->sc_ah);
        struct ath_buf *bf;
        struct ath_vif *avp;
        struct sk_buff *skb;
        struct ath_txq *cabq;
        struct ieee80211_tx_info *info;
        int cabq_depth;

        if (aphy->state != ATH_WIPHY_ACTIVE)
                return NULL;

        avp = (void *)vif->drv_priv;
        cabq = sc->beacon.cabq;

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

        /* Release the old beacon first */

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

        /* Get a new beacon from mac80211 */

        skb = ieee80211_beacon_get(hw, vif);
        bf->bf_mpdu = skb;
        if (skb == NULL)
                return NULL;
        ((struct ieee80211_mgmt *)skb->data)->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 = bf->bf_dmacontext =
                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;
                ath_print(common, ATH_DBG_FATAL,
                          "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_print(common, ATH_DBG_BEACON,
                                  "Flushing previous cabq traffic\n");
                        ath_draintxq(sc, cabq, false);
                }
        }

        ath_beacon_setup(sc, avp, bf);

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

        return bf;
}

/*
 * Startup beacon transmission for adhoc mode when they are sent entirely
 * by the hardware using the self-linked descriptor + veol trick.
*/
static void ath_beacon_start_adhoc(struct ath_softc *sc,
                                   struct ieee80211_vif *vif)
{
        struct ath_hw *ah = sc->sc_ah;
        struct ath_common *common = ath9k_hw_common(ah);
        struct ath_buf *bf;
        struct ath_vif *avp;
        struct sk_buff *skb;

        avp = (void *)vif->drv_priv;

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

        bf = avp->av_bcbuf;
        skb = bf->bf_mpdu;

        ath_beacon_setup(sc, avp, bf);

        /* NB: caller is known to have already stopped tx dma */
        ath9k_hw_puttxbuf(ah, sc->beacon.beaconq, bf->bf_daddr);
        ath9k_hw_txstart(ah, sc->beacon.beaconq);
        ath_print(common, ATH_DBG_BEACON, "TXDP%u = %llx (%p)\n",
                  sc->beacon.beaconq, ito64(bf->bf_daddr), bf->bf_desc);
}

int ath_beaconq_setup(struct ath_hw *ah)
{
        struct ath9k_tx_queue_info qi;

        memset(&qi, 0, sizeof(qi));
        qi.tqi_aifs = 1;
        qi.tqi_cwmin = 0;
        qi.tqi_cwmax = 0;
        /* NB: don't enable any interrupts */
        return ath9k_hw_setuptxqueue(ah, ATH9K_TX_QUEUE_BEACON, &qi);
}

int ath_beacon_alloc(struct ath_wiphy *aphy, struct ieee80211_vif *vif)
{
        struct ath_softc *sc = aphy->sc;
        struct ath_common *common = ath9k_hw_common(sc->sc_ah);
        struct ath_vif *avp;
        struct ath_buf *bf;
        struct sk_buff *skb;
        __le64 tstamp;

        avp = (void *)vif->drv_priv;

        /* Allocate a beacon descriptor if we haven't done so. */
        if (!avp->av_bcbuf) {
                /* Allocate beacon state for hostap/ibss.  We know
                 * a buffer is available. */
                avp->av_bcbuf = list_first_entry(&sc->beacon.bbuf,
                                                 struct ath_buf, list);
                list_del(&avp->av_bcbuf->list);

                if (sc->sc_ah->opmode == NL80211_IFTYPE_AP ||
                    !(sc->sc_ah->caps.hw_caps & ATH9K_HW_CAP_VEOL)) {
                        int slot;
                        /*
                         * Assign the vif to a beacon xmit slot. As
                         * above, this cannot fail to find one.
                         */
                        avp->av_bslot = 0;
                        for (slot = 0; slot < ATH_BCBUF; slot++)
                                if (sc->beacon.bslot[slot] == NULL) {
                                        /*
                                         * XXX hack, space out slots to better
                                         * deal with misses
                                         */
                                        if (slot+1 < ATH_BCBUF &&
                                            sc->beacon.bslot[slot+1] == NULL) {
                                                avp->av_bslot = slot+1;
                                                break;
                                        }
                                        avp->av_bslot = slot;
                                        /* NB: keep looking for a double slot */
                                }
                        BUG_ON(sc->beacon.bslot[avp->av_bslot] != NULL);
                        sc->beacon.bslot[avp->av_bslot] = vif;
                        sc->beacon.bslot_aphy[avp->av_bslot] = aphy;
                        sc->nbcnvifs++;
                }
        }

        /* release the previous beacon frame, if it already exists. */
        bf = avp->av_bcbuf;
        if (bf->bf_mpdu != NULL) {
                skb = bf->bf_mpdu;
                dma_unmap_single(sc->dev, bf->bf_dmacontext,
                                 skb->len, DMA_TO_DEVICE);
                dev_kfree_skb_any(skb);
                bf->bf_mpdu = NULL;
        }

        /* NB: the beacon data buffer must be 32-bit aligned. */
        skb = ieee80211_beacon_get(sc->hw, vif);
        if (skb == NULL) {
                ath_print(common, ATH_DBG_BEACON, "cannot get skb\n");
                return -ENOMEM;
        }

        tstamp = ((struct ieee80211_mgmt *)skb->data)->u.beacon.timestamp;
        sc->beacon.bc_tstamp = le64_to_cpu(tstamp);
        /* Calculate a TSF adjustment factor required for staggered beacons. */
        if (avp->av_bslot > 0) {
                u64 tsfadjust;
                int intval;

                intval = sc->beacon_interval ? : ATH_DEFAULT_BINTVAL;

                /*
                 * Calculate the TSF offset for this beacon slot, i.e., the
                 * number of usecs that need to be added to the timestamp field
                 * in Beacon and Probe Response frames. Beacon slot 0 is
                 * processed at the correct offset, so it does not require TSF
                 * adjustment. Other slots are adjusted to get the timestamp
                 * close to the TBTT for the BSS.
                 */
                tsfadjust = intval * avp->av_bslot / ATH_BCBUF;
                avp->tsf_adjust = cpu_to_le64(TU_TO_USEC(tsfadjust));

                ath_print(common, ATH_DBG_BEACON,
                          "stagger beacons, bslot %d intval "
                          "%u tsfadjust %llu\n",
                          avp->av_bslot, intval, (unsigned long long)tsfadjust);

                ((struct ieee80211_mgmt *)skb->data)->u.beacon.timestamp =
                        avp->tsf_adjust;
        } else
                avp->tsf_adjust = cpu_to_le64(0);

        bf->bf_mpdu = skb;
        bf->bf_buf_addr = bf->bf_dmacontext =
                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;
                ath_print(common, ATH_DBG_FATAL,
                          "dma_mapping_error on beacon alloc\n");
                return -ENOMEM;
        }

        return 0;
}

void ath_beacon_return(struct ath_softc *sc, struct ath_vif *avp)
{
        if (avp->av_bcbuf != NULL) {
                struct ath_buf *bf;

                if (avp->av_bslot != -1) {
                        sc->beacon.bslot[avp->av_bslot] = NULL;
                        sc->beacon.bslot_aphy[avp->av_bslot] = NULL;
                        sc->nbcnvifs--;
                }

                bf = avp->av_bcbuf;
                if (bf->bf_mpdu != NULL) {
                        struct sk_buff *skb = bf->bf_mpdu;
                        dma_unmap_single(sc->dev, bf->bf_dmacontext,
                                         skb->len, DMA_TO_DEVICE);
                        dev_kfree_skb_any(skb);
                        bf->bf_mpdu = NULL;
                }
                list_add_tail(&bf->list, &sc->beacon.bbuf);

                avp->av_bcbuf = NULL;
        }
}

void ath_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;
        struct ath_wiphy *aphy;
        int slot;
        u32 bfaddr, bc = 0, tsftu;
        u64 tsf;
        u16 intval;

        /*
         * 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 (sc->beacon.bmisscnt < BSTUCK_THRESH) {
                        ath_print(common, ATH_DBG_BEACON,
                                  "missed %u consecutive beacons\n",
                                  sc->beacon.bmisscnt);
                } else if (sc->beacon.bmisscnt >= BSTUCK_THRESH) {
                        ath_print(common, ATH_DBG_BEACON,
                                  "beacon is officially stuck\n");
                        sc->sc_flags |= SC_OP_TSF_RESET;
                        ath_reset(sc, false);
                }

                return;
        }

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

        /*
         * Generate beacon frames. we are sending frames
         * staggered so calculate the slot for this frame based
         * on the tsf to safeguard against missing an swba.
         */

        intval = sc->beacon_interval ? : ATH_DEFAULT_BINTVAL;

        tsf = ath9k_hw_gettsf64(ah);
        tsftu = TSF_TO_TU(tsf>>32, tsf);
        slot = ((tsftu % intval) * ATH_BCBUF) / intval;
        /*
         * Reverse the slot order to get slot 0 on the TBTT offset that does
         * not require TSF adjustment and other slots adding
         * slot/ATH_BCBUF * beacon_int to timestamp. For example, with
         * ATH_BCBUF = 4, we process beacon slots as follows: 3 2 1 0 3 2 1 ..
         * and slot 0 is at correct offset to TBTT.
         */
        slot = ATH_BCBUF - slot - 1;
        vif = sc->beacon.bslot[slot];
        aphy = sc->beacon.bslot_aphy[slot];

        ath_print(common, ATH_DBG_BEACON,
                  "slot %d [tsf %llu tsftu %u intval %u] vif %p\n",
                  slot, tsf, tsftu, intval, vif);

        bfaddr = 0;
        if (vif) {
                bf = ath_beacon_generate(aphy->hw, vif);
                if (bf != NULL) {
                        bfaddr = bf->bf_daddr;
                        bc = 1;
                }
        }

        /*
         * 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; /* commit next beacon */
                sc->beacon.slotupdate = slot;
        } else if (sc->beacon.updateslot == COMMIT && sc->beacon.slotupdate == slot) {
                ath9k_hw_setslottime(sc->sc_ah, sc->beacon.slottime);
                sc->beacon.updateslot = OK;
        }
        if (bfaddr != 0) {
                /*
                 * Stop any current dma and put the new frame(s) on the queue.
                 * This should never fail since we check above that no frames
                 * are still pending on the queue.
                 */
                if (!ath9k_hw_stoptxdma(ah, sc->beacon.beaconq)) {
                        ath_print(common, ATH_DBG_FATAL,
                                "beacon queue %u did not stop?\n", sc->beacon.beaconq);
                }

                /* NB: cabq traffic should already be queued and primed */
                ath9k_hw_puttxbuf(ah, sc->beacon.beaconq, bfaddr);
                ath9k_hw_txstart(ah, sc->beacon.beaconq);

                sc->beacon.ast_be_xmit += bc;     /* XXX per-vif? */
        }
}

static void ath9k_beacon_init(struct ath_softc *sc,
                              u32 next_beacon,
                              u32 beacon_period)
{
        if (beacon_period & ATH9K_BEACON_RESET_TSF)
                ath9k_ps_wakeup(sc);

        ath9k_hw_beaconinit(sc->sc_ah, next_beacon, beacon_period);

        if (beacon_period & ATH9K_BEACON_RESET_TSF)
                ath9k_ps_restore(sc);
}

/*
 * 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 ath_beacon_config_ap(struct ath_softc *sc,
                                 struct ath_beacon_config *conf)
{
        u32 nexttbtt, intval;

        /* Configure the timers only when the TSF has to be reset */

        if (!(sc->sc_flags & SC_OP_TSF_RESET))
                return;

        /* NB: the beacon interval is kept internally in TU's */
        intval = conf->beacon_interval & ATH9K_BEACON_PERIOD;
        intval /= ATH_BCBUF;    /* for staggered beacons */
        nexttbtt = intval;
        intval |= ATH9K_BEACON_RESET_TSF;

        /*
         * In AP mode we enable the beacon timers and SWBA interrupts to
         * prepare beacon frames.
         */
        intval |= ATH9K_BEACON_ENA;
        sc->imask |= ATH9K_INT_SWBA;
        ath_beaconq_config(sc);

        /* Set the computed AP beacon timers */

        ath9k_hw_set_interrupts(sc->sc_ah, 0);
        ath9k_beacon_init(sc, nexttbtt, intval);
        sc->beacon.bmisscnt = 0;
        ath9k_hw_set_interrupts(sc->sc_ah, sc->imask);

        /* Clear the reset TSF flag, so that subsequent beacon updation
           will not reset the HW TSF. */

        sc->sc_flags &= ~SC_OP_TSF_RESET;
}

/*
 * 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 ath_beacon_config_sta(struct ath_softc *sc,
                                  struct ath_beacon_config *conf)
{
        struct ath_common *common = ath9k_hw_common(sc->sc_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;

        memset(&bs, 0, sizeof(bs));
        intval = conf->beacon_interval & ATH9K_BEACON_PERIOD;

        /*
         * Setup dtim and cfp parameters according to
         * last beacon we received (which may be none).
         */
        dtimperiod = conf->dtim_period;
        if (dtimperiod <= 0)            /* NB: 0 if not known */
                dtimperiod = 1;
        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;
        if (sleepduration <= 0)
                sleepduration = intval;

        /*
         * Pull nexttbtt forward to reflect the current
         * TSF and calculate dtim+cfp state for the result.
         */
        tsf = ath9k_hw_gettsf64(sc->sc_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_print(common, ATH_DBG_BEACON, "tsf: %llu tsftu: %u\n", tsf, tsftu);
        ath_print(common, ATH_DBG_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_set_interrupts(sc->sc_ah, 0);
        ath9k_hw_set_sta_beacon_timers(sc->sc_ah, &bs);
        sc->imask |= ATH9K_INT_BMISS;
        ath9k_hw_set_interrupts(sc->sc_ah, sc->imask);
}

static void ath_beacon_config_adhoc(struct ath_softc *sc,
                                    struct ath_beacon_config *conf,
                                    struct ieee80211_vif *vif)
{
        struct ath_common *common = ath9k_hw_common(sc->sc_ah);
        u64 tsf;
        u32 tsftu, intval, nexttbtt;

        intval = conf->beacon_interval & ATH9K_BEACON_PERIOD;


        /* Pull nexttbtt forward to reflect the current TSF */

        nexttbtt = TSF_TO_TU(sc->beacon.bc_tstamp >> 32, sc->beacon.bc_tstamp);
        if (nexttbtt == 0)
                nexttbtt = intval;
        else if (intval)
                nexttbtt = roundup(nexttbtt, intval);

        tsf = ath9k_hw_gettsf64(sc->sc_ah);
        tsftu = TSF_TO_TU((u32)(tsf>>32), (u32)tsf) + FUDGE;
        do {
                nexttbtt += intval;
        } while (nexttbtt < tsftu);

        ath_print(common, ATH_DBG_BEACON,
                  "IBSS nexttbtt %u intval %u (%u)\n",
                  nexttbtt, intval, conf->beacon_interval);

        /*
         * In IBSS mode enable the beacon timers but only enable SWBA interrupts
         * if we need to manually prepare beacon frames.  Otherwise we use a
         * self-linked tx descriptor and let the hardware deal with things.
         */
        intval |= ATH9K_BEACON_ENA;
        if (!(sc->sc_ah->caps.hw_caps & ATH9K_HW_CAP_VEOL))
                sc->imask |= ATH9K_INT_SWBA;

        ath_beaconq_config(sc);

        /* Set the computed ADHOC beacon timers */

        ath9k_hw_set_interrupts(sc->sc_ah, 0);
        ath9k_beacon_init(sc, nexttbtt, intval);
        sc->beacon.bmisscnt = 0;
        ath9k_hw_set_interrupts(sc->sc_ah, sc->imask);

        /* FIXME: Handle properly when vif is NULL */
        if (vif && sc->sc_ah->caps.hw_caps & ATH9K_HW_CAP_VEOL)
                ath_beacon_start_adhoc(sc, vif);
}

void ath_beacon_config(struct ath_softc *sc, struct ieee80211_vif *vif)
{
        struct ath_beacon_config *cur_conf = &sc->cur_beacon_conf;
        struct ath_common *common = ath9k_hw_common(sc->sc_ah);
        enum nl80211_iftype iftype;

        /* Setup the beacon configuration parameters */

        if (vif) {
                struct ieee80211_bss_conf *bss_conf = &vif->bss_conf;

                iftype = vif->type;

                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;
        } else {
                iftype = sc->sc_ah->opmode;
        }

        /*
         * 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;

        switch (iftype) {
        case NL80211_IFTYPE_AP:
                ath_beacon_config_ap(sc, cur_conf);
                break;
        case NL80211_IFTYPE_ADHOC:
        case NL80211_IFTYPE_MESH_POINT:
                ath_beacon_config_adhoc(sc, cur_conf, vif);
                break;
        case NL80211_IFTYPE_STATION:
                ath_beacon_config_sta(sc, cur_conf);
                break;
        default:
                ath_print(common, ATH_DBG_CONFIG,
                          "Unsupported beaconing mode\n");
                return;
        }

        sc->sc_flags |= SC_OP_BEACONS;
}