drivers/net/wireless/ath/ath9k/beacon.c

/*
 * 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
*/
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, 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");
		return 0;
	} else {
		ath9k_hw_resettxqueue(ah, sc->beacon.beaconq);
		return 1;
	}
}

/*
 *  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 ath_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;

	ath9k_reset_beacon_status(sc);

	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 ath_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");
		dev_kfree_skb_any(skb);
	}
}

static struct ath_buf *ath_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;
	int cabq_depth;

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

	ath9k_reset_beacon_status(sc);

	/* Release the old beacon first */

	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;
	}

	/* 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 = 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);
		}
	}

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

	while (skb) {
		ath_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);
}

void ath_beacon_tasklet(unsigned long data)
{
	struct ath_softc *sc = (struct ath_softc *)data;
	struct ath_beacon_config *cur_conf = &sc->cur_beacon_conf;
	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;
	u32 bfaddr, bc = 0;

	if (work_pending(&sc->hw_reset_work)) {
		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;
			ieee80211_queue_work(sc->hw, &sc->hw_reset_work);
		}

		return;
	}

	/*
	 * 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.
	 */


	if (ah->opmode == NL80211_IFTYPE_AP) {
		u16 intval;
		u32 tsftu;
		u64 tsf;

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

		ath_dbg(common, BEACON,
			"slot %d [tsf %llu tsftu %u intval %u] vif %p\n",
			slot, tsf, tsftu / ATH_BCBUF, intval, vif);
	} else {
		slot = 0;
		vif = sc->beacon.bslot[slot];
	}


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

		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; /* commit next beacon */
		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 (bfaddr != 0) {
		/* NB: cabq traffic should already be queued and primed */
		ath9k_hw_puttxbuf(ah, sc->beacon.beaconq, bfaddr);

		if (!edma)
			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 nexttbtt, u32 intval)
{
	struct ath_hw *ah = sc->sc_ah;

	ath9k_hw_disable_interrupts(ah);
	ath9k_hw_reset_tsf(ah);
	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);

	ath_beaconq_config(sc);
	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);

	ath_beaconq_config(sc);
	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;
	}
}