summaryrefslogtreecommitdiffstats
path: root/drivers/net/wireless/ath/ath9k/beacon.c
blob: 4d4b22d52dfd230a7a61b3f0dd8b5b612c38af1f (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
/*
 * 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
*/
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;
	int qnum;

	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. */
		qnum = sc->tx.hwq_map[WME_AC_BE];
		ath9k_hw_get_txq_props(ah, qnum, &qi_be);
		qi.tqi_aifs = qi_be.tqi_aifs;
		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_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, 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_desc *ds;
	struct ath9k_11n_rate_series series[4];
	int flags, antenna, ctsrate = 0, ctsduration = 0;
	struct ieee80211_supported_band *sband;
	u8 rate = 0;

	ds = bf->bf_desc;
	flags = ATH9K_TXDESC_NOACK;

	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);

	sband = &sc->sbands[common->hw->conf.channel->band];
	rate = sband->bitrates[rateidx].hw_value;
	if (sc->sc_flags & SC_OP_PREAMBLE_SHORT)
		rate |= sband->bitrates[rateidx].hw_value_short;

	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, bf->bf_buf_addr,
			    sc->beacon.beaconq);

	memset(series, 0, sizeof(struct ath9k_11n_rate_series) * 4);
	series[0].Tries = 1;
	series[0].Rate = rate;
	series[0].ChSel = common->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, info->control.rates[0].idx);

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

	return bf;
}

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->opmode == NL80211_IFTYPE_ADHOC ||
		    sc->sc_ah->opmode == NL80211_IFTYPE_MESH_POINT) {
			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) {
					avp->av_bslot = slot;

					/* NB: keep looking for a double slot */
					if (slot == 0 || !sc->beacon.bslot[slot-1])
						break;
				}
			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) {
		ah->slottime = sc->beacon.slottime;
		ath9k_hw_init_global_settings(ah);
		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)
{
	struct ath_hw *ah = sc->sc_ah;
	u32 nexttbtt, intval;

	/* 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;

	if (sc->sc_flags & SC_OP_TSF_RESET)
		intval |= ATH9K_BEACON_RESET_TSF;

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

	/* Set the computed AP beacon timers */

	ath9k_hw_set_interrupts(ah, 0);
	ath9k_beacon_init(sc, nexttbtt, intval);
	sc->beacon.bmisscnt = 0;
	ath9k_hw_set_interrupts(ah, ah->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_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 (!common->curaid) {
		ath_print(common, ATH_DBG_BEACON,
			 "STA is not yet associated..skipping beacon config\n");
		return;
	}

	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(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(ah, 0);
	ath9k_hw_set_sta_beacon_timers(ah, &bs);
	ah->imask |= ATH9K_INT_BMISS;
	ath9k_hw_set_interrupts(ah, ah->imask);
}

static void ath_beacon_config_adhoc(struct ath_softc *sc,
				    struct ath_beacon_config *conf,
				    struct ieee80211_vif *vif)
{
	struct ath_hw *ah = sc->sc_ah;
	struct ath_common *common = ath9k_hw_common(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(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;
	ah->imask |= ATH9K_INT_SWBA;

	ath_beaconq_config(sc);

	/* Set the computed ADHOC beacon timers */

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

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;
}