summaryrefslogtreecommitdiff
path: root/drivers/net/wireless/zd1211rw/zd_mac.c
blob: 07513e48b8f250a1dd788dc3f7fb900fa2366592 (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
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
/* ZD1211 USB-WLAN driver for Linux
 *
 * Copyright (C) 2005-2007 Ulrich Kunitz <kune@deine-taler.de>
 * Copyright (C) 2006-2007 Daniel Drake <dsd@gentoo.org>
 * Copyright (C) 2006-2007 Michael Wu <flamingice@sourmilk.net>
 * Copyright (C) 2007-2008 Luis R. Rodriguez <mcgrof@winlab.rutgers.edu>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */

#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/usb.h>
#include <linux/jiffies.h>
#include <net/ieee80211_radiotap.h>

#include "zd_def.h"
#include "zd_chip.h"
#include "zd_mac.h"
#include "zd_rf.h"

struct zd_reg_alpha2_map {
	u32 reg;
	char alpha2[2];
};

static struct zd_reg_alpha2_map reg_alpha2_map[] = {
	{ ZD_REGDOMAIN_FCC, "US" },
	{ ZD_REGDOMAIN_IC, "CA" },
	{ ZD_REGDOMAIN_ETSI, "DE" }, /* Generic ETSI, use most restrictive */
	{ ZD_REGDOMAIN_JAPAN, "JP" },
	{ ZD_REGDOMAIN_JAPAN_ADD, "JP" },
	{ ZD_REGDOMAIN_SPAIN, "ES" },
	{ ZD_REGDOMAIN_FRANCE, "FR" },
};

/* This table contains the hardware specific values for the modulation rates. */
static const struct ieee80211_rate zd_rates[] = {
	{ .bitrate = 10,
	  .hw_value = ZD_CCK_RATE_1M, },
	{ .bitrate = 20,
	  .hw_value = ZD_CCK_RATE_2M,
	  .hw_value_short = ZD_CCK_RATE_2M | ZD_CCK_PREA_SHORT,
	  .flags = IEEE80211_RATE_SHORT_PREAMBLE },
	{ .bitrate = 55,
	  .hw_value = ZD_CCK_RATE_5_5M,
	  .hw_value_short = ZD_CCK_RATE_5_5M | ZD_CCK_PREA_SHORT,
	  .flags = IEEE80211_RATE_SHORT_PREAMBLE },
	{ .bitrate = 110,
	  .hw_value = ZD_CCK_RATE_11M,
	  .hw_value_short = ZD_CCK_RATE_11M | ZD_CCK_PREA_SHORT,
	  .flags = IEEE80211_RATE_SHORT_PREAMBLE },
	{ .bitrate = 60,
	  .hw_value = ZD_OFDM_RATE_6M,
	  .flags = 0 },
	{ .bitrate = 90,
	  .hw_value = ZD_OFDM_RATE_9M,
	  .flags = 0 },
	{ .bitrate = 120,
	  .hw_value = ZD_OFDM_RATE_12M,
	  .flags = 0 },
	{ .bitrate = 180,
	  .hw_value = ZD_OFDM_RATE_18M,
	  .flags = 0 },
	{ .bitrate = 240,
	  .hw_value = ZD_OFDM_RATE_24M,
	  .flags = 0 },
	{ .bitrate = 360,
	  .hw_value = ZD_OFDM_RATE_36M,
	  .flags = 0 },
	{ .bitrate = 480,
	  .hw_value = ZD_OFDM_RATE_48M,
	  .flags = 0 },
	{ .bitrate = 540,
	  .hw_value = ZD_OFDM_RATE_54M,
	  .flags = 0 },
};

static const struct ieee80211_channel zd_channels[] = {
	{ .center_freq = 2412, .hw_value = 1 },
	{ .center_freq = 2417, .hw_value = 2 },
	{ .center_freq = 2422, .hw_value = 3 },
	{ .center_freq = 2427, .hw_value = 4 },
	{ .center_freq = 2432, .hw_value = 5 },
	{ .center_freq = 2437, .hw_value = 6 },
	{ .center_freq = 2442, .hw_value = 7 },
	{ .center_freq = 2447, .hw_value = 8 },
	{ .center_freq = 2452, .hw_value = 9 },
	{ .center_freq = 2457, .hw_value = 10 },
	{ .center_freq = 2462, .hw_value = 11 },
	{ .center_freq = 2467, .hw_value = 12 },
	{ .center_freq = 2472, .hw_value = 13 },
	{ .center_freq = 2484, .hw_value = 14 },
};

static void housekeeping_init(struct zd_mac *mac);
static void housekeeping_enable(struct zd_mac *mac);
static void housekeeping_disable(struct zd_mac *mac);

static int zd_reg2alpha2(u8 regdomain, char *alpha2)
{
	unsigned int i;
	struct zd_reg_alpha2_map *reg_map;
	for (i = 0; i < ARRAY_SIZE(reg_alpha2_map); i++) {
		reg_map = &reg_alpha2_map[i];
		if (regdomain == reg_map->reg) {
			alpha2[0] = reg_map->alpha2[0];
			alpha2[1] = reg_map->alpha2[1];
			return 0;
		}
	}
	return 1;
}

int zd_mac_preinit_hw(struct ieee80211_hw *hw)
{
	int r;
	u8 addr[ETH_ALEN];
	struct zd_mac *mac = zd_hw_mac(hw);

	r = zd_chip_read_mac_addr_fw(&mac->chip, addr);
	if (r)
		return r;

	SET_IEEE80211_PERM_ADDR(hw, addr);

	return 0;
}

int zd_mac_init_hw(struct ieee80211_hw *hw)
{
	int r;
	struct zd_mac *mac = zd_hw_mac(hw);
	struct zd_chip *chip = &mac->chip;
	char alpha2[2];
	u8 default_regdomain;

	r = zd_chip_enable_int(chip);
	if (r)
		goto out;
	r = zd_chip_init_hw(chip);
	if (r)
		goto disable_int;

	ZD_ASSERT(!irqs_disabled());

	r = zd_read_regdomain(chip, &default_regdomain);
	if (r)
		goto disable_int;
	spin_lock_irq(&mac->lock);
	mac->regdomain = mac->default_regdomain = default_regdomain;
	spin_unlock_irq(&mac->lock);

	/* We must inform the device that we are doing encryption/decryption in
	 * software at the moment. */
	r = zd_set_encryption_type(chip, ENC_SNIFFER);
	if (r)
		goto disable_int;

	r = zd_reg2alpha2(mac->regdomain, alpha2);
	if (!r)
		regulatory_hint(hw->wiphy, alpha2);

	r = 0;
disable_int:
	zd_chip_disable_int(chip);
out:
	return r;
}

void zd_mac_clear(struct zd_mac *mac)
{
	flush_workqueue(zd_workqueue);
	zd_chip_clear(&mac->chip);
	ZD_ASSERT(!spin_is_locked(&mac->lock));
	ZD_MEMCLEAR(mac, sizeof(struct zd_mac));
}

static int set_rx_filter(struct zd_mac *mac)
{
	unsigned long flags;
	u32 filter = STA_RX_FILTER;

	spin_lock_irqsave(&mac->lock, flags);
	if (mac->pass_ctrl)
		filter |= RX_FILTER_CTRL;
	spin_unlock_irqrestore(&mac->lock, flags);

	return zd_iowrite32(&mac->chip, CR_RX_FILTER, filter);
}

static int set_mc_hash(struct zd_mac *mac)
{
	struct zd_mc_hash hash;
	zd_mc_clear(&hash);
	return zd_chip_set_multicast_hash(&mac->chip, &hash);
}

static int zd_op_start(struct ieee80211_hw *hw)
{
	struct zd_mac *mac = zd_hw_mac(hw);
	struct zd_chip *chip = &mac->chip;
	struct zd_usb *usb = &chip->usb;
	int r;

	if (!usb->initialized) {
		r = zd_usb_init_hw(usb);
		if (r)
			goto out;
	}

	r = zd_chip_enable_int(chip);
	if (r < 0)
		goto out;

	r = zd_chip_set_basic_rates(chip, CR_RATES_80211B | CR_RATES_80211G);
	if (r < 0)
		goto disable_int;
	r = set_rx_filter(mac);
	if (r)
		goto disable_int;
	r = set_mc_hash(mac);
	if (r)
		goto disable_int;
	r = zd_chip_switch_radio_on(chip);
	if (r < 0)
		goto disable_int;
	r = zd_chip_enable_rxtx(chip);
	if (r < 0)
		goto disable_radio;
	r = zd_chip_enable_hwint(chip);
	if (r < 0)
		goto disable_rxtx;

	housekeeping_enable(mac);
	return 0;
disable_rxtx:
	zd_chip_disable_rxtx(chip);
disable_radio:
	zd_chip_switch_radio_off(chip);
disable_int:
	zd_chip_disable_int(chip);
out:
	return r;
}

static void zd_op_stop(struct ieee80211_hw *hw)
{
	struct zd_mac *mac = zd_hw_mac(hw);
	struct zd_chip *chip = &mac->chip;
	struct sk_buff *skb;
	struct sk_buff_head *ack_wait_queue = &mac->ack_wait_queue;

	/* The order here deliberately is a little different from the open()
	 * method, since we need to make sure there is no opportunity for RX
	 * frames to be processed by mac80211 after we have stopped it.
	 */

	zd_chip_disable_rxtx(chip);
	housekeeping_disable(mac);
	flush_workqueue(zd_workqueue);

	zd_chip_disable_hwint(chip);
	zd_chip_switch_radio_off(chip);
	zd_chip_disable_int(chip);


	while ((skb = skb_dequeue(ack_wait_queue)))
		dev_kfree_skb_any(skb);
}

/**
 * tx_status - reports tx status of a packet if required
 * @hw - a &struct ieee80211_hw pointer
 * @skb - a sk-buffer
 * @flags: extra flags to set in the TX status info
 * @ackssi: ACK signal strength
 * @success - True for successfull transmission of the frame
 *
 * This information calls ieee80211_tx_status_irqsafe() if required by the
 * control information. It copies the control information into the status
 * information.
 *
 * If no status information has been requested, the skb is freed.
 */
static void tx_status(struct ieee80211_hw *hw, struct sk_buff *skb,
		      int ackssi, bool success)
{
	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);

	ieee80211_tx_info_clear_status(info);

	if (success)
		info->flags |= IEEE80211_TX_STAT_ACK;
	info->status.ack_signal = ackssi;
	ieee80211_tx_status_irqsafe(hw, skb);
}

/**
 * zd_mac_tx_failed - callback for failed frames
 * @dev: the mac80211 wireless device
 *
 * This function is called if a frame couldn't be succesfully be
 * transferred. The first frame from the tx queue, will be selected and
 * reported as error to the upper layers.
 */
void zd_mac_tx_failed(struct ieee80211_hw *hw)
{
	struct sk_buff_head *q = &zd_hw_mac(hw)->ack_wait_queue;
	struct sk_buff *skb;

	skb = skb_dequeue(q);
	if (skb == NULL)
		return;

	tx_status(hw, skb, 0, 0);
}

/**
 * zd_mac_tx_to_dev - callback for USB layer
 * @skb: a &sk_buff pointer
 * @error: error value, 0 if transmission successful
 *
 * Informs the MAC layer that the frame has successfully transferred to the
 * device. If an ACK is required and the transfer to the device has been
 * successful, the packets are put on the @ack_wait_queue with
 * the control set removed.
 */
void zd_mac_tx_to_dev(struct sk_buff *skb, int error)
{
	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
	struct ieee80211_hw *hw = info->rate_driver_data[0];

	skb_pull(skb, sizeof(struct zd_ctrlset));
	if (unlikely(error ||
	    (info->flags & IEEE80211_TX_CTL_NO_ACK))) {
		tx_status(hw, skb, 0, !error);
	} else {
		struct sk_buff_head *q =
			&zd_hw_mac(hw)->ack_wait_queue;

		skb_queue_tail(q, skb);
		while (skb_queue_len(q) > ZD_MAC_MAX_ACK_WAITERS)
			zd_mac_tx_failed(hw);
	}
}

static int zd_calc_tx_length_us(u8 *service, u8 zd_rate, u16 tx_length)
{
	/* ZD_PURE_RATE() must be used to remove the modulation type flag of
	 * the zd-rate values.
	 */
	static const u8 rate_divisor[] = {
		[ZD_PURE_RATE(ZD_CCK_RATE_1M)]   =  1,
		[ZD_PURE_RATE(ZD_CCK_RATE_2M)]	 =  2,
		/* Bits must be doubled. */
		[ZD_PURE_RATE(ZD_CCK_RATE_5_5M)] = 11,
		[ZD_PURE_RATE(ZD_CCK_RATE_11M)]	 = 11,
		[ZD_PURE_RATE(ZD_OFDM_RATE_6M)]  =  6,
		[ZD_PURE_RATE(ZD_OFDM_RATE_9M)]  =  9,
		[ZD_PURE_RATE(ZD_OFDM_RATE_12M)] = 12,
		[ZD_PURE_RATE(ZD_OFDM_RATE_18M)] = 18,
		[ZD_PURE_RATE(ZD_OFDM_RATE_24M)] = 24,
		[ZD_PURE_RATE(ZD_OFDM_RATE_36M)] = 36,
		[ZD_PURE_RATE(ZD_OFDM_RATE_48M)] = 48,
		[ZD_PURE_RATE(ZD_OFDM_RATE_54M)] = 54,
	};

	u32 bits = (u32)tx_length * 8;
	u32 divisor;

	divisor = rate_divisor[ZD_PURE_RATE(zd_rate)];
	if (divisor == 0)
		return -EINVAL;

	switch (zd_rate) {
	case ZD_CCK_RATE_5_5M:
		bits = (2*bits) + 10; /* round up to the next integer */
		break;
	case ZD_CCK_RATE_11M:
		if (service) {
			u32 t = bits % 11;
			*service &= ~ZD_PLCP_SERVICE_LENGTH_EXTENSION;
			if (0 < t && t <= 3) {
				*service |= ZD_PLCP_SERVICE_LENGTH_EXTENSION;
			}
		}
		bits += 10; /* round up to the next integer */
		break;
	}

	return bits/divisor;
}

static void cs_set_control(struct zd_mac *mac, struct zd_ctrlset *cs,
	                   struct ieee80211_hdr *header,
	                   struct ieee80211_tx_info *info)
{
	/*
	 * CONTROL TODO:
	 * - if backoff needed, enable bit 0
	 * - if burst (backoff not needed) disable bit 0
	 */

	cs->control = 0;

	/* First fragment */
	if (info->flags & IEEE80211_TX_CTL_FIRST_FRAGMENT)
		cs->control |= ZD_CS_NEED_RANDOM_BACKOFF;

	/* Multicast */
	if (is_multicast_ether_addr(header->addr1))
		cs->control |= ZD_CS_MULTICAST;

	/* PS-POLL */
	if (ieee80211_is_pspoll(header->frame_control))
		cs->control |= ZD_CS_PS_POLL_FRAME;

	if (info->control.rates[0].flags & IEEE80211_TX_RC_USE_RTS_CTS)
		cs->control |= ZD_CS_RTS;

	if (info->control.rates[0].flags & IEEE80211_TX_RC_USE_CTS_PROTECT)
		cs->control |= ZD_CS_SELF_CTS;

	/* FIXME: Management frame? */
}

static int zd_mac_config_beacon(struct ieee80211_hw *hw, struct sk_buff *beacon)
{
	struct zd_mac *mac = zd_hw_mac(hw);
	int r;
	u32 tmp, j = 0;
	/* 4 more bytes for tail CRC */
	u32 full_len = beacon->len + 4;

	r = zd_iowrite32(&mac->chip, CR_BCN_FIFO_SEMAPHORE, 0);
	if (r < 0)
		return r;
	r = zd_ioread32(&mac->chip, CR_BCN_FIFO_SEMAPHORE, &tmp);
	if (r < 0)
		return r;

	while (tmp & 0x2) {
		r = zd_ioread32(&mac->chip, CR_BCN_FIFO_SEMAPHORE, &tmp);
		if (r < 0)
			return r;
		if ((++j % 100) == 0) {
			printk(KERN_ERR "CR_BCN_FIFO_SEMAPHORE not ready\n");
			if (j >= 500)  {
				printk(KERN_ERR "Giving up beacon config.\n");
				return -ETIMEDOUT;
			}
		}
		msleep(1);
	}

	r = zd_iowrite32(&mac->chip, CR_BCN_FIFO, full_len - 1);
	if (r < 0)
		return r;
	if (zd_chip_is_zd1211b(&mac->chip)) {
		r = zd_iowrite32(&mac->chip, CR_BCN_LENGTH, full_len - 1);
		if (r < 0)
			return r;
	}

	for (j = 0 ; j < beacon->len; j++) {
		r = zd_iowrite32(&mac->chip, CR_BCN_FIFO,
				*((u8 *)(beacon->data + j)));
		if (r < 0)
			return r;
	}

	for (j = 0; j < 4; j++) {
		r = zd_iowrite32(&mac->chip, CR_BCN_FIFO, 0x0);
		if (r < 0)
			return r;
	}

	r = zd_iowrite32(&mac->chip, CR_BCN_FIFO_SEMAPHORE, 1);
	if (r < 0)
		return r;

	/* 802.11b/g 2.4G CCK 1Mb
	 * 802.11a, not yet implemented, uses different values (see GPL vendor
	 * driver)
	 */
	return zd_iowrite32(&mac->chip, CR_BCN_PLCP_CFG, 0x00000400 |
			(full_len << 19));
}

static int fill_ctrlset(struct zd_mac *mac,
			struct sk_buff *skb)
{
	int r;
	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
	unsigned int frag_len = skb->len + FCS_LEN;
	unsigned int packet_length;
	struct ieee80211_rate *txrate;
	struct zd_ctrlset *cs = (struct zd_ctrlset *)
		skb_push(skb, sizeof(struct zd_ctrlset));
	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);

	ZD_ASSERT(frag_len <= 0xffff);

	txrate = ieee80211_get_tx_rate(mac->hw, info);

	cs->modulation = txrate->hw_value;
	if (info->control.rates[0].flags & IEEE80211_TX_RC_USE_SHORT_PREAMBLE)
		cs->modulation = txrate->hw_value_short;

	cs->tx_length = cpu_to_le16(frag_len);

	cs_set_control(mac, cs, hdr, info);

	packet_length = frag_len + sizeof(struct zd_ctrlset) + 10;
	ZD_ASSERT(packet_length <= 0xffff);
	/* ZD1211B: Computing the length difference this way, gives us
	 * flexibility to compute the packet length.
	 */
	cs->packet_length = cpu_to_le16(zd_chip_is_zd1211b(&mac->chip) ?
			packet_length - frag_len : packet_length);

	/*
	 * CURRENT LENGTH:
	 * - transmit frame length in microseconds
	 * - seems to be derived from frame length
	 * - see Cal_Us_Service() in zdinlinef.h
	 * - if macp->bTxBurstEnable is enabled, then multiply by 4
	 *  - bTxBurstEnable is never set in the vendor driver
	 *
	 * SERVICE:
	 * - "for PLCP configuration"
	 * - always 0 except in some situations at 802.11b 11M
	 * - see line 53 of zdinlinef.h
	 */
	cs->service = 0;
	r = zd_calc_tx_length_us(&cs->service, ZD_RATE(cs->modulation),
		                 le16_to_cpu(cs->tx_length));
	if (r < 0)
		return r;
	cs->current_length = cpu_to_le16(r);
	cs->next_frame_length = 0;

	return 0;
}

/**
 * zd_op_tx - transmits a network frame to the device
 *
 * @dev: mac80211 hardware device
 * @skb: socket buffer
 * @control: the control structure
 *
 * This function transmit an IEEE 802.11 network frame to the device. The
 * control block of the skbuff will be initialized. If necessary the incoming
 * mac80211 queues will be stopped.
 */
static int zd_op_tx(struct ieee80211_hw *hw, struct sk_buff *skb)
{
	struct zd_mac *mac = zd_hw_mac(hw);
	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
	int r;

	r = fill_ctrlset(mac, skb);
	if (r)
		return r;

	info->rate_driver_data[0] = hw;

	r = zd_usb_tx(&mac->chip.usb, skb);
	if (r)
		return r;
	return 0;
}

/**
 * filter_ack - filters incoming packets for acknowledgements
 * @dev: the mac80211 device
 * @rx_hdr: received header
 * @stats: the status for the received packet
 *
 * This functions looks for ACK packets and tries to match them with the
 * frames in the tx queue. If a match is found the frame will be dequeued and
 * the upper layers is informed about the successful transmission. If
 * mac80211 queues have been stopped and the number of frames still to be
 * transmitted is low the queues will be opened again.
 *
 * Returns 1 if the frame was an ACK, 0 if it was ignored.
 */
static int filter_ack(struct ieee80211_hw *hw, struct ieee80211_hdr *rx_hdr,
		      struct ieee80211_rx_status *stats)
{
	struct sk_buff *skb;
	struct sk_buff_head *q;
	unsigned long flags;

	if (!ieee80211_is_ack(rx_hdr->frame_control))
		return 0;

	q = &zd_hw_mac(hw)->ack_wait_queue;
	spin_lock_irqsave(&q->lock, flags);
	skb_queue_walk(q, skb) {
		struct ieee80211_hdr *tx_hdr;

		tx_hdr = (struct ieee80211_hdr *)skb->data;
		if (likely(!compare_ether_addr(tx_hdr->addr2, rx_hdr->addr1)))
		{
			__skb_unlink(skb, q);
			tx_status(hw, skb, stats->signal, 1);
			goto out;
		}
	}
out:
	spin_unlock_irqrestore(&q->lock, flags);
	return 1;
}

int zd_mac_rx(struct ieee80211_hw *hw, const u8 *buffer, unsigned int length)
{
	struct zd_mac *mac = zd_hw_mac(hw);
	struct ieee80211_rx_status stats;
	const struct rx_status *status;
	struct sk_buff *skb;
	int bad_frame = 0;
	__le16 fc;
	int need_padding;
	int i;
	u8 rate;

	if (length < ZD_PLCP_HEADER_SIZE + 10 /* IEEE80211_1ADDR_LEN */ +
	             FCS_LEN + sizeof(struct rx_status))
		return -EINVAL;

	memset(&stats, 0, sizeof(stats));

	/* Note about pass_failed_fcs and pass_ctrl access below:
	 * mac locking intentionally omitted here, as this is the only unlocked
	 * reader and the only writer is configure_filter. Plus, if there were
	 * any races accessing these variables, it wouldn't really matter.
	 * If mac80211 ever provides a way for us to access filter flags
	 * from outside configure_filter, we could improve on this. Also, this
	 * situation may change once we implement some kind of DMA-into-skb
	 * RX path. */

	/* Caller has to ensure that length >= sizeof(struct rx_status). */
	status = (struct rx_status *)
		(buffer + (length - sizeof(struct rx_status)));
	if (status->frame_status & ZD_RX_ERROR) {
		if (mac->pass_failed_fcs &&
				(status->frame_status & ZD_RX_CRC32_ERROR)) {
			stats.flag |= RX_FLAG_FAILED_FCS_CRC;
			bad_frame = 1;
		} else {
			return -EINVAL;
		}
	}

	stats.freq = zd_channels[_zd_chip_get_channel(&mac->chip) - 1].center_freq;
	stats.band = IEEE80211_BAND_2GHZ;
	stats.signal = status->signal_strength;
	stats.qual = zd_rx_qual_percent(buffer,
		                          length - sizeof(struct rx_status),
		                          status);

	rate = zd_rx_rate(buffer, status);

	/* todo: return index in the big switches in zd_rx_rate instead */
	for (i = 0; i < mac->band.n_bitrates; i++)
		if (rate == mac->band.bitrates[i].hw_value)
			stats.rate_idx = i;

	length -= ZD_PLCP_HEADER_SIZE + sizeof(struct rx_status);
	buffer += ZD_PLCP_HEADER_SIZE;

	/* Except for bad frames, filter each frame to see if it is an ACK, in
	 * which case our internal TX tracking is updated. Normally we then
	 * bail here as there's no need to pass ACKs on up to the stack, but
	 * there is also the case where the stack has requested us to pass
	 * control frames on up (pass_ctrl) which we must consider. */
	if (!bad_frame &&
			filter_ack(hw, (struct ieee80211_hdr *)buffer, &stats)
			&& !mac->pass_ctrl)
		return 0;

	fc = *(__le16 *)buffer;
	need_padding = ieee80211_is_data_qos(fc) ^ ieee80211_has_a4(fc);

	skb = dev_alloc_skb(length + (need_padding ? 2 : 0));
	if (skb == NULL)
		return -ENOMEM;
	if (need_padding) {
		/* Make sure the the payload data is 4 byte aligned. */
		skb_reserve(skb, 2);
	}

	memcpy(skb_put(skb, length), buffer, length);

	ieee80211_rx_irqsafe(hw, skb, &stats);
	return 0;
}

static int zd_op_add_interface(struct ieee80211_hw *hw,
				struct ieee80211_if_init_conf *conf)
{
	struct zd_mac *mac = zd_hw_mac(hw);

	/* using NL80211_IFTYPE_UNSPECIFIED to indicate no mode selected */
	if (mac->type != NL80211_IFTYPE_UNSPECIFIED)
		return -EOPNOTSUPP;

	switch (conf->type) {
	case NL80211_IFTYPE_MONITOR:
	case NL80211_IFTYPE_MESH_POINT:
	case NL80211_IFTYPE_STATION:
	case NL80211_IFTYPE_ADHOC:
		mac->type = conf->type;
		break;
	default:
		return -EOPNOTSUPP;
	}

	return zd_write_mac_addr(&mac->chip, conf->mac_addr);
}

static void zd_op_remove_interface(struct ieee80211_hw *hw,
				    struct ieee80211_if_init_conf *conf)
{
	struct zd_mac *mac = zd_hw_mac(hw);
	mac->type = NL80211_IFTYPE_UNSPECIFIED;
	zd_set_beacon_interval(&mac->chip, 0);
	zd_write_mac_addr(&mac->chip, NULL);
}

static int zd_op_config(struct ieee80211_hw *hw, u32 changed)
{
	struct zd_mac *mac = zd_hw_mac(hw);
	struct ieee80211_conf *conf = &hw->conf;

	return zd_chip_set_channel(&mac->chip, conf->channel->hw_value);
}

static int zd_op_config_interface(struct ieee80211_hw *hw,
				  struct ieee80211_vif *vif,
				   struct ieee80211_if_conf *conf)
{
	struct zd_mac *mac = zd_hw_mac(hw);
	int associated;
	int r;

	if (mac->type == NL80211_IFTYPE_MESH_POINT ||
	    mac->type == NL80211_IFTYPE_ADHOC) {
		associated = true;
		if (conf->changed & IEEE80211_IFCC_BEACON) {
			struct sk_buff *beacon = ieee80211_beacon_get(hw, vif);

			if (!beacon)
				return -ENOMEM;
			r = zd_mac_config_beacon(hw, beacon);
			if (r < 0)
				return r;
			r = zd_set_beacon_interval(&mac->chip, BCN_MODE_IBSS |
					hw->conf.beacon_int);
			if (r < 0)
				return r;
			kfree_skb(beacon);
		}
	} else
		associated = is_valid_ether_addr(conf->bssid);

	spin_lock_irq(&mac->lock);
	mac->associated = associated;
	spin_unlock_irq(&mac->lock);

	/* TODO: do hardware bssid filtering */
	return 0;
}

static void zd_process_intr(struct work_struct *work)
{
	u16 int_status;
	struct zd_mac *mac = container_of(work, struct zd_mac, process_intr);

	int_status = le16_to_cpu(*(__le16 *)(mac->intr_buffer+4));
	if (int_status & INT_CFG_NEXT_BCN) {
		if (net_ratelimit())
			dev_dbg_f(zd_mac_dev(mac), "INT_CFG_NEXT_BCN\n");
	} else
		dev_dbg_f(zd_mac_dev(mac), "Unsupported interrupt\n");

	zd_chip_enable_hwint(&mac->chip);
}


static void set_multicast_hash_handler(struct work_struct *work)
{
	struct zd_mac *mac =
		container_of(work, struct zd_mac, set_multicast_hash_work);
	struct zd_mc_hash hash;

	spin_lock_irq(&mac->lock);
	hash = mac->multicast_hash;
	spin_unlock_irq(&mac->lock);

	zd_chip_set_multicast_hash(&mac->chip, &hash);
}

static void set_rx_filter_handler(struct work_struct *work)
{
	struct zd_mac *mac =
		container_of(work, struct zd_mac, set_rx_filter_work);
	int r;

	dev_dbg_f(zd_mac_dev(mac), "\n");
	r = set_rx_filter(mac);
	if (r)
		dev_err(zd_mac_dev(mac), "set_rx_filter_handler error %d\n", r);
}

#define SUPPORTED_FIF_FLAGS \
	(FIF_PROMISC_IN_BSS | FIF_ALLMULTI | FIF_FCSFAIL | FIF_CONTROL | \
	FIF_OTHER_BSS | FIF_BCN_PRBRESP_PROMISC)
static void zd_op_configure_filter(struct ieee80211_hw *hw,
			unsigned int changed_flags,
			unsigned int *new_flags,
			int mc_count, struct dev_mc_list *mclist)
{
	struct zd_mc_hash hash;
	struct zd_mac *mac = zd_hw_mac(hw);
	unsigned long flags;
	int i;

	/* Only deal with supported flags */
	changed_flags &= SUPPORTED_FIF_FLAGS;
	*new_flags &= SUPPORTED_FIF_FLAGS;

	/* changed_flags is always populated but this driver
	 * doesn't support all FIF flags so its possible we don't
	 * need to do anything */
	if (!changed_flags)
		return;

	if (*new_flags & (FIF_PROMISC_IN_BSS | FIF_ALLMULTI)) {
		zd_mc_add_all(&hash);
	} else {
		zd_mc_clear(&hash);
		for (i = 0; i < mc_count; i++) {
			if (!mclist)
				break;
			dev_dbg_f(zd_mac_dev(mac), "mc addr %pM\n",
				  mclist->dmi_addr);
			zd_mc_add_addr(&hash, mclist->dmi_addr);
			mclist = mclist->next;
		}
	}

	spin_lock_irqsave(&mac->lock, flags);
	mac->pass_failed_fcs = !!(*new_flags & FIF_FCSFAIL);
	mac->pass_ctrl = !!(*new_flags & FIF_CONTROL);
	mac->multicast_hash = hash;
	spin_unlock_irqrestore(&mac->lock, flags);
	queue_work(zd_workqueue, &mac->set_multicast_hash_work);

	if (changed_flags & FIF_CONTROL)
		queue_work(zd_workqueue, &mac->set_rx_filter_work);

	/* no handling required for FIF_OTHER_BSS as we don't currently
	 * do BSSID filtering */
	/* FIXME: in future it would be nice to enable the probe response
	 * filter (so that the driver doesn't see them) until
	 * FIF_BCN_PRBRESP_PROMISC is set. however due to atomicity here, we'd
	 * have to schedule work to enable prbresp reception, which might
	 * happen too late. For now we'll just listen and forward them all the
	 * time. */
}

static void set_rts_cts_work(struct work_struct *work)
{
	struct zd_mac *mac =
		container_of(work, struct zd_mac, set_rts_cts_work);
	unsigned long flags;
	unsigned int short_preamble;

	mutex_lock(&mac->chip.mutex);

	spin_lock_irqsave(&mac->lock, flags);
	mac->updating_rts_rate = 0;
	short_preamble = mac->short_preamble;
	spin_unlock_irqrestore(&mac->lock, flags);

	zd_chip_set_rts_cts_rate_locked(&mac->chip, short_preamble);
	mutex_unlock(&mac->chip.mutex);
}

static void zd_op_bss_info_changed(struct ieee80211_hw *hw,
				   struct ieee80211_vif *vif,
				   struct ieee80211_bss_conf *bss_conf,
				   u32 changes)
{
	struct zd_mac *mac = zd_hw_mac(hw);
	unsigned long flags;

	dev_dbg_f(zd_mac_dev(mac), "changes: %x\n", changes);

	if (changes & BSS_CHANGED_ERP_PREAMBLE) {
		spin_lock_irqsave(&mac->lock, flags);
		mac->short_preamble = bss_conf->use_short_preamble;
		if (!mac->updating_rts_rate) {
			mac->updating_rts_rate = 1;
			/* FIXME: should disable TX here, until work has
			 * completed and RTS_CTS reg is updated */
			queue_work(zd_workqueue, &mac->set_rts_cts_work);
		}
		spin_unlock_irqrestore(&mac->lock, flags);
	}
}

static const struct ieee80211_ops zd_ops = {
	.tx			= zd_op_tx,
	.start			= zd_op_start,
	.stop			= zd_op_stop,
	.add_interface		= zd_op_add_interface,
	.remove_interface	= zd_op_remove_interface,
	.config			= zd_op_config,
	.config_interface	= zd_op_config_interface,
	.configure_filter	= zd_op_configure_filter,
	.bss_info_changed	= zd_op_bss_info_changed,
};

struct ieee80211_hw *zd_mac_alloc_hw(struct usb_interface *intf)
{
	struct zd_mac *mac;
	struct ieee80211_hw *hw;

	hw = ieee80211_alloc_hw(sizeof(struct zd_mac), &zd_ops);
	if (!hw) {
		dev_dbg_f(&intf->dev, "out of memory\n");
		return NULL;
	}

	mac = zd_hw_mac(hw);

	memset(mac, 0, sizeof(*mac));
	spin_lock_init(&mac->lock);
	mac->hw = hw;

	mac->type = NL80211_IFTYPE_UNSPECIFIED;

	memcpy(mac->channels, zd_channels, sizeof(zd_channels));
	memcpy(mac->rates, zd_rates, sizeof(zd_rates));
	mac->band.n_bitrates = ARRAY_SIZE(zd_rates);
	mac->band.bitrates = mac->rates;
	mac->band.n_channels = ARRAY_SIZE(zd_channels);
	mac->band.channels = mac->channels;

	hw->wiphy->bands[IEEE80211_BAND_2GHZ] = &mac->band;

	hw->flags = IEEE80211_HW_RX_INCLUDES_FCS |
		    IEEE80211_HW_SIGNAL_DB;

	hw->wiphy->interface_modes =
		BIT(NL80211_IFTYPE_MESH_POINT) |
		BIT(NL80211_IFTYPE_STATION) |
		BIT(NL80211_IFTYPE_ADHOC);

	hw->max_signal = 100;
	hw->queues = 1;
	hw->extra_tx_headroom = sizeof(struct zd_ctrlset);

	skb_queue_head_init(&mac->ack_wait_queue);

	zd_chip_init(&mac->chip, hw, intf);
	housekeeping_init(mac);
	INIT_WORK(&mac->set_multicast_hash_work, set_multicast_hash_handler);
	INIT_WORK(&mac->set_rts_cts_work, set_rts_cts_work);
	INIT_WORK(&mac->set_rx_filter_work, set_rx_filter_handler);
	INIT_WORK(&mac->process_intr, zd_process_intr);

	SET_IEEE80211_DEV(hw, &intf->dev);
	return hw;
}

#define LINK_LED_WORK_DELAY HZ

static void link_led_handler(struct work_struct *work)
{
	struct zd_mac *mac =
		container_of(work, struct zd_mac, housekeeping.link_led_work.work);
	struct zd_chip *chip = &mac->chip;
	int is_associated;
	int r;

	spin_lock_irq(&mac->lock);
	is_associated = mac->associated;
	spin_unlock_irq(&mac->lock);

	r = zd_chip_control_leds(chip,
		                 is_associated ? LED_ASSOCIATED : LED_SCANNING);
	if (r)
		dev_dbg_f(zd_mac_dev(mac), "zd_chip_control_leds error %d\n", r);

	queue_delayed_work(zd_workqueue, &mac->housekeeping.link_led_work,
		           LINK_LED_WORK_DELAY);
}

static void housekeeping_init(struct zd_mac *mac)
{
	INIT_DELAYED_WORK(&mac->housekeeping.link_led_work, link_led_handler);
}

static void housekeeping_enable(struct zd_mac *mac)
{
	dev_dbg_f(zd_mac_dev(mac), "\n");
	queue_delayed_work(zd_workqueue, &mac->housekeeping.link_led_work,
			   0);
}

static void housekeeping_disable(struct zd_mac *mac)
{
	dev_dbg_f(zd_mac_dev(mac), "\n");
	cancel_rearming_delayed_workqueue(zd_workqueue,
		&mac->housekeeping.link_led_work);
	zd_chip_control_leds(&mac->chip, LED_OFF);
}