Linux Audio

Check our new training course

Embedded Linux Audio

Check our new training course
with Creative Commons CC-BY-SA
lecture materials

Bootlin logo

Elixir Cross Referencer

Loading...
   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
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
/*

  Broadcom BCM43xx wireless driver

  DMA ringbuffer and descriptor allocation/management

  Copyright (c) 2005, 2006 Michael Buesch <mbuesch@freenet.de>

  Some code in this file is derived from the b44.c driver
  Copyright (C) 2002 David S. Miller
  Copyright (C) Pekka Pietikainen

  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; see the file COPYING.  If not, write to
  the Free Software Foundation, Inc., 51 Franklin Steet, Fifth Floor,
  Boston, MA 02110-1301, USA.

*/

#include "bcm43xx.h"
#include "bcm43xx_dma.h"
#include "bcm43xx_main.h"
#include "bcm43xx_debugfs.h"
#include "bcm43xx_power.h"
#include "bcm43xx_xmit.h"

#include <linux/dma-mapping.h>
#include <linux/pci.h>
#include <linux/delay.h>
#include <linux/skbuff.h>


static inline int free_slots(struct bcm43xx_dmaring *ring)
{
	return (ring->nr_slots - ring->used_slots);
}

static inline int next_slot(struct bcm43xx_dmaring *ring, int slot)
{
	assert(slot >= -1 && slot <= ring->nr_slots - 1);
	if (slot == ring->nr_slots - 1)
		return 0;
	return slot + 1;
}

static inline int prev_slot(struct bcm43xx_dmaring *ring, int slot)
{
	assert(slot >= 0 && slot <= ring->nr_slots - 1);
	if (slot == 0)
		return ring->nr_slots - 1;
	return slot - 1;
}

/* Request a slot for usage. */
static inline
int request_slot(struct bcm43xx_dmaring *ring)
{
	int slot;

	assert(ring->tx);
	assert(!ring->suspended);
	assert(free_slots(ring) != 0);

	slot = next_slot(ring, ring->current_slot);
	ring->current_slot = slot;
	ring->used_slots++;

	/* Check the number of available slots and suspend TX,
	 * if we are running low on free slots.
	 */
	if (unlikely(free_slots(ring) < ring->suspend_mark)) {
		netif_stop_queue(ring->bcm->net_dev);
		ring->suspended = 1;
	}
#ifdef CONFIG_BCM43XX_DEBUG
	if (ring->used_slots > ring->max_used_slots)
		ring->max_used_slots = ring->used_slots;
#endif /* CONFIG_BCM43XX_DEBUG*/

	return slot;
}

/* Return a slot to the free slots. */
static inline
void return_slot(struct bcm43xx_dmaring *ring, int slot)
{
	assert(ring->tx);

	ring->used_slots--;

	/* Check if TX is suspended and check if we have
	 * enough free slots to resume it again.
	 */
	if (unlikely(ring->suspended)) {
		if (free_slots(ring) >= ring->resume_mark) {
			ring->suspended = 0;
			netif_wake_queue(ring->bcm->net_dev);
		}
	}
}

u16 bcm43xx_dmacontroller_base(int dma64bit, int controller_idx)
{
	static const u16 map64[] = {
		BCM43xx_MMIO_DMA64_BASE0,
		BCM43xx_MMIO_DMA64_BASE1,
		BCM43xx_MMIO_DMA64_BASE2,
		BCM43xx_MMIO_DMA64_BASE3,
		BCM43xx_MMIO_DMA64_BASE4,
		BCM43xx_MMIO_DMA64_BASE5,
	};
	static const u16 map32[] = {
		BCM43xx_MMIO_DMA32_BASE0,
		BCM43xx_MMIO_DMA32_BASE1,
		BCM43xx_MMIO_DMA32_BASE2,
		BCM43xx_MMIO_DMA32_BASE3,
		BCM43xx_MMIO_DMA32_BASE4,
		BCM43xx_MMIO_DMA32_BASE5,
	};

	if (dma64bit) {
		assert(controller_idx >= 0 &&
		       controller_idx < ARRAY_SIZE(map64));
		return map64[controller_idx];
	}
	assert(controller_idx >= 0 &&
	       controller_idx < ARRAY_SIZE(map32));
	return map32[controller_idx];
}

static inline
dma_addr_t map_descbuffer(struct bcm43xx_dmaring *ring,
			  unsigned char *buf,
			  size_t len,
			  int tx)
{
	dma_addr_t dmaaddr;
	int direction = PCI_DMA_FROMDEVICE;

	if (tx)
		direction = PCI_DMA_TODEVICE;

	dmaaddr = pci_map_single(ring->bcm->pci_dev,
					 buf, len,
					 direction);

	return dmaaddr;
}

static inline
void unmap_descbuffer(struct bcm43xx_dmaring *ring,
		      dma_addr_t addr,
		      size_t len,
		      int tx)
{
	if (tx) {
		pci_unmap_single(ring->bcm->pci_dev,
				 addr, len,
				 PCI_DMA_TODEVICE);
	} else {
		pci_unmap_single(ring->bcm->pci_dev,
				 addr, len,
				 PCI_DMA_FROMDEVICE);
	}
}

static inline
void sync_descbuffer_for_cpu(struct bcm43xx_dmaring *ring,
			     dma_addr_t addr,
			     size_t len)
{
	assert(!ring->tx);

	pci_dma_sync_single_for_cpu(ring->bcm->pci_dev,
				    addr, len, PCI_DMA_FROMDEVICE);
}

static inline
void sync_descbuffer_for_device(struct bcm43xx_dmaring *ring,
				dma_addr_t addr,
				size_t len)
{
	assert(!ring->tx);

	pci_dma_sync_single_for_cpu(ring->bcm->pci_dev,
				    addr, len, PCI_DMA_TODEVICE);
}

/* Unmap and free a descriptor buffer. */
static inline
void free_descriptor_buffer(struct bcm43xx_dmaring *ring,
			    struct bcm43xx_dmadesc_meta *meta,
			    int irq_context)
{
	assert(meta->skb);
	if (irq_context)
		dev_kfree_skb_irq(meta->skb);
	else
		dev_kfree_skb(meta->skb);
	meta->skb = NULL;
}

static int alloc_ringmemory(struct bcm43xx_dmaring *ring)
{
	ring->descbase = pci_alloc_consistent(ring->bcm->pci_dev, BCM43xx_DMA_RINGMEMSIZE,
					    &(ring->dmabase));
	if (!ring->descbase) {
		/* Allocation may have failed due to pci_alloc_consistent
		   insisting on use of GFP_DMA, which is more restrictive
		   than necessary...  */
		struct dma_desc *rx_ring;
		dma_addr_t rx_ring_dma;

		rx_ring = kzalloc(BCM43xx_DMA_RINGMEMSIZE, GFP_KERNEL);
		if (!rx_ring)
			goto out_err;

		rx_ring_dma = pci_map_single(ring->bcm->pci_dev, rx_ring,
					     BCM43xx_DMA_RINGMEMSIZE,
					     PCI_DMA_BIDIRECTIONAL);

		if (pci_dma_mapping_error(rx_ring_dma) ||
		    rx_ring_dma + BCM43xx_DMA_RINGMEMSIZE > ring->bcm->dma_mask) {
			/* Sigh... */
			if (!pci_dma_mapping_error(rx_ring_dma))
				pci_unmap_single(ring->bcm->pci_dev,
						 rx_ring_dma, BCM43xx_DMA_RINGMEMSIZE,
						 PCI_DMA_BIDIRECTIONAL);
			rx_ring_dma = pci_map_single(ring->bcm->pci_dev,
						 rx_ring, BCM43xx_DMA_RINGMEMSIZE,
						 PCI_DMA_BIDIRECTIONAL);
			if (pci_dma_mapping_error(rx_ring_dma) ||
			    rx_ring_dma + BCM43xx_DMA_RINGMEMSIZE > ring->bcm->dma_mask) {
				assert(0);
				if (!pci_dma_mapping_error(rx_ring_dma))
					pci_unmap_single(ring->bcm->pci_dev,
							 rx_ring_dma, BCM43xx_DMA_RINGMEMSIZE,
							 PCI_DMA_BIDIRECTIONAL);
				goto out_err;
			}
                }

                ring->descbase = rx_ring;
                ring->dmabase = rx_ring_dma;
	}
	memset(ring->descbase, 0, BCM43xx_DMA_RINGMEMSIZE);

	return 0;
out_err:
	printk(KERN_ERR PFX "DMA ringmemory allocation failed\n");
	return -ENOMEM;
}

static void free_ringmemory(struct bcm43xx_dmaring *ring)
{
	struct device *dev = &(ring->bcm->pci_dev->dev);

	dma_free_coherent(dev, BCM43xx_DMA_RINGMEMSIZE,
			  ring->descbase, ring->dmabase);
}

/* Reset the RX DMA channel */
int bcm43xx_dmacontroller_rx_reset(struct bcm43xx_private *bcm,
				   u16 mmio_base, int dma64)
{
	int i;
	u32 value;
	u16 offset;

	offset = dma64 ? BCM43xx_DMA64_RXCTL : BCM43xx_DMA32_RXCTL;
	bcm43xx_write32(bcm, mmio_base + offset, 0);
	for (i = 0; i < 1000; i++) {
		offset = dma64 ? BCM43xx_DMA64_RXSTATUS : BCM43xx_DMA32_RXSTATUS;
		value = bcm43xx_read32(bcm, mmio_base + offset);
		if (dma64) {
			value &= BCM43xx_DMA64_RXSTAT;
			if (value == BCM43xx_DMA64_RXSTAT_DISABLED) {
				i = -1;
				break;
			}
		} else {
			value &= BCM43xx_DMA32_RXSTATE;
			if (value == BCM43xx_DMA32_RXSTAT_DISABLED) {
				i = -1;
				break;
			}
		}
		udelay(10);
	}
	if (i != -1) {
		printk(KERN_ERR PFX "Error: Wait on DMA RX status timed out.\n");
		return -ENODEV;
	}

	return 0;
}

/* Reset the RX DMA channel */
int bcm43xx_dmacontroller_tx_reset(struct bcm43xx_private *bcm,
				   u16 mmio_base, int dma64)
{
	int i;
	u32 value;
	u16 offset;

	for (i = 0; i < 1000; i++) {
		offset = dma64 ? BCM43xx_DMA64_TXSTATUS : BCM43xx_DMA32_TXSTATUS;
		value = bcm43xx_read32(bcm, mmio_base + offset);
		if (dma64) {
			value &= BCM43xx_DMA64_TXSTAT;
			if (value == BCM43xx_DMA64_TXSTAT_DISABLED ||
			    value == BCM43xx_DMA64_TXSTAT_IDLEWAIT ||
			    value == BCM43xx_DMA64_TXSTAT_STOPPED)
				break;
		} else {
			value &= BCM43xx_DMA32_TXSTATE;
			if (value == BCM43xx_DMA32_TXSTAT_DISABLED ||
			    value == BCM43xx_DMA32_TXSTAT_IDLEWAIT ||
			    value == BCM43xx_DMA32_TXSTAT_STOPPED)
				break;
		}
		udelay(10);
	}
	offset = dma64 ? BCM43xx_DMA64_TXCTL : BCM43xx_DMA32_TXCTL;
	bcm43xx_write32(bcm, mmio_base + offset, 0);
	for (i = 0; i < 1000; i++) {
		offset = dma64 ? BCM43xx_DMA64_TXSTATUS : BCM43xx_DMA32_TXSTATUS;
		value = bcm43xx_read32(bcm, mmio_base + offset);
		if (dma64) {
			value &= BCM43xx_DMA64_TXSTAT;
			if (value == BCM43xx_DMA64_TXSTAT_DISABLED) {
				i = -1;
				break;
			}
		} else {
			value &= BCM43xx_DMA32_TXSTATE;
			if (value == BCM43xx_DMA32_TXSTAT_DISABLED) {
				i = -1;
				break;
			}
		}
		udelay(10);
	}
	if (i != -1) {
		printk(KERN_ERR PFX "Error: Wait on DMA TX status timed out.\n");
		return -ENODEV;
	}
	/* ensure the reset is completed. */
	udelay(300);

	return 0;
}

static void fill_descriptor(struct bcm43xx_dmaring *ring,
			    struct bcm43xx_dmadesc_generic *desc,
			    dma_addr_t dmaaddr,
			    u16 bufsize,
			    int start, int end, int irq)
{
	int slot;

	slot = bcm43xx_dma_desc2idx(ring, desc);
	assert(slot >= 0 && slot < ring->nr_slots);

	if (ring->dma64) {
		u32 ctl0 = 0, ctl1 = 0;
		u32 addrlo, addrhi;
		u32 addrext;

		addrlo = (u32)(dmaaddr & 0xFFFFFFFF);
		addrhi = (((u64)dmaaddr >> 32) & ~BCM43xx_DMA64_ROUTING);
		addrext = (((u64)dmaaddr >> 32) >> BCM43xx_DMA64_ROUTING_SHIFT);
		addrhi |= ring->routing;
		if (slot == ring->nr_slots - 1)
			ctl0 |= BCM43xx_DMA64_DCTL0_DTABLEEND;
		if (start)
			ctl0 |= BCM43xx_DMA64_DCTL0_FRAMESTART;
		if (end)
			ctl0 |= BCM43xx_DMA64_DCTL0_FRAMEEND;
		if (irq)
			ctl0 |= BCM43xx_DMA64_DCTL0_IRQ;
		ctl1 |= (bufsize - ring->frameoffset)
			& BCM43xx_DMA64_DCTL1_BYTECNT;
		ctl1 |= (addrext << BCM43xx_DMA64_DCTL1_ADDREXT_SHIFT)
			& BCM43xx_DMA64_DCTL1_ADDREXT_MASK;

		desc->dma64.control0 = cpu_to_le32(ctl0);
		desc->dma64.control1 = cpu_to_le32(ctl1);
		desc->dma64.address_low = cpu_to_le32(addrlo);
		desc->dma64.address_high = cpu_to_le32(addrhi);
	} else {
		u32 ctl;
		u32 addr;
		u32 addrext;

		addr = (u32)(dmaaddr & ~BCM43xx_DMA32_ROUTING);
		addrext = (u32)(dmaaddr & BCM43xx_DMA32_ROUTING)
			   >> BCM43xx_DMA32_ROUTING_SHIFT;
		addr |= ring->routing;
		ctl = (bufsize - ring->frameoffset)
		      & BCM43xx_DMA32_DCTL_BYTECNT;
		if (slot == ring->nr_slots - 1)
			ctl |= BCM43xx_DMA32_DCTL_DTABLEEND;
		if (start)
			ctl |= BCM43xx_DMA32_DCTL_FRAMESTART;
		if (end)
			ctl |= BCM43xx_DMA32_DCTL_FRAMEEND;
		if (irq)
			ctl |= BCM43xx_DMA32_DCTL_IRQ;
		ctl |= (addrext << BCM43xx_DMA32_DCTL_ADDREXT_SHIFT)
		       & BCM43xx_DMA32_DCTL_ADDREXT_MASK;

		desc->dma32.control = cpu_to_le32(ctl);
		desc->dma32.address = cpu_to_le32(addr);
	}
}

static int setup_rx_descbuffer(struct bcm43xx_dmaring *ring,
			       struct bcm43xx_dmadesc_generic *desc,
			       struct bcm43xx_dmadesc_meta *meta,
			       gfp_t gfp_flags)
{
	struct bcm43xx_rxhdr *rxhdr;
	struct bcm43xx_hwxmitstatus *xmitstat;
	dma_addr_t dmaaddr;
	struct sk_buff *skb;

	assert(!ring->tx);

	skb = __dev_alloc_skb(ring->rx_buffersize, gfp_flags);
	if (unlikely(!skb))
		return -ENOMEM;
	dmaaddr = map_descbuffer(ring, skb->data, ring->rx_buffersize, 0);
	/* This hardware bug work-around adapted from the b44 driver.
	   The chip may be unable to do PCI DMA to/from anything above 1GB */
	if (pci_dma_mapping_error(dmaaddr) ||
	    dmaaddr + ring->rx_buffersize > ring->bcm->dma_mask) {
		/* This one has 30-bit addressing... */
		if (!pci_dma_mapping_error(dmaaddr))
			pci_unmap_single(ring->bcm->pci_dev,
					 dmaaddr, ring->rx_buffersize,
					 PCI_DMA_FROMDEVICE);
		dev_kfree_skb_any(skb);
		skb = __dev_alloc_skb(ring->rx_buffersize,GFP_DMA);
		if (skb == NULL)
			return -ENOMEM;
		dmaaddr = pci_map_single(ring->bcm->pci_dev,
					 skb->data, ring->rx_buffersize,
					 PCI_DMA_FROMDEVICE);
		if (pci_dma_mapping_error(dmaaddr) ||
		    dmaaddr + ring->rx_buffersize > ring->bcm->dma_mask) {
			assert(0);
			dev_kfree_skb_any(skb);
			return -ENOMEM;
		}
	}
	meta->skb = skb;
	meta->dmaaddr = dmaaddr;
	skb->dev = ring->bcm->net_dev;

	fill_descriptor(ring, desc, dmaaddr,
			ring->rx_buffersize, 0, 0, 0);

	rxhdr = (struct bcm43xx_rxhdr *)(skb->data);
	rxhdr->frame_length = 0;
	rxhdr->flags1 = 0;
	xmitstat = (struct bcm43xx_hwxmitstatus *)(skb->data);
	xmitstat->cookie = 0;

	return 0;
}

/* Allocate the initial descbuffers.
 * This is used for an RX ring only.
 */
static int alloc_initial_descbuffers(struct bcm43xx_dmaring *ring)
{
	int i, err = -ENOMEM;
	struct bcm43xx_dmadesc_generic *desc;
	struct bcm43xx_dmadesc_meta *meta;

	for (i = 0; i < ring->nr_slots; i++) {
		desc = bcm43xx_dma_idx2desc(ring, i, &meta);

		err = setup_rx_descbuffer(ring, desc, meta, GFP_KERNEL);
		if (err)
			goto err_unwind;
	}
	mb();
	ring->used_slots = ring->nr_slots;
	err = 0;
out:
	return err;

err_unwind:
	for (i--; i >= 0; i--) {
		desc = bcm43xx_dma_idx2desc(ring, i, &meta);

		unmap_descbuffer(ring, meta->dmaaddr, ring->rx_buffersize, 0);
		dev_kfree_skb(meta->skb);
	}
	goto out;
}

/* Do initial setup of the DMA controller.
 * Reset the controller, write the ring busaddress
 * and switch the "enable" bit on.
 */
static int dmacontroller_setup(struct bcm43xx_dmaring *ring)
{
	int err = 0;
	u32 value;
	u32 addrext;

	if (ring->tx) {
		if (ring->dma64) {
			u64 ringbase = (u64)(ring->dmabase);

			addrext = ((ringbase >> 32) >> BCM43xx_DMA64_ROUTING_SHIFT);
			value = BCM43xx_DMA64_TXENABLE;
			value |= (addrext << BCM43xx_DMA64_TXADDREXT_SHIFT)
				& BCM43xx_DMA64_TXADDREXT_MASK;
			bcm43xx_dma_write(ring, BCM43xx_DMA64_TXCTL, value);
			bcm43xx_dma_write(ring, BCM43xx_DMA64_TXRINGLO,
					(ringbase & 0xFFFFFFFF));
			bcm43xx_dma_write(ring, BCM43xx_DMA64_TXRINGHI,
					((ringbase >> 32) & ~BCM43xx_DMA64_ROUTING)
					| ring->routing);
		} else {
			u32 ringbase = (u32)(ring->dmabase);

			addrext = (ringbase >> BCM43xx_DMA32_ROUTING_SHIFT);
			value = BCM43xx_DMA32_TXENABLE;
			value |= (addrext << BCM43xx_DMA32_TXADDREXT_SHIFT)
				& BCM43xx_DMA32_TXADDREXT_MASK;
			bcm43xx_dma_write(ring, BCM43xx_DMA32_TXCTL, value);
			bcm43xx_dma_write(ring, BCM43xx_DMA32_TXRING,
					(ringbase & ~BCM43xx_DMA32_ROUTING)
					| ring->routing);
		}
	} else {
		err = alloc_initial_descbuffers(ring);
		if (err)
			goto out;
		if (ring->dma64) {
			u64 ringbase = (u64)(ring->dmabase);

			addrext = ((ringbase >> 32) >> BCM43xx_DMA64_ROUTING_SHIFT);
			value = (ring->frameoffset << BCM43xx_DMA64_RXFROFF_SHIFT);
			value |= BCM43xx_DMA64_RXENABLE;
			value |= (addrext << BCM43xx_DMA64_RXADDREXT_SHIFT)
				& BCM43xx_DMA64_RXADDREXT_MASK;
			bcm43xx_dma_write(ring, BCM43xx_DMA64_RXCTL, value);
			bcm43xx_dma_write(ring, BCM43xx_DMA64_RXRINGLO,
					(ringbase & 0xFFFFFFFF));
			bcm43xx_dma_write(ring, BCM43xx_DMA64_RXRINGHI,
					((ringbase >> 32) & ~BCM43xx_DMA64_ROUTING)
					| ring->routing);
			bcm43xx_dma_write(ring, BCM43xx_DMA64_RXINDEX, 200);
		} else {
			u32 ringbase = (u32)(ring->dmabase);

			addrext = (ringbase >> BCM43xx_DMA32_ROUTING_SHIFT);
			value = (ring->frameoffset << BCM43xx_DMA32_RXFROFF_SHIFT);
			value |= BCM43xx_DMA32_RXENABLE;
			value |= (addrext << BCM43xx_DMA32_RXADDREXT_SHIFT)
				& BCM43xx_DMA32_RXADDREXT_MASK;
			bcm43xx_dma_write(ring, BCM43xx_DMA32_RXCTL, value);
			bcm43xx_dma_write(ring, BCM43xx_DMA32_RXRING,
					(ringbase & ~BCM43xx_DMA32_ROUTING)
					| ring->routing);
			bcm43xx_dma_write(ring, BCM43xx_DMA32_RXINDEX, 200);
		}
	}

out:
	return err;
}

/* Shutdown the DMA controller. */
static void dmacontroller_cleanup(struct bcm43xx_dmaring *ring)
{
	if (ring->tx) {
		bcm43xx_dmacontroller_tx_reset(ring->bcm, ring->mmio_base, ring->dma64);
		if (ring->dma64) {
			bcm43xx_dma_write(ring, BCM43xx_DMA64_TXRINGLO, 0);
			bcm43xx_dma_write(ring, BCM43xx_DMA64_TXRINGHI, 0);
		} else
			bcm43xx_dma_write(ring, BCM43xx_DMA32_TXRING, 0);
	} else {
		bcm43xx_dmacontroller_rx_reset(ring->bcm, ring->mmio_base, ring->dma64);
		if (ring->dma64) {
			bcm43xx_dma_write(ring, BCM43xx_DMA64_RXRINGLO, 0);
			bcm43xx_dma_write(ring, BCM43xx_DMA64_RXRINGHI, 0);
		} else
			bcm43xx_dma_write(ring, BCM43xx_DMA32_RXRING, 0);
	}
}

static void free_all_descbuffers(struct bcm43xx_dmaring *ring)
{
	struct bcm43xx_dmadesc_generic *desc;
	struct bcm43xx_dmadesc_meta *meta;
	int i;

	if (!ring->used_slots)
		return;
	for (i = 0; i < ring->nr_slots; i++) {
		desc = bcm43xx_dma_idx2desc(ring, i, &meta);

		if (!meta->skb) {
			assert(ring->tx);
			continue;
		}
		if (ring->tx) {
			unmap_descbuffer(ring, meta->dmaaddr,
					meta->skb->len, 1);
		} else {
			unmap_descbuffer(ring, meta->dmaaddr,
					ring->rx_buffersize, 0);
		}
		free_descriptor_buffer(ring, meta, 0);
	}
}

/* Main initialization function. */
static
struct bcm43xx_dmaring * bcm43xx_setup_dmaring(struct bcm43xx_private *bcm,
					       int controller_index,
					       int for_tx,
					       int dma64)
{
	struct bcm43xx_dmaring *ring;
	int err;
	int nr_slots;

	ring = kzalloc(sizeof(*ring), GFP_KERNEL);
	if (!ring)
		goto out;

	nr_slots = BCM43xx_RXRING_SLOTS;
	if (for_tx)
		nr_slots = BCM43xx_TXRING_SLOTS;

	ring->meta = kcalloc(nr_slots, sizeof(struct bcm43xx_dmadesc_meta),
			     GFP_KERNEL);
	if (!ring->meta)
		goto err_kfree_ring;

	ring->routing = BCM43xx_DMA32_CLIENTTRANS;
	if (dma64)
		ring->routing = BCM43xx_DMA64_CLIENTTRANS;

	ring->bcm = bcm;
	ring->nr_slots = nr_slots;
	ring->suspend_mark = ring->nr_slots * BCM43xx_TXSUSPEND_PERCENT / 100;
	ring->resume_mark = ring->nr_slots * BCM43xx_TXRESUME_PERCENT / 100;
	assert(ring->suspend_mark < ring->resume_mark);
	ring->mmio_base = bcm43xx_dmacontroller_base(dma64, controller_index);
	ring->index = controller_index;
	ring->dma64 = !!dma64;
	if (for_tx) {
		ring->tx = 1;
		ring->current_slot = -1;
	} else {
		if (ring->index == 0) {
			ring->rx_buffersize = BCM43xx_DMA0_RX_BUFFERSIZE;
			ring->frameoffset = BCM43xx_DMA0_RX_FRAMEOFFSET;
		} else if (ring->index == 3) {
			ring->rx_buffersize = BCM43xx_DMA3_RX_BUFFERSIZE;
			ring->frameoffset = BCM43xx_DMA3_RX_FRAMEOFFSET;
		} else
			assert(0);
	}

	err = alloc_ringmemory(ring);
	if (err)
		goto err_kfree_meta;
	err = dmacontroller_setup(ring);
	if (err)
		goto err_free_ringmemory;
	return ring;

out:
	printk(KERN_ERR PFX "Error in bcm43xx_setup_dmaring\n");
	return ring;

err_free_ringmemory:
	free_ringmemory(ring);
err_kfree_meta:
	kfree(ring->meta);
err_kfree_ring:
	kfree(ring);
	ring = NULL;
	goto out;
}

/* Main cleanup function. */
static void bcm43xx_destroy_dmaring(struct bcm43xx_dmaring *ring)
{
	if (!ring)
		return;

	dprintk(KERN_INFO PFX "DMA-%s 0x%04X (%s) max used slots: %d/%d\n",
		(ring->dma64) ? "64" : "32",
		ring->mmio_base,
		(ring->tx) ? "TX" : "RX",
		ring->max_used_slots, ring->nr_slots);
	/* Device IRQs are disabled prior entering this function,
	 * so no need to take care of concurrency with rx handler stuff.
	 */
	dmacontroller_cleanup(ring);
	free_all_descbuffers(ring);
	free_ringmemory(ring);

	kfree(ring->meta);
	kfree(ring);
}

void bcm43xx_dma_free(struct bcm43xx_private *bcm)
{
	struct bcm43xx_dma *dma;

	if (bcm43xx_using_pio(bcm))
		return;
	dma = bcm43xx_current_dma(bcm);

	bcm43xx_destroy_dmaring(dma->rx_ring3);
	dma->rx_ring3 = NULL;
	bcm43xx_destroy_dmaring(dma->rx_ring0);
	dma->rx_ring0 = NULL;

	bcm43xx_destroy_dmaring(dma->tx_ring5);
	dma->tx_ring5 = NULL;
	bcm43xx_destroy_dmaring(dma->tx_ring4);
	dma->tx_ring4 = NULL;
	bcm43xx_destroy_dmaring(dma->tx_ring3);
	dma->tx_ring3 = NULL;
	bcm43xx_destroy_dmaring(dma->tx_ring2);
	dma->tx_ring2 = NULL;
	bcm43xx_destroy_dmaring(dma->tx_ring1);
	dma->tx_ring1 = NULL;
	bcm43xx_destroy_dmaring(dma->tx_ring0);
	dma->tx_ring0 = NULL;
}

int bcm43xx_dma_init(struct bcm43xx_private *bcm)
{
	struct bcm43xx_dma *dma = bcm43xx_current_dma(bcm);
	struct bcm43xx_dmaring *ring;
	int err = -ENOMEM;
	int dma64 = 0;

	bcm->dma_mask = bcm43xx_get_supported_dma_mask(bcm);
	if (bcm->dma_mask == DMA_64BIT_MASK)
		dma64 = 1;
	err = pci_set_dma_mask(bcm->pci_dev, bcm->dma_mask);
	if (err)
		goto no_dma;
	err = pci_set_consistent_dma_mask(bcm->pci_dev, bcm->dma_mask);
	if (err)
		goto no_dma;

	/* setup TX DMA channels. */
	ring = bcm43xx_setup_dmaring(bcm, 0, 1, dma64);
	if (!ring)
		goto out;
	dma->tx_ring0 = ring;

	ring = bcm43xx_setup_dmaring(bcm, 1, 1, dma64);
	if (!ring)
		goto err_destroy_tx0;
	dma->tx_ring1 = ring;

	ring = bcm43xx_setup_dmaring(bcm, 2, 1, dma64);
	if (!ring)
		goto err_destroy_tx1;
	dma->tx_ring2 = ring;

	ring = bcm43xx_setup_dmaring(bcm, 3, 1, dma64);
	if (!ring)
		goto err_destroy_tx2;
	dma->tx_ring3 = ring;

	ring = bcm43xx_setup_dmaring(bcm, 4, 1, dma64);
	if (!ring)
		goto err_destroy_tx3;
	dma->tx_ring4 = ring;

	ring = bcm43xx_setup_dmaring(bcm, 5, 1, dma64);
	if (!ring)
		goto err_destroy_tx4;
	dma->tx_ring5 = ring;

	/* setup RX DMA channels. */
	ring = bcm43xx_setup_dmaring(bcm, 0, 0, dma64);
	if (!ring)
		goto err_destroy_tx5;
	dma->rx_ring0 = ring;

	if (bcm->current_core->rev < 5) {
		ring = bcm43xx_setup_dmaring(bcm, 3, 0, dma64);
		if (!ring)
			goto err_destroy_rx0;
		dma->rx_ring3 = ring;
	}

	dprintk(KERN_INFO PFX "%d-bit DMA initialized\n",
		(bcm->dma_mask == DMA_64BIT_MASK) ? 64 :
		(bcm->dma_mask == DMA_32BIT_MASK) ? 32 : 30);
	err = 0;
out:
	return err;

err_destroy_rx0:
	bcm43xx_destroy_dmaring(dma->rx_ring0);
	dma->rx_ring0 = NULL;
err_destroy_tx5:
	bcm43xx_destroy_dmaring(dma->tx_ring5);
	dma->tx_ring5 = NULL;
err_destroy_tx4:
	bcm43xx_destroy_dmaring(dma->tx_ring4);
	dma->tx_ring4 = NULL;
err_destroy_tx3:
	bcm43xx_destroy_dmaring(dma->tx_ring3);
	dma->tx_ring3 = NULL;
err_destroy_tx2:
	bcm43xx_destroy_dmaring(dma->tx_ring2);
	dma->tx_ring2 = NULL;
err_destroy_tx1:
	bcm43xx_destroy_dmaring(dma->tx_ring1);
	dma->tx_ring1 = NULL;
err_destroy_tx0:
	bcm43xx_destroy_dmaring(dma->tx_ring0);
	dma->tx_ring0 = NULL;
no_dma:
#ifdef CONFIG_BCM43XX_PIO
	printk(KERN_WARNING PFX "DMA not supported on this device."
				" Falling back to PIO.\n");
	bcm->__using_pio = 1;
	return -ENOSYS;
#else
	printk(KERN_ERR PFX "FATAL: DMA not supported and PIO not configured. "
			    "Please recompile the driver with PIO support.\n");
	return -ENODEV;
#endif /* CONFIG_BCM43XX_PIO */
}

/* Generate a cookie for the TX header. */
static u16 generate_cookie(struct bcm43xx_dmaring *ring,
			   int slot)
{
	u16 cookie = 0x1000;

	/* Use the upper 4 bits of the cookie as
	 * DMA controller ID and store the slot number
	 * in the lower 12 bits.
	 * Note that the cookie must never be 0, as this
	 * is a special value used in RX path.
	 */
	switch (ring->index) {
	case 0:
		cookie = 0xA000;
		break;
	case 1:
		cookie = 0xB000;
		break;
	case 2:
		cookie = 0xC000;
		break;
	case 3:
		cookie = 0xD000;
		break;
	case 4:
		cookie = 0xE000;
		break;
	case 5:
		cookie = 0xF000;
		break;
	}
	assert(((u16)slot & 0xF000) == 0x0000);
	cookie |= (u16)slot;

	return cookie;
}

/* Inspect a cookie and find out to which controller/slot it belongs. */
static
struct bcm43xx_dmaring * parse_cookie(struct bcm43xx_private *bcm,
				      u16 cookie, int *slot)
{
	struct bcm43xx_dma *dma = bcm43xx_current_dma(bcm);
	struct bcm43xx_dmaring *ring = NULL;

	switch (cookie & 0xF000) {
	case 0xA000:
		ring = dma->tx_ring0;
		break;
	case 0xB000:
		ring = dma->tx_ring1;
		break;
	case 0xC000:
		ring = dma->tx_ring2;
		break;
	case 0xD000:
		ring = dma->tx_ring3;
		break;
	case 0xE000:
		ring = dma->tx_ring4;
		break;
	case 0xF000:
		ring = dma->tx_ring5;
		break;
	default:
		assert(0);
	}
	*slot = (cookie & 0x0FFF);
	assert(*slot >= 0 && *slot < ring->nr_slots);

	return ring;
}

static void dmacontroller_poke_tx(struct bcm43xx_dmaring *ring,
				  int slot)
{
	u16 offset;
	int descsize;

	/* Everything is ready to start. Buffers are DMA mapped and
	 * associated with slots.
	 * "slot" is the last slot of the new frame we want to transmit.
	 * Close your seat belts now, please.
	 */
	wmb();
	slot = next_slot(ring, slot);
	offset = (ring->dma64) ? BCM43xx_DMA64_TXINDEX : BCM43xx_DMA32_TXINDEX;
	descsize = (ring->dma64) ? sizeof(struct bcm43xx_dmadesc64)
		: sizeof(struct bcm43xx_dmadesc32);
	bcm43xx_dma_write(ring, offset,
			(u32)(slot * descsize));
}

static void dma_tx_fragment(struct bcm43xx_dmaring *ring,
			    struct sk_buff *skb,
			    u8 cur_frag)
{
	int slot;
	struct bcm43xx_dmadesc_generic *desc;
	struct bcm43xx_dmadesc_meta *meta;
	dma_addr_t dmaaddr;
	struct sk_buff *bounce_skb;

	assert(skb_shinfo(skb)->nr_frags == 0);

	slot = request_slot(ring);
	desc = bcm43xx_dma_idx2desc(ring, slot, &meta);

	/* Add a device specific TX header. */
	assert(skb_headroom(skb) >= sizeof(struct bcm43xx_txhdr));
	/* Reserve enough headroom for the device tx header. */
	__skb_push(skb, sizeof(struct bcm43xx_txhdr));
	/* Now calculate and add the tx header.
	 * The tx header includes the PLCP header.
	 */
	bcm43xx_generate_txhdr(ring->bcm,
			       (struct bcm43xx_txhdr *)skb->data,
			       skb->data + sizeof(struct bcm43xx_txhdr),
			       skb->len - sizeof(struct bcm43xx_txhdr),
			       (cur_frag == 0),
			       generate_cookie(ring, slot));
	dmaaddr = map_descbuffer(ring, skb->data, skb->len, 1);
	if (dma_mapping_error(dmaaddr) || dmaaddr + skb->len > ring->bcm->dma_mask) {
		/* chip cannot handle DMA to/from > 1GB, use bounce buffer (copied from b44 driver) */
		if (!dma_mapping_error(dmaaddr))
			unmap_descbuffer(ring, dmaaddr, skb->len, 1);
		bounce_skb = __dev_alloc_skb(skb->len, GFP_ATOMIC|GFP_DMA);
		if (!bounce_skb)
			return;
		dmaaddr = map_descbuffer(ring, bounce_skb->data, bounce_skb->len, 1);
		if (dma_mapping_error(dmaaddr) || dmaaddr + skb->len > ring->bcm->dma_mask) {
			if (!dma_mapping_error(dmaaddr))
				unmap_descbuffer(ring, dmaaddr, skb->len, 1);
			dev_kfree_skb_any(bounce_skb);
			assert(0);
			return;
		}
		skb_copy_from_linear_data(skb, skb_put(bounce_skb, skb->len),
					  skb->len);
		dev_kfree_skb_any(skb);
		skb = bounce_skb;
	}

	meta->skb = skb;
	meta->dmaaddr = dmaaddr;

	fill_descriptor(ring, desc, dmaaddr,
			skb->len, 1, 1, 1);

	/* Now transfer the whole frame. */
	dmacontroller_poke_tx(ring, slot);
}

int bcm43xx_dma_tx(struct bcm43xx_private *bcm,
		   struct ieee80211_txb *txb)
{
	/* We just received a packet from the kernel network subsystem.
	 * Add headers and DMA map the memory. Poke
	 * the device to send the stuff.
	 * Note that this is called from atomic context.
	 */
	struct bcm43xx_dmaring *ring = bcm43xx_current_dma(bcm)->tx_ring1;
	u8 i;
	struct sk_buff *skb;

	assert(ring->tx);
	if (unlikely(free_slots(ring) < txb->nr_frags)) {
		/* The queue should be stopped,
		 * if we are low on free slots.
		 * If this ever triggers, we have to lower the suspend_mark.
		 */
		dprintkl(KERN_ERR PFX "Out of DMA descriptor slots!\n");
		return -ENOMEM;
	}

	for (i = 0; i < txb->nr_frags; i++) {
		skb = txb->fragments[i];
		/* Take skb from ieee80211_txb_free */
		txb->fragments[i] = NULL;
		dma_tx_fragment(ring, skb, i);
	}
	ieee80211_txb_free(txb);

	return 0;
}

void bcm43xx_dma_handle_xmitstatus(struct bcm43xx_private *bcm,
				   struct bcm43xx_xmitstatus *status)
{
	struct bcm43xx_dmaring *ring;
	struct bcm43xx_dmadesc_generic *desc;
	struct bcm43xx_dmadesc_meta *meta;
	int is_last_fragment;
	int slot;
	u32 tmp;

	ring = parse_cookie(bcm, status->cookie, &slot);
	assert(ring);
	assert(ring->tx);
	while (1) {
		assert(slot >= 0 && slot < ring->nr_slots);
		desc = bcm43xx_dma_idx2desc(ring, slot, &meta);

		if (ring->dma64) {
			tmp = le32_to_cpu(desc->dma64.control0);
			is_last_fragment = !!(tmp & BCM43xx_DMA64_DCTL0_FRAMEEND);
		} else {
			tmp = le32_to_cpu(desc->dma32.control);
			is_last_fragment = !!(tmp & BCM43xx_DMA32_DCTL_FRAMEEND);
		}
		unmap_descbuffer(ring, meta->dmaaddr, meta->skb->len, 1);
		free_descriptor_buffer(ring, meta, 1);
		/* Everything belonging to the slot is unmapped
		 * and freed, so we can return it.
		 */
		return_slot(ring, slot);

		if (is_last_fragment)
			break;
		slot = next_slot(ring, slot);
	}
	bcm->stats.last_tx = jiffies;
}

static void dma_rx(struct bcm43xx_dmaring *ring,
		   int *slot)
{
	struct bcm43xx_dmadesc_generic *desc;
	struct bcm43xx_dmadesc_meta *meta;
	struct bcm43xx_rxhdr *rxhdr;
	struct sk_buff *skb;
	u16 len;
	int err;
	dma_addr_t dmaaddr;

	desc = bcm43xx_dma_idx2desc(ring, *slot, &meta);

	sync_descbuffer_for_cpu(ring, meta->dmaaddr, ring->rx_buffersize);
	skb = meta->skb;

	if (ring->index == 3) {
		/* We received an xmit status. */
		struct bcm43xx_hwxmitstatus *hw = (struct bcm43xx_hwxmitstatus *)skb->data;
		struct bcm43xx_xmitstatus stat;
		int i = 0;

		stat.cookie = le16_to_cpu(hw->cookie);
		while (stat.cookie == 0) {
			if (unlikely(++i >= 10000)) {
				assert(0);
				break;
			}
			udelay(2);
			barrier();
			stat.cookie = le16_to_cpu(hw->cookie);
		}
		stat.flags = hw->flags;
		stat.cnt1 = hw->cnt1;
		stat.cnt2 = hw->cnt2;
		stat.seq = le16_to_cpu(hw->seq);
		stat.unknown = le16_to_cpu(hw->unknown);

		bcm43xx_debugfs_log_txstat(ring->bcm, &stat);
		bcm43xx_dma_handle_xmitstatus(ring->bcm, &stat);
		/* recycle the descriptor buffer. */
		sync_descbuffer_for_device(ring, meta->dmaaddr, ring->rx_buffersize);

		return;
	}
	rxhdr = (struct bcm43xx_rxhdr *)skb->data;
	len = le16_to_cpu(rxhdr->frame_length);
	if (len == 0) {
		int i = 0;

		do {
			udelay(2);
			barrier();
			len = le16_to_cpu(rxhdr->frame_length);
		} while (len == 0 && i++ < 5);
		if (unlikely(len == 0)) {
			/* recycle the descriptor buffer. */
			sync_descbuffer_for_device(ring, meta->dmaaddr,
						   ring->rx_buffersize);
			goto drop;
		}
	}
	if (unlikely(len > ring->rx_buffersize)) {
		/* The data did not fit into one descriptor buffer
		 * and is split over multiple buffers.
		 * This should never happen, as we try to allocate buffers
		 * big enough. So simply ignore this packet.
		 */
		int cnt = 0;
		s32 tmp = len;

		while (1) {
			desc = bcm43xx_dma_idx2desc(ring, *slot, &meta);
			/* recycle the descriptor buffer. */
			sync_descbuffer_for_device(ring, meta->dmaaddr,
						   ring->rx_buffersize);
			*slot = next_slot(ring, *slot);
			cnt++;
			tmp -= ring->rx_buffersize;
			if (tmp <= 0)
				break;
		}
		printkl(KERN_ERR PFX "DMA RX buffer too small "
			"(len: %u, buffer: %u, nr-dropped: %d)\n",
			len, ring->rx_buffersize, cnt);
		goto drop;
	}
	len -= IEEE80211_FCS_LEN;

	dmaaddr = meta->dmaaddr;
	err = setup_rx_descbuffer(ring, desc, meta, GFP_ATOMIC);
	if (unlikely(err)) {
		dprintkl(KERN_ERR PFX "DMA RX: setup_rx_descbuffer() failed\n");
		sync_descbuffer_for_device(ring, dmaaddr,
					   ring->rx_buffersize);
		goto drop;
	}

	unmap_descbuffer(ring, dmaaddr, ring->rx_buffersize, 0);
	skb_put(skb, len + ring->frameoffset);
	skb_pull(skb, ring->frameoffset);

	err = bcm43xx_rx(ring->bcm, skb, rxhdr);
	if (err) {
		dev_kfree_skb_irq(skb);
		goto drop;
	}

drop:
	return;
}

void bcm43xx_dma_rx(struct bcm43xx_dmaring *ring)
{
	u32 status;
	u16 descptr;
	int slot, current_slot;
#ifdef CONFIG_BCM43XX_DEBUG
	int used_slots = 0;
#endif

	assert(!ring->tx);
	if (ring->dma64) {
		status = bcm43xx_dma_read(ring, BCM43xx_DMA64_RXSTATUS);
		descptr = (status & BCM43xx_DMA64_RXSTATDPTR);
		current_slot = descptr / sizeof(struct bcm43xx_dmadesc64);
	} else {
		status = bcm43xx_dma_read(ring, BCM43xx_DMA32_RXSTATUS);
		descptr = (status & BCM43xx_DMA32_RXDPTR);
		current_slot = descptr / sizeof(struct bcm43xx_dmadesc32);
	}
	assert(current_slot >= 0 && current_slot < ring->nr_slots);

	slot = ring->current_slot;
	for ( ; slot != current_slot; slot = next_slot(ring, slot)) {
		dma_rx(ring, &slot);
#ifdef CONFIG_BCM43XX_DEBUG
		if (++used_slots > ring->max_used_slots)
			ring->max_used_slots = used_slots;
#endif
	}
	if (ring->dma64) {
		bcm43xx_dma_write(ring, BCM43xx_DMA64_RXINDEX,
				(u32)(slot * sizeof(struct bcm43xx_dmadesc64)));
	} else {
		bcm43xx_dma_write(ring, BCM43xx_DMA32_RXINDEX,
				(u32)(slot * sizeof(struct bcm43xx_dmadesc32)));
	}
	ring->current_slot = slot;
}

void bcm43xx_dma_tx_suspend(struct bcm43xx_dmaring *ring)
{
	assert(ring->tx);
	bcm43xx_power_saving_ctl_bits(ring->bcm, -1, 1);
	if (ring->dma64) {
		bcm43xx_dma_write(ring, BCM43xx_DMA64_TXCTL,
				bcm43xx_dma_read(ring, BCM43xx_DMA64_TXCTL)
				| BCM43xx_DMA64_TXSUSPEND);
	} else {
		bcm43xx_dma_write(ring, BCM43xx_DMA32_TXCTL,
				bcm43xx_dma_read(ring, BCM43xx_DMA32_TXCTL)
				| BCM43xx_DMA32_TXSUSPEND);
	}
}

void bcm43xx_dma_tx_resume(struct bcm43xx_dmaring *ring)
{
	assert(ring->tx);
	if (ring->dma64) {
		bcm43xx_dma_write(ring, BCM43xx_DMA64_TXCTL,
				bcm43xx_dma_read(ring, BCM43xx_DMA64_TXCTL)
				& ~BCM43xx_DMA64_TXSUSPEND);
	} else {
		bcm43xx_dma_write(ring, BCM43xx_DMA32_TXCTL,
				bcm43xx_dma_read(ring, BCM43xx_DMA32_TXCTL)
				& ~BCM43xx_DMA32_TXSUSPEND);
	}
	bcm43xx_power_saving_ctl_bits(ring->bcm, -1, -1);
}