aboutsummaryrefslogtreecommitdiff
path: root/arch/arm/mach-bcmring/dma.c
blob: 1024396797e16f6c839383da409731bfaef494d3 (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
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
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
/*****************************************************************************
* Copyright 2004 - 2008 Broadcom Corporation.  All rights reserved.
*
* Unless you and Broadcom execute a separate written software license
* agreement governing use of this software, this software is licensed to you
* under the terms of the GNU General Public License version 2, available at
* http://www.broadcom.com/licenses/GPLv2.php (the "GPL").
*
* Notwithstanding the above, under no circumstances may you combine this
* software in any way with any other Broadcom software provided under a
* license other than the GPL, without Broadcom's express prior written
* consent.
*****************************************************************************/

/****************************************************************************/
/**
*   @file   dma.c
*
*   @brief  Implements the DMA interface.
*/
/****************************************************************************/

/* ---- Include Files ---------------------------------------------------- */

#include <linux/module.h>
#include <linux/device.h>
#include <linux/dma-mapping.h>
#include <linux/interrupt.h>
#include <linux/sched.h>
#include <linux/irqreturn.h>
#include <linux/proc_fs.h>
#include <linux/slab.h>

#include <mach/timer.h>

#include <linux/pfn.h>
#include <linux/atomic.h>
#include <linux/sched.h>
#include <mach/dma.h>

/* ---- Public Variables ------------------------------------------------- */

/* ---- Private Constants and Types -------------------------------------- */

#define MAKE_HANDLE(controllerIdx, channelIdx)    (((controllerIdx) << 4) | (channelIdx))

#define CONTROLLER_FROM_HANDLE(handle)    (((handle) >> 4) & 0x0f)
#define CHANNEL_FROM_HANDLE(handle)       ((handle) & 0x0f)


/* ---- Private Variables ------------------------------------------------ */

static DMA_Global_t gDMA;
static struct proc_dir_entry *gDmaDir;

#include "dma_device.c"

/* ---- Private Function Prototypes -------------------------------------- */

/* ---- Functions  ------------------------------------------------------- */

/****************************************************************************/
/**
*   Displays information for /proc/dma/channels
*/
/****************************************************************************/

static int dma_proc_read_channels(char *buf, char **start, off_t offset,
				  int count, int *eof, void *data)
{
	int controllerIdx;
	int channelIdx;
	int limit = count - 200;
	int len = 0;
	DMA_Channel_t *channel;

	if (down_interruptible(&gDMA.lock) < 0) {
		return -ERESTARTSYS;
	}

	for (controllerIdx = 0; controllerIdx < DMA_NUM_CONTROLLERS;
	     controllerIdx++) {
		for (channelIdx = 0; channelIdx < DMA_NUM_CHANNELS;
		     channelIdx++) {
			if (len >= limit) {
				break;
			}

			channel =
			    &gDMA.controller[controllerIdx].channel[channelIdx];

			len +=
			    sprintf(buf + len, "%d:%d ", controllerIdx,
				    channelIdx);

			if ((channel->flags & DMA_CHANNEL_FLAG_IS_DEDICATED) !=
			    0) {
				len +=
				    sprintf(buf + len, "Dedicated for %s ",
					    DMA_gDeviceAttribute[channel->
								 devType].name);
			} else {
				len += sprintf(buf + len, "Shared ");
			}

			if ((channel->flags & DMA_CHANNEL_FLAG_NO_ISR) != 0) {
				len += sprintf(buf + len, "No ISR ");
			}

			if ((channel->flags & DMA_CHANNEL_FLAG_LARGE_FIFO) != 0) {
				len += sprintf(buf + len, "Fifo: 128 ");
			} else {
				len += sprintf(buf + len, "Fifo: 64  ");
			}

			if ((channel->flags & DMA_CHANNEL_FLAG_IN_USE) != 0) {
				len +=
				    sprintf(buf + len, "InUse by %s",
					    DMA_gDeviceAttribute[channel->
								 devType].name);
#if (DMA_DEBUG_TRACK_RESERVATION)
				len +=
				    sprintf(buf + len, " (%s:%d)",
					    channel->fileName,
					    channel->lineNum);
#endif
			} else {
				len += sprintf(buf + len, "Avail ");
			}

			if (channel->lastDevType != DMA_DEVICE_NONE) {
				len +=
				    sprintf(buf + len, "Last use: %s ",
					    DMA_gDeviceAttribute[channel->
								 lastDevType].
					    name);
			}

			len += sprintf(buf + len, "\n");
		}
	}
	up(&gDMA.lock);
	*eof = 1;

	return len;
}

/****************************************************************************/
/**
*   Displays information for /proc/dma/devices
*/
/****************************************************************************/

static int dma_proc_read_devices(char *buf, char **start, off_t offset,
				 int count, int *eof, void *data)
{
	int limit = count - 200;
	int len = 0;
	int devIdx;

	if (down_interruptible(&gDMA.lock) < 0) {
		return -ERESTARTSYS;
	}

	for (devIdx = 0; devIdx < DMA_NUM_DEVICE_ENTRIES; devIdx++) {
		DMA_DeviceAttribute_t *devAttr = &DMA_gDeviceAttribute[devIdx];

		if (devAttr->name == NULL) {
			continue;
		}

		if (len >= limit) {
			break;
		}

		len += sprintf(buf + len, "%-12s ", devAttr->name);

		if ((devAttr->flags & DMA_DEVICE_FLAG_IS_DEDICATED) != 0) {
			len +=
			    sprintf(buf + len, "Dedicated %d:%d ",
				    devAttr->dedicatedController,
				    devAttr->dedicatedChannel);
		} else {
			len += sprintf(buf + len, "Shared DMA:");
			if ((devAttr->flags & DMA_DEVICE_FLAG_ON_DMA0) != 0) {
				len += sprintf(buf + len, "0");
			}
			if ((devAttr->flags & DMA_DEVICE_FLAG_ON_DMA1) != 0) {
				len += sprintf(buf + len, "1");
			}
			len += sprintf(buf + len, " ");
		}
		if ((devAttr->flags & DMA_DEVICE_FLAG_NO_ISR) != 0) {
			len += sprintf(buf + len, "NoISR ");
		}
		if ((devAttr->flags & DMA_DEVICE_FLAG_ALLOW_LARGE_FIFO) != 0) {
			len += sprintf(buf + len, "Allow-128 ");
		}

		len +=
		    sprintf(buf + len,
			    "Xfer #: %Lu Ticks: %Lu Bytes: %Lu DescLen: %u\n",
			    devAttr->numTransfers, devAttr->transferTicks,
			    devAttr->transferBytes,
			    devAttr->ring.bytesAllocated);

	}

	up(&gDMA.lock);
	*eof = 1;

	return len;
}

/****************************************************************************/
/**
*   Determines if a DMA_Device_t is "valid".
*
*   @return
*       TRUE        - dma device is valid
*       FALSE       - dma device isn't valid
*/
/****************************************************************************/

static inline int IsDeviceValid(DMA_Device_t device)
{
	return (device >= 0) && (device < DMA_NUM_DEVICE_ENTRIES);
}

/****************************************************************************/
/**
*   Translates a DMA handle into a pointer to a channel.
*
*   @return
*       non-NULL    - pointer to DMA_Channel_t
*       NULL        - DMA Handle was invalid
*/
/****************************************************************************/

static inline DMA_Channel_t *HandleToChannel(DMA_Handle_t handle)
{
	int controllerIdx;
	int channelIdx;

	controllerIdx = CONTROLLER_FROM_HANDLE(handle);
	channelIdx = CHANNEL_FROM_HANDLE(handle);

	if ((controllerIdx > DMA_NUM_CONTROLLERS)
	    || (channelIdx > DMA_NUM_CHANNELS)) {
		return NULL;
	}
	return &gDMA.controller[controllerIdx].channel[channelIdx];
}

/****************************************************************************/
/**
*   Interrupt handler which is called to process DMA interrupts.
*/
/****************************************************************************/

static irqreturn_t dma_interrupt_handler(int irq, void *dev_id)
{
	DMA_Channel_t *channel;
	DMA_DeviceAttribute_t *devAttr;
	int irqStatus;

	channel = (DMA_Channel_t *) dev_id;

	/* Figure out why we were called, and knock down the interrupt */

	irqStatus = dmacHw_getInterruptStatus(channel->dmacHwHandle);
	dmacHw_clearInterrupt(channel->dmacHwHandle);

	if ((channel->devType < 0)
	    || (channel->devType > DMA_NUM_DEVICE_ENTRIES)) {
		printk(KERN_ERR "dma_interrupt_handler: Invalid devType: %d\n",
		       channel->devType);
		return IRQ_NONE;
	}
	devAttr = &DMA_gDeviceAttribute[channel->devType];

	/* Update stats */

	if ((irqStatus & dmacHw_INTERRUPT_STATUS_TRANS) != 0) {
		devAttr->transferTicks +=
		    (timer_get_tick_count() - devAttr->transferStartTime);
	}

	if ((irqStatus & dmacHw_INTERRUPT_STATUS_ERROR) != 0) {
		printk(KERN_ERR
		       "dma_interrupt_handler: devType :%d DMA error (%s)\n",
		       channel->devType, devAttr->name);
	} else {
		devAttr->numTransfers++;
		devAttr->transferBytes += devAttr->numBytes;
	}

	/* Call any installed handler */

	if (devAttr->devHandler != NULL) {
		devAttr->devHandler(channel->devType, irqStatus,
				    devAttr->userData);
	}

	return IRQ_HANDLED;
}

/****************************************************************************/
/**
*   Allocates memory to hold a descriptor ring. The descriptor ring then
*   needs to be populated by making one or more calls to
*   dna_add_descriptors.
*
*   The returned descriptor ring will be automatically initialized.
*
*   @return
*       0           Descriptor ring was allocated successfully
*       -EINVAL     Invalid parameters passed in
*       -ENOMEM     Unable to allocate memory for the desired number of descriptors.
*/
/****************************************************************************/

int dma_alloc_descriptor_ring(DMA_DescriptorRing_t *ring,	/* Descriptor ring to populate */
			      int numDescriptors	/* Number of descriptors that need to be allocated. */
    ) {
	size_t bytesToAlloc = dmacHw_descriptorLen(numDescriptors);

	if ((ring == NULL) || (numDescriptors <= 0)) {
		return -EINVAL;
	}

	ring->physAddr = 0;
	ring->descriptorsAllocated = 0;
	ring->bytesAllocated = 0;

	ring->virtAddr = dma_alloc_writecombine(NULL,
						     bytesToAlloc,
						     &ring->physAddr,
						     GFP_KERNEL);
	if (ring->virtAddr == NULL) {
		return -ENOMEM;
	}

	ring->bytesAllocated = bytesToAlloc;
	ring->descriptorsAllocated = numDescriptors;

	return dma_init_descriptor_ring(ring, numDescriptors);
}

EXPORT_SYMBOL(dma_alloc_descriptor_ring);

/****************************************************************************/
/**
*   Releases the memory which was previously allocated for a descriptor ring.
*/
/****************************************************************************/

void dma_free_descriptor_ring(DMA_DescriptorRing_t *ring	/* Descriptor to release */
    ) {
	if (ring->virtAddr != NULL) {
		dma_free_writecombine(NULL,
				      ring->bytesAllocated,
				      ring->virtAddr, ring->physAddr);
	}

	ring->bytesAllocated = 0;
	ring->descriptorsAllocated = 0;
	ring->virtAddr = NULL;
	ring->physAddr = 0;
}

EXPORT_SYMBOL(dma_free_descriptor_ring);

/****************************************************************************/
/**
*   Initializes a descriptor ring, so that descriptors can be added to it.
*   Once a descriptor ring has been allocated, it may be reinitialized for
*   use with additional/different regions of memory.
*
*   Note that if 7 descriptors are allocated, it's perfectly acceptable to
*   initialize the ring with a smaller number of descriptors. The amount
*   of memory allocated for the descriptor ring will not be reduced, and
*   the descriptor ring may be reinitialized later
*
*   @return
*       0           Descriptor ring was initialized successfully
*       -ENOMEM     The descriptor which was passed in has insufficient space
*                   to hold the desired number of descriptors.
*/
/****************************************************************************/

int dma_init_descriptor_ring(DMA_DescriptorRing_t *ring,	/* Descriptor ring to initialize */
			     int numDescriptors	/* Number of descriptors to initialize. */
    ) {
	if (ring->virtAddr == NULL) {
		return -EINVAL;
	}
	if (dmacHw_initDescriptor(ring->virtAddr,
				  ring->physAddr,
				  ring->bytesAllocated, numDescriptors) < 0) {
		printk(KERN_ERR
		       "dma_init_descriptor_ring: dmacHw_initDescriptor failed\n");
		return -ENOMEM;
	}

	return 0;
}

EXPORT_SYMBOL(dma_init_descriptor_ring);

/****************************************************************************/
/**
*   Determines the number of descriptors which would be required for a
*   transfer of the indicated memory region.
*
*   This function also needs to know which DMA device this transfer will
*   be destined for, so that the appropriate DMA configuration can be retrieved.
*   DMA parameters such as transfer width, and whether this is a memory-to-memory
*   or memory-to-peripheral, etc can all affect the actual number of descriptors
*   required.
*
*   @return
*       > 0     Returns the number of descriptors required for the indicated transfer
*       -ENODEV - Device handed in is invalid.
*       -EINVAL Invalid parameters
*       -ENOMEM Memory exhausted
*/
/****************************************************************************/

int dma_calculate_descriptor_count(DMA_Device_t device,	/* DMA Device that this will be associated with */
				   dma_addr_t srcData,	/* Place to get data to write to device */
				   dma_addr_t dstData,	/* Pointer to device data address */
				   size_t numBytes	/* Number of bytes to transfer to the device */
    ) {
	int numDescriptors;
	DMA_DeviceAttribute_t *devAttr;

	if (!IsDeviceValid(device)) {
		return -ENODEV;
	}
	devAttr = &DMA_gDeviceAttribute[device];

	numDescriptors = dmacHw_calculateDescriptorCount(&devAttr->config,
							      (void *)srcData,
							      (void *)dstData,
							      numBytes);
	if (numDescriptors < 0) {
		printk(KERN_ERR
		       "dma_calculate_descriptor_count: dmacHw_calculateDescriptorCount failed\n");
		return -EINVAL;
	}

	return numDescriptors;
}

EXPORT_SYMBOL(dma_calculate_descriptor_count);

/****************************************************************************/
/**
*   Adds a region of memory to the descriptor ring. Note that it may take
*   multiple descriptors for each region of memory. It is the callers
*   responsibility to allocate a sufficiently large descriptor ring.
*
*   @return
*       0       Descriptors were added successfully
*       -ENODEV Device handed in is invalid.
*       -EINVAL Invalid parameters
*       -ENOMEM Memory exhausted
*/
/****************************************************************************/

int dma_add_descriptors(DMA_DescriptorRing_t *ring,	/* Descriptor ring to add descriptors to */
			DMA_Device_t device,	/* DMA Device that descriptors are for */
			dma_addr_t srcData,	/* Place to get data (memory or device) */
			dma_addr_t dstData,	/* Place to put data (memory or device) */
			size_t numBytes	/* Number of bytes to transfer to the device */
    ) {
	int rc;
	DMA_DeviceAttribute_t *devAttr;

	if (!IsDeviceValid(device)) {
		return -ENODEV;
	}
	devAttr = &DMA_gDeviceAttribute[device];

	rc = dmacHw_setDataDescriptor(&devAttr->config,
				      ring->virtAddr,
				      (void *)srcData,
				      (void *)dstData, numBytes);
	if (rc < 0) {
		printk(KERN_ERR
		       "dma_add_descriptors: dmacHw_setDataDescriptor failed with code: %d\n",
		       rc);
		return -ENOMEM;
	}

	return 0;
}

EXPORT_SYMBOL(dma_add_descriptors);

/****************************************************************************/
/**
*   Sets the descriptor ring associated with a device.
*
*   Once set, the descriptor ring will be associated with the device, even
*   across channel request/free calls. Passing in a NULL descriptor ring
*   will release any descriptor ring currently associated with the device.
*
*   Note: If you call dma_transfer, or one of the other dma_alloc_ functions
*         the descriptor ring may be released and reallocated.
*
*   Note: This function will release the descriptor memory for any current
*         descriptor ring associated with this device.
*
*   @return
*       0       Descriptors were added successfully
*       -ENODEV Device handed in is invalid.
*/
/****************************************************************************/

int dma_set_device_descriptor_ring(DMA_Device_t device,	/* Device to update the descriptor ring for. */
				   DMA_DescriptorRing_t *ring	/* Descriptor ring to add descriptors to */
    ) {
	DMA_DeviceAttribute_t *devAttr;

	if (!IsDeviceValid(device)) {
		return -ENODEV;
	}
	devAttr = &DMA_gDeviceAttribute[device];

	/* Free the previously allocated descriptor ring */

	dma_free_descriptor_ring(&devAttr->ring);

	if (ring != NULL) {
		/* Copy in the new one */

		devAttr->ring = *ring;
	}

	/* Set things up so that if dma_transfer is called then this descriptor */
	/* ring will get freed. */

	devAttr->prevSrcData = 0;
	devAttr->prevDstData = 0;
	devAttr->prevNumBytes = 0;

	return 0;
}

EXPORT_SYMBOL(dma_set_device_descriptor_ring);

/****************************************************************************/
/**
*   Retrieves the descriptor ring associated with a device.
*
*   @return
*       0       Descriptors were added successfully
*       -ENODEV Device handed in is invalid.
*/
/****************************************************************************/

int dma_get_device_descriptor_ring(DMA_Device_t device,	/* Device to retrieve the descriptor ring for. */
				   DMA_DescriptorRing_t *ring	/* Place to store retrieved ring */
    ) {
	DMA_DeviceAttribute_t *devAttr;

	memset(ring, 0, sizeof(*ring));

	if (!IsDeviceValid(device)) {
		return -ENODEV;
	}
	devAttr = &DMA_gDeviceAttribute[device];

	*ring = devAttr->ring;

	return 0;
}

EXPORT_SYMBOL(dma_get_device_descriptor_ring);

/****************************************************************************/
/**
*   Configures a DMA channel.
*
*   @return
*       >= 0    - Initialization was successful.
*
*       -EBUSY  - Device is currently being used.
*       -ENODEV - Device handed in is invalid.
*/
/****************************************************************************/

static int ConfigChannel(DMA_Handle_t handle)
{
	DMA_Channel_t *channel;
	DMA_DeviceAttribute_t *devAttr;
	int controllerIdx;

	channel = HandleToChannel(handle);
	if (channel == NULL) {
		return -ENODEV;
	}
	devAttr = &DMA_gDeviceAttribute[channel->devType];
	controllerIdx = CONTROLLER_FROM_HANDLE(handle);

	if ((devAttr->flags & DMA_DEVICE_FLAG_PORT_PER_DMAC) != 0) {
		if (devAttr->config.transferType ==
		    dmacHw_TRANSFER_TYPE_MEM_TO_PERIPHERAL) {
			devAttr->config.dstPeripheralPort =
			    devAttr->dmacPort[controllerIdx];
		} else if (devAttr->config.transferType ==
			   dmacHw_TRANSFER_TYPE_PERIPHERAL_TO_MEM) {
			devAttr->config.srcPeripheralPort =
			    devAttr->dmacPort[controllerIdx];
		}
	}

	if (dmacHw_configChannel(channel->dmacHwHandle, &devAttr->config) != 0) {
		printk(KERN_ERR "ConfigChannel: dmacHw_configChannel failed\n");
		return -EIO;
	}

	return 0;
}

/****************************************************************************/
/**
*   Initializes all of the data structures associated with the DMA.
*   @return
*       >= 0    - Initialization was successful.
*
*       -EBUSY  - Device is currently being used.
*       -ENODEV - Device handed in is invalid.
*/
/****************************************************************************/

int dma_init(void)
{
	int rc = 0;
	int controllerIdx;
	int channelIdx;
	DMA_Device_t devIdx;
	DMA_Channel_t *channel;
	DMA_Handle_t dedicatedHandle;

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

	sema_init(&gDMA.lock, 0);
	init_waitqueue_head(&gDMA.freeChannelQ);

	/* Initialize the Hardware */

	dmacHw_initDma();

	/* Start off by marking all of the DMA channels as shared. */

	for (controllerIdx = 0; controllerIdx < DMA_NUM_CONTROLLERS;
	     controllerIdx++) {
		for (channelIdx = 0; channelIdx < DMA_NUM_CHANNELS;
		     channelIdx++) {
			channel =
			    &gDMA.controller[controllerIdx].channel[channelIdx];

			channel->flags = 0;
			channel->devType = DMA_DEVICE_NONE;
			channel->lastDevType = DMA_DEVICE_NONE;

#if (DMA_DEBUG_TRACK_RESERVATION)
			channel->fileName = "";
			channel->lineNum = 0;
#endif

			channel->dmacHwHandle =
			    dmacHw_getChannelHandle(dmacHw_MAKE_CHANNEL_ID
						    (controllerIdx,
						     channelIdx));
			dmacHw_initChannel(channel->dmacHwHandle);
		}
	}

	/* Record any special attributes that channels may have */

	gDMA.controller[0].channel[0].flags |= DMA_CHANNEL_FLAG_LARGE_FIFO;
	gDMA.controller[0].channel[1].flags |= DMA_CHANNEL_FLAG_LARGE_FIFO;
	gDMA.controller[1].channel[0].flags |= DMA_CHANNEL_FLAG_LARGE_FIFO;
	gDMA.controller[1].channel[1].flags |= DMA_CHANNEL_FLAG_LARGE_FIFO;

	/* Now walk through and record the dedicated channels. */

	for (devIdx = 0; devIdx < DMA_NUM_DEVICE_ENTRIES; devIdx++) {
		DMA_DeviceAttribute_t *devAttr = &DMA_gDeviceAttribute[devIdx];

		if (((devAttr->flags & DMA_DEVICE_FLAG_NO_ISR) != 0)
		    && ((devAttr->flags & DMA_DEVICE_FLAG_IS_DEDICATED) == 0)) {
			printk(KERN_ERR
			       "DMA Device: %s Can only request NO_ISR for dedicated devices\n",
			       devAttr->name);
			rc = -EINVAL;
			goto out;
		}

		if ((devAttr->flags & DMA_DEVICE_FLAG_IS_DEDICATED) != 0) {
			/* This is a dedicated device. Mark the channel as being reserved. */

			if (devAttr->dedicatedController >= DMA_NUM_CONTROLLERS) {
				printk(KERN_ERR
				       "DMA Device: %s DMA Controller %d is out of range\n",
				       devAttr->name,
				       devAttr->dedicatedController);
				rc = -EINVAL;
				goto out;
			}

			if (devAttr->dedicatedChannel >= DMA_NUM_CHANNELS) {
				printk(KERN_ERR
				       "DMA Device: %s DMA Channel %d is out of range\n",
				       devAttr->name,
				       devAttr->dedicatedChannel);
				rc = -EINVAL;
				goto out;
			}

			dedicatedHandle =
			    MAKE_HANDLE(devAttr->dedicatedController,
					devAttr->dedicatedChannel);
			channel = HandleToChannel(dedicatedHandle);

			if ((channel->flags & DMA_CHANNEL_FLAG_IS_DEDICATED) !=
			    0) {
				printk
				    ("DMA Device: %s attempting to use same DMA Controller:Channel (%d:%d) as %s\n",
				     devAttr->name,
				     devAttr->dedicatedController,
				     devAttr->dedicatedChannel,
				     DMA_gDeviceAttribute[channel->devType].
				     name);
				rc = -EBUSY;
				goto out;
			}

			channel->flags |= DMA_CHANNEL_FLAG_IS_DEDICATED;
			channel->devType = devIdx;

			if (devAttr->flags & DMA_DEVICE_FLAG_NO_ISR) {
				channel->flags |= DMA_CHANNEL_FLAG_NO_ISR;
			}

			/* For dedicated channels, we can go ahead and configure the DMA channel now */
			/* as well. */

			ConfigChannel(dedicatedHandle);
		}
	}

	/* Go through and register the interrupt handlers */

	for (controllerIdx = 0; controllerIdx < DMA_NUM_CONTROLLERS;
	     controllerIdx++) {
		for (channelIdx = 0; channelIdx < DMA_NUM_CHANNELS;
		     channelIdx++) {
			channel =
			    &gDMA.controller[controllerIdx].channel[channelIdx];

			if ((channel->flags & DMA_CHANNEL_FLAG_NO_ISR) == 0) {
				snprintf(channel->name, sizeof(channel->name),
					 "dma %d:%d %s", controllerIdx,
					 channelIdx,
					 channel->devType ==
					 DMA_DEVICE_NONE ? "" :
					 DMA_gDeviceAttribute[channel->devType].
					 name);

				rc =
				     request_irq(IRQ_DMA0C0 +
						 (controllerIdx *
						  DMA_NUM_CHANNELS) +
						 channelIdx,
						 dma_interrupt_handler,
						 IRQF_DISABLED, channel->name,
						 channel);
				if (rc != 0) {
					printk(KERN_ERR
					       "request_irq for IRQ_DMA%dC%d failed\n",
					       controllerIdx, channelIdx);
				}
			}
		}
	}

	/* Create /proc/dma/channels and /proc/dma/devices */

	gDmaDir = proc_mkdir("dma", NULL);

	if (gDmaDir == NULL) {
		printk(KERN_ERR "Unable to create /proc/dma\n");
	} else {
		create_proc_read_entry("channels", 0, gDmaDir,
				       dma_proc_read_channels, NULL);
		create_proc_read_entry("devices", 0, gDmaDir,
				       dma_proc_read_devices, NULL);
	}

out:

	up(&gDMA.lock);

	return rc;
}

/****************************************************************************/
/**
*   Reserves a channel for use with @a dev. If the device is setup to use
*   a shared channel, then this function will block until a free channel
*   becomes available.
*
*   @return
*       >= 0    - A valid DMA Handle.
*       -EBUSY  - Device is currently being used.
*       -ENODEV - Device handed in is invalid.
*/
/****************************************************************************/

#if (DMA_DEBUG_TRACK_RESERVATION)
DMA_Handle_t dma_request_channel_dbg
    (DMA_Device_t dev, const char *fileName, int lineNum)
#else
DMA_Handle_t dma_request_channel(DMA_Device_t dev)
#endif
{
	DMA_Handle_t handle;
	DMA_DeviceAttribute_t *devAttr;
	DMA_Channel_t *channel;
	int controllerIdx;
	int controllerIdx2;
	int channelIdx;

	if (down_interruptible(&gDMA.lock) < 0) {
		return -ERESTARTSYS;
	}

	if ((dev < 0) || (dev >= DMA_NUM_DEVICE_ENTRIES)) {
		handle = -ENODEV;
		goto out;
	}
	devAttr = &DMA_gDeviceAttribute[dev];

#if (DMA_DEBUG_TRACK_RESERVATION)
	{
		char *s;

		s = strrchr(fileName, '/');
		if (s != NULL) {
			fileName = s + 1;
		}
	}
#endif
	if ((devAttr->flags & DMA_DEVICE_FLAG_IN_USE) != 0) {
		/* This device has already been requested and not been freed */

		printk(KERN_ERR "%s: device %s is already requested\n",
		       __func__, devAttr->name);
		handle = -EBUSY;
		goto out;
	}

	if ((devAttr->flags & DMA_DEVICE_FLAG_IS_DEDICATED) != 0) {
		/* This device has a dedicated channel. */

		channel =
		    &gDMA.controller[devAttr->dedicatedController].
		    channel[devAttr->dedicatedChannel];
		if ((channel->flags & DMA_CHANNEL_FLAG_IN_USE) != 0) {
			handle = -EBUSY;
			goto out;
		}

		channel->flags |= DMA_CHANNEL_FLAG_IN_USE;
		devAttr->flags |= DMA_DEVICE_FLAG_IN_USE;

#if (DMA_DEBUG_TRACK_RESERVATION)
		channel->fileName = fileName;
		channel->lineNum = lineNum;
#endif
		handle =
		    MAKE_HANDLE(devAttr->dedicatedController,
				devAttr->dedicatedChannel);
		goto out;
	}

	/* This device needs to use one of the shared channels. */

	handle = DMA_INVALID_HANDLE;
	while (handle == DMA_INVALID_HANDLE) {
		/* Scan through the shared channels and see if one is available */

		for (controllerIdx2 = 0; controllerIdx2 < DMA_NUM_CONTROLLERS;
		     controllerIdx2++) {
			/* Check to see if we should try on controller 1 first. */

			controllerIdx = controllerIdx2;
			if ((devAttr->
			     flags & DMA_DEVICE_FLAG_ALLOC_DMA1_FIRST) != 0) {
				controllerIdx = 1 - controllerIdx;
			}

			/* See if the device is available on the controller being tested */

			if ((devAttr->
			     flags & (DMA_DEVICE_FLAG_ON_DMA0 << controllerIdx))
			    != 0) {
				for (channelIdx = 0;
				     channelIdx < DMA_NUM_CHANNELS;
				     channelIdx++) {
					channel =
					    &gDMA.controller[controllerIdx].
					    channel[channelIdx];

					if (((channel->
					      flags &
					      DMA_CHANNEL_FLAG_IS_DEDICATED) ==
					     0)
					    &&
					    ((channel->
					      flags & DMA_CHANNEL_FLAG_IN_USE)
					     == 0)) {
						if (((channel->
						      flags &
						      DMA_CHANNEL_FLAG_LARGE_FIFO)
						     != 0)
						    &&
						    ((devAttr->
						      flags &
						      DMA_DEVICE_FLAG_ALLOW_LARGE_FIFO)
						     == 0)) {
							/* This channel is a large fifo - don't tie it up */
							/* with devices that we don't want using it. */

							continue;
						}

						channel->flags |=
						    DMA_CHANNEL_FLAG_IN_USE;
						channel->devType = dev;
						devAttr->flags |=
						    DMA_DEVICE_FLAG_IN_USE;

#if (DMA_DEBUG_TRACK_RESERVATION)
						channel->fileName = fileName;
						channel->lineNum = lineNum;
#endif
						handle =
						    MAKE_HANDLE(controllerIdx,
								channelIdx);

						/* Now that we've reserved the channel - we can go ahead and configure it */

						if (ConfigChannel(handle) != 0) {
							handle = -EIO;
							printk(KERN_ERR
							       "dma_request_channel: ConfigChannel failed\n");
						}
						goto out;
					}
				}
			}
		}

		/* No channels are currently available. Let's wait for one to free up. */

		{
			DEFINE_WAIT(wait);

			prepare_to_wait(&gDMA.freeChannelQ, &wait,
					TASK_INTERRUPTIBLE);
			up(&gDMA.lock);
			schedule();
			finish_wait(&gDMA.freeChannelQ, &wait);

			if (signal_pending(current)) {
				/* We don't currently hold gDMA.lock, so we return directly */

				return -ERESTARTSYS;
			}
		}

		if (down_interruptible(&gDMA.lock)) {
			return -ERESTARTSYS;
		}
	}

out:
	up(&gDMA.lock);

	return handle;
}

/* Create both _dbg and non _dbg functions for modules. */

#if (DMA_DEBUG_TRACK_RESERVATION)
#undef dma_request_channel
DMA_Handle_t dma_request_channel(DMA_Device_t dev)
{
	return dma_request_channel_dbg(dev, __FILE__, __LINE__);
}

EXPORT_SYMBOL(dma_request_channel_dbg);
#endif
EXPORT_SYMBOL(dma_request_channel);

/****************************************************************************/
/**
*   Frees a previously allocated DMA Handle.
*/
/****************************************************************************/

int dma_free_channel(DMA_Handle_t handle	/* DMA handle. */
    ) {
	int rc = 0;
	DMA_Channel_t *channel;
	DMA_DeviceAttribute_t *devAttr;

	if (down_interruptible(&gDMA.lock) < 0) {
		return -ERESTARTSYS;
	}

	channel = HandleToChannel(handle);
	if (channel == NULL) {
		rc = -EINVAL;
		goto out;
	}

	devAttr = &DMA_gDeviceAttribute[channel->devType];

	if ((channel->flags & DMA_CHANNEL_FLAG_IS_DEDICATED) == 0) {
		channel->lastDevType = channel->devType;
		channel->devType = DMA_DEVICE_NONE;
	}
	channel->flags &= ~DMA_CHANNEL_FLAG_IN_USE;
	devAttr->flags &= ~DMA_DEVICE_FLAG_IN_USE;

out:
	up(&gDMA.lock);

	wake_up_interruptible(&gDMA.freeChannelQ);

	return rc;
}

EXPORT_SYMBOL(dma_free_channel);

/****************************************************************************/
/**
*   Determines if a given device has been configured as using a shared
*   channel.
*
*   @return
*       0           Device uses a dedicated channel
*       > zero      Device uses a shared channel
*       < zero      Error code
*/
/****************************************************************************/

int dma_device_is_channel_shared(DMA_Device_t device	/* Device to check. */
    ) {
	DMA_DeviceAttribute_t *devAttr;

	if (!IsDeviceValid(device)) {
		return -ENODEV;
	}
	devAttr = &DMA_gDeviceAttribute[device];

	return ((devAttr->flags & DMA_DEVICE_FLAG_IS_DEDICATED) == 0);
}

EXPORT_SYMBOL(dma_device_is_channel_shared);

/****************************************************************************/
/**
*   Allocates buffers for the descriptors. This is normally done automatically
*   but needs to be done explicitly when initiating a dma from interrupt
*   context.
*
*   @return
*       0       Descriptors were allocated successfully
*       -EINVAL Invalid device type for this kind of transfer
*               (i.e. the device is _MEM_TO_DEV and not _DEV_TO_MEM)
*       -ENOMEM Memory exhausted
*/
/****************************************************************************/

int dma_alloc_descriptors(DMA_Handle_t handle,	/* DMA Handle */
			  dmacHw_TRANSFER_TYPE_e transferType,	/* Type of transfer being performed */
			  dma_addr_t srcData,	/* Place to get data to write to device */
			  dma_addr_t dstData,	/* Pointer to device data address */
			  size_t numBytes	/* Number of bytes to transfer to the device */
    ) {
	DMA_Channel_t *channel;
	DMA_DeviceAttribute_t *devAttr;
	int numDescriptors;
	size_t ringBytesRequired;
	int rc = 0;

	channel = HandleToChannel(handle);
	if (channel == NULL) {
		return -ENODEV;
	}

	devAttr = &DMA_gDeviceAttribute[channel->devType];

	if (devAttr->config.transferType != transferType) {
		return -EINVAL;
	}

	/* Figure out how many descriptors we need. */

	/* printk("srcData: 0x%08x dstData: 0x%08x, numBytes: %d\n", */
	/*        srcData, dstData, numBytes); */

	numDescriptors = dmacHw_calculateDescriptorCount(&devAttr->config,
							      (void *)srcData,
							      (void *)dstData,
							      numBytes);
	if (numDescriptors < 0) {
		printk(KERN_ERR "%s: dmacHw_calculateDescriptorCount failed\n",
		       __func__);
		return -EINVAL;
	}

	/* Check to see if we can reuse the existing descriptor ring, or if we need to allocate */
	/* a new one. */

	ringBytesRequired = dmacHw_descriptorLen(numDescriptors);

	/* printk("ringBytesRequired: %d\n", ringBytesRequired); */

	if (ringBytesRequired > devAttr->ring.bytesAllocated) {
		/* Make sure that this code path is never taken from interrupt context. */
		/* It's OK for an interrupt to initiate a DMA transfer, but the descriptor */
		/* allocation needs to have already been done. */

		might_sleep();

		/* Free the old descriptor ring and allocate a new one. */

		dma_free_descriptor_ring(&devAttr->ring);

		/* And allocate a new one. */

		rc =
		     dma_alloc_descriptor_ring(&devAttr->ring,
					       numDescriptors);
		if (rc < 0) {
			printk(KERN_ERR
			       "%s: dma_alloc_descriptor_ring(%d) failed\n",
			       __func__, numDescriptors);
			return rc;
		}
		/* Setup the descriptor for this transfer */

		if (dmacHw_initDescriptor(devAttr->ring.virtAddr,
					  devAttr->ring.physAddr,
					  devAttr->ring.bytesAllocated,
					  numDescriptors) < 0) {
			printk(KERN_ERR "%s: dmacHw_initDescriptor failed\n",
			       __func__);
			return -EINVAL;
		}
	} else {
		/* We've already got enough ring buffer allocated. All we need to do is reset */
		/* any control information, just in case the previous DMA was stopped. */

		dmacHw_resetDescriptorControl(devAttr->ring.virtAddr);
	}

	/* dma_alloc/free both set the prevSrc/DstData to 0. If they happen to be the same */
	/* as last time, then we don't need to call setDataDescriptor again. */

	if (dmacHw_setDataDescriptor(&devAttr->config,
				     devAttr->ring.virtAddr,
				     (void *)srcData,
				     (void *)dstData, numBytes) < 0) {
		printk(KERN_ERR "%s: dmacHw_setDataDescriptor failed\n",
		       __func__);
		return -EINVAL;
	}

	/* Remember the critical information for this transfer so that we can eliminate */
	/* another call to dma_alloc_descriptors if the caller reuses the same buffers */

	devAttr->prevSrcData = srcData;
	devAttr->prevDstData = dstData;
	devAttr->prevNumBytes = numBytes;

	return 0;
}

EXPORT_SYMBOL(dma_alloc_descriptors);

/****************************************************************************/
/**
*   Allocates and sets up descriptors for a double buffered circular buffer.
*
*   This is primarily intended to be used for things like the ingress samples
*   from a microphone.
*
*   @return
*       > 0     Number of descriptors actually allocated.
*       -EINVAL Invalid device type for this kind of transfer
*               (i.e. the device is _MEM_TO_DEV and not _DEV_TO_MEM)
*       -ENOMEM Memory exhausted
*/
/****************************************************************************/

int dma_alloc_double_dst_descriptors(DMA_Handle_t handle,	/* DMA Handle */
				     dma_addr_t srcData,	/* Physical address of source data */
				     dma_addr_t dstData1,	/* Physical address of first destination buffer */
				     dma_addr_t dstData2,	/* Physical address of second destination buffer */
				     size_t numBytes	/* Number of bytes in each destination buffer */
    ) {
	DMA_Channel_t *channel;
	DMA_DeviceAttribute_t *devAttr;
	int numDst1Descriptors;
	int numDst2Descriptors;
	int numDescriptors;
	size_t ringBytesRequired;
	int rc = 0;

	channel = HandleToChannel(handle);
	if (channel == NULL) {
		return -ENODEV;
	}

	devAttr = &DMA_gDeviceAttribute[channel->devType];

	/* Figure out how many descriptors we need. */

	/* printk("srcData: 0x%08x dstData: 0x%08x, numBytes: %d\n", */
	/*        srcData, dstData, numBytes); */

	numDst1Descriptors =
	     dmacHw_calculateDescriptorCount(&devAttr->config, (void *)srcData,
					     (void *)dstData1, numBytes);
	if (numDst1Descriptors < 0) {
		return -EINVAL;
	}
	numDst2Descriptors =
	     dmacHw_calculateDescriptorCount(&devAttr->config, (void *)srcData,
					     (void *)dstData2, numBytes);
	if (numDst2Descriptors < 0) {
		return -EINVAL;
	}
	numDescriptors = numDst1Descriptors + numDst2Descriptors;
	/* printk("numDescriptors: %d\n", numDescriptors); */

	/* Check to see if we can reuse the existing descriptor ring, or if we need to allocate */
	/* a new one. */

	ringBytesRequired = dmacHw_descriptorLen(numDescriptors);

	/* printk("ringBytesRequired: %d\n", ringBytesRequired); */

	if (ringBytesRequired > devAttr->ring.bytesAllocated) {
		/* Make sure that this code path is never taken from interrupt context. */
		/* It's OK for an interrupt to initiate a DMA transfer, but the descriptor */
		/* allocation needs to have already been done. */

		might_sleep();

		/* Free the old descriptor ring and allocate a new one. */

		dma_free_descriptor_ring(&devAttr->ring);

		/* And allocate a new one. */

		rc =
		     dma_alloc_descriptor_ring(&devAttr->ring,
					       numDescriptors);
		if (rc < 0) {
			printk(KERN_ERR
			       "%s: dma_alloc_descriptor_ring(%d) failed\n",
			       __func__, ringBytesRequired);
			return rc;
		}
	}

	/* Setup the descriptor for this transfer. Since this function is used with */
	/* CONTINUOUS DMA operations, we need to reinitialize every time, otherwise */
	/* setDataDescriptor will keep trying to append onto the end. */

	if (dmacHw_initDescriptor(devAttr->ring.virtAddr,
				  devAttr->ring.physAddr,
				  devAttr->ring.bytesAllocated,
				  numDescriptors) < 0) {
		printk(KERN_ERR "%s: dmacHw_initDescriptor failed\n", __func__);
		return -EINVAL;
	}

	/* dma_alloc/free both set the prevSrc/DstData to 0. If they happen to be the same */
	/* as last time, then we don't need to call setDataDescriptor again. */

	if (dmacHw_setDataDescriptor(&devAttr->config,
				     devAttr->ring.virtAddr,
				     (void *)srcData,
				     (void *)dstData1, numBytes) < 0) {
		printk(KERN_ERR "%s: dmacHw_setDataDescriptor 1 failed\n",
		       __func__);
		return -EINVAL;
	}
	if (dmacHw_setDataDescriptor(&devAttr->config,
				     devAttr->ring.virtAddr,
				     (void *)srcData,
				     (void *)dstData2, numBytes) < 0) {
		printk(KERN_ERR "%s: dmacHw_setDataDescriptor 2 failed\n",
		       __func__);
		return -EINVAL;
	}

	/* You should use dma_start_transfer rather than dma_transfer_xxx so we don't */
	/* try to make the 'prev' variables right. */

	devAttr->prevSrcData = 0;
	devAttr->prevDstData = 0;
	devAttr->prevNumBytes = 0;

	return numDescriptors;
}

EXPORT_SYMBOL(dma_alloc_double_dst_descriptors);

/****************************************************************************/
/**
*   Initiates a transfer when the descriptors have already been setup.
*
*   This is a special case, and normally, the dma_transfer_xxx functions should
*   be used.
*
*   @return
*       0       Transfer was started successfully
*       -ENODEV Invalid handle
*/
/****************************************************************************/

int dma_start_transfer(DMA_Handle_t handle)
{
	DMA_Channel_t *channel;
	DMA_DeviceAttribute_t *devAttr;

	channel = HandleToChannel(handle);
	if (channel == NULL) {
		return -ENODEV;
	}
	devAttr = &DMA_gDeviceAttribute[channel->devType];

	dmacHw_initiateTransfer(channel->dmacHwHandle, &devAttr->config,
				devAttr->ring.virtAddr);

	/* Since we got this far, everything went successfully */

	return 0;
}

EXPORT_SYMBOL(dma_start_transfer);

/****************************************************************************/
/**
*   Stops a previously started DMA transfer.
*
*   @return
*       0       Transfer was stopped successfully
*       -ENODEV Invalid handle
*/
/****************************************************************************/

int dma_stop_transfer(DMA_Handle_t handle)
{
	DMA_Channel_t *channel;

	channel = HandleToChannel(handle);
	if (channel == NULL) {
		return -ENODEV;
	}

	dmacHw_stopTransfer(channel->dmacHwHandle);

	return 0;
}

EXPORT_SYMBOL(dma_stop_transfer);

/****************************************************************************/
/**
*   Waits for a DMA to complete by polling. This function is only intended
*   to be used for testing. Interrupts should be used for most DMA operations.
*/
/****************************************************************************/

int dma_wait_transfer_done(DMA_Handle_t handle)
{
	DMA_Channel_t *channel;
	dmacHw_TRANSFER_STATUS_e status;

	channel = HandleToChannel(handle);
	if (channel == NULL) {
		return -ENODEV;
	}

	while ((status =
		dmacHw_transferCompleted(channel->dmacHwHandle)) ==
	       dmacHw_TRANSFER_STATUS_BUSY) {
		;
	}

	if (status == dmacHw_TRANSFER_STATUS_ERROR) {
		printk(KERN_ERR "%s: DMA transfer failed\n", __func__);
		return -EIO;
	}
	return 0;
}

EXPORT_SYMBOL(dma_wait_transfer_done);

/****************************************************************************/
/**
*   Initiates a DMA, allocating the descriptors as required.
*
*   @return
*       0       Transfer was started successfully
*       -EINVAL Invalid device type for this kind of transfer
*               (i.e. the device is _DEV_TO_MEM and not _MEM_TO_DEV)
*/
/****************************************************************************/

int dma_transfer(DMA_Handle_t handle,	/* DMA Handle */
		 dmacHw_TRANSFER_TYPE_e transferType,	/* Type of transfer being performed */
		 dma_addr_t srcData,	/* Place to get data to write to device */
		 dma_addr_t dstData,	/* Pointer to device data address */
		 size_t numBytes	/* Number of bytes to transfer to the device */
    ) {
	DMA_Channel_t *channel;
	DMA_DeviceAttribute_t *devAttr;
	int rc = 0;

	channel = HandleToChannel(handle);
	if (channel == NULL) {
		return -ENODEV;
	}

	devAttr = &DMA_gDeviceAttribute[channel->devType];

	if (devAttr->config.transferType != transferType) {
		return -EINVAL;
	}

	/* We keep track of the information about the previous request for this */
	/* device, and if the attributes match, then we can use the descriptors we setup */
	/* the last time, and not have to reinitialize everything. */

	{
		rc =
		     dma_alloc_descriptors(handle, transferType, srcData,
					   dstData, numBytes);
		if (rc != 0) {
			return rc;
		}
	}

	/* And kick off the transfer */

	devAttr->numBytes = numBytes;
	devAttr->transferStartTime = timer_get_tick_count();

	dmacHw_initiateTransfer(channel->dmacHwHandle, &devAttr->config,
				devAttr->ring.virtAddr);

	/* Since we got this far, everything went successfully */

	return 0;
}

EXPORT_SYMBOL(dma_transfer);

/****************************************************************************/
/**
*   Set the callback function which will be called when a transfer completes.
*   If a NULL callback function is set, then no callback will occur.
*
*   @note   @a devHandler will be called from IRQ context.
*
*   @return
*       0       - Success
*       -ENODEV - Device handed in is invalid.
*/
/****************************************************************************/

int dma_set_device_handler(DMA_Device_t dev,	/* Device to set the callback for. */
			   DMA_DeviceHandler_t devHandler,	/* Function to call when the DMA completes */
			   void *userData	/* Pointer which will be passed to devHandler. */
    ) {
	DMA_DeviceAttribute_t *devAttr;
	unsigned long flags;

	if (!IsDeviceValid(dev)) {
		return -ENODEV;
	}
	devAttr = &DMA_gDeviceAttribute[dev];

	local_irq_save(flags);

	devAttr->userData = userData;
	devAttr->devHandler = devHandler;

	local_irq_restore(flags);

	return 0;
}

EXPORT_SYMBOL(dma_set_device_handler);