summaryrefslogtreecommitdiffstats
path: root/drivers/spi/spi-atmel.c
blob: 31cfc8711547a26616fb7d8cf31ae9b28ea51cc9 (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
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
/*
 * Driver for Atmel AT32 and AT91 SPI Controllers
 *
 * Copyright (C) 2006 Atmel Corporation
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/clk.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/delay.h>
#include <linux/dma-mapping.h>
#include <linux/dmaengine.h>
#include <linux/err.h>
#include <linux/interrupt.h>
#include <linux/spi/spi.h>
#include <linux/slab.h>
#include <linux/platform_data/atmel.h>
#include <linux/platform_data/dma-atmel.h>
#include <linux/of.h>

#include <linux/io.h>
#include <linux/gpio.h>

/* SPI register offsets */
#define SPI_CR					0x0000
#define SPI_MR					0x0004
#define SPI_RDR					0x0008
#define SPI_TDR					0x000c
#define SPI_SR					0x0010
#define SPI_IER					0x0014
#define SPI_IDR					0x0018
#define SPI_IMR					0x001c
#define SPI_CSR0				0x0030
#define SPI_CSR1				0x0034
#define SPI_CSR2				0x0038
#define SPI_CSR3				0x003c
#define SPI_VERSION				0x00fc
#define SPI_RPR					0x0100
#define SPI_RCR					0x0104
#define SPI_TPR					0x0108
#define SPI_TCR					0x010c
#define SPI_RNPR				0x0110
#define SPI_RNCR				0x0114
#define SPI_TNPR				0x0118
#define SPI_TNCR				0x011c
#define SPI_PTCR				0x0120
#define SPI_PTSR				0x0124

/* Bitfields in CR */
#define SPI_SPIEN_OFFSET			0
#define SPI_SPIEN_SIZE				1
#define SPI_SPIDIS_OFFSET			1
#define SPI_SPIDIS_SIZE				1
#define SPI_SWRST_OFFSET			7
#define SPI_SWRST_SIZE				1
#define SPI_LASTXFER_OFFSET			24
#define SPI_LASTXFER_SIZE			1

/* Bitfields in MR */
#define SPI_MSTR_OFFSET				0
#define SPI_MSTR_SIZE				1
#define SPI_PS_OFFSET				1
#define SPI_PS_SIZE				1
#define SPI_PCSDEC_OFFSET			2
#define SPI_PCSDEC_SIZE				1
#define SPI_FDIV_OFFSET				3
#define SPI_FDIV_SIZE				1
#define SPI_MODFDIS_OFFSET			4
#define SPI_MODFDIS_SIZE			1
#define SPI_WDRBT_OFFSET			5
#define SPI_WDRBT_SIZE				1
#define SPI_LLB_OFFSET				7
#define SPI_LLB_SIZE				1
#define SPI_PCS_OFFSET				16
#define SPI_PCS_SIZE				4
#define SPI_DLYBCS_OFFSET			24
#define SPI_DLYBCS_SIZE				8

/* Bitfields in RDR */
#define SPI_RD_OFFSET				0
#define SPI_RD_SIZE				16

/* Bitfields in TDR */
#define SPI_TD_OFFSET				0
#define SPI_TD_SIZE				16

/* Bitfields in SR */
#define SPI_RDRF_OFFSET				0
#define SPI_RDRF_SIZE				1
#define SPI_TDRE_OFFSET				1
#define SPI_TDRE_SIZE				1
#define SPI_MODF_OFFSET				2
#define SPI_MODF_SIZE				1
#define SPI_OVRES_OFFSET			3
#define SPI_OVRES_SIZE				1
#define SPI_ENDRX_OFFSET			4
#define SPI_ENDRX_SIZE				1
#define SPI_ENDTX_OFFSET			5
#define SPI_ENDTX_SIZE				1
#define SPI_RXBUFF_OFFSET			6
#define SPI_RXBUFF_SIZE				1
#define SPI_TXBUFE_OFFSET			7
#define SPI_TXBUFE_SIZE				1
#define SPI_NSSR_OFFSET				8
#define SPI_NSSR_SIZE				1
#define SPI_TXEMPTY_OFFSET			9
#define SPI_TXEMPTY_SIZE			1
#define SPI_SPIENS_OFFSET			16
#define SPI_SPIENS_SIZE				1

/* Bitfields in CSR0 */
#define SPI_CPOL_OFFSET				0
#define SPI_CPOL_SIZE				1
#define SPI_NCPHA_OFFSET			1
#define SPI_NCPHA_SIZE				1
#define SPI_CSAAT_OFFSET			3
#define SPI_CSAAT_SIZE				1
#define SPI_BITS_OFFSET				4
#define SPI_BITS_SIZE				4
#define SPI_SCBR_OFFSET				8
#define SPI_SCBR_SIZE				8
#define SPI_DLYBS_OFFSET			16
#define SPI_DLYBS_SIZE				8
#define SPI_DLYBCT_OFFSET			24
#define SPI_DLYBCT_SIZE				8

/* Bitfields in RCR */
#define SPI_RXCTR_OFFSET			0
#define SPI_RXCTR_SIZE				16

/* Bitfields in TCR */
#define SPI_TXCTR_OFFSET			0
#define SPI_TXCTR_SIZE				16

/* Bitfields in RNCR */
#define SPI_RXNCR_OFFSET			0
#define SPI_RXNCR_SIZE				16

/* Bitfields in TNCR */
#define SPI_TXNCR_OFFSET			0
#define SPI_TXNCR_SIZE				16

/* Bitfields in PTCR */
#define SPI_RXTEN_OFFSET			0
#define SPI_RXTEN_SIZE				1
#define SPI_RXTDIS_OFFSET			1
#define SPI_RXTDIS_SIZE				1
#define SPI_TXTEN_OFFSET			8
#define SPI_TXTEN_SIZE				1
#define SPI_TXTDIS_OFFSET			9
#define SPI_TXTDIS_SIZE				1

/* Constants for BITS */
#define SPI_BITS_8_BPT				0
#define SPI_BITS_9_BPT				1
#define SPI_BITS_10_BPT				2
#define SPI_BITS_11_BPT				3
#define SPI_BITS_12_BPT				4
#define SPI_BITS_13_BPT				5
#define SPI_BITS_14_BPT				6
#define SPI_BITS_15_BPT				7
#define SPI_BITS_16_BPT				8

/* Bit manipulation macros */
#define SPI_BIT(name) \
	(1 << SPI_##name##_OFFSET)
#define SPI_BF(name,value) \
	(((value) & ((1 << SPI_##name##_SIZE) - 1)) << SPI_##name##_OFFSET)
#define SPI_BFEXT(name,value) \
	(((value) >> SPI_##name##_OFFSET) & ((1 << SPI_##name##_SIZE) - 1))
#define SPI_BFINS(name,value,old) \
	( ((old) & ~(((1 << SPI_##name##_SIZE) - 1) << SPI_##name##_OFFSET)) \
	  | SPI_BF(name,value))

/* Register access macros */
#define spi_readl(port,reg) \
	__raw_readl((port)->regs + SPI_##reg)
#define spi_writel(port,reg,value) \
	__raw_writel((value), (port)->regs + SPI_##reg)

/* use PIO for small transfers, avoiding DMA setup/teardown overhead and
 * cache operations; better heuristics consider wordsize and bitrate.
 */
#define DMA_MIN_BYTES	16

struct atmel_spi_dma {
	struct dma_chan			*chan_rx;
	struct dma_chan			*chan_tx;
	struct scatterlist		sgrx;
	struct scatterlist		sgtx;
	struct dma_async_tx_descriptor	*data_desc_rx;
	struct dma_async_tx_descriptor	*data_desc_tx;

	struct at_dma_slave	dma_slave;
};

struct atmel_spi_caps {
	bool	is_spi2;
	bool	has_wdrbt;
	bool	has_dma_support;
};

/*
 * The core SPI transfer engine just talks to a register bank to set up
 * DMA transfers; transfer queue progress is driven by IRQs.  The clock
 * framework provides the base clock, subdivided for each spi_device.
 */
struct atmel_spi {
	spinlock_t		lock;
	unsigned long		flags;

	phys_addr_t		phybase;
	void __iomem		*regs;
	int			irq;
	struct clk		*clk;
	struct platform_device	*pdev;
	struct spi_device	*stay;

	u8			stopping;
	struct list_head	queue;
	struct tasklet_struct	tasklet;
	struct spi_transfer	*current_transfer;
	unsigned long		current_remaining_bytes;
	struct spi_transfer	*next_transfer;
	unsigned long		next_remaining_bytes;
	int			done_status;

	/* scratch buffer */
	void			*buffer;
	dma_addr_t		buffer_dma;

	struct atmel_spi_caps	caps;

	bool			use_dma;
	bool			use_pdc;
	/* dmaengine data */
	struct atmel_spi_dma	dma;
};

/* Controller-specific per-slave state */
struct atmel_spi_device {
	unsigned int		npcs_pin;
	u32			csr;
};

#define BUFFER_SIZE		PAGE_SIZE
#define INVALID_DMA_ADDRESS	0xffffffff

/*
 * Version 2 of the SPI controller has
 *  - CR.LASTXFER
 *  - SPI_MR.DIV32 may become FDIV or must-be-zero (here: always zero)
 *  - SPI_SR.TXEMPTY, SPI_SR.NSSR (and corresponding irqs)
 *  - SPI_CSRx.CSAAT
 *  - SPI_CSRx.SBCR allows faster clocking
 */
static bool atmel_spi_is_v2(struct atmel_spi *as)
{
	return as->caps.is_spi2;
}

/*
 * Earlier SPI controllers (e.g. on at91rm9200) have a design bug whereby
 * they assume that spi slave device state will not change on deselect, so
 * that automagic deselection is OK.  ("NPCSx rises if no data is to be
 * transmitted")  Not so!  Workaround uses nCSx pins as GPIOs; or newer
 * controllers have CSAAT and friends.
 *
 * Since the CSAAT functionality is a bit weird on newer controllers as
 * well, we use GPIO to control nCSx pins on all controllers, updating
 * MR.PCS to avoid confusing the controller.  Using GPIOs also lets us
 * support active-high chipselects despite the controller's belief that
 * only active-low devices/systems exists.
 *
 * However, at91rm9200 has a second erratum whereby nCS0 doesn't work
 * right when driven with GPIO.  ("Mode Fault does not allow more than one
 * Master on Chip Select 0.")  No workaround exists for that ... so for
 * nCS0 on that chip, we (a) don't use the GPIO, (b) can't support CS_HIGH,
 * and (c) will trigger that first erratum in some cases.
 */

static void cs_activate(struct atmel_spi *as, struct spi_device *spi)
{
	struct atmel_spi_device *asd = spi->controller_state;
	unsigned active = spi->mode & SPI_CS_HIGH;
	u32 mr;

	if (atmel_spi_is_v2(as)) {
		spi_writel(as, CSR0 + 4 * spi->chip_select, asd->csr);
		/* For the low SPI version, there is a issue that PDC transfer
		 * on CS1,2,3 needs SPI_CSR0.BITS config as SPI_CSR1,2,3.BITS
		 */
		spi_writel(as, CSR0, asd->csr);
		if (as->caps.has_wdrbt) {
			spi_writel(as, MR,
					SPI_BF(PCS, ~(0x01 << spi->chip_select))
					| SPI_BIT(WDRBT)
					| SPI_BIT(MODFDIS)
					| SPI_BIT(MSTR));
		} else {
			spi_writel(as, MR,
					SPI_BF(PCS, ~(0x01 << spi->chip_select))
					| SPI_BIT(MODFDIS)
					| SPI_BIT(MSTR));
		}

		mr = spi_readl(as, MR);
		gpio_set_value(asd->npcs_pin, active);
	} else {
		u32 cpol = (spi->mode & SPI_CPOL) ? SPI_BIT(CPOL) : 0;
		int i;
		u32 csr;

		/* Make sure clock polarity is correct */
		for (i = 0; i < spi->master->num_chipselect; i++) {
			csr = spi_readl(as, CSR0 + 4 * i);
			if ((csr ^ cpol) & SPI_BIT(CPOL))
				spi_writel(as, CSR0 + 4 * i,
						csr ^ SPI_BIT(CPOL));
		}

		mr = spi_readl(as, MR);
		mr = SPI_BFINS(PCS, ~(1 << spi->chip_select), mr);
		if (spi->chip_select != 0)
			gpio_set_value(asd->npcs_pin, active);
		spi_writel(as, MR, mr);
	}

	dev_dbg(&spi->dev, "activate %u%s, mr %08x\n",
			asd->npcs_pin, active ? " (high)" : "",
			mr);
}

static void cs_deactivate(struct atmel_spi *as, struct spi_device *spi)
{
	struct atmel_spi_device *asd = spi->controller_state;
	unsigned active = spi->mode & SPI_CS_HIGH;
	u32 mr;

	/* only deactivate *this* device; sometimes transfers to
	 * another device may be active when this routine is called.
	 */
	mr = spi_readl(as, MR);
	if (~SPI_BFEXT(PCS, mr) & (1 << spi->chip_select)) {
		mr = SPI_BFINS(PCS, 0xf, mr);
		spi_writel(as, MR, mr);
	}

	dev_dbg(&spi->dev, "DEactivate %u%s, mr %08x\n",
			asd->npcs_pin, active ? " (low)" : "",
			mr);

	if (atmel_spi_is_v2(as) || spi->chip_select != 0)
		gpio_set_value(asd->npcs_pin, !active);
}

static void atmel_spi_lock(struct atmel_spi *as)
{
	spin_lock_irqsave(&as->lock, as->flags);
}

static void atmel_spi_unlock(struct atmel_spi *as)
{
	spin_unlock_irqrestore(&as->lock, as->flags);
}

static inline bool atmel_spi_use_dma(struct atmel_spi *as,
				struct spi_transfer *xfer)
{
	return as->use_dma && xfer->len >= DMA_MIN_BYTES;
}

static inline int atmel_spi_xfer_is_last(struct spi_message *msg,
					struct spi_transfer *xfer)
{
	return msg->transfers.prev == &xfer->transfer_list;
}

static inline int atmel_spi_xfer_can_be_chained(struct spi_transfer *xfer)
{
	return xfer->delay_usecs == 0 && !xfer->cs_change;
}

static int atmel_spi_dma_slave_config(struct atmel_spi *as,
				struct dma_slave_config *slave_config,
				u8 bits_per_word)
{
	int err = 0;

	if (bits_per_word > 8) {
		slave_config->dst_addr_width = DMA_SLAVE_BUSWIDTH_2_BYTES;
		slave_config->src_addr_width = DMA_SLAVE_BUSWIDTH_2_BYTES;
	} else {
		slave_config->dst_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
		slave_config->src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
	}

	slave_config->dst_addr = (dma_addr_t)as->phybase + SPI_TDR;
	slave_config->src_addr = (dma_addr_t)as->phybase + SPI_RDR;
	slave_config->src_maxburst = 1;
	slave_config->dst_maxburst = 1;
	slave_config->device_fc = false;

	slave_config->direction = DMA_MEM_TO_DEV;
	if (dmaengine_slave_config(as->dma.chan_tx, slave_config)) {
		dev_err(&as->pdev->dev,
			"failed to configure tx dma channel\n");
		err = -EINVAL;
	}

	slave_config->direction = DMA_DEV_TO_MEM;
	if (dmaengine_slave_config(as->dma.chan_rx, slave_config)) {
		dev_err(&as->pdev->dev,
			"failed to configure rx dma channel\n");
		err = -EINVAL;
	}

	return err;
}

static bool filter(struct dma_chan *chan, void *slave)
{
	struct	at_dma_slave *sl = slave;

	if (sl->dma_dev == chan->device->dev) {
		chan->private = sl;
		return true;
	} else {
		return false;
	}
}

static int atmel_spi_configure_dma(struct atmel_spi *as)
{
	struct at_dma_slave *sdata = &as->dma.dma_slave;
	struct dma_slave_config	slave_config;
	int err;

	if (sdata && sdata->dma_dev) {
		dma_cap_mask_t mask;

		/* Try to grab two DMA channels */
		dma_cap_zero(mask);
		dma_cap_set(DMA_SLAVE, mask);
		as->dma.chan_tx = dma_request_channel(mask, filter, sdata);
		if (as->dma.chan_tx)
			as->dma.chan_rx =
				dma_request_channel(mask, filter, sdata);
	}
	if (!as->dma.chan_rx || !as->dma.chan_tx) {
		dev_err(&as->pdev->dev,
			"DMA channel not available, SPI unable to use DMA\n");
		err = -EBUSY;
		goto error;
	}

	err = atmel_spi_dma_slave_config(as, &slave_config, 8);
	if (err)
		goto error;

	dev_info(&as->pdev->dev,
			"Using %s (tx) and %s (rx) for DMA transfers\n",
			dma_chan_name(as->dma.chan_tx),
			dma_chan_name(as->dma.chan_rx));
	return 0;
error:
	if (as->dma.chan_rx)
		dma_release_channel(as->dma.chan_rx);
	if (as->dma.chan_tx)
		dma_release_channel(as->dma.chan_tx);
	return err;
}

static void atmel_spi_stop_dma(struct atmel_spi *as)
{
	if (as->dma.chan_rx)
		as->dma.chan_rx->device->device_control(as->dma.chan_rx,
							DMA_TERMINATE_ALL, 0);
	if (as->dma.chan_tx)
		as->dma.chan_tx->device->device_control(as->dma.chan_tx,
							DMA_TERMINATE_ALL, 0);
}

static void atmel_spi_release_dma(struct atmel_spi *as)
{
	if (as->dma.chan_rx)
		dma_release_channel(as->dma.chan_rx);
	if (as->dma.chan_tx)
		dma_release_channel(as->dma.chan_tx);
}

/* This function is called by the DMA driver from tasklet context */
static void dma_callback(void *data)
{
	struct spi_master	*master = data;
	struct atmel_spi	*as = spi_master_get_devdata(master);

	/* trigger SPI tasklet */
	tasklet_schedule(&as->tasklet);
}

/*
 * Next transfer using PIO.
 * lock is held, spi tasklet is blocked
 */
static void atmel_spi_next_xfer_pio(struct spi_master *master,
				struct spi_transfer *xfer)
{
	struct atmel_spi	*as = spi_master_get_devdata(master);

	dev_vdbg(master->dev.parent, "atmel_spi_next_xfer_pio\n");

	as->current_remaining_bytes = xfer->len;

	/* Make sure data is not remaining in RDR */
	spi_readl(as, RDR);
	while (spi_readl(as, SR) & SPI_BIT(RDRF)) {
		spi_readl(as, RDR);
		cpu_relax();
	}

	if (xfer->tx_buf)
		if (xfer->bits_per_word > 8)
			spi_writel(as, TDR, *(u16 *)(xfer->tx_buf));
		else
			spi_writel(as, TDR, *(u8 *)(xfer->tx_buf));
	else
		spi_writel(as, TDR, 0);

	dev_dbg(master->dev.parent,
		"  start pio xfer %p: len %u tx %p rx %p bitpw %d\n",
		xfer, xfer->len, xfer->tx_buf, xfer->rx_buf,
		xfer->bits_per_word);

	/* Enable relevant interrupts */
	spi_writel(as, IER, SPI_BIT(RDRF) | SPI_BIT(OVRES));
}

/*
 * Submit next transfer for DMA.
 * lock is held, spi tasklet is blocked
 */
static int atmel_spi_next_xfer_dma_submit(struct spi_master *master,
				struct spi_transfer *xfer,
				u32 *plen)
{
	struct atmel_spi	*as = spi_master_get_devdata(master);
	struct dma_chan		*rxchan = as->dma.chan_rx;
	struct dma_chan		*txchan = as->dma.chan_tx;
	struct dma_async_tx_descriptor *rxdesc;
	struct dma_async_tx_descriptor *txdesc;
	struct dma_slave_config	slave_config;
	dma_cookie_t		cookie;
	u32	len = *plen;

	dev_vdbg(master->dev.parent, "atmel_spi_next_xfer_dma_submit\n");

	/* Check that the channels are available */
	if (!rxchan || !txchan)
		return -ENODEV;

	/* release lock for DMA operations */
	atmel_spi_unlock(as);

	/* prepare the RX dma transfer */
	sg_init_table(&as->dma.sgrx, 1);
	if (xfer->rx_buf) {
		as->dma.sgrx.dma_address = xfer->rx_dma + xfer->len - *plen;
	} else {
		as->dma.sgrx.dma_address = as->buffer_dma;
		if (len > BUFFER_SIZE)
			len = BUFFER_SIZE;
	}

	/* prepare the TX dma transfer */
	sg_init_table(&as->dma.sgtx, 1);
	if (xfer->tx_buf) {
		as->dma.sgtx.dma_address = xfer->tx_dma + xfer->len - *plen;
	} else {
		as->dma.sgtx.dma_address = as->buffer_dma;
		if (len > BUFFER_SIZE)
			len = BUFFER_SIZE;
		memset(as->buffer, 0, len);
	}

	sg_dma_len(&as->dma.sgtx) = len;
	sg_dma_len(&as->dma.sgrx) = len;

	*plen = len;

	if (atmel_spi_dma_slave_config(as, &slave_config, 8))
		goto err_exit;

	/* Send both scatterlists */
	rxdesc = rxchan->device->device_prep_slave_sg(rxchan,
					&as->dma.sgrx,
					1,
					DMA_FROM_DEVICE,
					DMA_PREP_INTERRUPT | DMA_CTRL_ACK,
					NULL);
	if (!rxdesc)
		goto err_dma;

	txdesc = txchan->device->device_prep_slave_sg(txchan,
					&as->dma.sgtx,
					1,
					DMA_TO_DEVICE,
					DMA_PREP_INTERRUPT | DMA_CTRL_ACK,
					NULL);
	if (!txdesc)
		goto err_dma;

	dev_dbg(master->dev.parent,
		"  start dma xfer %p: len %u tx %p/%08x rx %p/%08x\n",
		xfer, xfer->len, xfer->tx_buf, xfer->tx_dma,
		xfer->rx_buf, xfer->rx_dma);

	/* Enable relevant interrupts */
	spi_writel(as, IER, SPI_BIT(OVRES));

	/* Put the callback on the RX transfer only, that should finish last */
	rxdesc->callback = dma_callback;
	rxdesc->callback_param = master;

	/* Submit and fire RX and TX with TX last so we're ready to read! */
	cookie = rxdesc->tx_submit(rxdesc);
	if (dma_submit_error(cookie))
		goto err_dma;
	cookie = txdesc->tx_submit(txdesc);
	if (dma_submit_error(cookie))
		goto err_dma;
	rxchan->device->device_issue_pending(rxchan);
	txchan->device->device_issue_pending(txchan);

	/* take back lock */
	atmel_spi_lock(as);
	return 0;

err_dma:
	spi_writel(as, IDR, SPI_BIT(OVRES));
	atmel_spi_stop_dma(as);
err_exit:
	atmel_spi_lock(as);
	return -ENOMEM;
}

static void atmel_spi_next_xfer_data(struct spi_master *master,
				struct spi_transfer *xfer,
				dma_addr_t *tx_dma,
				dma_addr_t *rx_dma,
				u32 *plen)
{
	struct atmel_spi	*as = spi_master_get_devdata(master);
	u32			len = *plen;

	/* use scratch buffer only when rx or tx data is unspecified */
	if (xfer->rx_buf)
		*rx_dma = xfer->rx_dma + xfer->len - *plen;
	else {
		*rx_dma = as->buffer_dma;
		if (len > BUFFER_SIZE)
			len = BUFFER_SIZE;
	}

	if (xfer->tx_buf)
		*tx_dma = xfer->tx_dma + xfer->len - *plen;
	else {
		*tx_dma = as->buffer_dma;
		if (len > BUFFER_SIZE)
			len = BUFFER_SIZE;
		memset(as->buffer, 0, len);
		dma_sync_single_for_device(&as->pdev->dev,
				as->buffer_dma, len, DMA_TO_DEVICE);
	}

	*plen = len;
}

/*
 * Submit next transfer for PDC.
 * lock is held, spi irq is blocked
 */
static void atmel_spi_pdc_next_xfer(struct spi_master *master,
				struct spi_message *msg)
{
	struct atmel_spi	*as = spi_master_get_devdata(master);
	struct spi_transfer	*xfer;
	u32			len, remaining;
	u32			ieval;
	dma_addr_t		tx_dma, rx_dma;

	if (!as->current_transfer)
		xfer = list_entry(msg->transfers.next,
				struct spi_transfer, transfer_list);
	else if (!as->next_transfer)
		xfer = list_entry(as->current_transfer->transfer_list.next,
				struct spi_transfer, transfer_list);
	else
		xfer = NULL;

	if (xfer) {
		spi_writel(as, PTCR, SPI_BIT(RXTDIS) | SPI_BIT(TXTDIS));

		len = xfer->len;
		atmel_spi_next_xfer_data(master, xfer, &tx_dma, &rx_dma, &len);
		remaining = xfer->len - len;

		spi_writel(as, RPR, rx_dma);
		spi_writel(as, TPR, tx_dma);

		if (msg->spi->bits_per_word > 8)
			len >>= 1;
		spi_writel(as, RCR, len);
		spi_writel(as, TCR, len);

		dev_dbg(&msg->spi->dev,
			"  start xfer %p: len %u tx %p/%08x rx %p/%08x\n",
			xfer, xfer->len, xfer->tx_buf, xfer->tx_dma,
			xfer->rx_buf, xfer->rx_dma);
	} else {
		xfer = as->next_transfer;
		remaining = as->next_remaining_bytes;
	}

	as->current_transfer = xfer;
	as->current_remaining_bytes = remaining;

	if (remaining > 0)
		len = remaining;
	else if (!atmel_spi_xfer_is_last(msg, xfer)
			&& atmel_spi_xfer_can_be_chained(xfer)) {
		xfer = list_entry(xfer->transfer_list.next,
				struct spi_transfer, transfer_list);
		len = xfer->len;
	} else
		xfer = NULL;

	as->next_transfer = xfer;

	if (xfer) {
		u32	total;

		total = len;
		atmel_spi_next_xfer_data(master, xfer, &tx_dma, &rx_dma, &len);
		as->next_remaining_bytes = total - len;

		spi_writel(as, RNPR, rx_dma);
		spi_writel(as, TNPR, tx_dma);

		if (msg->spi->bits_per_word > 8)
			len >>= 1;
		spi_writel(as, RNCR, len);
		spi_writel(as, TNCR, len);

		dev_dbg(&msg->spi->dev,
			"  next xfer %p: len %u tx %p/%08x rx %p/%08x\n",
			xfer, xfer->len, xfer->tx_buf, xfer->tx_dma,
			xfer->rx_buf, xfer->rx_dma);
		ieval = SPI_BIT(ENDRX) | SPI_BIT(OVRES);
	} else {
		spi_writel(as, RNCR, 0);
		spi_writel(as, TNCR, 0);
		ieval = SPI_BIT(RXBUFF) | SPI_BIT(ENDRX) | SPI_BIT(OVRES);
	}

	/* REVISIT: We're waiting for ENDRX before we start the next
	 * transfer because we need to handle some difficult timing
	 * issues otherwise. If we wait for ENDTX in one transfer and
	 * then starts waiting for ENDRX in the next, it's difficult
	 * to tell the difference between the ENDRX interrupt we're
	 * actually waiting for and the ENDRX interrupt of the
	 * previous transfer.
	 *
	 * It should be doable, though. Just not now...
	 */
	spi_writel(as, IER, ieval);
	spi_writel(as, PTCR, SPI_BIT(TXTEN) | SPI_BIT(RXTEN));
}

/*
 * Choose way to submit next transfer and start it.
 * lock is held, spi tasklet is blocked
 */
static void atmel_spi_dma_next_xfer(struct spi_master *master,
				struct spi_message *msg)
{
	struct atmel_spi	*as = spi_master_get_devdata(master);
	struct spi_transfer	*xfer;
	u32	remaining, len;

	remaining = as->current_remaining_bytes;
	if (remaining) {
		xfer = as->current_transfer;
		len = remaining;
	} else {
		if (!as->current_transfer)
			xfer = list_entry(msg->transfers.next,
				struct spi_transfer, transfer_list);
		else
			xfer = list_entry(
				as->current_transfer->transfer_list.next,
					struct spi_transfer, transfer_list);

		as->current_transfer = xfer;
		len = xfer->len;
	}

	if (atmel_spi_use_dma(as, xfer)) {
		u32 total = len;
		if (!atmel_spi_next_xfer_dma_submit(master, xfer, &len)) {
			as->current_remaining_bytes = total - len;
			return;
		} else {
			dev_err(&msg->spi->dev, "unable to use DMA, fallback to PIO\n");
		}
	}

	/* use PIO if error appened using DMA */
	atmel_spi_next_xfer_pio(master, xfer);
}

static void atmel_spi_next_message(struct spi_master *master)
{
	struct atmel_spi	*as = spi_master_get_devdata(master);
	struct spi_message	*msg;
	struct spi_device	*spi;

	BUG_ON(as->current_transfer);

	msg = list_entry(as->queue.next, struct spi_message, queue);
	spi = msg->spi;

	dev_dbg(master->dev.parent, "start message %p for %s\n",
			msg, dev_name(&spi->dev));

	/* select chip if it's not still active */
	if (as->stay) {
		if (as->stay != spi) {
			cs_deactivate(as, as->stay);
			cs_activate(as, spi);
		}
		as->stay = NULL;
	} else
		cs_activate(as, spi);

	if (as->use_pdc)
		atmel_spi_pdc_next_xfer(master, msg);
	else
		atmel_spi_dma_next_xfer(master, msg);
}

/*
 * For DMA, tx_buf/tx_dma have the same relationship as rx_buf/rx_dma:
 *  - The buffer is either valid for CPU access, else NULL
 *  - If the buffer is valid, so is its DMA address
 *
 * This driver manages the dma address unless message->is_dma_mapped.
 */
static int
atmel_spi_dma_map_xfer(struct atmel_spi *as, struct spi_transfer *xfer)
{
	struct device	*dev = &as->pdev->dev;

	xfer->tx_dma = xfer->rx_dma = INVALID_DMA_ADDRESS;
	if (xfer->tx_buf) {
		/* tx_buf is a const void* where we need a void * for the dma
		 * mapping */
		void *nonconst_tx = (void *)xfer->tx_buf;

		xfer->tx_dma = dma_map_single(dev,
				nonconst_tx, xfer->len,
				DMA_TO_DEVICE);
		if (dma_mapping_error(dev, xfer->tx_dma))
			return -ENOMEM;
	}
	if (xfer->rx_buf) {
		xfer->rx_dma = dma_map_single(dev,
				xfer->rx_buf, xfer->len,
				DMA_FROM_DEVICE);
		if (dma_mapping_error(dev, xfer->rx_dma)) {
			if (xfer->tx_buf)
				dma_unmap_single(dev,
						xfer->tx_dma, xfer->len,
						DMA_TO_DEVICE);
			return -ENOMEM;
		}
	}
	return 0;
}

static void atmel_spi_dma_unmap_xfer(struct spi_master *master,
				     struct spi_transfer *xfer)
{
	if (xfer->tx_dma != INVALID_DMA_ADDRESS)
		dma_unmap_single(master->dev.parent, xfer->tx_dma,
				 xfer->len, DMA_TO_DEVICE);
	if (xfer->rx_dma != INVALID_DMA_ADDRESS)
		dma_unmap_single(master->dev.parent, xfer->rx_dma,
				 xfer->len, DMA_FROM_DEVICE);
}

static void atmel_spi_disable_pdc_transfer(struct atmel_spi *as)
{
	spi_writel(as, PTCR, SPI_BIT(RXTDIS) | SPI_BIT(TXTDIS));
}

static void
atmel_spi_msg_done(struct spi_master *master, struct atmel_spi *as,
		struct spi_message *msg, int stay)
{
	if (!stay || as->done_status < 0)
		cs_deactivate(as, msg->spi);
	else
		as->stay = msg->spi;

	list_del(&msg->queue);
	msg->status = as->done_status;

	dev_dbg(master->dev.parent,
		"xfer complete: %u bytes transferred\n",
		msg->actual_length);

	atmel_spi_unlock(as);
	msg->complete(msg->context);
	atmel_spi_lock(as);

	as->current_transfer = NULL;
	as->next_transfer = NULL;
	as->done_status = 0;

	/* continue if needed */
	if (list_empty(&as->queue) || as->stopping) {
		if (as->use_pdc)
			atmel_spi_disable_pdc_transfer(as);
	} else {
		atmel_spi_next_message(master);
	}
}

/* Called from IRQ
 * lock is held
 *
 * Must update "current_remaining_bytes" to keep track of data
 * to transfer.
 */
static void
atmel_spi_pump_pio_data(struct atmel_spi *as, struct spi_transfer *xfer)
{
	u8		*txp;
	u8		*rxp;
	u16		*txp16;
	u16		*rxp16;
	unsigned long	xfer_pos = xfer->len - as->current_remaining_bytes;

	if (xfer->rx_buf) {
		if (xfer->bits_per_word > 8) {
			rxp16 = (u16 *)(((u8 *)xfer->rx_buf) + xfer_pos);
			*rxp16 = spi_readl(as, RDR);
		} else {
			rxp = ((u8 *)xfer->rx_buf) + xfer_pos;
			*rxp = spi_readl(as, RDR);
		}
	} else {
		spi_readl(as, RDR);
	}
	if (xfer->bits_per_word > 8) {
		as->current_remaining_bytes -= 2;
		if (as->current_remaining_bytes < 0)
			as->current_remaining_bytes = 0;
	} else {
		as->current_remaining_bytes--;
	}

	if (as->current_remaining_bytes) {
		if (xfer->tx_buf) {
			if (xfer->bits_per_word > 8) {
				txp16 = (u16 *)(((u8 *)xfer->tx_buf)
							+ xfer_pos + 2);
				spi_writel(as, TDR, *txp16);
			} else {
				txp = ((u8 *)xfer->tx_buf) + xfer_pos + 1;
				spi_writel(as, TDR, *txp);
			}
		} else {
			spi_writel(as, TDR, 0);
		}
	}
}

/* Tasklet
 * Called from DMA callback + pio transfer and overrun IRQ.
 */
static void atmel_spi_tasklet_func(unsigned long data)
{
	struct spi_master	*master = (struct spi_master *)data;
	struct atmel_spi	*as = spi_master_get_devdata(master);
	struct spi_message	*msg;
	struct spi_transfer	*xfer;

	dev_vdbg(master->dev.parent, "atmel_spi_tasklet_func\n");

	atmel_spi_lock(as);

	xfer = as->current_transfer;

	if (xfer == NULL)
		/* already been there */
		goto tasklet_out;

	msg = list_entry(as->queue.next, struct spi_message, queue);

	if (as->current_remaining_bytes == 0) {
		if (as->done_status < 0) {
			/* error happened (overrun) */
			if (atmel_spi_use_dma(as, xfer))
				atmel_spi_stop_dma(as);
		} else {
			/* only update length if no error */
			msg->actual_length += xfer->len;
		}

		if (atmel_spi_use_dma(as, xfer))
			if (!msg->is_dma_mapped)
				atmel_spi_dma_unmap_xfer(master, xfer);

		if (xfer->delay_usecs)
			udelay(xfer->delay_usecs);

		if (atmel_spi_xfer_is_last(msg, xfer) || as->done_status < 0) {
			/* report completed (or erroneous) message */
			atmel_spi_msg_done(master, as, msg, xfer->cs_change);
		} else {
			if (xfer->cs_change) {
				cs_deactivate(as, msg->spi);
				udelay(1);
				cs_activate(as, msg->spi);
			}

			/*
			 * Not done yet. Submit the next transfer.
			 *
			 * FIXME handle protocol options for xfer
			 */
			atmel_spi_dma_next_xfer(master, msg);
		}
	} else {
		/*
		 * Keep going, we still have data to send in
		 * the current transfer.
		 */
		atmel_spi_dma_next_xfer(master, msg);
	}

tasklet_out:
	atmel_spi_unlock(as);
}

/* Interrupt
 *
 * No need for locking in this Interrupt handler: done_status is the
 * only information modified. What we need is the update of this field
 * before tasklet runs. This is ensured by using barrier.
 */
static irqreturn_t
atmel_spi_pio_interrupt(int irq, void *dev_id)
{
	struct spi_master	*master = dev_id;
	struct atmel_spi	*as = spi_master_get_devdata(master);
	u32			status, pending, imr;
	struct spi_transfer	*xfer;
	int			ret = IRQ_NONE;

	imr = spi_readl(as, IMR);
	status = spi_readl(as, SR);
	pending = status & imr;

	if (pending & SPI_BIT(OVRES)) {
		ret = IRQ_HANDLED;
		spi_writel(as, IDR, SPI_BIT(OVRES));
		dev_warn(master->dev.parent, "overrun\n");

		/*
		 * When we get an overrun, we disregard the current
		 * transfer. Data will not be copied back from any
		 * bounce buffer and msg->actual_len will not be
		 * updated with the last xfer.
		 *
		 * We will also not process any remaning transfers in
		 * the message.
		 *
		 * All actions are done in tasklet with done_status indication
		 */
		as->done_status = -EIO;
		smp_wmb();

		/* Clear any overrun happening while cleaning up */
		spi_readl(as, SR);

		tasklet_schedule(&as->tasklet);

	} else if (pending & SPI_BIT(RDRF)) {
		atmel_spi_lock(as);

		if (as->current_remaining_bytes) {
			ret = IRQ_HANDLED;
			xfer = as->current_transfer;
			atmel_spi_pump_pio_data(as, xfer);
			if (!as->current_remaining_bytes) {
				/* no more data to xfer, kick tasklet */
				spi_writel(as, IDR, pending);
				tasklet_schedule(&as->tasklet);
			}
		}

		atmel_spi_unlock(as);
	} else {
		WARN_ONCE(pending, "IRQ not handled, pending = %x\n", pending);
		ret = IRQ_HANDLED;
		spi_writel(as, IDR, pending);
	}

	return ret;
}

static irqreturn_t
atmel_spi_pdc_interrupt(int irq, void *dev_id)
{
	struct spi_master	*master = dev_id;
	struct atmel_spi	*as = spi_master_get_devdata(master);
	struct spi_message	*msg;
	struct spi_transfer	*xfer;
	u32			status, pending, imr;
	int			ret = IRQ_NONE;

	atmel_spi_lock(as);

	xfer = as->current_transfer;
	msg = list_entry(as->queue.next, struct spi_message, queue);

	imr = spi_readl(as, IMR);
	status = spi_readl(as, SR);
	pending = status & imr;

	if (pending & SPI_BIT(OVRES)) {
		int timeout;

		ret = IRQ_HANDLED;

		spi_writel(as, IDR, (SPI_BIT(RXBUFF) | SPI_BIT(ENDRX)
				     | SPI_BIT(OVRES)));

		/*
		 * When we get an overrun, we disregard the current
		 * transfer. Data will not be copied back from any
		 * bounce buffer and msg->actual_len will not be
		 * updated with the last xfer.
		 *
		 * We will also not process any remaning transfers in
		 * the message.
		 *
		 * First, stop the transfer and unmap the DMA buffers.
		 */
		spi_writel(as, PTCR, SPI_BIT(RXTDIS) | SPI_BIT(TXTDIS));
		if (!msg->is_dma_mapped)
			atmel_spi_dma_unmap_xfer(master, xfer);

		/* REVISIT: udelay in irq is unfriendly */
		if (xfer->delay_usecs)
			udelay(xfer->delay_usecs);

		dev_warn(master->dev.parent, "overrun (%u/%u remaining)\n",
			 spi_readl(as, TCR), spi_readl(as, RCR));

		/*
		 * Clean up DMA registers and make sure the data
		 * registers are empty.
		 */
		spi_writel(as, RNCR, 0);
		spi_writel(as, TNCR, 0);
		spi_writel(as, RCR, 0);
		spi_writel(as, TCR, 0);
		for (timeout = 1000; timeout; timeout--)
			if (spi_readl(as, SR) & SPI_BIT(TXEMPTY))
				break;
		if (!timeout)
			dev_warn(master->dev.parent,
				 "timeout waiting for TXEMPTY");
		while (spi_readl(as, SR) & SPI_BIT(RDRF))
			spi_readl(as, RDR);

		/* Clear any overrun happening while cleaning up */
		spi_readl(as, SR);

		as->done_status = -EIO;
		atmel_spi_msg_done(master, as, msg, 0);
	} else if (pending & (SPI_BIT(RXBUFF) | SPI_BIT(ENDRX))) {
		ret = IRQ_HANDLED;

		spi_writel(as, IDR, pending);

		if (as->current_remaining_bytes == 0) {
			msg->actual_length += xfer->len;

			if (!msg->is_dma_mapped)
				atmel_spi_dma_unmap_xfer(master, xfer);

			/* REVISIT: udelay in irq is unfriendly */
			if (xfer->delay_usecs)
				udelay(xfer->delay_usecs);

			if (atmel_spi_xfer_is_last(msg, xfer)) {
				/* report completed message */
				atmel_spi_msg_done(master, as, msg,
						xfer->cs_change);
			} else {
				if (xfer->cs_change) {
					cs_deactivate(as, msg->spi);
					udelay(1);
					cs_activate(as, msg->spi);
				}

				/*
				 * Not done yet. Submit the next transfer.
				 *
				 * FIXME handle protocol options for xfer
				 */
				atmel_spi_pdc_next_xfer(master, msg);
			}
		} else {
			/*
			 * Keep going, we still have data to send in
			 * the current transfer.
			 */
			atmel_spi_pdc_next_xfer(master, msg);
		}
	}

	atmel_spi_unlock(as);

	return ret;
}

static int atmel_spi_setup(struct spi_device *spi)
{
	struct atmel_spi	*as;
	struct atmel_spi_device	*asd;
	u32			scbr, csr;
	unsigned int		bits = spi->bits_per_word;
	unsigned long		bus_hz;
	unsigned int		npcs_pin;
	int			ret;

	as = spi_master_get_devdata(spi->master);

	if (as->stopping)
		return -ESHUTDOWN;

	if (spi->chip_select > spi->master->num_chipselect) {
		dev_dbg(&spi->dev,
				"setup: invalid chipselect %u (%u defined)\n",
				spi->chip_select, spi->master->num_chipselect);
		return -EINVAL;
	}

	/* see notes above re chipselect */
	if (!atmel_spi_is_v2(as)
			&& spi->chip_select == 0
			&& (spi->mode & SPI_CS_HIGH)) {
		dev_dbg(&spi->dev, "setup: can't be active-high\n");
		return -EINVAL;
	}

	/* v1 chips start out at half the peripheral bus speed. */
	bus_hz = clk_get_rate(as->clk);
	if (!atmel_spi_is_v2(as))
		bus_hz /= 2;

	if (spi->max_speed_hz) {
		/*
		 * Calculate the lowest divider that satisfies the
		 * constraint, assuming div32/fdiv/mbz == 0.
		 */
		scbr = DIV_ROUND_UP(bus_hz, spi->max_speed_hz);

		/*
		 * If the resulting divider doesn't fit into the
		 * register bitfield, we can't satisfy the constraint.
		 */
		if (scbr >= (1 << SPI_SCBR_SIZE)) {
			dev_dbg(&spi->dev,
				"setup: %d Hz too slow, scbr %u; min %ld Hz\n",
				spi->max_speed_hz, scbr, bus_hz/255);
			return -EINVAL;
		}
	} else
		/* speed zero means "as slow as possible" */
		scbr = 0xff;

	csr = SPI_BF(SCBR, scbr) | SPI_BF(BITS, bits - 8);
	if (spi->mode & SPI_CPOL)
		csr |= SPI_BIT(CPOL);
	if (!(spi->mode & SPI_CPHA))
		csr |= SPI_BIT(NCPHA);

	/* DLYBS is mostly irrelevant since we manage chipselect using GPIOs.
	 *
	 * DLYBCT would add delays between words, slowing down transfers.
	 * It could potentially be useful to cope with DMA bottlenecks, but
	 * in those cases it's probably best to just use a lower bitrate.
	 */
	csr |= SPI_BF(DLYBS, 0);
	csr |= SPI_BF(DLYBCT, 0);

	/* chipselect must have been muxed as GPIO (e.g. in board setup) */
	npcs_pin = (unsigned int)spi->controller_data;

	if (gpio_is_valid(spi->cs_gpio))
		npcs_pin = spi->cs_gpio;

	asd = spi->controller_state;
	if (!asd) {
		asd = kzalloc(sizeof(struct atmel_spi_device), GFP_KERNEL);
		if (!asd)
			return -ENOMEM;

		ret = gpio_request(npcs_pin, dev_name(&spi->dev));
		if (ret) {
			kfree(asd);
			return ret;
		}

		asd->npcs_pin = npcs_pin;
		spi->controller_state = asd;
		gpio_direction_output(npcs_pin, !(spi->mode & SPI_CS_HIGH));
	} else {
		atmel_spi_lock(as);
		if (as->stay == spi)
			as->stay = NULL;
		cs_deactivate(as, spi);
		atmel_spi_unlock(as);
	}

	asd->csr = csr;

	dev_dbg(&spi->dev,
		"setup: %lu Hz bpw %u mode 0x%x -> csr%d %08x\n",
		bus_hz / scbr, bits, spi->mode, spi->chip_select, csr);

	if (!atmel_spi_is_v2(as))
		spi_writel(as, CSR0 + 4 * spi->chip_select, csr);

	return 0;
}

static int atmel_spi_transfer(struct spi_device *spi, struct spi_message *msg)
{
	struct atmel_spi	*as;
	struct spi_transfer	*xfer;
	struct device		*controller = spi->master->dev.parent;
	u8			bits;
	struct atmel_spi_device	*asd;

	as = spi_master_get_devdata(spi->master);

	dev_dbg(controller, "new message %p submitted for %s\n",
			msg, dev_name(&spi->dev));

	if (unlikely(list_empty(&msg->transfers)))
		return -EINVAL;

	if (as->stopping)
		return -ESHUTDOWN;

	list_for_each_entry(xfer, &msg->transfers, transfer_list) {
		if (!(xfer->tx_buf || xfer->rx_buf) && xfer->len) {
			dev_dbg(&spi->dev, "missing rx or tx buf\n");
			return -EINVAL;
		}

		if (xfer->bits_per_word) {
			asd = spi->controller_state;
			bits = (asd->csr >> 4) & 0xf;
			if (bits != xfer->bits_per_word - 8) {
				dev_dbg(&spi->dev, "you can't yet change "
					 "bits_per_word in transfers\n");
				return -ENOPROTOOPT;
			}
		}

		if (xfer->bits_per_word > 8) {
			if (xfer->len % 2) {
				dev_dbg(&spi->dev, "buffer len should be 16 bits aligned\n");
				return -EINVAL;
			}
		}

		/* FIXME implement these protocol options!! */
		if (xfer->speed_hz < spi->max_speed_hz) {
			dev_dbg(&spi->dev, "can't change speed in transfer\n");
			return -ENOPROTOOPT;
		}

		/*
		 * DMA map early, for performance (empties dcache ASAP) and
		 * better fault reporting.
		 */
		if ((!msg->is_dma_mapped) && (atmel_spi_use_dma(as, xfer)
			|| as->use_pdc)) {
			if (atmel_spi_dma_map_xfer(as, xfer) < 0)
				return -ENOMEM;
		}
	}

#ifdef VERBOSE
	list_for_each_entry(xfer, &msg->transfers, transfer_list) {
		dev_dbg(controller,
			"  xfer %p: len %u tx %p/%08x rx %p/%08x\n",
			xfer, xfer->len,
			xfer->tx_buf, xfer->tx_dma,
			xfer->rx_buf, xfer->rx_dma);
	}
#endif

	msg->status = -EINPROGRESS;
	msg->actual_length = 0;

	atmel_spi_lock(as);
	list_add_tail(&msg->queue, &as->queue);
	if (!as->current_transfer)
		atmel_spi_next_message(spi->master);
	atmel_spi_unlock(as);

	return 0;
}

static void atmel_spi_cleanup(struct spi_device *spi)
{
	struct atmel_spi	*as = spi_master_get_devdata(spi->master);
	struct atmel_spi_device	*asd = spi->controller_state;
	unsigned		gpio = (unsigned) spi->controller_data;

	if (!asd)
		return;

	atmel_spi_lock(as);
	if (as->stay == spi) {
		as->stay = NULL;
		cs_deactivate(as, spi);
	}
	atmel_spi_unlock(as);

	spi->controller_state = NULL;
	gpio_free(gpio);
	kfree(asd);
}

static inline unsigned int atmel_get_version(struct atmel_spi *as)
{
	return spi_readl(as, VERSION) & 0x00000fff;
}

static void atmel_get_caps(struct atmel_spi *as)
{
	unsigned int version;

	version = atmel_get_version(as);
	dev_info(&as->pdev->dev, "version: 0x%x\n", version);

	as->caps.is_spi2 = version > 0x121;
	as->caps.has_wdrbt = version >= 0x210;
	as->caps.has_dma_support = version >= 0x212;
}

/*-------------------------------------------------------------------------*/

static int atmel_spi_probe(struct platform_device *pdev)
{
	struct resource		*regs;
	int			irq;
	struct clk		*clk;
	int			ret;
	struct spi_master	*master;
	struct atmel_spi	*as;

	regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	if (!regs)
		return -ENXIO;

	irq = platform_get_irq(pdev, 0);
	if (irq < 0)
		return irq;

	clk = clk_get(&pdev->dev, "spi_clk");
	if (IS_ERR(clk))
		return PTR_ERR(clk);

	/* setup spi core then atmel-specific driver state */
	ret = -ENOMEM;
	master = spi_alloc_master(&pdev->dev, sizeof *as);
	if (!master)
		goto out_free;

	/* the spi->mode bits understood by this driver: */
	master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH;
	master->bits_per_word_mask = SPI_BPW_RANGE_MASK(8, 16);
	master->dev.of_node = pdev->dev.of_node;
	master->bus_num = pdev->id;
	master->num_chipselect = master->dev.of_node ? 0 : 4;
	master->setup = atmel_spi_setup;
	master->transfer = atmel_spi_transfer;
	master->cleanup = atmel_spi_cleanup;
	platform_set_drvdata(pdev, master);

	as = spi_master_get_devdata(master);

	/*
	 * Scratch buffer is used for throwaway rx and tx data.
	 * It's coherent to minimize dcache pollution.
	 */
	as->buffer = dma_alloc_coherent(&pdev->dev, BUFFER_SIZE,
					&as->buffer_dma, GFP_KERNEL);
	if (!as->buffer)
		goto out_free;

	spin_lock_init(&as->lock);
	INIT_LIST_HEAD(&as->queue);

	as->pdev = pdev;
	as->regs = ioremap(regs->start, resource_size(regs));
	if (!as->regs)
		goto out_free_buffer;
	as->phybase = regs->start;
	as->irq = irq;
	as->clk = clk;

	atmel_get_caps(as);

	as->use_dma = false;
	as->use_pdc = false;
	if (as->caps.has_dma_support) {
		if (atmel_spi_configure_dma(as) == 0)
			as->use_dma = true;
	} else {
		as->use_pdc = true;
	}

	if (as->caps.has_dma_support && !as->use_dma)
		dev_info(&pdev->dev, "Atmel SPI Controller using PIO only\n");

	if (as->use_pdc) {
		ret = request_irq(irq, atmel_spi_pdc_interrupt, 0,
					dev_name(&pdev->dev), master);
	} else {
		tasklet_init(&as->tasklet, atmel_spi_tasklet_func,
					(unsigned long)master);

		ret = request_irq(irq, atmel_spi_pio_interrupt, 0,
					dev_name(&pdev->dev), master);
	}
	if (ret)
		goto out_unmap_regs;

	/* Initialize the hardware */
	clk_enable(clk);
	spi_writel(as, CR, SPI_BIT(SWRST));
	spi_writel(as, CR, SPI_BIT(SWRST)); /* AT91SAM9263 Rev B workaround */
	if (as->caps.has_wdrbt) {
		spi_writel(as, MR, SPI_BIT(WDRBT) | SPI_BIT(MODFDIS)
				| SPI_BIT(MSTR));
	} else {
		spi_writel(as, MR, SPI_BIT(MSTR) | SPI_BIT(MODFDIS));
	}

	if (as->use_pdc)
		spi_writel(as, PTCR, SPI_BIT(RXTDIS) | SPI_BIT(TXTDIS));
	spi_writel(as, CR, SPI_BIT(SPIEN));

	/* go! */
	dev_info(&pdev->dev, "Atmel SPI Controller at 0x%08lx (irq %d)\n",
			(unsigned long)regs->start, irq);

	ret = spi_register_master(master);
	if (ret)
		goto out_free_dma;

	return 0;

out_free_dma:
	if (as->use_dma)
		atmel_spi_release_dma(as);

	spi_writel(as, CR, SPI_BIT(SWRST));
	spi_writel(as, CR, SPI_BIT(SWRST)); /* AT91SAM9263 Rev B workaround */
	clk_disable(clk);
	free_irq(irq, master);
out_unmap_regs:
	iounmap(as->regs);
out_free_buffer:
	if (!as->use_pdc)
		tasklet_kill(&as->tasklet);
	dma_free_coherent(&pdev->dev, BUFFER_SIZE, as->buffer,
			as->buffer_dma);
out_free:
	clk_put(clk);
	spi_master_put(master);
	return ret;
}

static int atmel_spi_remove(struct platform_device *pdev)
{
	struct spi_master	*master = platform_get_drvdata(pdev);
	struct atmel_spi	*as = spi_master_get_devdata(master);
	struct spi_message	*msg;
	struct spi_transfer	*xfer;

	/* reset the hardware and block queue progress */
	spin_lock_irq(&as->lock);
	as->stopping = 1;
	if (as->use_dma) {
		atmel_spi_stop_dma(as);
		atmel_spi_release_dma(as);
	}

	spi_writel(as, CR, SPI_BIT(SWRST));
	spi_writel(as, CR, SPI_BIT(SWRST)); /* AT91SAM9263 Rev B workaround */
	spi_readl(as, SR);
	spin_unlock_irq(&as->lock);

	/* Terminate remaining queued transfers */
	list_for_each_entry(msg, &as->queue, queue) {
		list_for_each_entry(xfer, &msg->transfers, transfer_list) {
			if (!msg->is_dma_mapped
				&& (atmel_spi_use_dma(as, xfer)
					|| as->use_pdc))
				atmel_spi_dma_unmap_xfer(master, xfer);
		}
		msg->status = -ESHUTDOWN;
		msg->complete(msg->context);
	}

	if (!as->use_pdc)
		tasklet_kill(&as->tasklet);
	dma_free_coherent(&pdev->dev, BUFFER_SIZE, as->buffer,
			as->buffer_dma);

	clk_disable(as->clk);
	clk_put(as->clk);
	free_irq(as->irq, master);
	iounmap(as->regs);

	spi_unregister_master(master);

	return 0;
}

#ifdef	CONFIG_PM

static int atmel_spi_suspend(struct platform_device *pdev, pm_message_t mesg)
{
	struct spi_master	*master = platform_get_drvdata(pdev);
	struct atmel_spi	*as = spi_master_get_devdata(master);

	clk_disable(as->clk);
	return 0;
}

static int atmel_spi_resume(struct platform_device *pdev)
{
	struct spi_master	*master = platform_get_drvdata(pdev);
	struct atmel_spi	*as = spi_master_get_devdata(master);

	clk_enable(as->clk);
	return 0;
}

#else
#define	atmel_spi_suspend	NULL
#define	atmel_spi_resume	NULL
#endif

#if defined(CONFIG_OF)
static const struct of_device_id atmel_spi_dt_ids[] = {
	{ .compatible = "atmel,at91rm9200-spi" },
	{ /* sentinel */ }
};

MODULE_DEVICE_TABLE(of, atmel_spi_dt_ids);
#endif

static struct platform_driver atmel_spi_driver = {
	.driver		= {
		.name	= "atmel_spi",
		.owner	= THIS_MODULE,
		.of_match_table	= of_match_ptr(atmel_spi_dt_ids),
	},
	.suspend	= atmel_spi_suspend,
	.resume		= atmel_spi_resume,
	.probe		= atmel_spi_probe,
	.remove		= atmel_spi_remove,
};
module_platform_driver(atmel_spi_driver);

MODULE_DESCRIPTION("Atmel AT32/AT91 SPI Controller driver");
MODULE_AUTHOR("Haavard Skinnemoen (Atmel)");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:atmel_spi");