summaryrefslogtreecommitdiffstats
path: root/drivers/net/can/grcan.c
blob: 897c6b113d3f843607136f643d2a62a2bb76f0c8 (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
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
/*
 * Socket CAN driver for Aeroflex Gaisler GRCAN and GRHCAN.
 *
 * 2012 (c) Aeroflex Gaisler AB
 *
 * This driver supports GRCAN and GRHCAN CAN controllers available in the GRLIB
 * VHDL IP core library.
 *
 * Full documentation of the GRCAN core can be found here:
 * http://www.gaisler.com/products/grlib/grip.pdf
 *
 * See "Documentation/devicetree/bindings/net/can/grcan.txt" for information on
 * open firmware properties.
 *
 * See "Documentation/ABI/testing/sysfs-class-net-grcan" for information on the
 * sysfs interface.
 *
 * See "Documentation/admin-guide/kernel-parameters.rst" for information on the module
 * parameters.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the
 * Free Software Foundation; either version 2 of the License, or (at your
 * option) any later version.
 *
 * Contributors: Andreas Larsson <andreas@gaisler.com>
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/interrupt.h>
#include <linux/netdevice.h>
#include <linux/delay.h>
#include <linux/io.h>
#include <linux/can/dev.h>
#include <linux/spinlock.h>
#include <linux/of_platform.h>
#include <linux/of_irq.h>

#include <linux/dma-mapping.h>

#define DRV_NAME	"grcan"

#define GRCAN_NAPI_WEIGHT	32

#define GRCAN_RESERVE_SIZE(slot1, slot2) (((slot2) - (slot1)) / 4 - 1)

struct grcan_registers {
	u32 conf;	/* 0x00 */
	u32 stat;	/* 0x04 */
	u32 ctrl;	/* 0x08 */
	u32 __reserved1[GRCAN_RESERVE_SIZE(0x08, 0x18)];
	u32 smask;	/* 0x18 - CanMASK */
	u32 scode;	/* 0x1c - CanCODE */
	u32 __reserved2[GRCAN_RESERVE_SIZE(0x1c, 0x100)];
	u32 pimsr;	/* 0x100 */
	u32 pimr;	/* 0x104 */
	u32 pisr;	/* 0x108 */
	u32 pir;	/* 0x10C */
	u32 imr;	/* 0x110 */
	u32 picr;	/* 0x114 */
	u32 __reserved3[GRCAN_RESERVE_SIZE(0x114, 0x200)];
	u32 txctrl;	/* 0x200 */
	u32 txaddr;	/* 0x204 */
	u32 txsize;	/* 0x208 */
	u32 txwr;	/* 0x20C */
	u32 txrd;	/* 0x210 */
	u32 txirq;	/* 0x214 */
	u32 __reserved4[GRCAN_RESERVE_SIZE(0x214, 0x300)];
	u32 rxctrl;	/* 0x300 */
	u32 rxaddr;	/* 0x304 */
	u32 rxsize;	/* 0x308 */
	u32 rxwr;	/* 0x30C */
	u32 rxrd;	/* 0x310 */
	u32 rxirq;	/* 0x314 */
	u32 rxmask;	/* 0x318 */
	u32 rxcode;	/* 0x31C */
};

#define GRCAN_CONF_ABORT	0x00000001
#define GRCAN_CONF_ENABLE0	0x00000002
#define GRCAN_CONF_ENABLE1	0x00000004
#define GRCAN_CONF_SELECT	0x00000008
#define GRCAN_CONF_SILENT	0x00000010
#define GRCAN_CONF_SAM		0x00000020 /* Available in some hardware */
#define GRCAN_CONF_BPR		0x00000300 /* Note: not BRP */
#define GRCAN_CONF_RSJ		0x00007000
#define GRCAN_CONF_PS1		0x00f00000
#define GRCAN_CONF_PS2		0x000f0000
#define GRCAN_CONF_SCALER	0xff000000
#define GRCAN_CONF_OPERATION						\
	(GRCAN_CONF_ABORT | GRCAN_CONF_ENABLE0 | GRCAN_CONF_ENABLE1	\
	 | GRCAN_CONF_SELECT | GRCAN_CONF_SILENT | GRCAN_CONF_SAM)
#define GRCAN_CONF_TIMING						\
	(GRCAN_CONF_BPR | GRCAN_CONF_RSJ | GRCAN_CONF_PS1		\
	 | GRCAN_CONF_PS2 | GRCAN_CONF_SCALER)

#define GRCAN_CONF_RSJ_MIN	1
#define GRCAN_CONF_RSJ_MAX	4
#define GRCAN_CONF_PS1_MIN	1
#define GRCAN_CONF_PS1_MAX	15
#define GRCAN_CONF_PS2_MIN	2
#define GRCAN_CONF_PS2_MAX	8
#define GRCAN_CONF_SCALER_MIN	0
#define GRCAN_CONF_SCALER_MAX	255
#define GRCAN_CONF_SCALER_INC	1

#define GRCAN_CONF_BPR_BIT	8
#define GRCAN_CONF_RSJ_BIT	12
#define GRCAN_CONF_PS1_BIT	20
#define GRCAN_CONF_PS2_BIT	16
#define GRCAN_CONF_SCALER_BIT	24

#define GRCAN_STAT_PASS		0x000001
#define GRCAN_STAT_OFF		0x000002
#define GRCAN_STAT_OR		0x000004
#define GRCAN_STAT_AHBERR	0x000008
#define GRCAN_STAT_ACTIVE	0x000010
#define GRCAN_STAT_RXERRCNT	0x00ff00
#define GRCAN_STAT_TXERRCNT	0xff0000

#define GRCAN_STAT_ERRCTR_RELATED	(GRCAN_STAT_PASS | GRCAN_STAT_OFF)

#define GRCAN_STAT_RXERRCNT_BIT	8
#define GRCAN_STAT_TXERRCNT_BIT	16

#define GRCAN_STAT_ERRCNT_WARNING_LIMIT	96
#define GRCAN_STAT_ERRCNT_PASSIVE_LIMIT	127

#define GRCAN_CTRL_RESET	0x2
#define GRCAN_CTRL_ENABLE	0x1

#define GRCAN_TXCTRL_ENABLE	0x1
#define GRCAN_TXCTRL_ONGOING	0x2
#define GRCAN_TXCTRL_SINGLE	0x4

#define GRCAN_RXCTRL_ENABLE	0x1
#define GRCAN_RXCTRL_ONGOING	0x2

/* Relative offset of IRQ sources to AMBA Plug&Play */
#define GRCAN_IRQIX_IRQ		0
#define GRCAN_IRQIX_TXSYNC	1
#define GRCAN_IRQIX_RXSYNC	2

#define GRCAN_IRQ_PASS		0x00001
#define GRCAN_IRQ_OFF		0x00002
#define GRCAN_IRQ_OR		0x00004
#define GRCAN_IRQ_RXAHBERR	0x00008
#define GRCAN_IRQ_TXAHBERR	0x00010
#define GRCAN_IRQ_RXIRQ		0x00020
#define GRCAN_IRQ_TXIRQ		0x00040
#define GRCAN_IRQ_RXFULL	0x00080
#define GRCAN_IRQ_TXEMPTY	0x00100
#define GRCAN_IRQ_RX		0x00200
#define GRCAN_IRQ_TX		0x00400
#define GRCAN_IRQ_RXSYNC	0x00800
#define GRCAN_IRQ_TXSYNC	0x01000
#define GRCAN_IRQ_RXERRCTR	0x02000
#define GRCAN_IRQ_TXERRCTR	0x04000
#define GRCAN_IRQ_RXMISS	0x08000
#define GRCAN_IRQ_TXLOSS	0x10000

#define GRCAN_IRQ_NONE	0
#define GRCAN_IRQ_ALL							\
	(GRCAN_IRQ_PASS | GRCAN_IRQ_OFF | GRCAN_IRQ_OR			\
	 | GRCAN_IRQ_RXAHBERR | GRCAN_IRQ_TXAHBERR			\
	 | GRCAN_IRQ_RXIRQ | GRCAN_IRQ_TXIRQ				\
	 | GRCAN_IRQ_RXFULL | GRCAN_IRQ_TXEMPTY				\
	 | GRCAN_IRQ_RX | GRCAN_IRQ_TX | GRCAN_IRQ_RXSYNC		\
	 | GRCAN_IRQ_TXSYNC | GRCAN_IRQ_RXERRCTR			\
	 | GRCAN_IRQ_TXERRCTR | GRCAN_IRQ_RXMISS			\
	 | GRCAN_IRQ_TXLOSS)

#define GRCAN_IRQ_ERRCTR_RELATED (GRCAN_IRQ_RXERRCTR | GRCAN_IRQ_TXERRCTR \
				  | GRCAN_IRQ_PASS | GRCAN_IRQ_OFF)
#define GRCAN_IRQ_ERRORS (GRCAN_IRQ_ERRCTR_RELATED | GRCAN_IRQ_OR	\
			  | GRCAN_IRQ_TXAHBERR | GRCAN_IRQ_RXAHBERR	\
			  | GRCAN_IRQ_TXLOSS)
#define GRCAN_IRQ_DEFAULT (GRCAN_IRQ_RX | GRCAN_IRQ_TX | GRCAN_IRQ_ERRORS)

#define GRCAN_MSG_SIZE		16

#define GRCAN_MSG_IDE		0x80000000
#define GRCAN_MSG_RTR		0x40000000
#define GRCAN_MSG_BID		0x1ffc0000
#define GRCAN_MSG_EID		0x1fffffff
#define GRCAN_MSG_IDE_BIT	31
#define GRCAN_MSG_RTR_BIT	30
#define GRCAN_MSG_BID_BIT	18
#define GRCAN_MSG_EID_BIT	0

#define GRCAN_MSG_DLC		0xf0000000
#define GRCAN_MSG_TXERRC	0x00ff0000
#define GRCAN_MSG_RXERRC	0x0000ff00
#define GRCAN_MSG_DLC_BIT	28
#define GRCAN_MSG_TXERRC_BIT	16
#define GRCAN_MSG_RXERRC_BIT	8
#define GRCAN_MSG_AHBERR	0x00000008
#define GRCAN_MSG_OR		0x00000004
#define GRCAN_MSG_OFF		0x00000002
#define GRCAN_MSG_PASS		0x00000001

#define GRCAN_MSG_DATA_SLOT_INDEX(i) (2 + (i) / 4)
#define GRCAN_MSG_DATA_SHIFT(i) ((3 - (i) % 4) * 8)

#define GRCAN_BUFFER_ALIGNMENT		1024
#define GRCAN_DEFAULT_BUFFER_SIZE	1024
#define GRCAN_VALID_TR_SIZE_MASK	0x001fffc0

#define GRCAN_INVALID_BUFFER_SIZE(s)			\
	((s) == 0 || ((s) & ~GRCAN_VALID_TR_SIZE_MASK))

#if GRCAN_INVALID_BUFFER_SIZE(GRCAN_DEFAULT_BUFFER_SIZE)
#error "Invalid default buffer size"
#endif

struct grcan_dma_buffer {
	size_t size;
	void *buf;
	dma_addr_t handle;
};

struct grcan_dma {
	size_t base_size;
	void *base_buf;
	dma_addr_t base_handle;
	struct grcan_dma_buffer tx;
	struct grcan_dma_buffer rx;
};

/* GRCAN configuration parameters */
struct grcan_device_config {
	unsigned short enable0;
	unsigned short enable1;
	unsigned short select;
	unsigned int txsize;
	unsigned int rxsize;
};

#define GRCAN_DEFAULT_DEVICE_CONFIG {				\
		.enable0	= 0,				\
		.enable1	= 0,				\
		.select		= 0,				\
		.txsize		= GRCAN_DEFAULT_BUFFER_SIZE,	\
		.rxsize		= GRCAN_DEFAULT_BUFFER_SIZE,	\
		}

#define GRCAN_TXBUG_SAFE_GRLIB_VERSION	0x4100
#define GRLIB_VERSION_MASK		0xffff

/* GRCAN private data structure */
struct grcan_priv {
	struct can_priv can;	/* must be the first member */
	struct net_device *dev;
	struct napi_struct napi;

	struct grcan_registers __iomem *regs;	/* ioremap'ed registers */
	struct grcan_device_config config;
	struct grcan_dma dma;

	struct sk_buff **echo_skb;	/* We allocate this on our own */
	u8 *txdlc;			/* Length of queued frames */

	/* The echo skb pointer, pointing into echo_skb and indicating which
	 * frames can be echoed back. See the "Notes on the tx cyclic buffer
	 * handling"-comment for grcan_start_xmit for more details.
	 */
	u32 eskbp;

	/* Lock for controlling changes to the netif tx queue state, accesses to
	 * the echo_skb pointer eskbp and for making sure that a running reset
	 * and/or a close of the interface is done without interference from
	 * other parts of the code.
	 *
	 * The echo_skb pointer, eskbp, should only be accessed under this lock
	 * as it can be changed in several places and together with decisions on
	 * whether to wake up the tx queue.
	 *
	 * The tx queue must never be woken up if there is a running reset or
	 * close in progress.
	 *
	 * A running reset (see below on need_txbug_workaround) should never be
	 * done if the interface is closing down and several running resets
	 * should never be scheduled simultaneously.
	 */
	spinlock_t lock;

	/* Whether a workaround is needed due to a bug in older hardware. In
	 * this case, the driver both tries to prevent the bug from being
	 * triggered and recovers, if the bug nevertheless happens, by doing a
	 * running reset. A running reset, resets the device and continues from
	 * where it were without being noticeable from outside the driver (apart
	 * from slight delays).
	 */
	bool need_txbug_workaround;

	/* To trigger initization of running reset and to trigger running reset
	 * respectively in the case of a hanged device due to a txbug.
	 */
	struct timer_list hang_timer;
	struct timer_list rr_timer;

	/* To avoid waking up the netif queue and restarting timers
	 * when a reset is scheduled or when closing of the device is
	 * undergoing
	 */
	bool resetting;
	bool closing;
};

/* Wait time for a short wait for ongoing to clear */
#define GRCAN_SHORTWAIT_USECS	10

/* Limit on the number of transmitted bits of an eff frame according to the CAN
 * specification: 1 bit start of frame, 32 bits arbitration field, 6 bits
 * control field, 8 bytes data field, 16 bits crc field, 2 bits ACK field and 7
 * bits end of frame
 */
#define GRCAN_EFF_FRAME_MAX_BITS	(1+32+6+8*8+16+2+7)

#if defined(__BIG_ENDIAN)
static inline u32 grcan_read_reg(u32 __iomem *reg)
{
	return ioread32be(reg);
}

static inline void grcan_write_reg(u32 __iomem *reg, u32 val)
{
	iowrite32be(val, reg);
}
#else
static inline u32 grcan_read_reg(u32 __iomem *reg)
{
	return ioread32(reg);
}

static inline void grcan_write_reg(u32 __iomem *reg, u32 val)
{
	iowrite32(val, reg);
}
#endif

static inline void grcan_clear_bits(u32 __iomem *reg, u32 mask)
{
	grcan_write_reg(reg, grcan_read_reg(reg) & ~mask);
}

static inline void grcan_set_bits(u32 __iomem *reg, u32 mask)
{
	grcan_write_reg(reg, grcan_read_reg(reg) | mask);
}

static inline u32 grcan_read_bits(u32 __iomem *reg, u32 mask)
{
	return grcan_read_reg(reg) & mask;
}

static inline void grcan_write_bits(u32 __iomem *reg, u32 value, u32 mask)
{
	u32 old = grcan_read_reg(reg);

	grcan_write_reg(reg, (old & ~mask) | (value & mask));
}

/* a and b should both be in [0,size] and a == b == size should not hold */
static inline u32 grcan_ring_add(u32 a, u32 b, u32 size)
{
	u32 sum = a + b;

	if (sum < size)
		return sum;
	else
		return sum - size;
}

/* a and b should both be in [0,size) */
static inline u32 grcan_ring_sub(u32 a, u32 b, u32 size)
{
	return grcan_ring_add(a, size - b, size);
}

/* Available slots for new transmissions */
static inline u32 grcan_txspace(size_t txsize, u32 txwr, u32 eskbp)
{
	u32 slots = txsize / GRCAN_MSG_SIZE - 1;
	u32 used = grcan_ring_sub(txwr, eskbp, txsize) / GRCAN_MSG_SIZE;

	return slots - used;
}

/* Configuration parameters that can be set via module parameters */
static struct grcan_device_config grcan_module_config =
	GRCAN_DEFAULT_DEVICE_CONFIG;

static const struct can_bittiming_const grcan_bittiming_const = {
	.name		= DRV_NAME,
	.tseg1_min	= GRCAN_CONF_PS1_MIN + 1,
	.tseg1_max	= GRCAN_CONF_PS1_MAX + 1,
	.tseg2_min	= GRCAN_CONF_PS2_MIN,
	.tseg2_max	= GRCAN_CONF_PS2_MAX,
	.sjw_max	= GRCAN_CONF_RSJ_MAX,
	.brp_min	= GRCAN_CONF_SCALER_MIN + 1,
	.brp_max	= GRCAN_CONF_SCALER_MAX + 1,
	.brp_inc	= GRCAN_CONF_SCALER_INC,
};

static int grcan_set_bittiming(struct net_device *dev)
{
	struct grcan_priv *priv = netdev_priv(dev);
	struct grcan_registers __iomem *regs = priv->regs;
	struct can_bittiming *bt = &priv->can.bittiming;
	u32 timing = 0;
	int bpr, rsj, ps1, ps2, scaler;

	/* Should never happen - function will not be called when
	 * device is up
	 */
	if (grcan_read_bits(&regs->ctrl, GRCAN_CTRL_ENABLE))
		return -EBUSY;

	bpr = 0; /* Note bpr and brp are different concepts */
	rsj = bt->sjw;
	ps1 = (bt->prop_seg + bt->phase_seg1) - 1; /* tseg1 - 1 */
	ps2 = bt->phase_seg2;
	scaler = (bt->brp - 1);
	netdev_dbg(dev, "Request for BPR=%d, RSJ=%d, PS1=%d, PS2=%d, SCALER=%d",
		   bpr, rsj, ps1, ps2, scaler);
	if (!(ps1 > ps2)) {
		netdev_err(dev, "PS1 > PS2 must hold: PS1=%d, PS2=%d\n",
			   ps1, ps2);
		return -EINVAL;
	}
	if (!(ps2 >= rsj)) {
		netdev_err(dev, "PS2 >= RSJ must hold: PS2=%d, RSJ=%d\n",
			   ps2, rsj);
		return -EINVAL;
	}

	timing |= (bpr << GRCAN_CONF_BPR_BIT) & GRCAN_CONF_BPR;
	timing |= (rsj << GRCAN_CONF_RSJ_BIT) & GRCAN_CONF_RSJ;
	timing |= (ps1 << GRCAN_CONF_PS1_BIT) & GRCAN_CONF_PS1;
	timing |= (ps2 << GRCAN_CONF_PS2_BIT) & GRCAN_CONF_PS2;
	timing |= (scaler << GRCAN_CONF_SCALER_BIT) & GRCAN_CONF_SCALER;
	netdev_info(dev, "setting timing=0x%x\n", timing);
	grcan_write_bits(&regs->conf, timing, GRCAN_CONF_TIMING);

	return 0;
}

static int grcan_get_berr_counter(const struct net_device *dev,
				  struct can_berr_counter *bec)
{
	struct grcan_priv *priv = netdev_priv(dev);
	struct grcan_registers __iomem *regs = priv->regs;
	u32 status = grcan_read_reg(&regs->stat);

	bec->txerr = (status & GRCAN_STAT_TXERRCNT) >> GRCAN_STAT_TXERRCNT_BIT;
	bec->rxerr = (status & GRCAN_STAT_RXERRCNT) >> GRCAN_STAT_RXERRCNT_BIT;
	return 0;
}

static int grcan_poll(struct napi_struct *napi, int budget);

/* Reset device, but keep configuration information */
static void grcan_reset(struct net_device *dev)
{
	struct grcan_priv *priv = netdev_priv(dev);
	struct grcan_registers __iomem *regs = priv->regs;
	u32 config = grcan_read_reg(&regs->conf);

	grcan_set_bits(&regs->ctrl, GRCAN_CTRL_RESET);
	grcan_write_reg(&regs->conf, config);

	priv->eskbp = grcan_read_reg(&regs->txrd);
	priv->can.state = CAN_STATE_STOPPED;

	/* Turn off hardware filtering - regs->rxcode set to 0 by reset */
	grcan_write_reg(&regs->rxmask, 0);
}

/* stop device without changing any configurations */
static void grcan_stop_hardware(struct net_device *dev)
{
	struct grcan_priv *priv = netdev_priv(dev);
	struct grcan_registers __iomem *regs = priv->regs;

	grcan_write_reg(&regs->imr, GRCAN_IRQ_NONE);
	grcan_clear_bits(&regs->txctrl, GRCAN_TXCTRL_ENABLE);
	grcan_clear_bits(&regs->rxctrl, GRCAN_RXCTRL_ENABLE);
	grcan_clear_bits(&regs->ctrl, GRCAN_CTRL_ENABLE);
}

/* Let priv->eskbp catch up to regs->txrd and echo back the skbs if echo
 * is true and free them otherwise.
 *
 * If budget is >= 0, stop after handling at most budget skbs. Otherwise,
 * continue until priv->eskbp catches up to regs->txrd.
 *
 * priv->lock *must* be held when calling this function
 */
static int catch_up_echo_skb(struct net_device *dev, int budget, bool echo)
{
	struct grcan_priv *priv = netdev_priv(dev);
	struct grcan_registers __iomem *regs = priv->regs;
	struct grcan_dma *dma = &priv->dma;
	struct net_device_stats *stats = &dev->stats;
	int i, work_done;

	/* Updates to priv->eskbp and wake-ups of the queue needs to
	 * be atomic towards the reads of priv->eskbp and shut-downs
	 * of the queue in grcan_start_xmit.
	 */
	u32 txrd = grcan_read_reg(&regs->txrd);

	for (work_done = 0; work_done < budget || budget < 0; work_done++) {
		if (priv->eskbp == txrd)
			break;
		i = priv->eskbp / GRCAN_MSG_SIZE;
		if (echo) {
			/* Normal echo of messages */
			stats->tx_packets++;
			stats->tx_bytes += priv->txdlc[i];
			priv->txdlc[i] = 0;
			can_get_echo_skb(dev, i);
		} else {
			/* For cleanup of untransmitted messages */
			can_free_echo_skb(dev, i);
		}

		priv->eskbp = grcan_ring_add(priv->eskbp, GRCAN_MSG_SIZE,
					     dma->tx.size);
		txrd = grcan_read_reg(&regs->txrd);
	}
	return work_done;
}

static void grcan_lost_one_shot_frame(struct net_device *dev)
{
	struct grcan_priv *priv = netdev_priv(dev);
	struct grcan_registers __iomem *regs = priv->regs;
	struct grcan_dma *dma = &priv->dma;
	u32 txrd;
	unsigned long flags;

	spin_lock_irqsave(&priv->lock, flags);

	catch_up_echo_skb(dev, -1, true);

	if (unlikely(grcan_read_bits(&regs->txctrl, GRCAN_TXCTRL_ENABLE))) {
		/* Should never happen */
		netdev_err(dev, "TXCTRL enabled at TXLOSS in one shot mode\n");
	} else {
		/* By the time an GRCAN_IRQ_TXLOSS is generated in
		 * one-shot mode there is no problem in writing
		 * to TXRD even in versions of the hardware in
		 * which GRCAN_TXCTRL_ONGOING is not cleared properly
		 * in one-shot mode.
		 */

		/* Skip message and discard echo-skb */
		txrd = grcan_read_reg(&regs->txrd);
		txrd = grcan_ring_add(txrd, GRCAN_MSG_SIZE, dma->tx.size);
		grcan_write_reg(&regs->txrd, txrd);
		catch_up_echo_skb(dev, -1, false);

		if (!priv->resetting && !priv->closing &&
		    !(priv->can.ctrlmode & CAN_CTRLMODE_LISTENONLY)) {
			netif_wake_queue(dev);
			grcan_set_bits(&regs->txctrl, GRCAN_TXCTRL_ENABLE);
		}
	}

	spin_unlock_irqrestore(&priv->lock, flags);
}

static void grcan_err(struct net_device *dev, u32 sources, u32 status)
{
	struct grcan_priv *priv = netdev_priv(dev);
	struct grcan_registers __iomem *regs = priv->regs;
	struct grcan_dma *dma = &priv->dma;
	struct net_device_stats *stats = &dev->stats;
	struct can_frame cf;

	/* Zero potential error_frame */
	memset(&cf, 0, sizeof(cf));

	/* Message lost interrupt. This might be due to arbitration error, but
	 * is also triggered when there is no one else on the can bus or when
	 * there is a problem with the hardware interface or the bus itself. As
	 * arbitration errors can not be singled out, no error frames are
	 * generated reporting this event as an arbitration error.
	 */
	if (sources & GRCAN_IRQ_TXLOSS) {
		/* Take care of failed one-shot transmit */
		if (priv->can.ctrlmode & CAN_CTRLMODE_ONE_SHOT)
			grcan_lost_one_shot_frame(dev);

		/* Stop printing as soon as error passive or bus off is in
		 * effect to limit the amount of txloss debug printouts.
		 */
		if (!(status & GRCAN_STAT_ERRCTR_RELATED)) {
			netdev_dbg(dev, "tx message lost\n");
			stats->tx_errors++;
		}
	}

	/* Conditions dealing with the error counters. There is no interrupt for
	 * error warning, but there are interrupts for increases of the error
	 * counters.
	 */
	if ((sources & GRCAN_IRQ_ERRCTR_RELATED) ||
	    (status & GRCAN_STAT_ERRCTR_RELATED)) {
		enum can_state state = priv->can.state;
		enum can_state oldstate = state;
		u32 txerr = (status & GRCAN_STAT_TXERRCNT)
			>> GRCAN_STAT_TXERRCNT_BIT;
		u32 rxerr = (status & GRCAN_STAT_RXERRCNT)
			>> GRCAN_STAT_RXERRCNT_BIT;

		/* Figure out current state */
		if (status & GRCAN_STAT_OFF) {
			state = CAN_STATE_BUS_OFF;
		} else if (status & GRCAN_STAT_PASS) {
			state = CAN_STATE_ERROR_PASSIVE;
		} else if (txerr >= GRCAN_STAT_ERRCNT_WARNING_LIMIT ||
			   rxerr >= GRCAN_STAT_ERRCNT_WARNING_LIMIT) {
			state = CAN_STATE_ERROR_WARNING;
		} else {
			state = CAN_STATE_ERROR_ACTIVE;
		}

		/* Handle and report state changes */
		if (state != oldstate) {
			switch (state) {
			case CAN_STATE_BUS_OFF:
				netdev_dbg(dev, "bus-off\n");
				netif_carrier_off(dev);
				priv->can.can_stats.bus_off++;

				/* Prevent the hardware from recovering from bus
				 * off on its own if restart is disabled.
				 */
				if (!priv->can.restart_ms)
					grcan_stop_hardware(dev);

				cf.can_id |= CAN_ERR_BUSOFF;
				break;

			case CAN_STATE_ERROR_PASSIVE:
				netdev_dbg(dev, "Error passive condition\n");
				priv->can.can_stats.error_passive++;

				cf.can_id |= CAN_ERR_CRTL;
				if (txerr >= GRCAN_STAT_ERRCNT_PASSIVE_LIMIT)
					cf.data[1] |= CAN_ERR_CRTL_TX_PASSIVE;
				if (rxerr >= GRCAN_STAT_ERRCNT_PASSIVE_LIMIT)
					cf.data[1] |= CAN_ERR_CRTL_RX_PASSIVE;
				break;

			case CAN_STATE_ERROR_WARNING:
				netdev_dbg(dev, "Error warning condition\n");
				priv->can.can_stats.error_warning++;

				cf.can_id |= CAN_ERR_CRTL;
				if (txerr >= GRCAN_STAT_ERRCNT_WARNING_LIMIT)
					cf.data[1] |= CAN_ERR_CRTL_TX_WARNING;
				if (rxerr >= GRCAN_STAT_ERRCNT_WARNING_LIMIT)
					cf.data[1] |= CAN_ERR_CRTL_RX_WARNING;
				break;

			case CAN_STATE_ERROR_ACTIVE:
				netdev_dbg(dev, "Error active condition\n");
				cf.can_id |= CAN_ERR_CRTL;
				break;

			default:
				/* There are no others at this point */
				break;
			}
			cf.data[6] = txerr;
			cf.data[7] = rxerr;
			priv->can.state = state;
		}

		/* Report automatic restarts */
		if (priv->can.restart_ms && oldstate == CAN_STATE_BUS_OFF) {
			unsigned long flags;

			cf.can_id |= CAN_ERR_RESTARTED;
			netdev_dbg(dev, "restarted\n");
			priv->can.can_stats.restarts++;
			netif_carrier_on(dev);

			spin_lock_irqsave(&priv->lock, flags);

			if (!priv->resetting && !priv->closing) {
				u32 txwr = grcan_read_reg(&regs->txwr);

				if (grcan_txspace(dma->tx.size, txwr,
						  priv->eskbp))
					netif_wake_queue(dev);
			}

			spin_unlock_irqrestore(&priv->lock, flags);
		}
	}

	/* Data overrun interrupt */
	if ((sources & GRCAN_IRQ_OR) || (status & GRCAN_STAT_OR)) {
		netdev_dbg(dev, "got data overrun interrupt\n");
		stats->rx_over_errors++;
		stats->rx_errors++;

		cf.can_id |= CAN_ERR_CRTL;
		cf.data[1] |= CAN_ERR_CRTL_RX_OVERFLOW;
	}

	/* AHB bus error interrupts (not CAN bus errors) - shut down the
	 * device.
	 */
	if (sources & (GRCAN_IRQ_TXAHBERR | GRCAN_IRQ_RXAHBERR) ||
	    (status & GRCAN_STAT_AHBERR)) {
		char *txrx = "";
		unsigned long flags;

		if (sources & GRCAN_IRQ_TXAHBERR) {
			txrx = "on tx ";
			stats->tx_errors++;
		} else if (sources & GRCAN_IRQ_RXAHBERR) {
			txrx = "on rx ";
			stats->rx_errors++;
		}
		netdev_err(dev, "Fatal AHB buss error %s- halting device\n",
			   txrx);

		spin_lock_irqsave(&priv->lock, flags);

		/* Prevent anything to be enabled again and halt device */
		priv->closing = true;
		netif_stop_queue(dev);
		grcan_stop_hardware(dev);
		priv->can.state = CAN_STATE_STOPPED;

		spin_unlock_irqrestore(&priv->lock, flags);
	}

	/* Pass on error frame if something to report,
	 * i.e. id contains some information
	 */
	if (cf.can_id) {
		struct can_frame *skb_cf;
		struct sk_buff *skb = alloc_can_err_skb(dev, &skb_cf);

		if (skb == NULL) {
			netdev_dbg(dev, "could not allocate error frame\n");
			return;
		}
		skb_cf->can_id |= cf.can_id;
		memcpy(skb_cf->data, cf.data, sizeof(cf.data));

		netif_rx(skb);
	}
}

static irqreturn_t grcan_interrupt(int irq, void *dev_id)
{
	struct net_device *dev = dev_id;
	struct grcan_priv *priv = netdev_priv(dev);
	struct grcan_registers __iomem *regs = priv->regs;
	u32 sources, status;

	/* Find out the source */
	sources = grcan_read_reg(&regs->pimsr);
	if (!sources)
		return IRQ_NONE;
	grcan_write_reg(&regs->picr, sources);
	status = grcan_read_reg(&regs->stat);

	/* If we got TX progress, the device has not hanged,
	 * so disable the hang timer
	 */
	if (priv->need_txbug_workaround &&
	    (sources & (GRCAN_IRQ_TX | GRCAN_IRQ_TXLOSS))) {
		del_timer(&priv->hang_timer);
	}

	/* Frame(s) received or transmitted */
	if (sources & (GRCAN_IRQ_TX | GRCAN_IRQ_RX)) {
		/* Disable tx/rx interrupts and schedule poll(). No need for
		 * locking as interference from a running reset at worst leads
		 * to an extra interrupt.
		 */
		grcan_clear_bits(&regs->imr, GRCAN_IRQ_TX | GRCAN_IRQ_RX);
		napi_schedule(&priv->napi);
	}

	/* (Potential) error conditions to take care of */
	if (sources & GRCAN_IRQ_ERRORS)
		grcan_err(dev, sources, status);

	return IRQ_HANDLED;
}

/* Reset device and restart operations from where they were.
 *
 * This assumes that RXCTRL & RXCTRL is properly disabled and that RX
 * is not ONGOING (TX might be stuck in ONGOING due to a harwrware bug
 * for single shot)
 */
static void grcan_running_reset(struct timer_list *t)
{
	struct grcan_priv *priv = from_timer(priv, t, rr_timer);
	struct net_device *dev = priv->dev;
	struct grcan_registers __iomem *regs = priv->regs;
	unsigned long flags;

	/* This temporarily messes with eskbp, so we need to lock
	 * priv->lock
	 */
	spin_lock_irqsave(&priv->lock, flags);

	priv->resetting = false;
	del_timer(&priv->hang_timer);
	del_timer(&priv->rr_timer);

	if (!priv->closing) {
		/* Save and reset - config register preserved by grcan_reset */
		u32 imr = grcan_read_reg(&regs->imr);

		u32 txaddr = grcan_read_reg(&regs->txaddr);
		u32 txsize = grcan_read_reg(&regs->txsize);
		u32 txwr = grcan_read_reg(&regs->txwr);
		u32 txrd = grcan_read_reg(&regs->txrd);
		u32 eskbp = priv->eskbp;

		u32 rxaddr = grcan_read_reg(&regs->rxaddr);
		u32 rxsize = grcan_read_reg(&regs->rxsize);
		u32 rxwr = grcan_read_reg(&regs->rxwr);
		u32 rxrd = grcan_read_reg(&regs->rxrd);

		grcan_reset(dev);

		/* Restore */
		grcan_write_reg(&regs->txaddr, txaddr);
		grcan_write_reg(&regs->txsize, txsize);
		grcan_write_reg(&regs->txwr, txwr);
		grcan_write_reg(&regs->txrd, txrd);
		priv->eskbp = eskbp;

		grcan_write_reg(&regs->rxaddr, rxaddr);
		grcan_write_reg(&regs->rxsize, rxsize);
		grcan_write_reg(&regs->rxwr, rxwr);
		grcan_write_reg(&regs->rxrd, rxrd);

		/* Turn on device again */
		grcan_write_reg(&regs->imr, imr);
		priv->can.state = CAN_STATE_ERROR_ACTIVE;
		grcan_write_reg(&regs->txctrl, GRCAN_TXCTRL_ENABLE
				| (priv->can.ctrlmode & CAN_CTRLMODE_ONE_SHOT
				   ? GRCAN_TXCTRL_SINGLE : 0));
		grcan_write_reg(&regs->rxctrl, GRCAN_RXCTRL_ENABLE);
		grcan_write_reg(&regs->ctrl, GRCAN_CTRL_ENABLE);

		/* Start queue if there is size and listen-onle mode is not
		 * enabled
		 */
		if (grcan_txspace(priv->dma.tx.size, txwr, priv->eskbp) &&
		    !(priv->can.ctrlmode & CAN_CTRLMODE_LISTENONLY))
			netif_wake_queue(dev);
	}

	spin_unlock_irqrestore(&priv->lock, flags);

	netdev_err(dev, "Device reset and restored\n");
}

/* Waiting time in usecs corresponding to the transmission of three maximum
 * sized can frames in the given bitrate (in bits/sec). Waiting for this amount
 * of time makes sure that the can controller have time to finish sending or
 * receiving a frame with a good margin.
 *
 * usecs/sec * number of frames * bits/frame / bits/sec
 */
static inline u32 grcan_ongoing_wait_usecs(__u32 bitrate)
{
	return 1000000 * 3 * GRCAN_EFF_FRAME_MAX_BITS / bitrate;
}

/* Set timer so that it will not fire until after a period in which the can
 * controller have a good margin to finish transmitting a frame unless it has
 * hanged
 */
static inline void grcan_reset_timer(struct timer_list *timer, __u32 bitrate)
{
	u32 wait_jiffies = usecs_to_jiffies(grcan_ongoing_wait_usecs(bitrate));

	mod_timer(timer, jiffies + wait_jiffies);
}

/* Disable channels and schedule a running reset */
static void grcan_initiate_running_reset(struct timer_list *t)
{
	struct grcan_priv *priv = from_timer(priv, t, hang_timer);
	struct net_device *dev = priv->dev;
	struct grcan_registers __iomem *regs = priv->regs;
	unsigned long flags;

	netdev_err(dev, "Device seems hanged - reset scheduled\n");

	spin_lock_irqsave(&priv->lock, flags);

	/* The main body of this function must never be executed again
	 * until after an execution of grcan_running_reset
	 */
	if (!priv->resetting && !priv->closing) {
		priv->resetting = true;
		netif_stop_queue(dev);
		grcan_clear_bits(&regs->txctrl, GRCAN_TXCTRL_ENABLE);
		grcan_clear_bits(&regs->rxctrl, GRCAN_RXCTRL_ENABLE);
		grcan_reset_timer(&priv->rr_timer, priv->can.bittiming.bitrate);
	}

	spin_unlock_irqrestore(&priv->lock, flags);
}

static void grcan_free_dma_buffers(struct net_device *dev)
{
	struct grcan_priv *priv = netdev_priv(dev);
	struct grcan_dma *dma = &priv->dma;

	dma_free_coherent(&dev->dev, dma->base_size, dma->base_buf,
			  dma->base_handle);
	memset(dma, 0, sizeof(*dma));
}

static int grcan_allocate_dma_buffers(struct net_device *dev,
				      size_t tsize, size_t rsize)
{
	struct grcan_priv *priv = netdev_priv(dev);
	struct grcan_dma *dma = &priv->dma;
	struct grcan_dma_buffer *large = rsize > tsize ? &dma->rx : &dma->tx;
	struct grcan_dma_buffer *small = rsize > tsize ? &dma->tx : &dma->rx;
	size_t shift;

	/* Need a whole number of GRCAN_BUFFER_ALIGNMENT for the large,
	 * i.e. first buffer
	 */
	size_t maxs = max(tsize, rsize);
	size_t lsize = ALIGN(maxs, GRCAN_BUFFER_ALIGNMENT);

	/* Put the small buffer after that */
	size_t ssize = min(tsize, rsize);

	/* Extra GRCAN_BUFFER_ALIGNMENT to allow for alignment */
	dma->base_size = lsize + ssize + GRCAN_BUFFER_ALIGNMENT;
	dma->base_buf = dma_alloc_coherent(&dev->dev,
					   dma->base_size,
					   &dma->base_handle,
					   GFP_KERNEL);

	if (!dma->base_buf)
		return -ENOMEM;

	dma->tx.size = tsize;
	dma->rx.size = rsize;

	large->handle = ALIGN(dma->base_handle, GRCAN_BUFFER_ALIGNMENT);
	small->handle = large->handle + lsize;
	shift = large->handle - dma->base_handle;

	large->buf = dma->base_buf + shift;
	small->buf = large->buf + lsize;

	return 0;
}

/* priv->lock *must* be held when calling this function */
static int grcan_start(struct net_device *dev)
{
	struct grcan_priv *priv = netdev_priv(dev);
	struct grcan_registers __iomem *regs = priv->regs;
	u32 confop, txctrl;

	grcan_reset(dev);

	grcan_write_reg(&regs->txaddr, priv->dma.tx.handle);
	grcan_write_reg(&regs->txsize, priv->dma.tx.size);
	/* regs->txwr, regs->txrd and priv->eskbp already set to 0 by reset */

	grcan_write_reg(&regs->rxaddr, priv->dma.rx.handle);
	grcan_write_reg(&regs->rxsize, priv->dma.rx.size);
	/* regs->rxwr and regs->rxrd already set to 0 by reset */

	/* Enable interrupts */
	grcan_read_reg(&regs->pir);
	grcan_write_reg(&regs->imr, GRCAN_IRQ_DEFAULT);

	/* Enable interfaces, channels and device */
	confop = GRCAN_CONF_ABORT
		| (priv->config.enable0 ? GRCAN_CONF_ENABLE0 : 0)
		| (priv->config.enable1 ? GRCAN_CONF_ENABLE1 : 0)
		| (priv->config.select ? GRCAN_CONF_SELECT : 0)
		| (priv->can.ctrlmode & CAN_CTRLMODE_LISTENONLY ?
		   GRCAN_CONF_SILENT : 0)
		| (priv->can.ctrlmode & CAN_CTRLMODE_3_SAMPLES ?
		   GRCAN_CONF_SAM : 0);
	grcan_write_bits(&regs->conf, confop, GRCAN_CONF_OPERATION);
	txctrl = GRCAN_TXCTRL_ENABLE
		| (priv->can.ctrlmode & CAN_CTRLMODE_ONE_SHOT
		   ? GRCAN_TXCTRL_SINGLE : 0);
	grcan_write_reg(&regs->txctrl, txctrl);
	grcan_write_reg(&regs->rxctrl, GRCAN_RXCTRL_ENABLE);
	grcan_write_reg(&regs->ctrl, GRCAN_CTRL_ENABLE);

	priv->can.state = CAN_STATE_ERROR_ACTIVE;

	return 0;
}

static int grcan_set_mode(struct net_device *dev, enum can_mode mode)
{
	struct grcan_priv *priv = netdev_priv(dev);
	unsigned long flags;
	int err = 0;

	if (mode == CAN_MODE_START) {
		/* This might be called to restart the device to recover from
		 * bus off errors
		 */
		spin_lock_irqsave(&priv->lock, flags);
		if (priv->closing || priv->resetting) {
			err = -EBUSY;
		} else {
			netdev_info(dev, "Restarting device\n");
			grcan_start(dev);
			if (!(priv->can.ctrlmode & CAN_CTRLMODE_LISTENONLY))
				netif_wake_queue(dev);
		}
		spin_unlock_irqrestore(&priv->lock, flags);
		return err;
	}
	return -EOPNOTSUPP;
}

static int grcan_open(struct net_device *dev)
{
	struct grcan_priv *priv = netdev_priv(dev);
	struct grcan_dma *dma = &priv->dma;
	unsigned long flags;
	int err;

	/* Allocate memory */
	err = grcan_allocate_dma_buffers(dev, priv->config.txsize,
					 priv->config.rxsize);
	if (err) {
		netdev_err(dev, "could not allocate DMA buffers\n");
		return err;
	}

	priv->echo_skb = kzalloc(dma->tx.size * sizeof(*priv->echo_skb),
				 GFP_KERNEL);
	if (!priv->echo_skb) {
		err = -ENOMEM;
		goto exit_free_dma_buffers;
	}
	priv->can.echo_skb_max = dma->tx.size;
	priv->can.echo_skb = priv->echo_skb;

	priv->txdlc = kzalloc(dma->tx.size * sizeof(*priv->txdlc), GFP_KERNEL);
	if (!priv->txdlc) {
		err = -ENOMEM;
		goto exit_free_echo_skb;
	}

	/* Get can device up */
	err = open_candev(dev);
	if (err)
		goto exit_free_txdlc;

	err = request_irq(dev->irq, grcan_interrupt, IRQF_SHARED,
			  dev->name, dev);
	if (err)
		goto exit_close_candev;

	spin_lock_irqsave(&priv->lock, flags);

	napi_enable(&priv->napi);
	grcan_start(dev);
	if (!(priv->can.ctrlmode & CAN_CTRLMODE_LISTENONLY))
		netif_start_queue(dev);
	priv->resetting = false;
	priv->closing = false;

	spin_unlock_irqrestore(&priv->lock, flags);

	return 0;

exit_close_candev:
	close_candev(dev);
exit_free_txdlc:
	kfree(priv->txdlc);
exit_free_echo_skb:
	kfree(priv->echo_skb);
exit_free_dma_buffers:
	grcan_free_dma_buffers(dev);
	return err;
}

static int grcan_close(struct net_device *dev)
{
	struct grcan_priv *priv = netdev_priv(dev);
	unsigned long flags;

	napi_disable(&priv->napi);

	spin_lock_irqsave(&priv->lock, flags);

	priv->closing = true;
	if (priv->need_txbug_workaround) {
		del_timer_sync(&priv->hang_timer);
		del_timer_sync(&priv->rr_timer);
	}
	netif_stop_queue(dev);
	grcan_stop_hardware(dev);
	priv->can.state = CAN_STATE_STOPPED;

	spin_unlock_irqrestore(&priv->lock, flags);

	free_irq(dev->irq, dev);
	close_candev(dev);

	grcan_free_dma_buffers(dev);
	priv->can.echo_skb_max = 0;
	priv->can.echo_skb = NULL;
	kfree(priv->echo_skb);
	kfree(priv->txdlc);

	return 0;
}

static int grcan_transmit_catch_up(struct net_device *dev, int budget)
{
	struct grcan_priv *priv = netdev_priv(dev);
	unsigned long flags;
	int work_done;

	spin_lock_irqsave(&priv->lock, flags);

	work_done = catch_up_echo_skb(dev, budget, true);
	if (work_done) {
		if (!priv->resetting && !priv->closing &&
		    !(priv->can.ctrlmode & CAN_CTRLMODE_LISTENONLY))
			netif_wake_queue(dev);

		/* With napi we don't get TX interrupts for a while,
		 * so prevent a running reset while catching up
		 */
		if (priv->need_txbug_workaround)
			del_timer(&priv->hang_timer);
	}

	spin_unlock_irqrestore(&priv->lock, flags);

	return work_done;
}

static int grcan_receive(struct net_device *dev, int budget)
{
	struct grcan_priv *priv = netdev_priv(dev);
	struct grcan_registers __iomem *regs = priv->regs;
	struct grcan_dma *dma = &priv->dma;
	struct net_device_stats *stats = &dev->stats;
	struct can_frame *cf;
	struct sk_buff *skb;
	u32 wr, rd, startrd;
	u32 *slot;
	u32 i, rtr, eff, j, shift;
	int work_done = 0;

	rd = grcan_read_reg(&regs->rxrd);
	startrd = rd;
	for (work_done = 0; work_done < budget; work_done++) {
		/* Check for packet to receive */
		wr = grcan_read_reg(&regs->rxwr);
		if (rd == wr)
			break;

		/* Take care of packet */
		skb = alloc_can_skb(dev, &cf);
		if (skb == NULL) {
			netdev_err(dev,
				   "dropping frame: skb allocation failed\n");
			stats->rx_dropped++;
			continue;
		}

		slot = dma->rx.buf + rd;
		eff = slot[0] & GRCAN_MSG_IDE;
		rtr = slot[0] & GRCAN_MSG_RTR;
		if (eff) {
			cf->can_id = ((slot[0] & GRCAN_MSG_EID)
				      >> GRCAN_MSG_EID_BIT);
			cf->can_id |= CAN_EFF_FLAG;
		} else {
			cf->can_id = ((slot[0] & GRCAN_MSG_BID)
				      >> GRCAN_MSG_BID_BIT);
		}
		cf->can_dlc = get_can_dlc((slot[1] & GRCAN_MSG_DLC)
					  >> GRCAN_MSG_DLC_BIT);
		if (rtr) {
			cf->can_id |= CAN_RTR_FLAG;
		} else {
			for (i = 0; i < cf->can_dlc; i++) {
				j = GRCAN_MSG_DATA_SLOT_INDEX(i);
				shift = GRCAN_MSG_DATA_SHIFT(i);
				cf->data[i] = (u8)(slot[j] >> shift);
			}
		}

		/* Update statistics and read pointer */
		stats->rx_packets++;
		stats->rx_bytes += cf->can_dlc;
		netif_receive_skb(skb);

		rd = grcan_ring_add(rd, GRCAN_MSG_SIZE, dma->rx.size);
	}

	/* Make sure everything is read before allowing hardware to
	 * use the memory
	 */
	mb();

	/* Update read pointer - no need to check for ongoing */
	if (likely(rd != startrd))
		grcan_write_reg(&regs->rxrd, rd);

	return work_done;
}

static int grcan_poll(struct napi_struct *napi, int budget)
{
	struct grcan_priv *priv = container_of(napi, struct grcan_priv, napi);
	struct net_device *dev = priv->dev;
	struct grcan_registers __iomem *regs = priv->regs;
	unsigned long flags;
	int tx_work_done, rx_work_done;
	int rx_budget = budget / 2;
	int tx_budget = budget - rx_budget;

	/* Half of the budget for receiveing messages */
	rx_work_done = grcan_receive(dev, rx_budget);

	/* Half of the budget for transmitting messages as that can trigger echo
	 * frames being received
	 */
	tx_work_done = grcan_transmit_catch_up(dev, tx_budget);

	if (rx_work_done < rx_budget && tx_work_done < tx_budget) {
		napi_complete(napi);

		/* Guarantee no interference with a running reset that otherwise
		 * could turn off interrupts.
		 */
		spin_lock_irqsave(&priv->lock, flags);

		/* Enable tx and rx interrupts again. No need to check
		 * priv->closing as napi_disable in grcan_close is waiting for
		 * scheduled napi calls to finish.
		 */
		grcan_set_bits(&regs->imr, GRCAN_IRQ_TX | GRCAN_IRQ_RX);

		spin_unlock_irqrestore(&priv->lock, flags);
	}

	return rx_work_done + tx_work_done;
}

/* Work tx bug by waiting while for the risky situation to clear. If that fails,
 * drop a frame in one-shot mode or indicate a busy device otherwise.
 *
 * Returns 0 on successful wait. Otherwise it sets *netdev_tx_status to the
 * value that should be returned by grcan_start_xmit when aborting the xmit.
 */
static int grcan_txbug_workaround(struct net_device *dev, struct sk_buff *skb,
				  u32 txwr, u32 oneshotmode,
				  netdev_tx_t *netdev_tx_status)
{
	struct grcan_priv *priv = netdev_priv(dev);
	struct grcan_registers __iomem *regs = priv->regs;
	struct grcan_dma *dma = &priv->dma;
	int i;
	unsigned long flags;

	/* Wait a while for ongoing to be cleared or read pointer to catch up to
	 * write pointer. The latter is needed due to a bug in older versions of
	 * GRCAN in which ONGOING is not cleared properly one-shot mode when a
	 * transmission fails.
	 */
	for (i = 0; i < GRCAN_SHORTWAIT_USECS; i++) {
		udelay(1);
		if (!grcan_read_bits(&regs->txctrl, GRCAN_TXCTRL_ONGOING) ||
		    grcan_read_reg(&regs->txrd) == txwr) {
			return 0;
		}
	}

	/* Clean up, in case the situation was not resolved */
	spin_lock_irqsave(&priv->lock, flags);
	if (!priv->resetting && !priv->closing) {
		/* Queue might have been stopped earlier in grcan_start_xmit */
		if (grcan_txspace(dma->tx.size, txwr, priv->eskbp))
			netif_wake_queue(dev);
		/* Set a timer to resolve a hanged tx controller */
		if (!timer_pending(&priv->hang_timer))
			grcan_reset_timer(&priv->hang_timer,
					  priv->can.bittiming.bitrate);
	}
	spin_unlock_irqrestore(&priv->lock, flags);

	if (oneshotmode) {
		/* In one-shot mode we should never end up here because
		 * then the interrupt handler increases txrd on TXLOSS,
		 * but it is consistent with one-shot mode to drop the
		 * frame in this case.
		 */
		kfree_skb(skb);
		*netdev_tx_status = NETDEV_TX_OK;
	} else {
		/* In normal mode the socket-can transmission queue get
		 * to keep the frame so that it can be retransmitted
		 * later
		 */
		*netdev_tx_status = NETDEV_TX_BUSY;
	}
	return -EBUSY;
}

/* Notes on the tx cyclic buffer handling:
 *
 * regs->txwr	- the next slot for the driver to put data to be sent
 * regs->txrd	- the next slot for the device to read data
 * priv->eskbp	- the next slot for the driver to call can_put_echo_skb for
 *
 * grcan_start_xmit can enter more messages as long as regs->txwr does
 * not reach priv->eskbp (within 1 message gap)
 *
 * The device sends messages until regs->txrd reaches regs->txwr
 *
 * The interrupt calls handler calls can_put_echo_skb until
 * priv->eskbp reaches regs->txrd
 */
static netdev_tx_t grcan_start_xmit(struct sk_buff *skb,
				    struct net_device *dev)
{
	struct grcan_priv *priv = netdev_priv(dev);
	struct grcan_registers __iomem *regs = priv->regs;
	struct grcan_dma *dma = &priv->dma;
	struct can_frame *cf = (struct can_frame *)skb->data;
	u32 id, txwr, txrd, space, txctrl;
	int slotindex;
	u32 *slot;
	u32 i, rtr, eff, dlc, tmp, err;
	int j, shift;
	unsigned long flags;
	u32 oneshotmode = priv->can.ctrlmode & CAN_CTRLMODE_ONE_SHOT;

	if (can_dropped_invalid_skb(dev, skb))
		return NETDEV_TX_OK;

	/* Trying to transmit in silent mode will generate error interrupts, but
	 * this should never happen - the queue should not have been started.
	 */
	if (priv->can.ctrlmode & CAN_CTRLMODE_LISTENONLY)
		return NETDEV_TX_BUSY;

	/* Reads of priv->eskbp and shut-downs of the queue needs to
	 * be atomic towards the updates to priv->eskbp and wake-ups
	 * of the queue in the interrupt handler.
	 */
	spin_lock_irqsave(&priv->lock, flags);

	txwr = grcan_read_reg(&regs->txwr);
	space = grcan_txspace(dma->tx.size, txwr, priv->eskbp);

	slotindex = txwr / GRCAN_MSG_SIZE;
	slot = dma->tx.buf + txwr;

	if (unlikely(space == 1))
		netif_stop_queue(dev);

	spin_unlock_irqrestore(&priv->lock, flags);
	/* End of critical section*/

	/* This should never happen. If circular buffer is full, the
	 * netif_stop_queue should have been stopped already.
	 */
	if (unlikely(!space)) {
		netdev_err(dev, "No buffer space, but queue is non-stopped.\n");
		return NETDEV_TX_BUSY;
	}

	/* Convert and write CAN message to DMA buffer */
	eff = cf->can_id & CAN_EFF_FLAG;
	rtr = cf->can_id & CAN_RTR_FLAG;
	id = cf->can_id & (eff ? CAN_EFF_MASK : CAN_SFF_MASK);
	dlc = cf->can_dlc;
	if (eff)
		tmp = (id << GRCAN_MSG_EID_BIT) & GRCAN_MSG_EID;
	else
		tmp = (id << GRCAN_MSG_BID_BIT) & GRCAN_MSG_BID;
	slot[0] = (eff ? GRCAN_MSG_IDE : 0) | (rtr ? GRCAN_MSG_RTR : 0) | tmp;

	slot[1] = ((dlc << GRCAN_MSG_DLC_BIT) & GRCAN_MSG_DLC);
	slot[2] = 0;
	slot[3] = 0;
	for (i = 0; i < dlc; i++) {
		j = GRCAN_MSG_DATA_SLOT_INDEX(i);
		shift = GRCAN_MSG_DATA_SHIFT(i);
		slot[j] |= cf->data[i] << shift;
	}

	/* Checking that channel has not been disabled. These cases
	 * should never happen
	 */
	txctrl = grcan_read_reg(&regs->txctrl);
	if (!(txctrl & GRCAN_TXCTRL_ENABLE))
		netdev_err(dev, "tx channel spuriously disabled\n");

	if (oneshotmode && !(txctrl & GRCAN_TXCTRL_SINGLE))
		netdev_err(dev, "one-shot mode spuriously disabled\n");

	/* Bug workaround for old version of grcan where updating txwr
	 * in the same clock cycle as the controller updates txrd to
	 * the current txwr could hang the can controller
	 */
	if (priv->need_txbug_workaround) {
		txrd = grcan_read_reg(&regs->txrd);
		if (unlikely(grcan_ring_sub(txwr, txrd, dma->tx.size) == 1)) {
			netdev_tx_t txstatus;

			err = grcan_txbug_workaround(dev, skb, txwr,
						     oneshotmode, &txstatus);
			if (err)
				return txstatus;
		}
	}

	/* Prepare skb for echoing. This must be after the bug workaround above
	 * as ownership of the skb is passed on by calling can_put_echo_skb.
	 * Returning NETDEV_TX_BUSY or accessing skb or cf after a call to
	 * can_put_echo_skb would be an error unless other measures are
	 * taken.
	 */
	priv->txdlc[slotindex] = cf->can_dlc; /* Store dlc for statistics */
	can_put_echo_skb(skb, dev, slotindex);

	/* Make sure everything is written before allowing hardware to
	 * read from the memory
	 */
	wmb();

	/* Update write pointer to start transmission */
	grcan_write_reg(&regs->txwr,
			grcan_ring_add(txwr, GRCAN_MSG_SIZE, dma->tx.size));

	return NETDEV_TX_OK;
}

/* ========== Setting up sysfs interface and module parameters ========== */

#define GRCAN_NOT_BOOL(unsigned_val) ((unsigned_val) > 1)

#define GRCAN_MODULE_PARAM(name, mtype, valcheckf, desc)		\
	static void grcan_sanitize_##name(struct platform_device *pd)	\
	{								\
		struct grcan_device_config grcan_default_config		\
			= GRCAN_DEFAULT_DEVICE_CONFIG;			\
		if (valcheckf(grcan_module_config.name)) {		\
			dev_err(&pd->dev,				\
				"Invalid module parameter value for "	\
				#name " - setting default\n");		\
			grcan_module_config.name =			\
				grcan_default_config.name;		\
		}							\
	}								\
	module_param_named(name, grcan_module_config.name,		\
			   mtype, S_IRUGO);				\
	MODULE_PARM_DESC(name, desc)

#define GRCAN_CONFIG_ATTR(name, desc)					\
	static ssize_t grcan_store_##name(struct device *sdev,		\
					  struct device_attribute *att,	\
					  const char *buf,		\
					  size_t count)			\
	{								\
		struct net_device *dev = to_net_dev(sdev);		\
		struct grcan_priv *priv = netdev_priv(dev);		\
		u8 val;							\
		int ret;						\
		if (dev->flags & IFF_UP)				\
			return -EBUSY;					\
		ret = kstrtou8(buf, 0, &val);				\
		if (ret < 0 || val > 1)					\
			return -EINVAL;					\
		priv->config.name = val;				\
		return count;						\
	}								\
	static ssize_t grcan_show_##name(struct device *sdev,		\
					 struct device_attribute *att,	\
					 char *buf)			\
	{								\
		struct net_device *dev = to_net_dev(sdev);		\
		struct grcan_priv *priv = netdev_priv(dev);		\
		return sprintf(buf, "%d\n", priv->config.name);		\
	}								\
	static DEVICE_ATTR(name, S_IRUGO | S_IWUSR,			\
			   grcan_show_##name,				\
			   grcan_store_##name);				\
	GRCAN_MODULE_PARAM(name, ushort, GRCAN_NOT_BOOL, desc)

/* The following configuration options are made available both via module
 * parameters and writable sysfs files. See the chapter about GRCAN in the
 * documentation for the GRLIB VHDL library for further details.
 */
GRCAN_CONFIG_ATTR(enable0,
		  "Configuration of physical interface 0. Determines\n"	\
		  "the \"Enable 0\" bit of the configuration register.\n" \
		  "Format: 0 | 1\nDefault: 0\n");

GRCAN_CONFIG_ATTR(enable1,
		  "Configuration of physical interface 1. Determines\n"	\
		  "the \"Enable 1\" bit of the configuration register.\n" \
		  "Format: 0 | 1\nDefault: 0\n");

GRCAN_CONFIG_ATTR(select,
		  "Select which physical interface to use.\n"	\
		  "Format: 0 | 1\nDefault: 0\n");

/* The tx and rx buffer size configuration options are only available via module
 * parameters.
 */
GRCAN_MODULE_PARAM(txsize, uint, GRCAN_INVALID_BUFFER_SIZE,
		   "Sets the size of the tx buffer.\n"			\
		   "Format: <unsigned int> where (txsize & ~0x1fffc0) == 0\n" \
		   "Default: 1024\n");
GRCAN_MODULE_PARAM(rxsize, uint, GRCAN_INVALID_BUFFER_SIZE,
		   "Sets the size of the rx buffer.\n"			\
		   "Format: <unsigned int> where (size & ~0x1fffc0) == 0\n" \
		   "Default: 1024\n");

/* Function that makes sure that configuration done using
 * module parameters are set to valid values
 */
static void grcan_sanitize_module_config(struct platform_device *ofdev)
{
	grcan_sanitize_enable0(ofdev);
	grcan_sanitize_enable1(ofdev);
	grcan_sanitize_select(ofdev);
	grcan_sanitize_txsize(ofdev);
	grcan_sanitize_rxsize(ofdev);
}

static const struct attribute *const sysfs_grcan_attrs[] = {
	/* Config attrs */
	&dev_attr_enable0.attr,
	&dev_attr_enable1.attr,
	&dev_attr_select.attr,
	NULL,
};

static const struct attribute_group sysfs_grcan_group = {
	.name	= "grcan",
	.attrs	= (struct attribute **)sysfs_grcan_attrs,
};

/* ========== Setting up the driver ========== */

static const struct net_device_ops grcan_netdev_ops = {
	.ndo_open	= grcan_open,
	.ndo_stop	= grcan_close,
	.ndo_start_xmit	= grcan_start_xmit,
	.ndo_change_mtu = can_change_mtu,
};

static int grcan_setup_netdev(struct platform_device *ofdev,
			      void __iomem *base,
			      int irq, u32 ambafreq, bool txbug)
{
	struct net_device *dev;
	struct grcan_priv *priv;
	struct grcan_registers __iomem *regs;
	int err;

	dev = alloc_candev(sizeof(struct grcan_priv), 0);
	if (!dev)
		return -ENOMEM;

	dev->irq = irq;
	dev->flags |= IFF_ECHO;
	dev->netdev_ops = &grcan_netdev_ops;
	dev->sysfs_groups[0] = &sysfs_grcan_group;

	priv = netdev_priv(dev);
	memcpy(&priv->config, &grcan_module_config,
	       sizeof(struct grcan_device_config));
	priv->dev = dev;
	priv->regs = base;
	priv->can.bittiming_const = &grcan_bittiming_const;
	priv->can.do_set_bittiming = grcan_set_bittiming;
	priv->can.do_set_mode = grcan_set_mode;
	priv->can.do_get_berr_counter = grcan_get_berr_counter;
	priv->can.clock.freq = ambafreq;
	priv->can.ctrlmode_supported =
		CAN_CTRLMODE_LISTENONLY | CAN_CTRLMODE_ONE_SHOT;
	priv->need_txbug_workaround = txbug;

	/* Discover if triple sampling is supported by hardware */
	regs = priv->regs;
	grcan_set_bits(&regs->ctrl, GRCAN_CTRL_RESET);
	grcan_set_bits(&regs->conf, GRCAN_CONF_SAM);
	if (grcan_read_bits(&regs->conf, GRCAN_CONF_SAM)) {
		priv->can.ctrlmode_supported |= CAN_CTRLMODE_3_SAMPLES;
		dev_dbg(&ofdev->dev, "Hardware supports triple-sampling\n");
	}

	spin_lock_init(&priv->lock);

	if (priv->need_txbug_workaround) {
		timer_setup(&priv->rr_timer, grcan_running_reset, 0);
		timer_setup(&priv->hang_timer, grcan_initiate_running_reset, 0);
	}

	netif_napi_add(dev, &priv->napi, grcan_poll, GRCAN_NAPI_WEIGHT);

	SET_NETDEV_DEV(dev, &ofdev->dev);
	dev_info(&ofdev->dev, "regs=0x%p, irq=%d, clock=%d\n",
		 priv->regs, dev->irq, priv->can.clock.freq);

	err = register_candev(dev);
	if (err)
		goto exit_free_candev;

	platform_set_drvdata(ofdev, dev);

	/* Reset device to allow bit-timing to be set. No need to call
	 * grcan_reset at this stage. That is done in grcan_open.
	 */
	grcan_write_reg(&regs->ctrl, GRCAN_CTRL_RESET);

	return 0;
exit_free_candev:
	free_candev(dev);
	return err;
}

static int grcan_probe(struct platform_device *ofdev)
{
	struct device_node *np = ofdev->dev.of_node;
	struct resource *res;
	u32 sysid, ambafreq;
	int irq, err;
	void __iomem *base;
	bool txbug = true;

	/* Compare GRLIB version number with the first that does not
	 * have the tx bug (see start_xmit)
	 */
	err = of_property_read_u32(np, "systemid", &sysid);
	if (!err && ((sysid & GRLIB_VERSION_MASK)
		     >= GRCAN_TXBUG_SAFE_GRLIB_VERSION))
		txbug = false;

	err = of_property_read_u32(np, "freq", &ambafreq);
	if (err) {
		dev_err(&ofdev->dev, "unable to fetch \"freq\" property\n");
		goto exit_error;
	}

	res = platform_get_resource(ofdev, IORESOURCE_MEM, 0);
	base = devm_ioremap_resource(&ofdev->dev, res);
	if (IS_ERR(base)) {
		err = PTR_ERR(base);
		goto exit_error;
	}

	irq = irq_of_parse_and_map(np, GRCAN_IRQIX_IRQ);
	if (!irq) {
		dev_err(&ofdev->dev, "no irq found\n");
		err = -ENODEV;
		goto exit_error;
	}

	grcan_sanitize_module_config(ofdev);

	err = grcan_setup_netdev(ofdev, base, irq, ambafreq, txbug);
	if (err)
		goto exit_dispose_irq;

	return 0;

exit_dispose_irq:
	irq_dispose_mapping(irq);
exit_error:
	dev_err(&ofdev->dev,
		"%s socket CAN driver initialization failed with error %d\n",
		DRV_NAME, err);
	return err;
}

static int grcan_remove(struct platform_device *ofdev)
{
	struct net_device *dev = platform_get_drvdata(ofdev);
	struct grcan_priv *priv = netdev_priv(dev);

	unregister_candev(dev); /* Will in turn call grcan_close */

	irq_dispose_mapping(dev->irq);
	netif_napi_del(&priv->napi);
	free_candev(dev);

	return 0;
}

static const struct of_device_id grcan_match[] = {
	{.name = "GAISLER_GRCAN"},
	{.name = "01_03d"},
	{.name = "GAISLER_GRHCAN"},
	{.name = "01_034"},
	{},
};

MODULE_DEVICE_TABLE(of, grcan_match);

static struct platform_driver grcan_driver = {
	.driver = {
		.name = DRV_NAME,
		.of_match_table = grcan_match,
	},
	.probe = grcan_probe,
	.remove = grcan_remove,
};

module_platform_driver(grcan_driver);

MODULE_AUTHOR("Aeroflex Gaisler AB.");
MODULE_DESCRIPTION("Socket CAN driver for Aeroflex Gaisler GRCAN");
MODULE_LICENSE("GPL");