summaryrefslogtreecommitdiffstats
path: root/drivers/net/ethernet/micrel/ks8851.c
blob: b44172a901edbeb5e899c8c9642cd1c84fbca1e3 (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
/* drivers/net/ethernet/micrel/ks8851.c
 *
 * Copyright 2009 Simtec Electronics
 *	http://www.simtec.co.uk/
 *	Ben Dooks <ben@simtec.co.uk>
 *
 * 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.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#define DEBUG

#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/ethtool.h>
#include <linux/cache.h>
#include <linux/crc32.h>
#include <linux/mii.h>
#include <linux/eeprom_93cx6.h>
#include <linux/regulator/consumer.h>

#include <linux/spi/spi.h>
#include <linux/gpio.h>
#include <linux/of_gpio.h>
#include <linux/of_net.h>

#include "ks8851.h"

/**
 * struct ks8851_rxctrl - KS8851 driver rx control
 * @mchash: Multicast hash-table data.
 * @rxcr1: KS_RXCR1 register setting
 * @rxcr2: KS_RXCR2 register setting
 *
 * Representation of the settings needs to control the receive filtering
 * such as the multicast hash-filter and the receive register settings. This
 * is used to make the job of working out if the receive settings change and
 * then issuing the new settings to the worker that will send the necessary
 * commands.
 */
struct ks8851_rxctrl {
	u16	mchash[4];
	u16	rxcr1;
	u16	rxcr2;
};

/**
 * union ks8851_tx_hdr - tx header data
 * @txb: The header as bytes
 * @txw: The header as 16bit, little-endian words
 *
 * A dual representation of the tx header data to allow
 * access to individual bytes, and to allow 16bit accesses
 * with 16bit alignment.
 */
union ks8851_tx_hdr {
	u8	txb[6];
	__le16	txw[3];
};

/**
 * struct ks8851_net - KS8851 driver private data
 * @netdev: The network device we're bound to
 * @spidev: The spi device we're bound to.
 * @lock: Lock to ensure that the device is not accessed when busy.
 * @statelock: Lock on this structure for tx list.
 * @mii: The MII state information for the mii calls.
 * @rxctrl: RX settings for @rxctrl_work.
 * @tx_work: Work queue for tx packets
 * @rxctrl_work: Work queue for updating RX mode and multicast lists
 * @txq: Queue of packets for transmission.
 * @spi_msg1: pre-setup SPI transfer with one message, @spi_xfer1.
 * @spi_msg2: pre-setup SPI transfer with two messages, @spi_xfer2.
 * @txh: Space for generating packet TX header in DMA-able data
 * @rxd: Space for receiving SPI data, in DMA-able space.
 * @txd: Space for transmitting SPI data, in DMA-able space.
 * @msg_enable: The message flags controlling driver output (see ethtool).
 * @fid: Incrementing frame id tag.
 * @rc_ier: Cached copy of KS_IER.
 * @rc_ccr: Cached copy of KS_CCR.
 * @rc_rxqcr: Cached copy of KS_RXQCR.
 * @eeprom: 93CX6 EEPROM state for accessing on-board EEPROM.
 * @vdd_reg:	Optional regulator supplying the chip
 * @vdd_io: Optional digital power supply for IO
 * @gpio: Optional reset_n gpio
 *
 * The @lock ensures that the chip is protected when certain operations are
 * in progress. When the read or write packet transfer is in progress, most
 * of the chip registers are not ccessible until the transfer is finished and
 * the DMA has been de-asserted.
 *
 * The @statelock is used to protect information in the structure which may
 * need to be accessed via several sources, such as the network driver layer
 * or one of the work queues.
 *
 * We align the buffers we may use for rx/tx to ensure that if the SPI driver
 * wants to DMA map them, it will not have any problems with data the driver
 * modifies.
 */
struct ks8851_net {
	struct net_device	*netdev;
	struct spi_device	*spidev;
	struct mutex		lock;
	spinlock_t		statelock;

	union ks8851_tx_hdr	txh ____cacheline_aligned;
	u8			rxd[8];
	u8			txd[8];

	u32			msg_enable ____cacheline_aligned;
	u16			tx_space;
	u8			fid;

	u16			rc_ier;
	u16			rc_rxqcr;
	u16			rc_ccr;

	struct mii_if_info	mii;
	struct ks8851_rxctrl	rxctrl;

	struct work_struct	tx_work;
	struct work_struct	rxctrl_work;

	struct sk_buff_head	txq;

	struct spi_message	spi_msg1;
	struct spi_message	spi_msg2;
	struct spi_transfer	spi_xfer1;
	struct spi_transfer	spi_xfer2[2];

	struct eeprom_93cx6	eeprom;
	struct regulator	*vdd_reg;
	struct regulator	*vdd_io;
	int			gpio;
};

static int msg_enable;

/* SPI frame opcodes */
#define KS_SPIOP_RD	(0x00)
#define KS_SPIOP_WR	(0x40)
#define KS_SPIOP_RXFIFO	(0x80)
#define KS_SPIOP_TXFIFO	(0xC0)

/* shift for byte-enable data */
#define BYTE_EN(_x)	((_x) << 2)

/* turn register number and byte-enable mask into data for start of packet */
#define MK_OP(_byteen, _reg) (BYTE_EN(_byteen) | (_reg)  << (8+2) | (_reg) >> 6)

/* SPI register read/write calls.
 *
 * All these calls issue SPI transactions to access the chip's registers. They
 * all require that the necessary lock is held to prevent accesses when the
 * chip is busy transferring packet data (RX/TX FIFO accesses).
 */

/**
 * ks8851_wrreg16 - write 16bit register value to chip
 * @ks: The chip state
 * @reg: The register address
 * @val: The value to write
 *
 * Issue a write to put the value @val into the register specified in @reg.
 */
static void ks8851_wrreg16(struct ks8851_net *ks, unsigned reg, unsigned val)
{
	struct spi_transfer *xfer = &ks->spi_xfer1;
	struct spi_message *msg = &ks->spi_msg1;
	__le16 txb[2];
	int ret;

	txb[0] = cpu_to_le16(MK_OP(reg & 2 ? 0xC : 0x03, reg) | KS_SPIOP_WR);
	txb[1] = cpu_to_le16(val);

	xfer->tx_buf = txb;
	xfer->rx_buf = NULL;
	xfer->len = 4;

	ret = spi_sync(ks->spidev, msg);
	if (ret < 0)
		netdev_err(ks->netdev, "spi_sync() failed\n");
}

/**
 * ks8851_wrreg8 - write 8bit register value to chip
 * @ks: The chip state
 * @reg: The register address
 * @val: The value to write
 *
 * Issue a write to put the value @val into the register specified in @reg.
 */
static void ks8851_wrreg8(struct ks8851_net *ks, unsigned reg, unsigned val)
{
	struct spi_transfer *xfer = &ks->spi_xfer1;
	struct spi_message *msg = &ks->spi_msg1;
	__le16 txb[2];
	int ret;
	int bit;

	bit = 1 << (reg & 3);

	txb[0] = cpu_to_le16(MK_OP(bit, reg) | KS_SPIOP_WR);
	txb[1] = val;

	xfer->tx_buf = txb;
	xfer->rx_buf = NULL;
	xfer->len = 3;

	ret = spi_sync(ks->spidev, msg);
	if (ret < 0)
		netdev_err(ks->netdev, "spi_sync() failed\n");
}

/**
 * ks8851_rdreg - issue read register command and return the data
 * @ks: The device state
 * @op: The register address and byte enables in message format.
 * @rxb: The RX buffer to return the result into
 * @rxl: The length of data expected.
 *
 * This is the low level read call that issues the necessary spi message(s)
 * to read data from the register specified in @op.
 */
static void ks8851_rdreg(struct ks8851_net *ks, unsigned op,
			 u8 *rxb, unsigned rxl)
{
	struct spi_transfer *xfer;
	struct spi_message *msg;
	__le16 *txb = (__le16 *)ks->txd;
	u8 *trx = ks->rxd;
	int ret;

	txb[0] = cpu_to_le16(op | KS_SPIOP_RD);

	if (ks->spidev->master->flags & SPI_MASTER_HALF_DUPLEX) {
		msg = &ks->spi_msg2;
		xfer = ks->spi_xfer2;

		xfer->tx_buf = txb;
		xfer->rx_buf = NULL;
		xfer->len = 2;

		xfer++;
		xfer->tx_buf = NULL;
		xfer->rx_buf = trx;
		xfer->len = rxl;
	} else {
		msg = &ks->spi_msg1;
		xfer = &ks->spi_xfer1;

		xfer->tx_buf = txb;
		xfer->rx_buf = trx;
		xfer->len = rxl + 2;
	}

	ret = spi_sync(ks->spidev, msg);
	if (ret < 0)
		netdev_err(ks->netdev, "read: spi_sync() failed\n");
	else if (ks->spidev->master->flags & SPI_MASTER_HALF_DUPLEX)
		memcpy(rxb, trx, rxl);
	else
		memcpy(rxb, trx + 2, rxl);
}

/**
 * ks8851_rdreg8 - read 8 bit register from device
 * @ks: The chip information
 * @reg: The register address
 *
 * Read a 8bit register from the chip, returning the result
*/
static unsigned ks8851_rdreg8(struct ks8851_net *ks, unsigned reg)
{
	u8 rxb[1];

	ks8851_rdreg(ks, MK_OP(1 << (reg & 3), reg), rxb, 1);
	return rxb[0];
}

/**
 * ks8851_rdreg16 - read 16 bit register from device
 * @ks: The chip information
 * @reg: The register address
 *
 * Read a 16bit register from the chip, returning the result
*/
static unsigned ks8851_rdreg16(struct ks8851_net *ks, unsigned reg)
{
	__le16 rx = 0;

	ks8851_rdreg(ks, MK_OP(reg & 2 ? 0xC : 0x3, reg), (u8 *)&rx, 2);
	return le16_to_cpu(rx);
}

/**
 * ks8851_rdreg32 - read 32 bit register from device
 * @ks: The chip information
 * @reg: The register address
 *
 * Read a 32bit register from the chip.
 *
 * Note, this read requires the address be aligned to 4 bytes.
*/
static unsigned ks8851_rdreg32(struct ks8851_net *ks, unsigned reg)
{
	__le32 rx = 0;

	WARN_ON(reg & 3);

	ks8851_rdreg(ks, MK_OP(0xf, reg), (u8 *)&rx, 4);
	return le32_to_cpu(rx);
}

/**
 * ks8851_soft_reset - issue one of the soft reset to the device
 * @ks: The device state.
 * @op: The bit(s) to set in the GRR
 *
 * Issue the relevant soft-reset command to the device's GRR register
 * specified by @op.
 *
 * Note, the delays are in there as a caution to ensure that the reset
 * has time to take effect and then complete. Since the datasheet does
 * not currently specify the exact sequence, we have chosen something
 * that seems to work with our device.
 */
static void ks8851_soft_reset(struct ks8851_net *ks, unsigned op)
{
	ks8851_wrreg16(ks, KS_GRR, op);
	mdelay(1);	/* wait a short time to effect reset */
	ks8851_wrreg16(ks, KS_GRR, 0);
	mdelay(1);	/* wait for condition to clear */
}

/**
 * ks8851_set_powermode - set power mode of the device
 * @ks: The device state
 * @pwrmode: The power mode value to write to KS_PMECR.
 *
 * Change the power mode of the chip.
 */
static void ks8851_set_powermode(struct ks8851_net *ks, unsigned pwrmode)
{
	unsigned pmecr;

	netif_dbg(ks, hw, ks->netdev, "setting power mode %d\n", pwrmode);

	pmecr = ks8851_rdreg16(ks, KS_PMECR);
	pmecr &= ~PMECR_PM_MASK;
	pmecr |= pwrmode;

	ks8851_wrreg16(ks, KS_PMECR, pmecr);
}

/**
 * ks8851_write_mac_addr - write mac address to device registers
 * @dev: The network device
 *
 * Update the KS8851 MAC address registers from the address in @dev.
 *
 * This call assumes that the chip is not running, so there is no need to
 * shutdown the RXQ process whilst setting this.
*/
static int ks8851_write_mac_addr(struct net_device *dev)
{
	struct ks8851_net *ks = netdev_priv(dev);
	int i;

	mutex_lock(&ks->lock);

	/*
	 * Wake up chip in case it was powered off when stopped; otherwise,
	 * the first write to the MAC address does not take effect.
	 */
	ks8851_set_powermode(ks, PMECR_PM_NORMAL);
	for (i = 0; i < ETH_ALEN; i++)
		ks8851_wrreg8(ks, KS_MAR(i), dev->dev_addr[i]);
	if (!netif_running(dev))
		ks8851_set_powermode(ks, PMECR_PM_SOFTDOWN);

	mutex_unlock(&ks->lock);

	return 0;
}

/**
 * ks8851_read_mac_addr - read mac address from device registers
 * @dev: The network device
 *
 * Update our copy of the KS8851 MAC address from the registers of @dev.
*/
static void ks8851_read_mac_addr(struct net_device *dev)
{
	struct ks8851_net *ks = netdev_priv(dev);
	int i;

	mutex_lock(&ks->lock);

	for (i = 0; i < ETH_ALEN; i++)
		dev->dev_addr[i] = ks8851_rdreg8(ks, KS_MAR(i));

	mutex_unlock(&ks->lock);
}

/**
 * ks8851_init_mac - initialise the mac address
 * @ks: The device structure
 *
 * Get or create the initial mac address for the device and then set that
 * into the station address register. A mac address supplied in the device
 * tree takes precedence. Otherwise, if there is an EEPROM present, then
 * we try that. If no valid mac address is found we use eth_random_addr()
 * to create a new one.
 */
static void ks8851_init_mac(struct ks8851_net *ks)
{
	struct net_device *dev = ks->netdev;
	const u8 *mac_addr;

	mac_addr = of_get_mac_address(ks->spidev->dev.of_node);
	if (!IS_ERR(mac_addr)) {
		memcpy(dev->dev_addr, mac_addr, ETH_ALEN);
		ks8851_write_mac_addr(dev);
		return;
	}

	if (ks->rc_ccr & CCR_EEPROM) {
		ks8851_read_mac_addr(dev);
		if (is_valid_ether_addr(dev->dev_addr))
			return;

		netdev_err(ks->netdev, "invalid mac address read %pM\n",
				dev->dev_addr);
	}

	eth_hw_addr_random(dev);
	ks8851_write_mac_addr(dev);
}

/**
 * ks8851_rdfifo - read data from the receive fifo
 * @ks: The device state.
 * @buff: The buffer address
 * @len: The length of the data to read
 *
 * Issue an RXQ FIFO read command and read the @len amount of data from
 * the FIFO into the buffer specified by @buff.
 */
static void ks8851_rdfifo(struct ks8851_net *ks, u8 *buff, unsigned len)
{
	struct spi_transfer *xfer = ks->spi_xfer2;
	struct spi_message *msg = &ks->spi_msg2;
	u8 txb[1];
	int ret;

	netif_dbg(ks, rx_status, ks->netdev,
		  "%s: %d@%p\n", __func__, len, buff);

	/* set the operation we're issuing */
	txb[0] = KS_SPIOP_RXFIFO;

	xfer->tx_buf = txb;
	xfer->rx_buf = NULL;
	xfer->len = 1;

	xfer++;
	xfer->rx_buf = buff;
	xfer->tx_buf = NULL;
	xfer->len = len;

	ret = spi_sync(ks->spidev, msg);
	if (ret < 0)
		netdev_err(ks->netdev, "%s: spi_sync() failed\n", __func__);
}

/**
 * ks8851_dbg_dumpkkt - dump initial packet contents to debug
 * @ks: The device state
 * @rxpkt: The data for the received packet
 *
 * Dump the initial data from the packet to dev_dbg().
*/
static void ks8851_dbg_dumpkkt(struct ks8851_net *ks, u8 *rxpkt)
{
	netdev_dbg(ks->netdev,
		   "pkt %02x%02x%02x%02x %02x%02x%02x%02x %02x%02x%02x%02x\n",
		   rxpkt[4], rxpkt[5], rxpkt[6], rxpkt[7],
		   rxpkt[8], rxpkt[9], rxpkt[10], rxpkt[11],
		   rxpkt[12], rxpkt[13], rxpkt[14], rxpkt[15]);
}

/**
 * ks8851_rx_pkts - receive packets from the host
 * @ks: The device information.
 *
 * This is called from the IRQ work queue when the system detects that there
 * are packets in the receive queue. Find out how many packets there are and
 * read them from the FIFO.
 */
static void ks8851_rx_pkts(struct ks8851_net *ks)
{
	struct sk_buff *skb;
	unsigned rxfc;
	unsigned rxlen;
	unsigned rxstat;
	u32 rxh;
	u8 *rxpkt;

	rxfc = ks8851_rdreg8(ks, KS_RXFC);

	netif_dbg(ks, rx_status, ks->netdev,
		  "%s: %d packets\n", __func__, rxfc);

	/* Currently we're issuing a read per packet, but we could possibly
	 * improve the code by issuing a single read, getting the receive
	 * header, allocating the packet and then reading the packet data
	 * out in one go.
	 *
	 * This form of operation would require us to hold the SPI bus'
	 * chipselect low during the entie transaction to avoid any
	 * reset to the data stream coming from the chip.
	 */

	for (; rxfc != 0; rxfc--) {
		rxh = ks8851_rdreg32(ks, KS_RXFHSR);
		rxstat = rxh & 0xffff;
		rxlen = (rxh >> 16) & 0xfff;

		netif_dbg(ks, rx_status, ks->netdev,
			  "rx: stat 0x%04x, len 0x%04x\n", rxstat, rxlen);

		/* the length of the packet includes the 32bit CRC */

		/* set dma read address */
		ks8851_wrreg16(ks, KS_RXFDPR, RXFDPR_RXFPAI | 0x00);

		/* start DMA access */
		ks8851_wrreg16(ks, KS_RXQCR, ks->rc_rxqcr | RXQCR_SDA);

		if (rxlen > 4) {
			unsigned int rxalign;

			rxlen -= 4;
			rxalign = ALIGN(rxlen, 4);
			skb = netdev_alloc_skb_ip_align(ks->netdev, rxalign);
			if (skb) {

				/* 4 bytes of status header + 4 bytes of
				 * garbage: we put them before ethernet
				 * header, so that they are copied,
				 * but ignored.
				 */

				rxpkt = skb_put(skb, rxlen) - 8;

				ks8851_rdfifo(ks, rxpkt, rxalign + 8);

				if (netif_msg_pktdata(ks))
					ks8851_dbg_dumpkkt(ks, rxpkt);

				skb->protocol = eth_type_trans(skb, ks->netdev);
				netif_rx_ni(skb);

				ks->netdev->stats.rx_packets++;
				ks->netdev->stats.rx_bytes += rxlen;
			}
		}

		/* end DMA access and dequeue packet */
		ks8851_wrreg16(ks, KS_RXQCR, ks->rc_rxqcr | RXQCR_RRXEF);
	}
}

/**
 * ks8851_irq - IRQ handler for dealing with interrupt requests
 * @irq: IRQ number
 * @_ks: cookie
 *
 * This handler is invoked when the IRQ line asserts to find out what happened.
 * As we cannot allow ourselves to sleep in HARDIRQ context, this handler runs
 * in thread context.
 *
 * Read the interrupt status, work out what needs to be done and then clear
 * any of the interrupts that are not needed.
 */
static irqreturn_t ks8851_irq(int irq, void *_ks)
{
	struct ks8851_net *ks = _ks;
	unsigned status;
	unsigned handled = 0;

	mutex_lock(&ks->lock);

	status = ks8851_rdreg16(ks, KS_ISR);

	netif_dbg(ks, intr, ks->netdev,
		  "%s: status 0x%04x\n", __func__, status);

	if (status & IRQ_LCI)
		handled |= IRQ_LCI;

	if (status & IRQ_LDI) {
		u16 pmecr = ks8851_rdreg16(ks, KS_PMECR);
		pmecr &= ~PMECR_WKEVT_MASK;
		ks8851_wrreg16(ks, KS_PMECR, pmecr | PMECR_WKEVT_LINK);

		handled |= IRQ_LDI;
	}

	if (status & IRQ_RXPSI)
		handled |= IRQ_RXPSI;

	if (status & IRQ_TXI) {
		handled |= IRQ_TXI;

		/* no lock here, tx queue should have been stopped */

		/* update our idea of how much tx space is available to the
		 * system */
		ks->tx_space = ks8851_rdreg16(ks, KS_TXMIR);

		netif_dbg(ks, intr, ks->netdev,
			  "%s: txspace %d\n", __func__, ks->tx_space);
	}

	if (status & IRQ_RXI)
		handled |= IRQ_RXI;

	if (status & IRQ_SPIBEI) {
		dev_err(&ks->spidev->dev, "%s: spi bus error\n", __func__);
		handled |= IRQ_SPIBEI;
	}

	ks8851_wrreg16(ks, KS_ISR, handled);

	if (status & IRQ_RXI) {
		/* the datasheet says to disable the rx interrupt during
		 * packet read-out, however we're masking the interrupt
		 * from the device so do not bother masking just the RX
		 * from the device. */

		ks8851_rx_pkts(ks);
	}

	/* if something stopped the rx process, probably due to wanting
	 * to change the rx settings, then do something about restarting
	 * it. */
	if (status & IRQ_RXPSI) {
		struct ks8851_rxctrl *rxc = &ks->rxctrl;

		/* update the multicast hash table */
		ks8851_wrreg16(ks, KS_MAHTR0, rxc->mchash[0]);
		ks8851_wrreg16(ks, KS_MAHTR1, rxc->mchash[1]);
		ks8851_wrreg16(ks, KS_MAHTR2, rxc->mchash[2]);
		ks8851_wrreg16(ks, KS_MAHTR3, rxc->mchash[3]);

		ks8851_wrreg16(ks, KS_RXCR2, rxc->rxcr2);
		ks8851_wrreg16(ks, KS_RXCR1, rxc->rxcr1);
	}

	mutex_unlock(&ks->lock);

	if (status & IRQ_LCI)
		mii_check_link(&ks->mii);

	if (status & IRQ_TXI)
		netif_wake_queue(ks->netdev);

	return IRQ_HANDLED;
}

/**
 * calc_txlen - calculate size of message to send packet
 * @len: Length of data
 *
 * Returns the size of the TXFIFO message needed to send
 * this packet.
 */
static inline unsigned calc_txlen(unsigned len)
{
	return ALIGN(len + 4, 4);
}

/**
 * ks8851_wrpkt - write packet to TX FIFO
 * @ks: The device state.
 * @txp: The sk_buff to transmit.
 * @irq: IRQ on completion of the packet.
 *
 * Send the @txp to the chip. This means creating the relevant packet header
 * specifying the length of the packet and the other information the chip
 * needs, such as IRQ on completion. Send the header and the packet data to
 * the device.
 */
static void ks8851_wrpkt(struct ks8851_net *ks, struct sk_buff *txp, bool irq)
{
	struct spi_transfer *xfer = ks->spi_xfer2;
	struct spi_message *msg = &ks->spi_msg2;
	unsigned fid = 0;
	int ret;

	netif_dbg(ks, tx_queued, ks->netdev, "%s: skb %p, %d@%p, irq %d\n",
		  __func__, txp, txp->len, txp->data, irq);

	fid = ks->fid++;
	fid &= TXFR_TXFID_MASK;

	if (irq)
		fid |= TXFR_TXIC;	/* irq on completion */

	/* start header at txb[1] to align txw entries */
	ks->txh.txb[1] = KS_SPIOP_TXFIFO;
	ks->txh.txw[1] = cpu_to_le16(fid);
	ks->txh.txw[2] = cpu_to_le16(txp->len);

	xfer->tx_buf = &ks->txh.txb[1];
	xfer->rx_buf = NULL;
	xfer->len = 5;

	xfer++;
	xfer->tx_buf = txp->data;
	xfer->rx_buf = NULL;
	xfer->len = ALIGN(txp->len, 4);

	ret = spi_sync(ks->spidev, msg);
	if (ret < 0)
		netdev_err(ks->netdev, "%s: spi_sync() failed\n", __func__);
}

/**
 * ks8851_done_tx - update and then free skbuff after transmitting
 * @ks: The device state
 * @txb: The buffer transmitted
 */
static void ks8851_done_tx(struct ks8851_net *ks, struct sk_buff *txb)
{
	struct net_device *dev = ks->netdev;

	dev->stats.tx_bytes += txb->len;
	dev->stats.tx_packets++;

	dev_kfree_skb(txb);
}

/**
 * ks8851_tx_work - process tx packet(s)
 * @work: The work strucutre what was scheduled.
 *
 * This is called when a number of packets have been scheduled for
 * transmission and need to be sent to the device.
 */
static void ks8851_tx_work(struct work_struct *work)
{
	struct ks8851_net *ks = container_of(work, struct ks8851_net, tx_work);
	struct sk_buff *txb;
	bool last = skb_queue_empty(&ks->txq);

	mutex_lock(&ks->lock);

	while (!last) {
		txb = skb_dequeue(&ks->txq);
		last = skb_queue_empty(&ks->txq);

		if (txb != NULL) {
			ks8851_wrreg16(ks, KS_RXQCR, ks->rc_rxqcr | RXQCR_SDA);
			ks8851_wrpkt(ks, txb, last);
			ks8851_wrreg16(ks, KS_RXQCR, ks->rc_rxqcr);
			ks8851_wrreg16(ks, KS_TXQCR, TXQCR_METFE);

			ks8851_done_tx(ks, txb);
		}
	}

	mutex_unlock(&ks->lock);
}

/**
 * ks8851_net_open - open network device
 * @dev: The network device being opened.
 *
 * Called when the network device is marked active, such as a user executing
 * 'ifconfig up' on the device.
 */
static int ks8851_net_open(struct net_device *dev)
{
	struct ks8851_net *ks = netdev_priv(dev);
	int ret;

	ret = request_threaded_irq(dev->irq, NULL, ks8851_irq,
				   IRQF_TRIGGER_LOW | IRQF_ONESHOT,
				   dev->name, ks);
	if (ret < 0) {
		netdev_err(dev, "failed to get irq\n");
		return ret;
	}

	/* lock the card, even if we may not actually be doing anything
	 * else at the moment */
	mutex_lock(&ks->lock);

	netif_dbg(ks, ifup, ks->netdev, "opening\n");

	/* bring chip out of any power saving mode it was in */
	ks8851_set_powermode(ks, PMECR_PM_NORMAL);

	/* issue a soft reset to the RX/TX QMU to put it into a known
	 * state. */
	ks8851_soft_reset(ks, GRR_QMU);

	/* setup transmission parameters */

	ks8851_wrreg16(ks, KS_TXCR, (TXCR_TXE | /* enable transmit process */
				     TXCR_TXPE | /* pad to min length */
				     TXCR_TXCRC | /* add CRC */
				     TXCR_TXFCE)); /* enable flow control */

	/* auto-increment tx data, reset tx pointer */
	ks8851_wrreg16(ks, KS_TXFDPR, TXFDPR_TXFPAI);

	/* setup receiver control */

	ks8851_wrreg16(ks, KS_RXCR1, (RXCR1_RXPAFMA | /*  from mac filter */
				      RXCR1_RXFCE | /* enable flow control */
				      RXCR1_RXBE | /* broadcast enable */
				      RXCR1_RXUE | /* unicast enable */
				      RXCR1_RXE)); /* enable rx block */

	/* transfer entire frames out in one go */
	ks8851_wrreg16(ks, KS_RXCR2, RXCR2_SRDBL_FRAME);

	/* set receive counter timeouts */
	ks8851_wrreg16(ks, KS_RXDTTR, 1000); /* 1ms after first frame to IRQ */
	ks8851_wrreg16(ks, KS_RXDBCTR, 4096); /* >4Kbytes in buffer to IRQ */
	ks8851_wrreg16(ks, KS_RXFCTR, 10);  /* 10 frames to IRQ */

	ks->rc_rxqcr = (RXQCR_RXFCTE |  /* IRQ on frame count exceeded */
			RXQCR_RXDBCTE | /* IRQ on byte count exceeded */
			RXQCR_RXDTTE);  /* IRQ on time exceeded */

	ks8851_wrreg16(ks, KS_RXQCR, ks->rc_rxqcr);

	/* clear then enable interrupts */

#define STD_IRQ (IRQ_LCI |	/* Link Change */	\
		 IRQ_TXI |	/* TX done */		\
		 IRQ_RXI |	/* RX done */		\
		 IRQ_SPIBEI |	/* SPI bus error */	\
		 IRQ_TXPSI |	/* TX process stop */	\
		 IRQ_RXPSI)	/* RX process stop */

	ks->rc_ier = STD_IRQ;
	ks8851_wrreg16(ks, KS_ISR, STD_IRQ);
	ks8851_wrreg16(ks, KS_IER, STD_IRQ);

	netif_start_queue(ks->netdev);

	netif_dbg(ks, ifup, ks->netdev, "network device up\n");

	mutex_unlock(&ks->lock);
	mii_check_link(&ks->mii);
	return 0;
}

/**
 * ks8851_net_stop - close network device
 * @dev: The device being closed.
 *
 * Called to close down a network device which has been active. Cancell any
 * work, shutdown the RX and TX process and then place the chip into a low
 * power state whilst it is not being used.
 */
static int ks8851_net_stop(struct net_device *dev)
{
	struct ks8851_net *ks = netdev_priv(dev);

	netif_info(ks, ifdown, dev, "shutting down\n");

	netif_stop_queue(dev);

	mutex_lock(&ks->lock);
	/* turn off the IRQs and ack any outstanding */
	ks8851_wrreg16(ks, KS_IER, 0x0000);
	ks8851_wrreg16(ks, KS_ISR, 0xffff);
	mutex_unlock(&ks->lock);

	/* stop any outstanding work */
	flush_work(&ks->tx_work);
	flush_work(&ks->rxctrl_work);

	mutex_lock(&ks->lock);
	/* shutdown RX process */
	ks8851_wrreg16(ks, KS_RXCR1, 0x0000);

	/* shutdown TX process */
	ks8851_wrreg16(ks, KS_TXCR, 0x0000);

	/* set powermode to soft power down to save power */
	ks8851_set_powermode(ks, PMECR_PM_SOFTDOWN);
	mutex_unlock(&ks->lock);

	/* ensure any queued tx buffers are dumped */
	while (!skb_queue_empty(&ks->txq)) {
		struct sk_buff *txb = skb_dequeue(&ks->txq);

		netif_dbg(ks, ifdown, ks->netdev,
			  "%s: freeing txb %p\n", __func__, txb);

		dev_kfree_skb(txb);
	}

	free_irq(dev->irq, ks);

	return 0;
}

/**
 * ks8851_start_xmit - transmit packet
 * @skb: The buffer to transmit
 * @dev: The device used to transmit the packet.
 *
 * Called by the network layer to transmit the @skb. Queue the packet for
 * the device and schedule the necessary work to transmit the packet when
 * it is free.
 *
 * We do this to firstly avoid sleeping with the network device locked,
 * and secondly so we can round up more than one packet to transmit which
 * means we can try and avoid generating too many transmit done interrupts.
 */
static netdev_tx_t ks8851_start_xmit(struct sk_buff *skb,
				     struct net_device *dev)
{
	struct ks8851_net *ks = netdev_priv(dev);
	unsigned needed = calc_txlen(skb->len);
	netdev_tx_t ret = NETDEV_TX_OK;

	netif_dbg(ks, tx_queued, ks->netdev,
		  "%s: skb %p, %d@%p\n", __func__, skb, skb->len, skb->data);

	spin_lock(&ks->statelock);

	if (needed > ks->tx_space) {
		netif_stop_queue(dev);
		ret = NETDEV_TX_BUSY;
	} else {
		ks->tx_space -= needed;
		skb_queue_tail(&ks->txq, skb);
	}

	spin_unlock(&ks->statelock);
	schedule_work(&ks->tx_work);

	return ret;
}

/**
 * ks8851_rxctrl_work - work handler to change rx mode
 * @work: The work structure this belongs to.
 *
 * Lock the device and issue the necessary changes to the receive mode from
 * the network device layer. This is done so that we can do this without
 * having to sleep whilst holding the network device lock.
 *
 * Since the recommendation from Micrel is that the RXQ is shutdown whilst the
 * receive parameters are programmed, we issue a write to disable the RXQ and
 * then wait for the interrupt handler to be triggered once the RXQ shutdown is
 * complete. The interrupt handler then writes the new values into the chip.
 */
static void ks8851_rxctrl_work(struct work_struct *work)
{
	struct ks8851_net *ks = container_of(work, struct ks8851_net, rxctrl_work);

	mutex_lock(&ks->lock);

	/* need to shutdown RXQ before modifying filter parameters */
	ks8851_wrreg16(ks, KS_RXCR1, 0x00);

	mutex_unlock(&ks->lock);
}

static void ks8851_set_rx_mode(struct net_device *dev)
{
	struct ks8851_net *ks = netdev_priv(dev);
	struct ks8851_rxctrl rxctrl;

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

	if (dev->flags & IFF_PROMISC) {
		/* interface to receive everything */

		rxctrl.rxcr1 = RXCR1_RXAE | RXCR1_RXINVF;
	} else if (dev->flags & IFF_ALLMULTI) {
		/* accept all multicast packets */

		rxctrl.rxcr1 = (RXCR1_RXME | RXCR1_RXAE |
				RXCR1_RXPAFMA | RXCR1_RXMAFMA);
	} else if (dev->flags & IFF_MULTICAST && !netdev_mc_empty(dev)) {
		struct netdev_hw_addr *ha;
		u32 crc;

		/* accept some multicast */

		netdev_for_each_mc_addr(ha, dev) {
			crc = ether_crc(ETH_ALEN, ha->addr);
			crc >>= (32 - 6);  /* get top six bits */

			rxctrl.mchash[crc >> 4] |= (1 << (crc & 0xf));
		}

		rxctrl.rxcr1 = RXCR1_RXME | RXCR1_RXPAFMA;
	} else {
		/* just accept broadcast / unicast */
		rxctrl.rxcr1 = RXCR1_RXPAFMA;
	}

	rxctrl.rxcr1 |= (RXCR1_RXUE | /* unicast enable */
			 RXCR1_RXBE | /* broadcast enable */
			 RXCR1_RXE | /* RX process enable */
			 RXCR1_RXFCE); /* enable flow control */

	rxctrl.rxcr2 |= RXCR2_SRDBL_FRAME;

	/* schedule work to do the actual set of the data if needed */

	spin_lock(&ks->statelock);

	if (memcmp(&rxctrl, &ks->rxctrl, sizeof(rxctrl)) != 0) {
		memcpy(&ks->rxctrl, &rxctrl, sizeof(ks->rxctrl));
		schedule_work(&ks->rxctrl_work);
	}

	spin_unlock(&ks->statelock);
}

static int ks8851_set_mac_address(struct net_device *dev, void *addr)
{
	struct sockaddr *sa = addr;

	if (netif_running(dev))
		return -EBUSY;

	if (!is_valid_ether_addr(sa->sa_data))
		return -EADDRNOTAVAIL;

	memcpy(dev->dev_addr, sa->sa_data, ETH_ALEN);
	return ks8851_write_mac_addr(dev);
}

static int ks8851_net_ioctl(struct net_device *dev, struct ifreq *req, int cmd)
{
	struct ks8851_net *ks = netdev_priv(dev);

	if (!netif_running(dev))
		return -EINVAL;

	return generic_mii_ioctl(&ks->mii, if_mii(req), cmd, NULL);
}

static const struct net_device_ops ks8851_netdev_ops = {
	.ndo_open		= ks8851_net_open,
	.ndo_stop		= ks8851_net_stop,
	.ndo_do_ioctl		= ks8851_net_ioctl,
	.ndo_start_xmit		= ks8851_start_xmit,
	.ndo_set_mac_address	= ks8851_set_mac_address,
	.ndo_set_rx_mode	= ks8851_set_rx_mode,
	.ndo_validate_addr	= eth_validate_addr,
};

/* ethtool support */

static void ks8851_get_drvinfo(struct net_device *dev,
			       struct ethtool_drvinfo *di)
{
	strlcpy(di->driver, "KS8851", sizeof(di->driver));
	strlcpy(di->version, "1.00", sizeof(di->version));
	strlcpy(di->bus_info, dev_name(dev->dev.parent), sizeof(di->bus_info));
}

static u32 ks8851_get_msglevel(struct net_device *dev)
{
	struct ks8851_net *ks = netdev_priv(dev);
	return ks->msg_enable;
}

static void ks8851_set_msglevel(struct net_device *dev, u32 to)
{
	struct ks8851_net *ks = netdev_priv(dev);
	ks->msg_enable = to;
}

static int ks8851_get_link_ksettings(struct net_device *dev,
				     struct ethtool_link_ksettings *cmd)
{
	struct ks8851_net *ks = netdev_priv(dev);

	mii_ethtool_get_link_ksettings(&ks->mii, cmd);

	return 0;
}

static int ks8851_set_link_ksettings(struct net_device *dev,
				     const struct ethtool_link_ksettings *cmd)
{
	struct ks8851_net *ks = netdev_priv(dev);
	return mii_ethtool_set_link_ksettings(&ks->mii, cmd);
}

static u32 ks8851_get_link(struct net_device *dev)
{
	struct ks8851_net *ks = netdev_priv(dev);
	return mii_link_ok(&ks->mii);
}

static int ks8851_nway_reset(struct net_device *dev)
{
	struct ks8851_net *ks = netdev_priv(dev);
	return mii_nway_restart(&ks->mii);
}

/* EEPROM support */

static void ks8851_eeprom_regread(struct eeprom_93cx6 *ee)
{
	struct ks8851_net *ks = ee->data;
	unsigned val;

	val = ks8851_rdreg16(ks, KS_EEPCR);

	ee->reg_data_out = (val & EEPCR_EESB) ? 1 : 0;
	ee->reg_data_clock = (val & EEPCR_EESCK) ? 1 : 0;
	ee->reg_chip_select = (val & EEPCR_EECS) ? 1 : 0;
}

static void ks8851_eeprom_regwrite(struct eeprom_93cx6 *ee)
{
	struct ks8851_net *ks = ee->data;
	unsigned val = EEPCR_EESA;	/* default - eeprom access on */

	if (ee->drive_data)
		val |= EEPCR_EESRWA;
	if (ee->reg_data_in)
		val |= EEPCR_EEDO;
	if (ee->reg_data_clock)
		val |= EEPCR_EESCK;
	if (ee->reg_chip_select)
		val |= EEPCR_EECS;

	ks8851_wrreg16(ks, KS_EEPCR, val);
}

/**
 * ks8851_eeprom_claim - claim device EEPROM and activate the interface
 * @ks: The network device state.
 *
 * Check for the presence of an EEPROM, and then activate software access
 * to the device.
 */
static int ks8851_eeprom_claim(struct ks8851_net *ks)
{
	if (!(ks->rc_ccr & CCR_EEPROM))
		return -ENOENT;

	mutex_lock(&ks->lock);

	/* start with clock low, cs high */
	ks8851_wrreg16(ks, KS_EEPCR, EEPCR_EESA | EEPCR_EECS);
	return 0;
}

/**
 * ks8851_eeprom_release - release the EEPROM interface
 * @ks: The device state
 *
 * Release the software access to the device EEPROM
 */
static void ks8851_eeprom_release(struct ks8851_net *ks)
{
	unsigned val = ks8851_rdreg16(ks, KS_EEPCR);

	ks8851_wrreg16(ks, KS_EEPCR, val & ~EEPCR_EESA);
	mutex_unlock(&ks->lock);
}

#define KS_EEPROM_MAGIC (0x00008851)

static int ks8851_set_eeprom(struct net_device *dev,
			     struct ethtool_eeprom *ee, u8 *data)
{
	struct ks8851_net *ks = netdev_priv(dev);
	int offset = ee->offset;
	int len = ee->len;
	u16 tmp;

	/* currently only support byte writing */
	if (len != 1)
		return -EINVAL;

	if (ee->magic != KS_EEPROM_MAGIC)
		return -EINVAL;

	if (ks8851_eeprom_claim(ks))
		return -ENOENT;

	eeprom_93cx6_wren(&ks->eeprom, true);

	/* ethtool currently only supports writing bytes, which means
	 * we have to read/modify/write our 16bit EEPROMs */

	eeprom_93cx6_read(&ks->eeprom, offset/2, &tmp);

	if (offset & 1) {
		tmp &= 0xff;
		tmp |= *data << 8;
	} else {
		tmp &= 0xff00;
		tmp |= *data;
	}

	eeprom_93cx6_write(&ks->eeprom, offset/2, tmp);
	eeprom_93cx6_wren(&ks->eeprom, false);

	ks8851_eeprom_release(ks);

	return 0;
}

static int ks8851_get_eeprom(struct net_device *dev,
			     struct ethtool_eeprom *ee, u8 *data)
{
	struct ks8851_net *ks = netdev_priv(dev);
	int offset = ee->offset;
	int len = ee->len;

	/* must be 2 byte aligned */
	if (len & 1 || offset & 1)
		return -EINVAL;

	if (ks8851_eeprom_claim(ks))
		return -ENOENT;

	ee->magic = KS_EEPROM_MAGIC;

	eeprom_93cx6_multiread(&ks->eeprom, offset/2, (__le16 *)data, len/2);
	ks8851_eeprom_release(ks);

	return 0;
}

static int ks8851_get_eeprom_len(struct net_device *dev)
{
	struct ks8851_net *ks = netdev_priv(dev);

	/* currently, we assume it is an 93C46 attached, so return 128 */
	return ks->rc_ccr & CCR_EEPROM ? 128 : 0;
}

static const struct ethtool_ops ks8851_ethtool_ops = {
	.get_drvinfo	= ks8851_get_drvinfo,
	.get_msglevel	= ks8851_get_msglevel,
	.set_msglevel	= ks8851_set_msglevel,
	.get_link	= ks8851_get_link,
	.nway_reset	= ks8851_nway_reset,
	.get_eeprom_len	= ks8851_get_eeprom_len,
	.get_eeprom	= ks8851_get_eeprom,
	.set_eeprom	= ks8851_set_eeprom,
	.get_link_ksettings = ks8851_get_link_ksettings,
	.set_link_ksettings = ks8851_set_link_ksettings,
};

/* MII interface controls */

/**
 * ks8851_phy_reg - convert MII register into a KS8851 register
 * @reg: MII register number.
 *
 * Return the KS8851 register number for the corresponding MII PHY register
 * if possible. Return zero if the MII register has no direct mapping to the
 * KS8851 register set.
 */
static int ks8851_phy_reg(int reg)
{
	switch (reg) {
	case MII_BMCR:
		return KS_P1MBCR;
	case MII_BMSR:
		return KS_P1MBSR;
	case MII_PHYSID1:
		return KS_PHY1ILR;
	case MII_PHYSID2:
		return KS_PHY1IHR;
	case MII_ADVERTISE:
		return KS_P1ANAR;
	case MII_LPA:
		return KS_P1ANLPR;
	}

	return 0x0;
}

/**
 * ks8851_phy_read - MII interface PHY register read.
 * @dev: The network device the PHY is on.
 * @phy_addr: Address of PHY (ignored as we only have one)
 * @reg: The register to read.
 *
 * This call reads data from the PHY register specified in @reg. Since the
 * device does not support all the MII registers, the non-existent values
 * are always returned as zero.
 *
 * We return zero for unsupported registers as the MII code does not check
 * the value returned for any error status, and simply returns it to the
 * caller. The mii-tool that the driver was tested with takes any -ve error
 * as real PHY capabilities, thus displaying incorrect data to the user.
 */
static int ks8851_phy_read(struct net_device *dev, int phy_addr, int reg)
{
	struct ks8851_net *ks = netdev_priv(dev);
	int ksreg;
	int result;

	ksreg = ks8851_phy_reg(reg);
	if (!ksreg)
		return 0x0;	/* no error return allowed, so use zero */

	mutex_lock(&ks->lock);
	result = ks8851_rdreg16(ks, ksreg);
	mutex_unlock(&ks->lock);

	return result;
}

static void ks8851_phy_write(struct net_device *dev,
			     int phy, int reg, int value)
{
	struct ks8851_net *ks = netdev_priv(dev);
	int ksreg;

	ksreg = ks8851_phy_reg(reg);
	if (ksreg) {
		mutex_lock(&ks->lock);
		ks8851_wrreg16(ks, ksreg, value);
		mutex_unlock(&ks->lock);
	}
}

/**
 * ks8851_read_selftest - read the selftest memory info.
 * @ks: The device state
 *
 * Read and check the TX/RX memory selftest information.
 */
static int ks8851_read_selftest(struct ks8851_net *ks)
{
	unsigned both_done = MBIR_TXMBF | MBIR_RXMBF;
	int ret = 0;
	unsigned rd;

	rd = ks8851_rdreg16(ks, KS_MBIR);

	if ((rd & both_done) != both_done) {
		netdev_warn(ks->netdev, "Memory selftest not finished\n");
		return 0;
	}

	if (rd & MBIR_TXMBFA) {
		netdev_err(ks->netdev, "TX memory selftest fail\n");
		ret |= 1;
	}

	if (rd & MBIR_RXMBFA) {
		netdev_err(ks->netdev, "RX memory selftest fail\n");
		ret |= 2;
	}

	return 0;
}

/* driver bus management functions */

#ifdef CONFIG_PM_SLEEP

static int ks8851_suspend(struct device *dev)
{
	struct ks8851_net *ks = dev_get_drvdata(dev);
	struct net_device *netdev = ks->netdev;

	if (netif_running(netdev)) {
		netif_device_detach(netdev);
		ks8851_net_stop(netdev);
	}

	return 0;
}

static int ks8851_resume(struct device *dev)
{
	struct ks8851_net *ks = dev_get_drvdata(dev);
	struct net_device *netdev = ks->netdev;

	if (netif_running(netdev)) {
		ks8851_net_open(netdev);
		netif_device_attach(netdev);
	}

	return 0;
}
#endif

static SIMPLE_DEV_PM_OPS(ks8851_pm_ops, ks8851_suspend, ks8851_resume);

static int ks8851_probe(struct spi_device *spi)
{
	struct net_device *ndev;
	struct ks8851_net *ks;
	int ret;
	unsigned cider;
	int gpio;

	ndev = alloc_etherdev(sizeof(struct ks8851_net));
	if (!ndev)
		return -ENOMEM;

	spi->bits_per_word = 8;

	ks = netdev_priv(ndev);

	ks->netdev = ndev;
	ks->spidev = spi;
	ks->tx_space = 6144;

	gpio = of_get_named_gpio_flags(spi->dev.of_node, "reset-gpios",
				       0, NULL);
	if (gpio == -EPROBE_DEFER) {
		ret = gpio;
		goto err_gpio;
	}

	ks->gpio = gpio;
	if (gpio_is_valid(gpio)) {
		ret = devm_gpio_request_one(&spi->dev, gpio,
					    GPIOF_OUT_INIT_LOW, "ks8851_rst_n");
		if (ret) {
			dev_err(&spi->dev, "reset gpio request failed\n");
			goto err_gpio;
		}
	}

	ks->vdd_io = devm_regulator_get(&spi->dev, "vdd-io");
	if (IS_ERR(ks->vdd_io)) {
		ret = PTR_ERR(ks->vdd_io);
		goto err_reg_io;
	}

	ret = regulator_enable(ks->vdd_io);
	if (ret) {
		dev_err(&spi->dev, "regulator vdd_io enable fail: %d\n",
			ret);
		goto err_reg_io;
	}

	ks->vdd_reg = devm_regulator_get(&spi->dev, "vdd");
	if (IS_ERR(ks->vdd_reg)) {
		ret = PTR_ERR(ks->vdd_reg);
		goto err_reg;
	}

	ret = regulator_enable(ks->vdd_reg);
	if (ret) {
		dev_err(&spi->dev, "regulator vdd enable fail: %d\n",
			ret);
		goto err_reg;
	}

	if (gpio_is_valid(gpio)) {
		usleep_range(10000, 11000);
		gpio_set_value(gpio, 1);
	}

	mutex_init(&ks->lock);
	spin_lock_init(&ks->statelock);

	INIT_WORK(&ks->tx_work, ks8851_tx_work);
	INIT_WORK(&ks->rxctrl_work, ks8851_rxctrl_work);

	/* initialise pre-made spi transfer messages */

	spi_message_init(&ks->spi_msg1);
	spi_message_add_tail(&ks->spi_xfer1, &ks->spi_msg1);

	spi_message_init(&ks->spi_msg2);
	spi_message_add_tail(&ks->spi_xfer2[0], &ks->spi_msg2);
	spi_message_add_tail(&ks->spi_xfer2[1], &ks->spi_msg2);

	/* setup EEPROM state */

	ks->eeprom.data = ks;
	ks->eeprom.width = PCI_EEPROM_WIDTH_93C46;
	ks->eeprom.register_read = ks8851_eeprom_regread;
	ks->eeprom.register_write = ks8851_eeprom_regwrite;

	/* setup mii state */
	ks->mii.dev		= ndev;
	ks->mii.phy_id		= 1,
	ks->mii.phy_id_mask	= 1;
	ks->mii.reg_num_mask	= 0xf;
	ks->mii.mdio_read	= ks8851_phy_read;
	ks->mii.mdio_write	= ks8851_phy_write;

	dev_info(&spi->dev, "message enable is %d\n", msg_enable);

	/* set the default message enable */
	ks->msg_enable = netif_msg_init(msg_enable, (NETIF_MSG_DRV |
						     NETIF_MSG_PROBE |
						     NETIF_MSG_LINK));

	skb_queue_head_init(&ks->txq);

	ndev->ethtool_ops = &ks8851_ethtool_ops;
	SET_NETDEV_DEV(ndev, &spi->dev);

	spi_set_drvdata(spi, ks);

	netif_carrier_off(ks->netdev);
	ndev->if_port = IF_PORT_100BASET;
	ndev->netdev_ops = &ks8851_netdev_ops;
	ndev->irq = spi->irq;

	/* issue a global soft reset to reset the device. */
	ks8851_soft_reset(ks, GRR_GSR);

	/* simple check for a valid chip being connected to the bus */
	cider = ks8851_rdreg16(ks, KS_CIDER);
	if ((cider & ~CIDER_REV_MASK) != CIDER_ID) {
		dev_err(&spi->dev, "failed to read device ID\n");
		ret = -ENODEV;
		goto err_id;
	}

	/* cache the contents of the CCR register for EEPROM, etc. */
	ks->rc_ccr = ks8851_rdreg16(ks, KS_CCR);

	ks8851_read_selftest(ks);
	ks8851_init_mac(ks);

	ret = register_netdev(ndev);
	if (ret) {
		dev_err(&spi->dev, "failed to register network device\n");
		goto err_netdev;
	}

	netdev_info(ndev, "revision %d, MAC %pM, IRQ %d, %s EEPROM\n",
		    CIDER_REV_GET(cider), ndev->dev_addr, ndev->irq,
		    ks->rc_ccr & CCR_EEPROM ? "has" : "no");

	return 0;

err_netdev:
err_id:
	if (gpio_is_valid(gpio))
		gpio_set_value(gpio, 0);
	regulator_disable(ks->vdd_reg);
err_reg:
	regulator_disable(ks->vdd_io);
err_reg_io:
err_gpio:
	free_netdev(ndev);
	return ret;
}

static int ks8851_remove(struct spi_device *spi)
{
	struct ks8851_net *priv = spi_get_drvdata(spi);

	if (netif_msg_drv(priv))
		dev_info(&spi->dev, "remove\n");

	unregister_netdev(priv->netdev);
	if (gpio_is_valid(priv->gpio))
		gpio_set_value(priv->gpio, 0);
	regulator_disable(priv->vdd_reg);
	regulator_disable(priv->vdd_io);
	free_netdev(priv->netdev);

	return 0;
}

static const struct of_device_id ks8851_match_table[] = {
	{ .compatible = "micrel,ks8851" },
	{ }
};
MODULE_DEVICE_TABLE(of, ks8851_match_table);

static struct spi_driver ks8851_driver = {
	.driver = {
		.name = "ks8851",
		.of_match_table = ks8851_match_table,
		.pm = &ks8851_pm_ops,
	},
	.probe = ks8851_probe,
	.remove = ks8851_remove,
};
module_spi_driver(ks8851_driver);

MODULE_DESCRIPTION("KS8851 Network driver");
MODULE_AUTHOR("Ben Dooks <ben@simtec.co.uk>");
MODULE_LICENSE("GPL");

module_param_named(message, msg_enable, int, 0);
MODULE_PARM_DESC(message, "Message verbosity level (0=none, 31=all)");
MODULE_ALIAS("spi:ks8851");