summaryrefslogtreecommitdiffstats
path: root/drivers/nfc/trf7970a.c
blob: 3b78b031e617df51e98101a231519a000cd159ed (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
/*
 * TI TRF7970a RFID/NFC Transceiver Driver
 *
 * Copyright (C) 2013 Texas Instruments Incorporated - http://www.ti.com
 *
 * Author: Erick Macias <emacias@ti.com>
 * Author: Felipe Balbi <balbi@ti.com>
 * Author: Mark A. Greer <mgreer@animalcreek.com>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2  of
 * the License as published by the Free Software Foundation.
 */

#include <linux/module.h>
#include <linux/device.h>
#include <linux/netdevice.h>
#include <linux/interrupt.h>
#include <linux/pm_runtime.h>
#include <linux/nfc.h>
#include <linux/skbuff.h>
#include <linux/delay.h>
#include <linux/gpio.h>
#include <linux/of.h>
#include <linux/of_gpio.h>
#include <linux/spi/spi.h>
#include <linux/regulator/consumer.h>

#include <net/nfc/nfc.h>
#include <net/nfc/digital.h>

/* There are 3 ways the host can communicate with the trf7970a:
 * parallel mode, SPI with Slave Select (SS) mode, and SPI without
 * SS mode.  The driver only supports the two SPI modes.
 *
 * The trf7970a is very timing sensitive and the VIN, EN2, and EN
 * pins must asserted in that order and with specific delays in between.
 * The delays used in the driver were provided by TI and have been
 * confirmed to work with this driver.
 *
 * Timeouts are implemented using the delayed workqueue kernel facility.
 * Timeouts are required so things don't hang when there is no response
 * from the trf7970a (or tag).  Using this mechanism creates a race with
 * interrupts, however.  That is, an interrupt and a timeout could occur
 * closely enough together that one is blocked by the mutex while the other
 * executes.  When the timeout handler executes first and blocks the
 * interrupt handler, it will eventually set the state to IDLE so the
 * interrupt handler will check the state and exit with no harm done.
 * When the interrupt handler executes first and blocks the timeout handler,
 * the cancel_delayed_work() call will know that it didn't cancel the
 * work item (i.e., timeout) and will return zero.  That return code is
 * used by the timer handler to indicate that it should ignore the timeout
 * once its unblocked.
 *
 * Aborting an active command isn't as simple as it seems because the only
 * way to abort a command that's already been sent to the tag is so turn
 * off power to the tag.  If we do that, though, we'd have to go through
 * the entire anticollision procedure again but the digital layer doesn't
 * support that.  So, if an abort is received before trf7970a_in_send_cmd()
 * has sent the command to the tag, it simply returns -ECANCELED.  If the
 * command has already been sent to the tag, then the driver continues
 * normally and recieves the response data (or error) but just before
 * sending the data upstream, it frees the rx_skb and sends -ECANCELED
 * upstream instead.  If the command failed, that error will be sent
 * upstream.
 *
 * When recieving data from a tag and the interrupt status register has
 * only the SRX bit set, it means that all of the data has been received
 * (once what's in the fifo has been read).  However, depending on timing
 * an interrupt status with only the SRX bit set may not be recived.  In
 * those cases, the timeout mechanism is used to wait 20 ms in case more
 * data arrives.  After 20 ms, it is assumed that all of the data has been
 * received and the accumulated rx data is sent upstream.  The
 * 'TRF7970A_ST_WAIT_FOR_RX_DATA_CONT' state is used for this purpose
 * (i.e., it indicates that some data has been received but we're not sure
 * if there is more coming so a timeout in this state means all data has
 * been received and there isn't an error).  The delay is 20 ms since delays
 * of ~16 ms have been observed during testing.
 *
 * Type 2 write and sector select commands respond with a 4-bit ACK or NACK.
 * Having only 4 bits in the FIFO won't normally generate an interrupt so
 * driver enables the '4_bit_RX' bit of the Special Functions register 1
 * to cause an interrupt in that case.  Leaving that bit for a read command
 * messes up the data returned so it is only enabled when the framing is
 * 'NFC_DIGITAL_FRAMING_NFCA_T2T' and the command is not a read command.
 * Unfortunately, that means that the driver has to peek into tx frames
 * when the framing is 'NFC_DIGITAL_FRAMING_NFCA_T2T'.  This is done by
 * the trf7970a_per_cmd_config() routine.
 *
 * ISO/IEC 15693 frames specify whether to use single or double sub-carrier
 * frequencies and whether to use low or high data rates in the flags byte
 * of the frame.  This means that the driver has to peek at all 15693 frames
 * to determine what speed to set the communication to.  In addition, write
 * and lock commands use the OPTION flag to indicate that an EOF must be
 * sent to the tag before it will send its response.  So the driver has to
 * examine all frames for that reason too.
 *
 * It is unclear how long to wait before sending the EOF.  According to the
 * Note under Table 1-1 in section 1.6 of
 * http://www.ti.com/lit/ug/scbu011/scbu011.pdf, that wait should be at least
 * 10 ms for TI Tag-it HF-I tags; however testing has shown that is not long
 * enough.  For this reason, the driver waits 20 ms which seems to work
 * reliably.
 */

#define TRF7970A_SUPPORTED_PROTOCOLS \
		(NFC_PROTO_MIFARE_MASK | NFC_PROTO_ISO14443_MASK |	\
		 NFC_PROTO_ISO14443_B_MASK | NFC_PROTO_FELICA_MASK | \
		 NFC_PROTO_ISO15693_MASK)

#define TRF7970A_AUTOSUSPEND_DELAY		30000 /* 30 seconds */

/* TX data must be prefixed with a FIFO reset cmd, a cmd that depends
 * on what the current framing is, the address of the TX length byte 1
 * register (0x1d), and the 2 byte length of the data to be transmitted.
 * That totals 5 bytes.
 */
#define TRF7970A_TX_SKB_HEADROOM		5

#define TRF7970A_RX_SKB_ALLOC_SIZE		256

#define TRF7970A_FIFO_SIZE			128

/* TX length is 3 nibbles long ==> 4KB - 1 bytes max */
#define TRF7970A_TX_MAX				(4096 - 1)

#define TRF7970A_WAIT_FOR_RX_DATA_TIMEOUT	20
#define TRF7970A_WAIT_FOR_FIFO_DRAIN_TIMEOUT	3
#define TRF7970A_WAIT_TO_ISSUE_ISO15693_EOF	20

/* Quirks */
/* Erratum: When reading IRQ Status register on trf7970a, we must issue a
 * read continuous command for IRQ Status and Collision Position registers.
 */
#define TRF7970A_QUIRK_IRQ_STATUS_READ_ERRATA	BIT(0)

/* Direct commands */
#define TRF7970A_CMD_IDLE			0x00
#define TRF7970A_CMD_SOFT_INIT			0x03
#define TRF7970A_CMD_RF_COLLISION		0x04
#define TRF7970A_CMD_RF_COLLISION_RESPONSE_N	0x05
#define TRF7970A_CMD_RF_COLLISION_RESPONSE_0	0x06
#define TRF7970A_CMD_FIFO_RESET			0x0f
#define TRF7970A_CMD_TRANSMIT_NO_CRC		0x10
#define TRF7970A_CMD_TRANSMIT			0x11
#define TRF7970A_CMD_DELAY_TRANSMIT_NO_CRC	0x12
#define TRF7970A_CMD_DELAY_TRANSMIT		0x13
#define TRF7970A_CMD_EOF			0x14
#define TRF7970A_CMD_CLOSE_SLOT			0x15
#define TRF7970A_CMD_BLOCK_RX			0x16
#define TRF7970A_CMD_ENABLE_RX			0x17
#define TRF7970A_CMD_TEST_EXT_RF		0x18
#define TRF7970A_CMD_TEST_INT_RF		0x19
#define TRF7970A_CMD_RX_GAIN_ADJUST		0x1a

/* Bits determining whether its a direct command or register R/W,
 * whether to use a continuous SPI transaction or not, and the actual
 * direct cmd opcode or regster address.
 */
#define TRF7970A_CMD_BIT_CTRL			BIT(7)
#define TRF7970A_CMD_BIT_RW			BIT(6)
#define TRF7970A_CMD_BIT_CONTINUOUS		BIT(5)
#define TRF7970A_CMD_BIT_OPCODE(opcode)		((opcode) & 0x1f)

/* Registers addresses */
#define TRF7970A_CHIP_STATUS_CTRL		0x00
#define TRF7970A_ISO_CTRL			0x01
#define TRF7970A_ISO14443B_TX_OPTIONS		0x02
#define TRF7970A_ISO14443A_HIGH_BITRATE_OPTIONS	0x03
#define TRF7970A_TX_TIMER_SETTING_H_BYTE	0x04
#define TRF7970A_TX_TIMER_SETTING_L_BYTE	0x05
#define TRF7970A_TX_PULSE_LENGTH_CTRL		0x06
#define TRF7970A_RX_NO_RESPONSE_WAIT		0x07
#define TRF7970A_RX_WAIT_TIME			0x08
#define TRF7970A_MODULATOR_SYS_CLK_CTRL		0x09
#define TRF7970A_RX_SPECIAL_SETTINGS		0x0a
#define TRF7970A_REG_IO_CTRL			0x0b
#define TRF7970A_IRQ_STATUS			0x0c
#define TRF7970A_COLLISION_IRQ_MASK		0x0d
#define TRF7970A_COLLISION_POSITION		0x0e
#define TRF7970A_RSSI_OSC_STATUS		0x0f
#define TRF7970A_SPECIAL_FCN_REG1		0x10
#define TRF7970A_SPECIAL_FCN_REG2		0x11
#define TRF7970A_RAM1				0x12
#define TRF7970A_RAM2				0x13
#define TRF7970A_ADJUTABLE_FIFO_IRQ_LEVELS	0x14
#define TRF7970A_NFC_LOW_FIELD_LEVEL		0x16
#define TRF7970A_NFCID1				0x17
#define TRF7970A_NFC_TARGET_LEVEL		0x18
#define TRF79070A_NFC_TARGET_PROTOCOL		0x19
#define TRF7970A_TEST_REGISTER1			0x1a
#define TRF7970A_TEST_REGISTER2			0x1b
#define TRF7970A_FIFO_STATUS			0x1c
#define TRF7970A_TX_LENGTH_BYTE1		0x1d
#define TRF7970A_TX_LENGTH_BYTE2		0x1e
#define TRF7970A_FIFO_IO_REGISTER		0x1f

/* Chip Status Control Register Bits */
#define TRF7970A_CHIP_STATUS_VRS5_3		BIT(0)
#define TRF7970A_CHIP_STATUS_REC_ON		BIT(1)
#define TRF7970A_CHIP_STATUS_AGC_ON		BIT(2)
#define TRF7970A_CHIP_STATUS_PM_ON		BIT(3)
#define TRF7970A_CHIP_STATUS_RF_PWR		BIT(4)
#define TRF7970A_CHIP_STATUS_RF_ON		BIT(5)
#define TRF7970A_CHIP_STATUS_DIRECT		BIT(6)
#define TRF7970A_CHIP_STATUS_STBY		BIT(7)

/* ISO Control Register Bits */
#define TRF7970A_ISO_CTRL_15693_SGL_1OF4_662	0x00
#define TRF7970A_ISO_CTRL_15693_SGL_1OF256_662	0x01
#define TRF7970A_ISO_CTRL_15693_SGL_1OF4_2648	0x02
#define TRF7970A_ISO_CTRL_15693_SGL_1OF256_2648	0x03
#define TRF7970A_ISO_CTRL_15693_DBL_1OF4_667a	0x04
#define TRF7970A_ISO_CTRL_15693_DBL_1OF256_667	0x05
#define TRF7970A_ISO_CTRL_15693_DBL_1OF4_2669	0x06
#define TRF7970A_ISO_CTRL_15693_DBL_1OF256_2669	0x07
#define TRF7970A_ISO_CTRL_14443A_106		0x08
#define TRF7970A_ISO_CTRL_14443A_212		0x09
#define TRF7970A_ISO_CTRL_14443A_424		0x0a
#define TRF7970A_ISO_CTRL_14443A_848		0x0b
#define TRF7970A_ISO_CTRL_14443B_106		0x0c
#define TRF7970A_ISO_CTRL_14443B_212		0x0d
#define TRF7970A_ISO_CTRL_14443B_424		0x0e
#define TRF7970A_ISO_CTRL_14443B_848		0x0f
#define TRF7970A_ISO_CTRL_FELICA_212		0x1a
#define TRF7970A_ISO_CTRL_FELICA_424		0x1b
#define TRF7970A_ISO_CTRL_RFID			BIT(5)
#define TRF7970A_ISO_CTRL_DIR_MODE		BIT(6)
#define TRF7970A_ISO_CTRL_RX_CRC_N		BIT(7)	/* true == No CRC */

#define TRF7970A_ISO_CTRL_RFID_SPEED_MASK	0x1f

/* Modulator and SYS_CLK Control Register Bits */
#define TRF7970A_MODULATOR_DEPTH(n)		((n) & 0x7)
#define TRF7970A_MODULATOR_DEPTH_ASK10		(TRF7970A_MODULATOR_DEPTH(0))
#define TRF7970A_MODULATOR_DEPTH_OOK		(TRF7970A_MODULATOR_DEPTH(1))
#define TRF7970A_MODULATOR_DEPTH_ASK7		(TRF7970A_MODULATOR_DEPTH(2))
#define TRF7970A_MODULATOR_DEPTH_ASK8_5		(TRF7970A_MODULATOR_DEPTH(3))
#define TRF7970A_MODULATOR_DEPTH_ASK13		(TRF7970A_MODULATOR_DEPTH(4))
#define TRF7970A_MODULATOR_DEPTH_ASK16		(TRF7970A_MODULATOR_DEPTH(5))
#define TRF7970A_MODULATOR_DEPTH_ASK22		(TRF7970A_MODULATOR_DEPTH(6))
#define TRF7970A_MODULATOR_DEPTH_ASK30		(TRF7970A_MODULATOR_DEPTH(7))
#define TRF7970A_MODULATOR_EN_ANA		BIT(3)
#define TRF7970A_MODULATOR_CLK(n)		(((n) & 0x3) << 4)
#define TRF7970A_MODULATOR_CLK_DISABLED		(TRF7970A_MODULATOR_CLK(0))
#define TRF7970A_MODULATOR_CLK_3_6		(TRF7970A_MODULATOR_CLK(1))
#define TRF7970A_MODULATOR_CLK_6_13		(TRF7970A_MODULATOR_CLK(2))
#define TRF7970A_MODULATOR_CLK_13_27		(TRF7970A_MODULATOR_CLK(3))
#define TRF7970A_MODULATOR_EN_OOK		BIT(6)
#define TRF7970A_MODULATOR_27MHZ		BIT(7)

/* IRQ Status Register Bits */
#define TRF7970A_IRQ_STATUS_NORESP		BIT(0) /* ISO15693 only */
#define TRF7970A_IRQ_STATUS_COL			BIT(1)
#define TRF7970A_IRQ_STATUS_FRAMING_EOF_ERROR	BIT(2)
#define TRF7970A_IRQ_STATUS_PARITY_ERROR	BIT(3)
#define TRF7970A_IRQ_STATUS_CRC_ERROR		BIT(4)
#define TRF7970A_IRQ_STATUS_FIFO		BIT(5)
#define TRF7970A_IRQ_STATUS_SRX			BIT(6)
#define TRF7970A_IRQ_STATUS_TX			BIT(7)

#define TRF7970A_IRQ_STATUS_ERROR				\
		(TRF7970A_IRQ_STATUS_COL |			\
		 TRF7970A_IRQ_STATUS_FRAMING_EOF_ERROR |	\
		 TRF7970A_IRQ_STATUS_PARITY_ERROR |		\
		 TRF7970A_IRQ_STATUS_CRC_ERROR)

#define TRF7970A_SPECIAL_FCN_REG1_COL_7_6		BIT(0)
#define TRF7970A_SPECIAL_FCN_REG1_14_ANTICOLL		BIT(1)
#define TRF7970A_SPECIAL_FCN_REG1_4_BIT_RX		BIT(2)
#define TRF7970A_SPECIAL_FCN_REG1_SP_DIR_MODE		BIT(3)
#define TRF7970A_SPECIAL_FCN_REG1_NEXT_SLOT_37US	BIT(4)
#define TRF7970A_SPECIAL_FCN_REG1_PAR43			BIT(5)

#define TRF7970A_ADJUTABLE_FIFO_IRQ_LEVELS_WLH_124	(0x0 << 2)
#define TRF7970A_ADJUTABLE_FIFO_IRQ_LEVELS_WLH_120	(0x1 << 2)
#define TRF7970A_ADJUTABLE_FIFO_IRQ_LEVELS_WLH_112	(0x2 << 2)
#define TRF7970A_ADJUTABLE_FIFO_IRQ_LEVELS_WLH_96	(0x3 << 2)
#define TRF7970A_ADJUTABLE_FIFO_IRQ_LEVELS_WLL_4	0x0
#define TRF7970A_ADJUTABLE_FIFO_IRQ_LEVELS_WLL_8	0x1
#define TRF7970A_ADJUTABLE_FIFO_IRQ_LEVELS_WLL_16	0x2
#define TRF7970A_ADJUTABLE_FIFO_IRQ_LEVELS_WLL_32	0x3

#define TRF7970A_FIFO_STATUS_OVERFLOW		BIT(7)

/* NFC (ISO/IEC 14443A) Type 2 Tag commands */
#define NFC_T2T_CMD_READ			0x30

/* ISO 15693 commands codes */
#define ISO15693_CMD_INVENTORY			0x01
#define ISO15693_CMD_READ_SINGLE_BLOCK		0x20
#define ISO15693_CMD_WRITE_SINGLE_BLOCK		0x21
#define ISO15693_CMD_LOCK_BLOCK			0x22
#define ISO15693_CMD_READ_MULTIPLE_BLOCK	0x23
#define ISO15693_CMD_WRITE_MULTIPLE_BLOCK	0x24
#define ISO15693_CMD_SELECT			0x25
#define ISO15693_CMD_RESET_TO_READY		0x26
#define ISO15693_CMD_WRITE_AFI			0x27
#define ISO15693_CMD_LOCK_AFI			0x28
#define ISO15693_CMD_WRITE_DSFID		0x29
#define ISO15693_CMD_LOCK_DSFID			0x2a
#define ISO15693_CMD_GET_SYSTEM_INFO		0x2b
#define ISO15693_CMD_GET_MULTIPLE_BLOCK_SECURITY_STATUS	0x2c

/* ISO 15693 request and response flags */
#define ISO15693_REQ_FLAG_SUB_CARRIER		BIT(0)
#define ISO15693_REQ_FLAG_DATA_RATE		BIT(1)
#define ISO15693_REQ_FLAG_INVENTORY		BIT(2)
#define ISO15693_REQ_FLAG_PROTOCOL_EXT		BIT(3)
#define ISO15693_REQ_FLAG_SELECT		BIT(4)
#define ISO15693_REQ_FLAG_AFI			BIT(4)
#define ISO15693_REQ_FLAG_ADDRESS		BIT(5)
#define ISO15693_REQ_FLAG_NB_SLOTS		BIT(5)
#define ISO15693_REQ_FLAG_OPTION		BIT(6)

#define ISO15693_REQ_FLAG_SPEED_MASK \
		(ISO15693_REQ_FLAG_SUB_CARRIER | ISO15693_REQ_FLAG_DATA_RATE)

enum trf7970a_state {
	TRF7970A_ST_OFF,
	TRF7970A_ST_IDLE,
	TRF7970A_ST_IDLE_RX_BLOCKED,
	TRF7970A_ST_WAIT_FOR_TX_FIFO,
	TRF7970A_ST_WAIT_FOR_RX_DATA,
	TRF7970A_ST_WAIT_FOR_RX_DATA_CONT,
	TRF7970A_ST_WAIT_TO_ISSUE_EOF,
	TRF7970A_ST_MAX
};

struct trf7970a {
	enum trf7970a_state		state;
	struct device			*dev;
	struct spi_device		*spi;
	struct regulator		*regulator;
	struct nfc_digital_dev		*ddev;
	u32				quirks;
	bool				aborting;
	struct sk_buff			*tx_skb;
	struct sk_buff			*rx_skb;
	nfc_digital_cmd_complete_t	cb;
	void				*cb_arg;
	u8				chip_status_ctrl;
	u8				iso_ctrl;
	u8				iso_ctrl_tech;
	u8				modulator_sys_clk_ctrl;
	u8				special_fcn_reg1;
	int				technology;
	int				framing;
	u8				tx_cmd;
	bool				issue_eof;
	int				en2_gpio;
	int				en_gpio;
	struct mutex			lock;
	unsigned int			timeout;
	bool				ignore_timeout;
	struct delayed_work		timeout_work;
};


static int trf7970a_cmd(struct trf7970a *trf, u8 opcode)
{
	u8 cmd = TRF7970A_CMD_BIT_CTRL | TRF7970A_CMD_BIT_OPCODE(opcode);
	int ret;

	dev_dbg(trf->dev, "cmd: 0x%x\n", cmd);

	ret = spi_write(trf->spi, &cmd, 1);
	if (ret)
		dev_err(trf->dev, "%s - cmd: 0x%x, ret: %d\n", __func__, cmd,
				ret);
	return ret;
}

static int trf7970a_read(struct trf7970a *trf, u8 reg, u8 *val)
{
	u8 addr = TRF7970A_CMD_BIT_RW | reg;
	int ret;

	ret = spi_write_then_read(trf->spi, &addr, 1, val, 1);
	if (ret)
		dev_err(trf->dev, "%s - addr: 0x%x, ret: %d\n", __func__, addr,
				ret);

	dev_dbg(trf->dev, "read(0x%x): 0x%x\n", addr, *val);

	return ret;
}

static int trf7970a_read_cont(struct trf7970a *trf, u8 reg,
		u8 *buf, size_t len)
{
	u8 addr = reg | TRF7970A_CMD_BIT_RW | TRF7970A_CMD_BIT_CONTINUOUS;
	int ret;

	dev_dbg(trf->dev, "read_cont(0x%x, %zd)\n", addr, len);

	ret = spi_write_then_read(trf->spi, &addr, 1, buf, len);
	if (ret)
		dev_err(trf->dev, "%s - addr: 0x%x, ret: %d\n", __func__, addr,
				ret);
	return ret;
}

static int trf7970a_write(struct trf7970a *trf, u8 reg, u8 val)
{
	u8 buf[2] = { reg, val };
	int ret;

	dev_dbg(trf->dev, "write(0x%x): 0x%x\n", reg, val);

	ret = spi_write(trf->spi, buf, 2);
	if (ret)
		dev_err(trf->dev, "%s - write: 0x%x 0x%x, ret: %d\n", __func__,
				buf[0], buf[1], ret);

	return ret;
}

static int trf7970a_read_irqstatus(struct trf7970a *trf, u8 *status)
{
	int ret;
	u8 buf[2];
	u8 addr;

	addr = TRF7970A_IRQ_STATUS | TRF7970A_CMD_BIT_RW;

	if (trf->quirks & TRF7970A_QUIRK_IRQ_STATUS_READ_ERRATA) {
		addr |= TRF7970A_CMD_BIT_CONTINUOUS;
		ret = spi_write_then_read(trf->spi, &addr, 1, buf, 2);
	} else {
		ret = spi_write_then_read(trf->spi, &addr, 1, buf, 1);
	}

	if (ret)
		dev_err(trf->dev, "%s - irqstatus: Status read failed: %d\n",
				__func__, ret);
	else
		*status = buf[0];

	return ret;
}

static void trf7970a_send_upstream(struct trf7970a *trf)
{
	u8 rssi;

	dev_kfree_skb_any(trf->tx_skb);
	trf->tx_skb = NULL;

	if (trf->rx_skb && !IS_ERR(trf->rx_skb) && !trf->aborting)
		print_hex_dump_debug("trf7970a rx data: ", DUMP_PREFIX_NONE,
				16, 1, trf->rx_skb->data, trf->rx_skb->len,
				false);

	/* According to the manual it is "good form" to reset the fifo and
	 * read the RSSI levels & oscillator status register here.  It doesn't
	 * explain why.
	 */
	trf7970a_cmd(trf, TRF7970A_CMD_FIFO_RESET);
	trf7970a_read(trf, TRF7970A_RSSI_OSC_STATUS, &rssi);

	trf->state = TRF7970A_ST_IDLE;

	if (trf->aborting) {
		dev_dbg(trf->dev, "Abort process complete\n");

		if (!IS_ERR(trf->rx_skb)) {
			kfree_skb(trf->rx_skb);
			trf->rx_skb = ERR_PTR(-ECANCELED);
		}

		trf->aborting = false;
	}

	trf->cb(trf->ddev, trf->cb_arg, trf->rx_skb);

	trf->rx_skb = NULL;
}

static void trf7970a_send_err_upstream(struct trf7970a *trf, int errno)
{
	dev_dbg(trf->dev, "Error - state: %d, errno: %d\n", trf->state, errno);

	kfree_skb(trf->rx_skb);
	trf->rx_skb = ERR_PTR(errno);

	trf7970a_send_upstream(trf);
}

static int trf7970a_transmit(struct trf7970a *trf, struct sk_buff *skb,
		unsigned int len)
{
	unsigned int timeout;
	int ret;

	print_hex_dump_debug("trf7970a tx data: ", DUMP_PREFIX_NONE,
			16, 1, skb->data, len, false);

	ret = spi_write(trf->spi, skb->data, len);
	if (ret) {
		dev_err(trf->dev, "%s - Can't send tx data: %d\n", __func__,
				ret);
		return ret;
	}

	skb_pull(skb, len);

	if (skb->len > 0) {
		trf->state = TRF7970A_ST_WAIT_FOR_TX_FIFO;
		timeout = TRF7970A_WAIT_FOR_FIFO_DRAIN_TIMEOUT;
	} else {
		if (trf->issue_eof) {
			trf->state = TRF7970A_ST_WAIT_TO_ISSUE_EOF;
			timeout = TRF7970A_WAIT_TO_ISSUE_ISO15693_EOF;
		} else {
			trf->state = TRF7970A_ST_WAIT_FOR_RX_DATA;
			timeout = trf->timeout;
		}
	}

	dev_dbg(trf->dev, "Setting timeout for %d ms, state: %d\n", timeout,
			trf->state);

	schedule_delayed_work(&trf->timeout_work, msecs_to_jiffies(timeout));

	return 0;
}

static void trf7970a_fill_fifo(struct trf7970a *trf)
{
	struct sk_buff *skb = trf->tx_skb;
	unsigned int len;
	int ret;
	u8 fifo_bytes;

	ret = trf7970a_read(trf, TRF7970A_FIFO_STATUS, &fifo_bytes);
	if (ret) {
		trf7970a_send_err_upstream(trf, ret);
		return;
	}

	dev_dbg(trf->dev, "Filling FIFO - fifo_bytes: 0x%x\n", fifo_bytes);

	if (fifo_bytes & TRF7970A_FIFO_STATUS_OVERFLOW) {
		dev_err(trf->dev, "%s - fifo overflow: 0x%x\n", __func__,
				fifo_bytes);
		trf7970a_send_err_upstream(trf, -EIO);
		return;
	}

	/* Calculate how much more data can be written to the fifo */
	len = TRF7970A_FIFO_SIZE - fifo_bytes;
	len = min(skb->len, len);

	ret = trf7970a_transmit(trf, skb, len);
	if (ret)
		trf7970a_send_err_upstream(trf, ret);
}

static void trf7970a_drain_fifo(struct trf7970a *trf, u8 status)
{
	struct sk_buff *skb = trf->rx_skb;
	int ret;
	u8 fifo_bytes;

	if (status & TRF7970A_IRQ_STATUS_ERROR) {
		trf7970a_send_err_upstream(trf, -EIO);
		return;
	}

	ret = trf7970a_read(trf, TRF7970A_FIFO_STATUS, &fifo_bytes);
	if (ret) {
		trf7970a_send_err_upstream(trf, ret);
		return;
	}

	dev_dbg(trf->dev, "Draining FIFO - fifo_bytes: 0x%x\n", fifo_bytes);

	if (!fifo_bytes)
		goto no_rx_data;

	if (fifo_bytes & TRF7970A_FIFO_STATUS_OVERFLOW) {
		dev_err(trf->dev, "%s - fifo overflow: 0x%x\n", __func__,
				fifo_bytes);
		trf7970a_send_err_upstream(trf, -EIO);
		return;
	}

	if (fifo_bytes > skb_tailroom(skb)) {
		skb = skb_copy_expand(skb, skb_headroom(skb),
				max_t(int, fifo_bytes,
					TRF7970A_RX_SKB_ALLOC_SIZE),
				GFP_KERNEL);
		if (!skb) {
			trf7970a_send_err_upstream(trf, -ENOMEM);
			return;
		}

		kfree_skb(trf->rx_skb);
		trf->rx_skb = skb;
	}

	ret = trf7970a_read_cont(trf, TRF7970A_FIFO_IO_REGISTER,
			skb_put(skb, fifo_bytes), fifo_bytes);
	if (ret) {
		trf7970a_send_err_upstream(trf, ret);
		return;
	}

	/* If received Type 2 ACK/NACK, shift right 4 bits and pass up */
	if ((trf->framing == NFC_DIGITAL_FRAMING_NFCA_T2T) && (skb->len == 1) &&
			(trf->special_fcn_reg1 ==
				 TRF7970A_SPECIAL_FCN_REG1_4_BIT_RX)) {
		skb->data[0] >>= 4;
		status = TRF7970A_IRQ_STATUS_SRX;
	} else {
		trf->state = TRF7970A_ST_WAIT_FOR_RX_DATA_CONT;
	}

no_rx_data:
	if (status == TRF7970A_IRQ_STATUS_SRX) { /* Receive complete */
		trf7970a_send_upstream(trf);
		return;
	}

	dev_dbg(trf->dev, "Setting timeout for %d ms\n",
			TRF7970A_WAIT_FOR_RX_DATA_TIMEOUT);

	schedule_delayed_work(&trf->timeout_work,
			msecs_to_jiffies(TRF7970A_WAIT_FOR_RX_DATA_TIMEOUT));
}

static irqreturn_t trf7970a_irq(int irq, void *dev_id)
{
	struct trf7970a *trf = dev_id;
	int ret;
	u8 status;

	mutex_lock(&trf->lock);

	if (trf->state == TRF7970A_ST_OFF) {
		mutex_unlock(&trf->lock);
		return IRQ_NONE;
	}

	ret = trf7970a_read_irqstatus(trf, &status);
	if (ret) {
		mutex_unlock(&trf->lock);
		return IRQ_NONE;
	}

	dev_dbg(trf->dev, "IRQ - state: %d, status: 0x%x\n", trf->state,
			status);

	if (!status) {
		mutex_unlock(&trf->lock);
		return IRQ_NONE;
	}

	switch (trf->state) {
	case TRF7970A_ST_IDLE:
	case TRF7970A_ST_IDLE_RX_BLOCKED:
		/* If getting interrupts caused by RF noise, turn off the
		 * receiver to avoid unnecessary interrupts.  It will be
		 * turned back on in trf7970a_in_send_cmd() when the next
		 * command is issued.
		 */
		if (status & TRF7970A_IRQ_STATUS_ERROR) {
			trf7970a_cmd(trf, TRF7970A_CMD_BLOCK_RX);
			trf->state = TRF7970A_ST_IDLE_RX_BLOCKED;
		}

		trf7970a_cmd(trf, TRF7970A_CMD_FIFO_RESET);
		break;
	case TRF7970A_ST_WAIT_FOR_TX_FIFO:
		if (status & TRF7970A_IRQ_STATUS_TX) {
			trf->ignore_timeout =
				!cancel_delayed_work(&trf->timeout_work);
			trf7970a_fill_fifo(trf);
		} else {
			trf7970a_send_err_upstream(trf, -EIO);
		}
		break;
	case TRF7970A_ST_WAIT_FOR_RX_DATA:
	case TRF7970A_ST_WAIT_FOR_RX_DATA_CONT:
		if (status & TRF7970A_IRQ_STATUS_SRX) {
			trf->ignore_timeout =
				!cancel_delayed_work(&trf->timeout_work);
			trf7970a_drain_fifo(trf, status);
		} else if (status == TRF7970A_IRQ_STATUS_TX) {
			trf7970a_cmd(trf, TRF7970A_CMD_FIFO_RESET);
		} else {
			trf7970a_send_err_upstream(trf, -EIO);
		}
		break;
	case TRF7970A_ST_WAIT_TO_ISSUE_EOF:
		if (status != TRF7970A_IRQ_STATUS_TX)
			trf7970a_send_err_upstream(trf, -EIO);
		break;
	default:
		dev_err(trf->dev, "%s - Driver in invalid state: %d\n",
				__func__, trf->state);
	}

	mutex_unlock(&trf->lock);
	return IRQ_HANDLED;
}

static void trf7970a_issue_eof(struct trf7970a *trf)
{
	int ret;

	dev_dbg(trf->dev, "Issuing EOF\n");

	ret = trf7970a_cmd(trf, TRF7970A_CMD_FIFO_RESET);
	if (ret)
		trf7970a_send_err_upstream(trf, ret);

	ret = trf7970a_cmd(trf, TRF7970A_CMD_EOF);
	if (ret)
		trf7970a_send_err_upstream(trf, ret);

	trf->state = TRF7970A_ST_WAIT_FOR_RX_DATA;

	dev_dbg(trf->dev, "Setting timeout for %d ms, state: %d\n",
			trf->timeout, trf->state);

	schedule_delayed_work(&trf->timeout_work,
			msecs_to_jiffies(trf->timeout));
}

static void trf7970a_timeout_work_handler(struct work_struct *work)
{
	struct trf7970a *trf = container_of(work, struct trf7970a,
			timeout_work.work);

	dev_dbg(trf->dev, "Timeout - state: %d, ignore_timeout: %d\n",
			trf->state, trf->ignore_timeout);

	mutex_lock(&trf->lock);

	if (trf->ignore_timeout)
		trf->ignore_timeout = false;
	else if (trf->state == TRF7970A_ST_WAIT_FOR_RX_DATA_CONT)
		trf7970a_send_upstream(trf); /* No more rx data so send up */
	else if (trf->state == TRF7970A_ST_WAIT_TO_ISSUE_EOF)
		trf7970a_issue_eof(trf);
	else
		trf7970a_send_err_upstream(trf, -ETIMEDOUT);

	mutex_unlock(&trf->lock);
}

static int trf7970a_init(struct trf7970a *trf)
{
	int ret;

	dev_dbg(trf->dev, "Initializing device - state: %d\n", trf->state);

	ret = trf7970a_cmd(trf, TRF7970A_CMD_SOFT_INIT);
	if (ret)
		goto err_out;

	ret = trf7970a_cmd(trf, TRF7970A_CMD_IDLE);
	if (ret)
		goto err_out;

	/* Must clear NFC Target Detection Level reg due to erratum */
	ret = trf7970a_write(trf, TRF7970A_NFC_TARGET_LEVEL, 0);
	if (ret)
		goto err_out;

	ret = trf7970a_write(trf, TRF7970A_ADJUTABLE_FIFO_IRQ_LEVELS,
			TRF7970A_ADJUTABLE_FIFO_IRQ_LEVELS_WLH_96 |
			TRF7970A_ADJUTABLE_FIFO_IRQ_LEVELS_WLL_32);
	if (ret)
		goto err_out;

	ret = trf7970a_write(trf, TRF7970A_SPECIAL_FCN_REG1, 0);
	if (ret)
		goto err_out;

	trf->special_fcn_reg1 = 0;

	trf->iso_ctrl = 0xff;
	return 0;

err_out:
	dev_dbg(trf->dev, "Couldn't init device: %d\n", ret);
	return ret;
}

static void trf7970a_switch_rf_off(struct trf7970a *trf)
{
	dev_dbg(trf->dev, "Switching rf off\n");

	trf->chip_status_ctrl &= ~TRF7970A_CHIP_STATUS_RF_ON;

	trf7970a_write(trf, TRF7970A_CHIP_STATUS_CTRL, trf->chip_status_ctrl);

	trf->aborting = false;
	trf->state = TRF7970A_ST_OFF;

	pm_runtime_mark_last_busy(trf->dev);
	pm_runtime_put_autosuspend(trf->dev);
}

static void trf7970a_switch_rf_on(struct trf7970a *trf)
{
	dev_dbg(trf->dev, "Switching rf on\n");

	pm_runtime_get_sync(trf->dev);

	trf->state = TRF7970A_ST_IDLE;
}

static int trf7970a_switch_rf(struct nfc_digital_dev *ddev, bool on)
{
	struct trf7970a *trf = nfc_digital_get_drvdata(ddev);

	dev_dbg(trf->dev, "Switching RF - state: %d, on: %d\n", trf->state, on);

	mutex_lock(&trf->lock);

	if (on) {
		switch (trf->state) {
		case TRF7970A_ST_OFF:
			trf7970a_switch_rf_on(trf);
			break;
		case TRF7970A_ST_IDLE:
		case TRF7970A_ST_IDLE_RX_BLOCKED:
			break;
		default:
			dev_err(trf->dev, "%s - Invalid request: %d %d\n",
					__func__, trf->state, on);
			trf7970a_switch_rf_off(trf);
		}
	} else {
		switch (trf->state) {
		case TRF7970A_ST_OFF:
			break;
		default:
			dev_err(trf->dev, "%s - Invalid request: %d %d\n",
					__func__, trf->state, on);
			/* FALLTHROUGH */
		case TRF7970A_ST_IDLE:
		case TRF7970A_ST_IDLE_RX_BLOCKED:
			trf7970a_switch_rf_off(trf);
		}
	}

	mutex_unlock(&trf->lock);
	return 0;
}

static int trf7970a_config_rf_tech(struct trf7970a *trf, int tech)
{
	int ret = 0;

	dev_dbg(trf->dev, "rf technology: %d\n", tech);

	switch (tech) {
	case NFC_DIGITAL_RF_TECH_106A:
		trf->iso_ctrl_tech = TRF7970A_ISO_CTRL_14443A_106;
		trf->modulator_sys_clk_ctrl = TRF7970A_MODULATOR_DEPTH_OOK;
		break;
	case NFC_DIGITAL_RF_TECH_106B:
		trf->iso_ctrl_tech = TRF7970A_ISO_CTRL_14443B_106;
		trf->modulator_sys_clk_ctrl = TRF7970A_MODULATOR_DEPTH_ASK10;
		break;
	case NFC_DIGITAL_RF_TECH_212F:
		trf->iso_ctrl_tech = TRF7970A_ISO_CTRL_FELICA_212;
		trf->modulator_sys_clk_ctrl = TRF7970A_MODULATOR_DEPTH_ASK10;
		break;
	case NFC_DIGITAL_RF_TECH_424F:
		trf->iso_ctrl_tech = TRF7970A_ISO_CTRL_FELICA_424;
		trf->modulator_sys_clk_ctrl = TRF7970A_MODULATOR_DEPTH_ASK10;
		break;
	case NFC_DIGITAL_RF_TECH_ISO15693:
		trf->iso_ctrl_tech = TRF7970A_ISO_CTRL_15693_SGL_1OF4_2648;
		trf->modulator_sys_clk_ctrl = TRF7970A_MODULATOR_DEPTH_OOK;
		break;
	default:
		dev_dbg(trf->dev, "Unsupported rf technology: %d\n", tech);
		return -EINVAL;
	}

	trf->technology = tech;

	return ret;
}

static int trf7970a_config_framing(struct trf7970a *trf, int framing)
{
	u8 iso_ctrl = trf->iso_ctrl_tech;
	int ret;

	dev_dbg(trf->dev, "framing: %d\n", framing);

	switch (framing) {
	case NFC_DIGITAL_FRAMING_NFCA_SHORT:
	case NFC_DIGITAL_FRAMING_NFCA_STANDARD:
		trf->tx_cmd = TRF7970A_CMD_TRANSMIT_NO_CRC;
		iso_ctrl |= TRF7970A_ISO_CTRL_RX_CRC_N;
		break;
	case NFC_DIGITAL_FRAMING_NFCA_STANDARD_WITH_CRC_A:
	case NFC_DIGITAL_FRAMING_NFCA_T4T:
	case NFC_DIGITAL_FRAMING_NFCB:
	case NFC_DIGITAL_FRAMING_NFCB_T4T:
	case NFC_DIGITAL_FRAMING_NFCF:
	case NFC_DIGITAL_FRAMING_NFCF_T3T:
	case NFC_DIGITAL_FRAMING_ISO15693_INVENTORY:
	case NFC_DIGITAL_FRAMING_ISO15693_T5T:
		trf->tx_cmd = TRF7970A_CMD_TRANSMIT;
		iso_ctrl &= ~TRF7970A_ISO_CTRL_RX_CRC_N;
		break;
	case NFC_DIGITAL_FRAMING_NFCA_T2T:
		trf->tx_cmd = TRF7970A_CMD_TRANSMIT;
		iso_ctrl |= TRF7970A_ISO_CTRL_RX_CRC_N;
		break;
	default:
		dev_dbg(trf->dev, "Unsupported Framing: %d\n", framing);
		return -EINVAL;
	}

	trf->framing = framing;

	if (iso_ctrl != trf->iso_ctrl) {
		ret = trf7970a_write(trf, TRF7970A_ISO_CTRL, iso_ctrl);
		if (ret)
			return ret;

		trf->iso_ctrl = iso_ctrl;

		ret = trf7970a_write(trf, TRF7970A_MODULATOR_SYS_CLK_CTRL,
				trf->modulator_sys_clk_ctrl);
		if (ret)
			return ret;
	}

	if (!(trf->chip_status_ctrl & TRF7970A_CHIP_STATUS_RF_ON)) {
		ret = trf7970a_write(trf, TRF7970A_CHIP_STATUS_CTRL,
				trf->chip_status_ctrl |
					TRF7970A_CHIP_STATUS_RF_ON);
		if (ret)
			return ret;

		trf->chip_status_ctrl |= TRF7970A_CHIP_STATUS_RF_ON;

		usleep_range(5000, 6000);
	}

	return 0;
}

static int trf7970a_in_configure_hw(struct nfc_digital_dev *ddev, int type,
		int param)
{
	struct trf7970a *trf = nfc_digital_get_drvdata(ddev);
	int ret;

	dev_dbg(trf->dev, "Configure hw - type: %d, param: %d\n", type, param);

	mutex_lock(&trf->lock);

	if (trf->state == TRF7970A_ST_OFF)
		trf7970a_switch_rf_on(trf);

	switch (type) {
	case NFC_DIGITAL_CONFIG_RF_TECH:
		ret = trf7970a_config_rf_tech(trf, param);
		break;
	case NFC_DIGITAL_CONFIG_FRAMING:
		ret = trf7970a_config_framing(trf, param);
		break;
	default:
		dev_dbg(trf->dev, "Unknown type: %d\n", type);
		ret = -EINVAL;
	}

	mutex_unlock(&trf->lock);
	return ret;
}

static int trf7970a_is_iso15693_write_or_lock(u8 cmd)
{
	switch (cmd) {
	case ISO15693_CMD_WRITE_SINGLE_BLOCK:
	case ISO15693_CMD_LOCK_BLOCK:
	case ISO15693_CMD_WRITE_MULTIPLE_BLOCK:
	case ISO15693_CMD_WRITE_AFI:
	case ISO15693_CMD_LOCK_AFI:
	case ISO15693_CMD_WRITE_DSFID:
	case ISO15693_CMD_LOCK_DSFID:
		return 1;
		break;
	default:
		return 0;
	}
}

static int trf7970a_per_cmd_config(struct trf7970a *trf, struct sk_buff *skb)
{
	u8 *req = skb->data;
	u8 special_fcn_reg1, iso_ctrl;
	int ret;

	trf->issue_eof = false;

	/* When issuing Type 2 read command, make sure the '4_bit_RX' bit in
	 * special functions register 1 is cleared; otherwise, its a write or
	 * sector select command and '4_bit_RX' must be set.
	 *
	 * When issuing an ISO 15693 command, inspect the flags byte to see
	 * what speed to use.  Also, remember if the OPTION flag is set on
	 * a Type 5 write or lock command so the driver will know that it
	 * has to send an EOF in order to get a response.
	 */
	if ((trf->technology == NFC_DIGITAL_RF_TECH_106A) &&
			(trf->framing == NFC_DIGITAL_FRAMING_NFCA_T2T)) {
		if (req[0] == NFC_T2T_CMD_READ)
			special_fcn_reg1 = 0;
		else
			special_fcn_reg1 = TRF7970A_SPECIAL_FCN_REG1_4_BIT_RX;

		if (special_fcn_reg1 != trf->special_fcn_reg1) {
			ret = trf7970a_write(trf, TRF7970A_SPECIAL_FCN_REG1,
					special_fcn_reg1);
			if (ret)
				return ret;

			trf->special_fcn_reg1 = special_fcn_reg1;
		}
	} else if (trf->technology == NFC_DIGITAL_RF_TECH_ISO15693) {
		iso_ctrl = trf->iso_ctrl & ~TRF7970A_ISO_CTRL_RFID_SPEED_MASK;

		switch (req[0] & ISO15693_REQ_FLAG_SPEED_MASK) {
		case 0x00:
			iso_ctrl |= TRF7970A_ISO_CTRL_15693_SGL_1OF4_662;
			break;
		case ISO15693_REQ_FLAG_SUB_CARRIER:
			iso_ctrl |= TRF7970A_ISO_CTRL_15693_DBL_1OF4_667a;
			break;
		case ISO15693_REQ_FLAG_DATA_RATE:
			iso_ctrl |= TRF7970A_ISO_CTRL_15693_SGL_1OF4_2648;
			break;
		case (ISO15693_REQ_FLAG_SUB_CARRIER |
				ISO15693_REQ_FLAG_DATA_RATE):
			iso_ctrl |= TRF7970A_ISO_CTRL_15693_DBL_1OF4_2669;
			break;
		}

		if (iso_ctrl != trf->iso_ctrl) {
			ret = trf7970a_write(trf, TRF7970A_ISO_CTRL, iso_ctrl);
			if (ret)
				return ret;

			trf->iso_ctrl = iso_ctrl;
		}

		if ((trf->framing == NFC_DIGITAL_FRAMING_ISO15693_T5T) &&
				trf7970a_is_iso15693_write_or_lock(req[1]) &&
				(req[0] & ISO15693_REQ_FLAG_OPTION))
			trf->issue_eof = true;
	}

	return 0;
}

static int trf7970a_in_send_cmd(struct nfc_digital_dev *ddev,
		struct sk_buff *skb, u16 timeout,
		nfc_digital_cmd_complete_t cb, void *arg)
{
	struct trf7970a *trf = nfc_digital_get_drvdata(ddev);
	char *prefix;
	unsigned int len;
	int ret;

	dev_dbg(trf->dev, "New request - state: %d, timeout: %d ms, len: %d\n",
			trf->state, timeout, skb->len);

	if (skb->len > TRF7970A_TX_MAX)
		return -EINVAL;

	mutex_lock(&trf->lock);

	if ((trf->state != TRF7970A_ST_IDLE) &&
			(trf->state != TRF7970A_ST_IDLE_RX_BLOCKED)) {
		dev_err(trf->dev, "%s - Bogus state: %d\n", __func__,
				trf->state);
		ret = -EIO;
		goto out_err;
	}

	if (trf->aborting) {
		dev_dbg(trf->dev, "Abort process complete\n");
		trf->aborting = false;
		ret = -ECANCELED;
		goto out_err;
	}

	trf->rx_skb = nfc_alloc_recv_skb(TRF7970A_RX_SKB_ALLOC_SIZE,
			GFP_KERNEL);
	if (!trf->rx_skb) {
		dev_dbg(trf->dev, "Can't alloc rx_skb\n");
		ret = -ENOMEM;
		goto out_err;
	}

	if (trf->state == TRF7970A_ST_IDLE_RX_BLOCKED) {
		ret = trf7970a_cmd(trf, TRF7970A_CMD_ENABLE_RX);
		if (ret)
			goto out_err;

		trf->state = TRF7970A_ST_IDLE;
	}

	ret = trf7970a_per_cmd_config(trf, skb);
	if (ret)
		goto out_err;

	trf->ddev = ddev;
	trf->tx_skb = skb;
	trf->cb = cb;
	trf->cb_arg = arg;
	trf->timeout = timeout;
	trf->ignore_timeout = false;

	len = skb->len;
	prefix = skb_push(skb, TRF7970A_TX_SKB_HEADROOM);

	/* TX data must be prefixed with a FIFO reset cmd, a cmd that depends
	 * on what the current framing is, the address of the TX length byte 1
	 * register (0x1d), and the 2 byte length of the data to be transmitted.
	 */
	prefix[0] = TRF7970A_CMD_BIT_CTRL |
			TRF7970A_CMD_BIT_OPCODE(TRF7970A_CMD_FIFO_RESET);
	prefix[1] = TRF7970A_CMD_BIT_CTRL |
			TRF7970A_CMD_BIT_OPCODE(trf->tx_cmd);
	prefix[2] = TRF7970A_CMD_BIT_CONTINUOUS | TRF7970A_TX_LENGTH_BYTE1;

	if (trf->framing == NFC_DIGITAL_FRAMING_NFCA_SHORT) {
		prefix[3] = 0x00;
		prefix[4] = 0x0f; /* 7 bits */
	} else {
		prefix[3] = (len & 0xf00) >> 4;
		prefix[3] |= ((len & 0xf0) >> 4);
		prefix[4] = ((len & 0x0f) << 4);
	}

	len = min_t(int, skb->len, TRF7970A_FIFO_SIZE);

	usleep_range(1000, 2000);

	ret = trf7970a_transmit(trf, skb, len);
	if (ret) {
		kfree_skb(trf->rx_skb);
		trf->rx_skb = NULL;
	}

out_err:
	mutex_unlock(&trf->lock);
	return ret;
}

static int trf7970a_tg_configure_hw(struct nfc_digital_dev *ddev,
		int type, int param)
{
	struct trf7970a *trf = nfc_digital_get_drvdata(ddev);

	dev_dbg(trf->dev, "Unsupported interface\n");

	return -EINVAL;
}

static int trf7970a_tg_send_cmd(struct nfc_digital_dev *ddev,
		struct sk_buff *skb, u16 timeout,
		nfc_digital_cmd_complete_t cb, void *arg)
{
	struct trf7970a *trf = nfc_digital_get_drvdata(ddev);

	dev_dbg(trf->dev, "Unsupported interface\n");

	return -EINVAL;
}

static int trf7970a_tg_listen(struct nfc_digital_dev *ddev,
		u16 timeout, nfc_digital_cmd_complete_t cb, void *arg)
{
	struct trf7970a *trf = nfc_digital_get_drvdata(ddev);

	dev_dbg(trf->dev, "Unsupported interface\n");

	return -EINVAL;
}

static int trf7970a_tg_listen_mdaa(struct nfc_digital_dev *ddev,
		struct digital_tg_mdaa_params *mdaa_params,
		u16 timeout, nfc_digital_cmd_complete_t cb, void *arg)
{
	struct trf7970a *trf = nfc_digital_get_drvdata(ddev);

	dev_dbg(trf->dev, "Unsupported interface\n");

	return -EINVAL;
}

static void trf7970a_abort_cmd(struct nfc_digital_dev *ddev)
{
	struct trf7970a *trf = nfc_digital_get_drvdata(ddev);

	dev_dbg(trf->dev, "Abort process initiated\n");

	mutex_lock(&trf->lock);

	switch (trf->state) {
	case TRF7970A_ST_WAIT_FOR_TX_FIFO:
	case TRF7970A_ST_WAIT_FOR_RX_DATA:
	case TRF7970A_ST_WAIT_FOR_RX_DATA_CONT:
	case TRF7970A_ST_WAIT_TO_ISSUE_EOF:
		trf->aborting = true;
		break;
	default:
		break;
	}

	mutex_unlock(&trf->lock);
}

static struct nfc_digital_ops trf7970a_nfc_ops = {
	.in_configure_hw	= trf7970a_in_configure_hw,
	.in_send_cmd		= trf7970a_in_send_cmd,
	.tg_configure_hw	= trf7970a_tg_configure_hw,
	.tg_send_cmd		= trf7970a_tg_send_cmd,
	.tg_listen		= trf7970a_tg_listen,
	.tg_listen_mdaa		= trf7970a_tg_listen_mdaa,
	.switch_rf		= trf7970a_switch_rf,
	.abort_cmd		= trf7970a_abort_cmd,
};

static int trf7970a_get_autosuspend_delay(struct device_node *np)
{
	int autosuspend_delay, ret;

	ret = of_property_read_u32(np, "autosuspend-delay", &autosuspend_delay);
	if (ret)
		autosuspend_delay = TRF7970A_AUTOSUSPEND_DELAY;

	of_node_put(np);

	return autosuspend_delay;
}

static int trf7970a_probe(struct spi_device *spi)
{
	struct device_node *np = spi->dev.of_node;
	const struct spi_device_id *id = spi_get_device_id(spi);
	struct trf7970a *trf;
	int uvolts, autosuspend_delay, ret;

	if (!np) {
		dev_err(&spi->dev, "No Device Tree entry\n");
		return -EINVAL;
	}

	trf = devm_kzalloc(&spi->dev, sizeof(*trf), GFP_KERNEL);
	if (!trf)
		return -ENOMEM;

	trf->state = TRF7970A_ST_OFF;
	trf->dev = &spi->dev;
	trf->spi = spi;
	trf->quirks = id->driver_data;

	spi->mode = SPI_MODE_1;
	spi->bits_per_word = 8;

	/* There are two enable pins - both must be present */
	trf->en_gpio = of_get_named_gpio(np, "ti,enable-gpios", 0);
	if (!gpio_is_valid(trf->en_gpio)) {
		dev_err(trf->dev, "No EN GPIO property\n");
		return trf->en_gpio;
	}

	ret = devm_gpio_request_one(trf->dev, trf->en_gpio,
			GPIOF_DIR_OUT | GPIOF_INIT_LOW, "EN");
	if (ret) {
		dev_err(trf->dev, "Can't request EN GPIO: %d\n", ret);
		return ret;
	}

	trf->en2_gpio = of_get_named_gpio(np, "ti,enable-gpios", 1);
	if (!gpio_is_valid(trf->en2_gpio)) {
		dev_err(trf->dev, "No EN2 GPIO property\n");
		return trf->en2_gpio;
	}

	ret = devm_gpio_request_one(trf->dev, trf->en2_gpio,
			GPIOF_DIR_OUT | GPIOF_INIT_LOW, "EN2");
	if (ret) {
		dev_err(trf->dev, "Can't request EN2 GPIO: %d\n", ret);
		return ret;
	}

	ret = devm_request_threaded_irq(trf->dev, spi->irq, NULL,
			trf7970a_irq, IRQF_TRIGGER_RISING | IRQF_ONESHOT,
			"trf7970a", trf);
	if (ret) {
		dev_err(trf->dev, "Can't request IRQ#%d: %d\n", spi->irq, ret);
		return ret;
	}

	mutex_init(&trf->lock);
	INIT_DELAYED_WORK(&trf->timeout_work, trf7970a_timeout_work_handler);

	trf->regulator = devm_regulator_get(&spi->dev, "vin");
	if (IS_ERR(trf->regulator)) {
		ret = PTR_ERR(trf->regulator);
		dev_err(trf->dev, "Can't get VIN regulator: %d\n", ret);
		goto err_destroy_lock;
	}

	ret = regulator_enable(trf->regulator);
	if (ret) {
		dev_err(trf->dev, "Can't enable VIN: %d\n", ret);
		goto err_destroy_lock;
	}

	uvolts = regulator_get_voltage(trf->regulator);

	if (uvolts > 4000000)
		trf->chip_status_ctrl = TRF7970A_CHIP_STATUS_VRS5_3;

	trf->ddev = nfc_digital_allocate_device(&trf7970a_nfc_ops,
			TRF7970A_SUPPORTED_PROTOCOLS,
			NFC_DIGITAL_DRV_CAPS_IN_CRC, TRF7970A_TX_SKB_HEADROOM,
			0);
	if (!trf->ddev) {
		dev_err(trf->dev, "Can't allocate NFC digital device\n");
		ret = -ENOMEM;
		goto err_disable_regulator;
	}

	nfc_digital_set_parent_dev(trf->ddev, trf->dev);
	nfc_digital_set_drvdata(trf->ddev, trf);
	spi_set_drvdata(spi, trf);

	autosuspend_delay = trf7970a_get_autosuspend_delay(np);

	pm_runtime_set_autosuspend_delay(trf->dev, autosuspend_delay);
	pm_runtime_use_autosuspend(trf->dev);
	pm_runtime_enable(trf->dev);

	ret = nfc_digital_register_device(trf->ddev);
	if (ret) {
		dev_err(trf->dev, "Can't register NFC digital device: %d\n",
				ret);
		goto err_free_ddev;
	}

	return 0;

err_free_ddev:
	pm_runtime_disable(trf->dev);
	nfc_digital_free_device(trf->ddev);
err_disable_regulator:
	regulator_disable(trf->regulator);
err_destroy_lock:
	mutex_destroy(&trf->lock);
	return ret;
}

static int trf7970a_remove(struct spi_device *spi)
{
	struct trf7970a *trf = spi_get_drvdata(spi);

	mutex_lock(&trf->lock);

	switch (trf->state) {
	case TRF7970A_ST_WAIT_FOR_TX_FIFO:
	case TRF7970A_ST_WAIT_FOR_RX_DATA:
	case TRF7970A_ST_WAIT_FOR_RX_DATA_CONT:
	case TRF7970A_ST_WAIT_TO_ISSUE_EOF:
		trf7970a_send_err_upstream(trf, -ECANCELED);
		/* FALLTHROUGH */
	case TRF7970A_ST_IDLE:
	case TRF7970A_ST_IDLE_RX_BLOCKED:
		pm_runtime_put_sync(trf->dev);
		break;
	default:
		break;
	}

	mutex_unlock(&trf->lock);

	pm_runtime_disable(trf->dev);

	nfc_digital_unregister_device(trf->ddev);
	nfc_digital_free_device(trf->ddev);

	regulator_disable(trf->regulator);

	mutex_destroy(&trf->lock);

	return 0;
}

#ifdef CONFIG_PM_RUNTIME
static int trf7970a_pm_runtime_suspend(struct device *dev)
{
	struct spi_device *spi = container_of(dev, struct spi_device, dev);
	struct trf7970a *trf = spi_get_drvdata(spi);
	int ret;

	dev_dbg(dev, "Runtime suspend\n");

	if (trf->state != TRF7970A_ST_OFF) {
		dev_dbg(dev, "Can't suspend - not in OFF state (%d)\n",
				trf->state);
		return -EBUSY;
	}

	gpio_set_value(trf->en_gpio, 0);
	gpio_set_value(trf->en2_gpio, 0);

	ret = regulator_disable(trf->regulator);
	if (ret)
		dev_err(dev, "%s - Can't disable VIN: %d\n", __func__, ret);

	return ret;
}

static int trf7970a_pm_runtime_resume(struct device *dev)
{
	struct spi_device *spi = container_of(dev, struct spi_device, dev);
	struct trf7970a *trf = spi_get_drvdata(spi);
	int ret;

	dev_dbg(dev, "Runtime resume\n");

	ret = regulator_enable(trf->regulator);
	if (ret) {
		dev_err(dev, "%s - Can't enable VIN: %d\n", __func__, ret);
		return ret;
	}

	usleep_range(5000, 6000);

	gpio_set_value(trf->en2_gpio, 1);
	usleep_range(1000, 2000);
	gpio_set_value(trf->en_gpio, 1);

	usleep_range(20000, 21000);

	ret = trf7970a_init(trf);
	if (ret) {
		dev_err(dev, "%s - Can't initialize: %d\n", __func__, ret);
		return ret;
	}

	pm_runtime_mark_last_busy(dev);

	return 0;
}
#endif

static const struct dev_pm_ops trf7970a_pm_ops = {
	SET_RUNTIME_PM_OPS(trf7970a_pm_runtime_suspend,
			trf7970a_pm_runtime_resume, NULL)
};

static const struct spi_device_id trf7970a_id_table[] = {
	{ "trf7970a", TRF7970A_QUIRK_IRQ_STATUS_READ_ERRATA },
	{ }
};
MODULE_DEVICE_TABLE(spi, trf7970a_id_table);

static struct spi_driver trf7970a_spi_driver = {
	.probe		= trf7970a_probe,
	.remove		= trf7970a_remove,
	.id_table	= trf7970a_id_table,
	.driver		= {
		.name	= "trf7970a",
		.owner	= THIS_MODULE,
		.pm	= &trf7970a_pm_ops,
	},
};

module_spi_driver(trf7970a_spi_driver);

MODULE_AUTHOR("Mark A. Greer <mgreer@animalcreek.com>");
MODULE_LICENSE("GPL v2");
MODULE_DESCRIPTION("TI trf7970a RFID/NFC Transceiver Driver");