summaryrefslogtreecommitdiff
path: root/drivers/nfc/st95hf/core.c
blob: e42850095892d41fbbf43dc797d28efd5a3d3537 (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
// SPDX-License-Identifier: GPL-2.0-only
/*
 * --------------------------------------------------------------------
 * Driver for ST NFC Transceiver ST95HF
 * --------------------------------------------------------------------
 * Copyright (C) 2015 STMicroelectronics Pvt. Ltd. All rights reserved.
 */

#include <linux/err.h>
#include <linux/gpio.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/module.h>
#include <linux/netdevice.h>
#include <linux/nfc.h>
#include <linux/of_gpio.h>
#include <linux/of.h>
#include <linux/of_irq.h>
#include <linux/property.h>
#include <linux/regulator/consumer.h>
#include <linux/wait.h>
#include <net/nfc/digital.h>
#include <net/nfc/nfc.h>

#include "spi.h"

/* supported protocols */
#define ST95HF_SUPPORTED_PROT		(NFC_PROTO_ISO14443_MASK | \
					NFC_PROTO_ISO14443_B_MASK | \
					NFC_PROTO_ISO15693_MASK)
/* driver capabilities */
#define ST95HF_CAPABILITIES		NFC_DIGITAL_DRV_CAPS_IN_CRC

/* Command Send Interface */
/* ST95HF_COMMAND_SEND CMD Ids */
#define ECHO_CMD			0x55
#define WRITE_REGISTER_CMD		0x9
#define PROTOCOL_SELECT_CMD		0x2
#define SEND_RECEIVE_CMD		0x4

/* Select protocol codes */
#define ISO15693_PROTOCOL_CODE		0x1
#define ISO14443A_PROTOCOL_CODE		0x2
#define ISO14443B_PROTOCOL_CODE		0x3

/*
 * head room len is 3
 * 1 byte for control byte
 * 1 byte for cmd
 * 1 byte for size
 */
#define ST95HF_HEADROOM_LEN		3

/*
 * tailroom is 1 for ISO14443A
 * and 0 for ISO14443B/ISO15693,
 * hence the max value 1 should be
 * taken.
 */
#define ST95HF_TAILROOM_LEN		1

/* Command Response interface */
#define MAX_RESPONSE_BUFFER_SIZE	280
#define ECHORESPONSE			0x55
#define ST95HF_ERR_MASK			0xF
#define ST95HF_TIMEOUT_ERROR		0x87
#define ST95HF_NFCA_CRC_ERR_MASK	0x20
#define ST95HF_NFCB_CRC_ERR_MASK	0x01

/* ST95HF transmission flag values */
#define TRFLAG_NFCA_SHORT_FRAME		0x07
#define TRFLAG_NFCA_STD_FRAME		0x08
#define TRFLAG_NFCA_STD_FRAME_CRC	0x28

/* Misc defs */
#define HIGH				1
#define LOW				0
#define ISO14443A_RATS_REQ		0xE0
#define RATS_TB1_PRESENT_MASK		0x20
#define RATS_TA1_PRESENT_MASK		0x10
#define TB1_FWI_MASK			0xF0
#define WTX_REQ_FROM_TAG		0xF2

#define MAX_CMD_LEN			0x7

#define MAX_CMD_PARAMS			4
struct cmd {
	int cmd_len;
	unsigned char cmd_id;
	unsigned char no_cmd_params;
	unsigned char cmd_params[MAX_CMD_PARAMS];
	enum req_type req;
};

struct param_list {
	int param_offset;
	int new_param_val;
};

/*
 * List of top-level cmds to be used internally by the driver.
 * All these commands are build on top of ST95HF basic commands
 * such as SEND_RECEIVE_CMD, PROTOCOL_SELECT_CMD, etc.
 * These top level cmds are used internally while implementing various ops of
 * digital layer/driver probe or extending the digital framework layer for
 * features that are not yet implemented there, for example, WTX cmd handling.
 */
enum st95hf_cmd_list {
	CMD_ECHO,
	CMD_ISO14443A_CONFIG,
	CMD_ISO14443A_DEMOGAIN,
	CMD_ISO14443B_DEMOGAIN,
	CMD_ISO14443A_PROTOCOL_SELECT,
	CMD_ISO14443B_PROTOCOL_SELECT,
	CMD_WTX_RESPONSE,
	CMD_FIELD_OFF,
	CMD_ISO15693_PROTOCOL_SELECT,
};

static const struct cmd cmd_array[] = {
	[CMD_ECHO] = {
		.cmd_len = 0x2,
		.cmd_id = ECHO_CMD,
		.no_cmd_params = 0,
		.req = SYNC,
	},
	[CMD_ISO14443A_CONFIG] = {
		.cmd_len = 0x7,
		.cmd_id = WRITE_REGISTER_CMD,
		.no_cmd_params = 0x4,
		.cmd_params = {0x3A, 0x00, 0x5A, 0x04},
		.req = SYNC,
	},
	[CMD_ISO14443A_DEMOGAIN] = {
		.cmd_len = 0x7,
		.cmd_id = WRITE_REGISTER_CMD,
		.no_cmd_params = 0x4,
		.cmd_params = {0x68, 0x01, 0x01, 0xDF},
		.req = SYNC,
	},
	[CMD_ISO14443B_DEMOGAIN] = {
		.cmd_len = 0x7,
		.cmd_id = WRITE_REGISTER_CMD,
		.no_cmd_params = 0x4,
		.cmd_params = {0x68, 0x01, 0x01, 0x51},
		.req = SYNC,
	},
	[CMD_ISO14443A_PROTOCOL_SELECT] = {
		.cmd_len = 0x7,
		.cmd_id = PROTOCOL_SELECT_CMD,
		.no_cmd_params = 0x4,
		.cmd_params = {ISO14443A_PROTOCOL_CODE, 0x00, 0x01, 0xA0},
		.req = SYNC,
	},
	[CMD_ISO14443B_PROTOCOL_SELECT] = {
		.cmd_len = 0x7,
		.cmd_id = PROTOCOL_SELECT_CMD,
		.no_cmd_params = 0x4,
		.cmd_params = {ISO14443B_PROTOCOL_CODE, 0x01, 0x03, 0xFF},
		.req = SYNC,
	},
	[CMD_WTX_RESPONSE] = {
		.cmd_len = 0x6,
		.cmd_id = SEND_RECEIVE_CMD,
		.no_cmd_params = 0x3,
		.cmd_params = {0xF2, 0x00, TRFLAG_NFCA_STD_FRAME_CRC},
		.req = ASYNC,
	},
	[CMD_FIELD_OFF] = {
		.cmd_len = 0x5,
		.cmd_id = PROTOCOL_SELECT_CMD,
		.no_cmd_params = 0x2,
		.cmd_params = {0x0, 0x0},
		.req = SYNC,
	},
	[CMD_ISO15693_PROTOCOL_SELECT] = {
		.cmd_len = 0x5,
		.cmd_id = PROTOCOL_SELECT_CMD,
		.no_cmd_params = 0x2,
		.cmd_params = {ISO15693_PROTOCOL_CODE, 0x0D},
		.req = SYNC,
	},
};

/* st95_digital_cmd_complete_arg stores client context */
struct st95_digital_cmd_complete_arg {
	struct sk_buff *skb_resp;
	nfc_digital_cmd_complete_t complete_cb;
	void *cb_usrarg;
	bool rats;
};

/*
 * structure containing ST95HF driver specific data.
 * @spicontext: structure containing information required
 *	for spi communication between st95hf and host.
 * @ddev: nfc digital device object.
 * @nfcdev: nfc device object.
 * @enable_gpio: gpio used to enable st95hf transceiver.
 * @complete_cb_arg: structure to store various context information
 *	that is passed from nfc requesting thread to the threaded ISR.
 * @st95hf_supply: regulator "consumer" for NFC device.
 * @sendrcv_trflag: last byte of frame send by sendrecv command
 *	of st95hf. This byte contains transmission flag info.
 * @exchange_lock: semaphore used for signaling the st95hf_remove
 *	function that the last outstanding async nfc request is finished.
 * @rm_lock: mutex for ensuring safe access of nfc digital object
 *	from threaded ISR. Usage of this mutex avoids any race between
 *	deletion of the object from st95hf_remove() and its access from
 *	the threaded ISR.
 * @nfcdev_free: flag to have the state of nfc device object.
 *	[alive | died]
 * @current_protocol: current nfc protocol.
 * @current_rf_tech: current rf technology.
 * @fwi: frame waiting index, received in reply of RATS according to
 *	digital protocol.
 */
struct st95hf_context {
	struct st95hf_spi_context spicontext;
	struct nfc_digital_dev *ddev;
	struct nfc_dev *nfcdev;
	unsigned int enable_gpio;
	struct st95_digital_cmd_complete_arg complete_cb_arg;
	struct regulator *st95hf_supply;
	unsigned char sendrcv_trflag;
	struct semaphore exchange_lock;
	struct mutex rm_lock;
	bool nfcdev_free;
	u8 current_protocol;
	u8 current_rf_tech;
	int fwi;
};

/*
 * st95hf_send_recv_cmd() is for sending commands to ST95HF
 * that are described in the cmd_array[]. It can optionally
 * receive the response if the cmd request is of type
 * SYNC. For that to happen caller must pass true to recv_res.
 * For ASYNC request, recv_res is ignored and the
 * function will never try to receive the response on behalf
 * of the caller.
 */
static int st95hf_send_recv_cmd(struct st95hf_context *st95context,
				enum st95hf_cmd_list cmd,
				int no_modif,
				struct param_list *list_array,
				bool recv_res)
{
	unsigned char spi_cmd_buffer[MAX_CMD_LEN];
	int i, ret;
	struct device *dev = &st95context->spicontext.spidev->dev;

	if (cmd_array[cmd].cmd_len > MAX_CMD_LEN)
		return -EINVAL;
	if (cmd_array[cmd].no_cmd_params < no_modif)
		return -EINVAL;
	if (no_modif && !list_array)
		return -EINVAL;

	spi_cmd_buffer[0] = ST95HF_COMMAND_SEND;
	spi_cmd_buffer[1] = cmd_array[cmd].cmd_id;
	spi_cmd_buffer[2] = cmd_array[cmd].no_cmd_params;

	memcpy(&spi_cmd_buffer[3], cmd_array[cmd].cmd_params,
	       spi_cmd_buffer[2]);

	for (i = 0; i < no_modif; i++) {
		if (list_array[i].param_offset >= cmd_array[cmd].no_cmd_params)
			return -EINVAL;
		spi_cmd_buffer[3 + list_array[i].param_offset] =
						list_array[i].new_param_val;
	}

	ret = st95hf_spi_send(&st95context->spicontext,
			      spi_cmd_buffer,
			      cmd_array[cmd].cmd_len,
			      cmd_array[cmd].req);
	if (ret) {
		dev_err(dev, "st95hf_spi_send failed with error %d\n", ret);
		return ret;
	}

	if (cmd_array[cmd].req == SYNC && recv_res) {
		unsigned char st95hf_response_arr[2];

		ret = st95hf_spi_recv_response(&st95context->spicontext,
					       st95hf_response_arr);
		if (ret < 0) {
			dev_err(dev, "spi error from st95hf_spi_recv_response(), err = 0x%x\n",
				ret);
			return ret;
		}

		if (st95hf_response_arr[0]) {
			dev_err(dev, "st95hf error from st95hf_spi_recv_response(), err = 0x%x\n",
				st95hf_response_arr[0]);
			return -EIO;
		}
	}

	return 0;
}

static int st95hf_echo_command(struct st95hf_context *st95context)
{
	int result = 0;
	unsigned char echo_response;

	result = st95hf_send_recv_cmd(st95context, CMD_ECHO, 0, NULL, false);
	if (result)
		return result;

	/* If control reached here, response can be taken */
	result = st95hf_spi_recv_echo_res(&st95context->spicontext,
					  &echo_response);
	if (result) {
		dev_err(&st95context->spicontext.spidev->dev,
			"err: echo response receieve error = 0x%x\n", result);
		return result;
	}

	if (echo_response == ECHORESPONSE)
		return 0;

	dev_err(&st95context->spicontext.spidev->dev, "err: echo res is 0x%x\n",
		echo_response);

	return -EIO;
}

static int secondary_configuration_type4a(struct st95hf_context *stcontext)
{
	int result = 0;
	struct device *dev = &stcontext->nfcdev->dev;

	/* 14443A config setting after select protocol */
	result = st95hf_send_recv_cmd(stcontext,
				      CMD_ISO14443A_CONFIG,
				      0,
				      NULL,
				      true);
	if (result) {
		dev_err(dev, "type a config cmd, err = 0x%x\n", result);
		return result;
	}

	/* 14443A demo gain setting */
	result = st95hf_send_recv_cmd(stcontext,
				      CMD_ISO14443A_DEMOGAIN,
				      0,
				      NULL,
				      true);
	if (result)
		dev_err(dev, "type a demogain cmd, err = 0x%x\n", result);

	return result;
}

static int secondary_configuration_type4b(struct st95hf_context *stcontext)
{
	int result = 0;
	struct device *dev = &stcontext->nfcdev->dev;

	result = st95hf_send_recv_cmd(stcontext,
				      CMD_ISO14443B_DEMOGAIN,
				      0,
				      NULL,
				      true);
	if (result)
		dev_err(dev, "type b demogain cmd, err = 0x%x\n", result);

	return result;
}

static int st95hf_select_protocol(struct st95hf_context *stcontext, int type)
{
	int result = 0;
	struct device *dev;

	dev = &stcontext->nfcdev->dev;

	switch (type) {
	case NFC_DIGITAL_RF_TECH_106A:
		stcontext->current_rf_tech = NFC_DIGITAL_RF_TECH_106A;
		result = st95hf_send_recv_cmd(stcontext,
					      CMD_ISO14443A_PROTOCOL_SELECT,
					      0,
					      NULL,
					      true);
		if (result) {
			dev_err(dev, "protocol sel, err = 0x%x\n",
				result);
			return result;
		}

		/* secondary config. for 14443Type 4A after protocol select */
		result = secondary_configuration_type4a(stcontext);
		if (result) {
			dev_err(dev, "type a secondary config, err = 0x%x\n",
				result);
			return result;
		}
		break;
	case NFC_DIGITAL_RF_TECH_106B:
		stcontext->current_rf_tech = NFC_DIGITAL_RF_TECH_106B;
		result = st95hf_send_recv_cmd(stcontext,
					      CMD_ISO14443B_PROTOCOL_SELECT,
					      0,
					      NULL,
					      true);
		if (result) {
			dev_err(dev, "protocol sel send, err = 0x%x\n",
				result);
			return result;
		}

		/*
		 * delay of 5-6 ms is required after select protocol
		 * command in case of ISO14443 Type B
		 */
		usleep_range(50000, 60000);

		/* secondary config. for 14443Type 4B after protocol select */
		result = secondary_configuration_type4b(stcontext);
		if (result) {
			dev_err(dev, "type b secondary config, err = 0x%x\n",
				result);
			return result;
		}
		break;
	case NFC_DIGITAL_RF_TECH_ISO15693:
		stcontext->current_rf_tech = NFC_DIGITAL_RF_TECH_ISO15693;
		result = st95hf_send_recv_cmd(stcontext,
					      CMD_ISO15693_PROTOCOL_SELECT,
					      0,
					      NULL,
					      true);
		if (result) {
			dev_err(dev, "protocol sel send, err = 0x%x\n",
				result);
			return result;
		}
		break;
	default:
		return -EINVAL;
	}

	return 0;
}

static void st95hf_send_st95enable_negativepulse(struct st95hf_context *st95con)
{
	/* First make irq_in pin high */
	gpio_set_value(st95con->enable_gpio, HIGH);

	/* wait for 1 milisecond */
	usleep_range(1000, 2000);

	/* Make irq_in pin low */
	gpio_set_value(st95con->enable_gpio, LOW);

	/* wait for minimum interrupt pulse to make st95 active */
	usleep_range(1000, 2000);

	/* At end make it high */
	gpio_set_value(st95con->enable_gpio, HIGH);
}

/*
 * Send a reset sequence over SPI bus (Reset command + wait 3ms +
 * negative pulse on st95hf enable gpio
 */
static int st95hf_send_spi_reset_sequence(struct st95hf_context *st95context)
{
	int result = 0;
	unsigned char reset_cmd = ST95HF_COMMAND_RESET;

	result = st95hf_spi_send(&st95context->spicontext,
				 &reset_cmd,
				 ST95HF_RESET_CMD_LEN,
				 ASYNC);
	if (result) {
		dev_err(&st95context->spicontext.spidev->dev,
			"spi reset sequence cmd error = %d", result);
		return result;
	}

	/* wait for 3 milisecond to complete the controller reset process */
	usleep_range(3000, 4000);

	/* send negative pulse to make st95hf active */
	st95hf_send_st95enable_negativepulse(st95context);

	/* wait for 10 milisecond : HFO setup time */
	usleep_range(10000, 20000);

	return result;
}

static int st95hf_por_sequence(struct st95hf_context *st95context)
{
	int nth_attempt = 1;
	int result;

	st95hf_send_st95enable_negativepulse(st95context);

	usleep_range(5000, 6000);
	do {
		/* send an ECHO command and checks ST95HF response */
		result = st95hf_echo_command(st95context);

		dev_dbg(&st95context->spicontext.spidev->dev,
			"response from echo function = 0x%x, attempt = %d\n",
			result, nth_attempt);

		if (!result)
			return 0;

		/* send an pulse on IRQ in case of the chip is on sleep state */
		if (nth_attempt == 2)
			st95hf_send_st95enable_negativepulse(st95context);
		else
			st95hf_send_spi_reset_sequence(st95context);

		/* delay of 50 milisecond */
		usleep_range(50000, 51000);
	} while (nth_attempt++ < 3);

	return -ETIMEDOUT;
}

static int iso14443_config_fdt(struct st95hf_context *st95context, int wtxm)
{
	int result = 0;
	struct device *dev = &st95context->spicontext.spidev->dev;
	struct nfc_digital_dev *nfcddev = st95context->ddev;
	unsigned char pp_typeb;
	struct param_list new_params[2];

	pp_typeb = cmd_array[CMD_ISO14443B_PROTOCOL_SELECT].cmd_params[2];

	if (nfcddev->curr_protocol == NFC_PROTO_ISO14443 &&
	    st95context->fwi < 4)
		st95context->fwi = 4;

	new_params[0].param_offset = 2;
	if (nfcddev->curr_protocol == NFC_PROTO_ISO14443)
		new_params[0].new_param_val = st95context->fwi;
	else if (nfcddev->curr_protocol == NFC_PROTO_ISO14443_B)
		new_params[0].new_param_val = pp_typeb;

	new_params[1].param_offset = 3;
	new_params[1].new_param_val = wtxm;

	switch (nfcddev->curr_protocol) {
	case NFC_PROTO_ISO14443:
		result = st95hf_send_recv_cmd(st95context,
					      CMD_ISO14443A_PROTOCOL_SELECT,
					      2,
					      new_params,
					      true);
		if (result) {
			dev_err(dev, "WTX type a sel proto, err = 0x%x\n",
				result);
			return result;
		}

		/* secondary config. for 14443Type 4A after protocol select */
		result = secondary_configuration_type4a(st95context);
		if (result) {
			dev_err(dev, "WTX type a second. config, err = 0x%x\n",
				result);
			return result;
		}
		break;
	case NFC_PROTO_ISO14443_B:
		result = st95hf_send_recv_cmd(st95context,
					      CMD_ISO14443B_PROTOCOL_SELECT,
					      2,
					      new_params,
					      true);
		if (result) {
			dev_err(dev, "WTX type b sel proto, err = 0x%x\n",
				result);
			return result;
		}

		/* secondary config. for 14443Type 4B after protocol select */
		result = secondary_configuration_type4b(st95context);
		if (result) {
			dev_err(dev, "WTX type b second. config, err = 0x%x\n",
				result);
			return result;
		}
		break;
	default:
		return -EINVAL;
	}

	return 0;
}

static int st95hf_handle_wtx(struct st95hf_context *stcontext,
			     bool new_wtx,
			     int wtx_val)
{
	int result = 0;
	unsigned char val_mm = 0;
	struct param_list new_params[1];
	struct nfc_digital_dev *nfcddev = stcontext->ddev;
	struct device *dev = &stcontext->nfcdev->dev;

	if (new_wtx) {
		result = iso14443_config_fdt(stcontext, wtx_val & 0x3f);
		if (result) {
			dev_err(dev, "Config. setting error on WTX req, err = 0x%x\n",
				result);
			return result;
		}

		/* Send response of wtx with ASYNC as no response expected */
		new_params[0].param_offset = 1;
		new_params[0].new_param_val = wtx_val;

		result = st95hf_send_recv_cmd(stcontext,
					      CMD_WTX_RESPONSE,
					      1,
					      new_params,
					      false);
		if (result)
			dev_err(dev, "WTX response send, err = 0x%x\n", result);
		return result;
	}

	/* if no new wtx, cofigure with default values */
	if (nfcddev->curr_protocol == NFC_PROTO_ISO14443)
		val_mm = cmd_array[CMD_ISO14443A_PROTOCOL_SELECT].cmd_params[3];
	else if (nfcddev->curr_protocol == NFC_PROTO_ISO14443_B)
		val_mm = cmd_array[CMD_ISO14443B_PROTOCOL_SELECT].cmd_params[3];

	result = iso14443_config_fdt(stcontext, val_mm);
	if (result)
		dev_err(dev, "Default config. setting error after WTX processing, err = 0x%x\n",
			result);

	return result;
}

static int st95hf_error_handling(struct st95hf_context *stcontext,
				 struct sk_buff *skb_resp,
				 int res_len)
{
	int result = 0;
	unsigned char error_byte;
	struct device *dev = &stcontext->nfcdev->dev;

	/* First check ST95HF specific error */
	if (skb_resp->data[0] & ST95HF_ERR_MASK) {
		if (skb_resp->data[0] == ST95HF_TIMEOUT_ERROR)
			result = -ETIMEDOUT;
		else
			result = -EIO;
	return  result;
	}

	/* Check for CRC err only if CRC is present in the tag response */
	switch (stcontext->current_rf_tech) {
	case NFC_DIGITAL_RF_TECH_106A:
		if (stcontext->sendrcv_trflag == TRFLAG_NFCA_STD_FRAME_CRC) {
			error_byte = skb_resp->data[res_len - 3];
			if (error_byte & ST95HF_NFCA_CRC_ERR_MASK) {
				/* CRC error occurred */
				dev_err(dev, "CRC error, byte received = 0x%x\n",
					error_byte);
				result = -EIO;
			}
		}
		break;
	case NFC_DIGITAL_RF_TECH_106B:
	case NFC_DIGITAL_RF_TECH_ISO15693:
		error_byte = skb_resp->data[res_len - 1];
		if (error_byte & ST95HF_NFCB_CRC_ERR_MASK) {
			/* CRC error occurred */
			dev_err(dev, "CRC error, byte received = 0x%x\n",
				error_byte);
			result = -EIO;
		}
		break;
	}

	return result;
}

static int st95hf_response_handler(struct st95hf_context *stcontext,
				   struct sk_buff *skb_resp,
				   int res_len)
{
	int result = 0;
	int skb_len;
	unsigned char val_mm;
	struct nfc_digital_dev *nfcddev = stcontext->ddev;
	struct device *dev = &stcontext->nfcdev->dev;
	struct st95_digital_cmd_complete_arg *cb_arg;

	cb_arg = &stcontext->complete_cb_arg;

	/* Process the response */
	skb_put(skb_resp, res_len);

	/* Remove st95 header */
	skb_pull(skb_resp, 2);

	skb_len = skb_resp->len;

	/* check if it is case of RATS request reply & FWI is present */
	if (nfcddev->curr_protocol == NFC_PROTO_ISO14443 && cb_arg->rats &&
	    (skb_resp->data[1] & RATS_TB1_PRESENT_MASK)) {
		if (skb_resp->data[1] & RATS_TA1_PRESENT_MASK)
			stcontext->fwi =
				(skb_resp->data[3] & TB1_FWI_MASK) >> 4;
		else
			stcontext->fwi =
				(skb_resp->data[2] & TB1_FWI_MASK) >> 4;

		val_mm = cmd_array[CMD_ISO14443A_PROTOCOL_SELECT].cmd_params[3];

		result = iso14443_config_fdt(stcontext, val_mm);
		if (result) {
			dev_err(dev, "error in config_fdt to handle fwi of ATS, error=%d\n",
				result);
			return result;
		}
	}
	cb_arg->rats = false;

	/* Remove CRC bytes only if received frames data has an eod (CRC) */
	switch (stcontext->current_rf_tech) {
	case NFC_DIGITAL_RF_TECH_106A:
		if (stcontext->sendrcv_trflag == TRFLAG_NFCA_STD_FRAME_CRC)
			skb_trim(skb_resp, (skb_len - 5));
		else
			skb_trim(skb_resp, (skb_len - 3));
		break;
	case NFC_DIGITAL_RF_TECH_106B:
	case NFC_DIGITAL_RF_TECH_ISO15693:
		skb_trim(skb_resp, (skb_len - 3));
		break;
	}

	return result;
}

static irqreturn_t st95hf_irq_handler(int irq, void  *st95hfcontext)
{
	struct st95hf_context *stcontext  =
		(struct st95hf_context *)st95hfcontext;

	if (stcontext->spicontext.req_issync) {
		complete(&stcontext->spicontext.done);
		stcontext->spicontext.req_issync = false;
		return IRQ_HANDLED;
	}

	return IRQ_WAKE_THREAD;
}

static irqreturn_t st95hf_irq_thread_handler(int irq, void  *st95hfcontext)
{
	int result = 0;
	int res_len;
	static bool wtx;
	struct device *spidevice;
	struct sk_buff *skb_resp;
	struct st95hf_context *stcontext  =
		(struct st95hf_context *)st95hfcontext;
	struct st95_digital_cmd_complete_arg *cb_arg;

	spidevice = &stcontext->spicontext.spidev->dev;

	/*
	 * check semaphore, if not down() already, then we don't
	 * know in which context the ISR is called and surely it
	 * will be a bug. Note that down() of the semaphore is done
	 * in the corresponding st95hf_in_send_cmd() and then
	 * only this ISR should be called. ISR will up() the
	 * semaphore before leaving. Hence when the ISR is called
	 * the correct behaviour is down_trylock() should always
	 * return 1 (indicating semaphore cant be taken and hence no
	 * change in semaphore count).
	 * If not, then we up() the semaphore and crash on
	 * a BUG() !
	 */
	if (!down_trylock(&stcontext->exchange_lock)) {
		up(&stcontext->exchange_lock);
		WARN(1, "unknown context in ST95HF ISR");
		return IRQ_NONE;
	}

	cb_arg = &stcontext->complete_cb_arg;
	skb_resp = cb_arg->skb_resp;

	mutex_lock(&stcontext->rm_lock);
	res_len = st95hf_spi_recv_response(&stcontext->spicontext,
					   skb_resp->data);
	if (res_len < 0) {
		dev_err(spidevice, "TISR spi response err = 0x%x\n", res_len);
		result = res_len;
		goto end;
	}

	/* if stcontext->nfcdev_free is true, it means remove already ran */
	if (stcontext->nfcdev_free) {
		result = -ENODEV;
		goto end;
	}

	if (skb_resp->data[2] == WTX_REQ_FROM_TAG) {
		/* Request for new FWT from tag */
		result = st95hf_handle_wtx(stcontext, true, skb_resp->data[3]);
		if (result)
			goto end;

		wtx = true;
		mutex_unlock(&stcontext->rm_lock);
		return IRQ_HANDLED;
	}

	result = st95hf_error_handling(stcontext, skb_resp, res_len);
	if (result)
		goto end;

	result = st95hf_response_handler(stcontext, skb_resp, res_len);
	if (result)
		goto end;

	/*
	 * If select protocol is done on wtx req. do select protocol
	 * again with default values
	 */
	if (wtx) {
		wtx = false;
		result = st95hf_handle_wtx(stcontext, false, 0);
		if (result)
			goto end;
	}

	/* call digital layer callback */
	cb_arg->complete_cb(stcontext->ddev, cb_arg->cb_usrarg, skb_resp);

	/* up the semaphore before returning */
	up(&stcontext->exchange_lock);
	mutex_unlock(&stcontext->rm_lock);

	return IRQ_HANDLED;

end:
	kfree_skb(skb_resp);
	wtx = false;
	cb_arg->rats = false;
	skb_resp = ERR_PTR(result);
	/* call of callback with error */
	cb_arg->complete_cb(stcontext->ddev, cb_arg->cb_usrarg, skb_resp);
	/* up the semaphore before returning */
	up(&stcontext->exchange_lock);
	mutex_unlock(&stcontext->rm_lock);
	return IRQ_HANDLED;
}

/* NFC ops functions definition */
static int st95hf_in_configure_hw(struct nfc_digital_dev *ddev,
				  int type,
				  int param)
{
	struct st95hf_context *stcontext = nfc_digital_get_drvdata(ddev);

	if (type == NFC_DIGITAL_CONFIG_RF_TECH)
		return st95hf_select_protocol(stcontext, param);

	if (type == NFC_DIGITAL_CONFIG_FRAMING) {
		switch (param) {
		case NFC_DIGITAL_FRAMING_NFCA_SHORT:
			stcontext->sendrcv_trflag = TRFLAG_NFCA_SHORT_FRAME;
			break;
		case NFC_DIGITAL_FRAMING_NFCA_STANDARD:
			stcontext->sendrcv_trflag = TRFLAG_NFCA_STD_FRAME;
			break;
		case NFC_DIGITAL_FRAMING_NFCA_T4T:
		case NFC_DIGITAL_FRAMING_NFCA_NFC_DEP:
		case NFC_DIGITAL_FRAMING_NFCA_STANDARD_WITH_CRC_A:
			stcontext->sendrcv_trflag = TRFLAG_NFCA_STD_FRAME_CRC;
			break;
		case NFC_DIGITAL_FRAMING_NFCB:
		case NFC_DIGITAL_FRAMING_ISO15693_INVENTORY:
		case NFC_DIGITAL_FRAMING_ISO15693_T5T:
			break;
		}
	}

	return 0;
}

static int rf_off(struct st95hf_context *stcontext)
{
	int rc;
	struct device *dev;

	dev = &stcontext->nfcdev->dev;

	rc = st95hf_send_recv_cmd(stcontext, CMD_FIELD_OFF, 0, NULL, true);
	if (rc)
		dev_err(dev, "protocol sel send field off, err = 0x%x\n", rc);

	return rc;
}

static int st95hf_in_send_cmd(struct nfc_digital_dev *ddev,
			      struct sk_buff *skb,
			      u16 timeout,
			      nfc_digital_cmd_complete_t cb,
			      void *arg)
{
	struct st95hf_context *stcontext = nfc_digital_get_drvdata(ddev);
	int rc;
	struct sk_buff *skb_resp;
	int len_data_to_tag = 0;

	skb_resp = nfc_alloc_recv_skb(MAX_RESPONSE_BUFFER_SIZE, GFP_KERNEL);
	if (!skb_resp) {
		rc = -ENOMEM;
		goto error;
	}

	switch (stcontext->current_rf_tech) {
	case NFC_DIGITAL_RF_TECH_106A:
		len_data_to_tag = skb->len + 1;
		skb_put_u8(skb, stcontext->sendrcv_trflag);
		break;
	case NFC_DIGITAL_RF_TECH_106B:
	case NFC_DIGITAL_RF_TECH_ISO15693:
		len_data_to_tag = skb->len;
		break;
	default:
		rc = -EINVAL;
		goto free_skb_resp;
	}

	skb_push(skb, 3);
	skb->data[0] = ST95HF_COMMAND_SEND;
	skb->data[1] = SEND_RECEIVE_CMD;
	skb->data[2] = len_data_to_tag;

	stcontext->complete_cb_arg.skb_resp = skb_resp;
	stcontext->complete_cb_arg.cb_usrarg = arg;
	stcontext->complete_cb_arg.complete_cb = cb;

	if ((skb->data[3] == ISO14443A_RATS_REQ) &&
	    ddev->curr_protocol == NFC_PROTO_ISO14443)
		stcontext->complete_cb_arg.rats = true;

	/*
	 * down the semaphore to indicate to remove func that an
	 * ISR is pending, note that it will not block here in any case.
	 * If found blocked, it is a BUG!
	 */
	rc = down_killable(&stcontext->exchange_lock);
	if (rc) {
		WARN(1, "Semaphore is not found up in st95hf_in_send_cmd\n");
		return rc;
	}

	rc = st95hf_spi_send(&stcontext->spicontext, skb->data,
			     skb->len,
			     ASYNC);
	if (rc) {
		dev_err(&stcontext->nfcdev->dev,
			"Error %d trying to perform data_exchange", rc);
		/* up the semaphore since ISR will never come in this case */
		up(&stcontext->exchange_lock);
		goto free_skb_resp;
	}

	kfree_skb(skb);

	return rc;

free_skb_resp:
	kfree_skb(skb_resp);
error:
	return rc;
}

/* p2p will be supported in a later release ! */
static int st95hf_tg_configure_hw(struct nfc_digital_dev *ddev,
				  int type,
				  int param)
{
	return 0;
}

static int st95hf_tg_send_cmd(struct nfc_digital_dev *ddev,
			      struct sk_buff *skb,
			      u16 timeout,
			      nfc_digital_cmd_complete_t cb,
			      void *arg)
{
	return 0;
}

static int st95hf_tg_listen(struct nfc_digital_dev *ddev,
			    u16 timeout,
			    nfc_digital_cmd_complete_t cb,
			    void *arg)
{
	return 0;
}

static int st95hf_tg_get_rf_tech(struct nfc_digital_dev *ddev, u8 *rf_tech)
{
	return 0;
}

static int st95hf_switch_rf(struct nfc_digital_dev *ddev, bool on)
{
	u8 rf_tech;
	struct st95hf_context *stcontext = nfc_digital_get_drvdata(ddev);

	rf_tech = ddev->curr_rf_tech;

	if (on)
		/* switch on RF field */
		return st95hf_select_protocol(stcontext, rf_tech);

	/* switch OFF RF field */
	return rf_off(stcontext);
}

/* TODO st95hf_abort_cmd */
static void st95hf_abort_cmd(struct nfc_digital_dev *ddev)
{
}

static struct nfc_digital_ops st95hf_nfc_digital_ops = {
	.in_configure_hw = st95hf_in_configure_hw,
	.in_send_cmd = st95hf_in_send_cmd,

	.tg_listen = st95hf_tg_listen,
	.tg_configure_hw = st95hf_tg_configure_hw,
	.tg_send_cmd = st95hf_tg_send_cmd,
	.tg_get_rf_tech = st95hf_tg_get_rf_tech,

	.switch_rf = st95hf_switch_rf,
	.abort_cmd = st95hf_abort_cmd,
};

static const struct spi_device_id st95hf_id[] = {
	{ "st95hf", 0 },
	{}
};
MODULE_DEVICE_TABLE(spi, st95hf_id);

static const struct of_device_id st95hf_spi_of_match[] = {
        { .compatible = "st,st95hf" },
        { },
};
MODULE_DEVICE_TABLE(of, st95hf_spi_of_match);

static int st95hf_probe(struct spi_device *nfc_spi_dev)
{
	int ret;

	struct st95hf_context *st95context;
	struct st95hf_spi_context *spicontext;

	nfc_info(&nfc_spi_dev->dev, "ST95HF driver probe called.\n");

	st95context = devm_kzalloc(&nfc_spi_dev->dev,
				   sizeof(struct st95hf_context),
				   GFP_KERNEL);
	if (!st95context)
		return -ENOMEM;

	spicontext = &st95context->spicontext;

	spicontext->spidev = nfc_spi_dev;

	st95context->fwi =
		cmd_array[CMD_ISO14443A_PROTOCOL_SELECT].cmd_params[2];

	if (device_property_present(&nfc_spi_dev->dev, "st95hfvin")) {
		st95context->st95hf_supply =
			devm_regulator_get(&nfc_spi_dev->dev,
					   "st95hfvin");
		if (IS_ERR(st95context->st95hf_supply)) {
			dev_err(&nfc_spi_dev->dev, "failed to acquire regulator\n");
			return PTR_ERR(st95context->st95hf_supply);
		}

		ret = regulator_enable(st95context->st95hf_supply);
		if (ret) {
			dev_err(&nfc_spi_dev->dev, "failed to enable regulator\n");
			return ret;
		}
	}

	init_completion(&spicontext->done);
	mutex_init(&spicontext->spi_lock);

	/*
	 * Store spicontext in spi device object for using it in
	 * remove function
	 */
	dev_set_drvdata(&nfc_spi_dev->dev, spicontext);

	st95context->enable_gpio =
		of_get_named_gpio(nfc_spi_dev->dev.of_node,
				  "enable-gpio",
				  0);
	if (!gpio_is_valid(st95context->enable_gpio)) {
		dev_err(&nfc_spi_dev->dev, "No valid enable gpio\n");
		ret = st95context->enable_gpio;
		goto err_disable_regulator;
	}

	ret = devm_gpio_request_one(&nfc_spi_dev->dev, st95context->enable_gpio,
				    GPIOF_DIR_OUT | GPIOF_INIT_HIGH,
				    "enable_gpio");
	if (ret)
		goto err_disable_regulator;

	if (nfc_spi_dev->irq > 0) {
		if (devm_request_threaded_irq(&nfc_spi_dev->dev,
					      nfc_spi_dev->irq,
					      st95hf_irq_handler,
					      st95hf_irq_thread_handler,
					      IRQF_TRIGGER_FALLING,
					      "st95hf",
					      (void *)st95context) < 0) {
			dev_err(&nfc_spi_dev->dev, "err: irq request for st95hf is failed\n");
			ret =  -EINVAL;
			goto err_disable_regulator;
		}
	} else {
		dev_err(&nfc_spi_dev->dev, "not a valid IRQ associated with ST95HF\n");
		ret = -EINVAL;
		goto err_disable_regulator;
	}

	/*
	 * First reset SPI to handle warm reset of the system.
	 * It will put the ST95HF device in Power ON state
	 * which make the state of device identical to state
	 * at the time of cold reset of the system.
	 */
	ret = st95hf_send_spi_reset_sequence(st95context);
	if (ret) {
		dev_err(&nfc_spi_dev->dev, "err: spi_reset_sequence failed\n");
		goto err_disable_regulator;
	}

	/* call PowerOnReset sequence of ST95hf to activate it */
	ret = st95hf_por_sequence(st95context);
	if (ret) {
		dev_err(&nfc_spi_dev->dev, "err: por seq failed for st95hf\n");
		goto err_disable_regulator;
	}

	/* create NFC dev object and register with NFC Subsystem */
	st95context->ddev = nfc_digital_allocate_device(&st95hf_nfc_digital_ops,
							ST95HF_SUPPORTED_PROT,
							ST95HF_CAPABILITIES,
							ST95HF_HEADROOM_LEN,
							ST95HF_TAILROOM_LEN);
	if (!st95context->ddev) {
		ret = -ENOMEM;
		goto err_disable_regulator;
	}

	st95context->nfcdev = st95context->ddev->nfc_dev;
	nfc_digital_set_parent_dev(st95context->ddev, &nfc_spi_dev->dev);

	ret =  nfc_digital_register_device(st95context->ddev);
	if (ret) {
		dev_err(&st95context->nfcdev->dev, "st95hf registration failed\n");
		goto err_free_digital_device;
	}

	/* store st95context in nfc device object */
	nfc_digital_set_drvdata(st95context->ddev, st95context);

	sema_init(&st95context->exchange_lock, 1);
	mutex_init(&st95context->rm_lock);

	return ret;

err_free_digital_device:
	nfc_digital_free_device(st95context->ddev);
err_disable_regulator:
	if (st95context->st95hf_supply)
		regulator_disable(st95context->st95hf_supply);

	return ret;
}

static int st95hf_remove(struct spi_device *nfc_spi_dev)
{
	int result = 0;
	unsigned char reset_cmd = ST95HF_COMMAND_RESET;
	struct st95hf_spi_context *spictx = dev_get_drvdata(&nfc_spi_dev->dev);

	struct st95hf_context *stcontext = container_of(spictx,
							struct st95hf_context,
							spicontext);

	mutex_lock(&stcontext->rm_lock);

	nfc_digital_unregister_device(stcontext->ddev);
	nfc_digital_free_device(stcontext->ddev);
	stcontext->nfcdev_free = true;

	mutex_unlock(&stcontext->rm_lock);

	/* if last in_send_cmd's ISR is pending, wait for it to finish */
	result = down_killable(&stcontext->exchange_lock);
	if (result == -EINTR)
		dev_err(&spictx->spidev->dev, "sleep for semaphore interrupted by signal\n");

	/* next reset the ST95HF controller */
	result = st95hf_spi_send(&stcontext->spicontext,
				 &reset_cmd,
				 ST95HF_RESET_CMD_LEN,
				 ASYNC);
	if (result) {
		dev_err(&spictx->spidev->dev,
			"ST95HF reset failed in remove() err = %d\n", result);
		return result;
	}

	/* wait for 3 ms to complete the controller reset process */
	usleep_range(3000, 4000);

	/* disable regulator */
	if (stcontext->st95hf_supply)
		regulator_disable(stcontext->st95hf_supply);

	return result;
}

/* Register as SPI protocol driver */
static struct spi_driver st95hf_driver = {
	.driver = {
		.name = "st95hf",
		.owner = THIS_MODULE,
		.of_match_table = of_match_ptr(st95hf_spi_of_match),
	},
	.id_table = st95hf_id,
	.probe = st95hf_probe,
	.remove = st95hf_remove,
};

module_spi_driver(st95hf_driver);

MODULE_AUTHOR("Shikha Singh <shikha.singh@st.com>");
MODULE_DESCRIPTION("ST NFC Transceiver ST95HF driver");
MODULE_LICENSE("GPL v2");