xref: /openbmc/linux/net/nfc/digital_technology.c (revision 31b90347)
1 /*
2  * NFC Digital Protocol stack
3  * Copyright (c) 2013, Intel Corporation.
4  *
5  * This program is free software; you can redistribute it and/or modify it
6  * under the terms and conditions of the GNU General Public License,
7  * version 2, as published by the Free Software Foundation.
8  *
9  * This program is distributed in the hope it will be useful, but WITHOUT
10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
12  * more details.
13  *
14  */
15 
16 #define pr_fmt(fmt) "digital: %s: " fmt, __func__
17 
18 #include "digital.h"
19 
20 #define DIGITAL_CMD_SENS_REQ    0x26
21 #define DIGITAL_CMD_ALL_REQ     0x52
22 #define DIGITAL_CMD_SEL_REQ_CL1 0x93
23 #define DIGITAL_CMD_SEL_REQ_CL2 0x95
24 #define DIGITAL_CMD_SEL_REQ_CL3 0x97
25 
26 #define DIGITAL_SDD_REQ_SEL_PAR 0x20
27 
28 #define DIGITAL_SDD_RES_CT  0x88
29 #define DIGITAL_SDD_RES_LEN 5
30 
31 #define DIGITAL_SEL_RES_NFCID1_COMPLETE(sel_res) (!((sel_res) & 0x04))
32 #define DIGITAL_SEL_RES_IS_T2T(sel_res) (!((sel_res) & 0x60))
33 #define DIGITAL_SEL_RES_IS_NFC_DEP(sel_res) ((sel_res) & 0x40)
34 
35 #define DIGITAL_SENS_RES_IS_T1T(sens_res) (((sens_res) & 0x0C00) == 0x0C00)
36 #define DIGITAL_SENS_RES_IS_VALID(sens_res) \
37 	((!((sens_res) & 0x001F) && (((sens_res) & 0x0C00) == 0x0C00)) || \
38 	(((sens_res) & 0x001F) && ((sens_res) & 0x0C00) != 0x0C00))
39 
40 #define DIGITAL_MIFARE_READ_RES_LEN 16
41 #define DIGITAL_MIFARE_ACK_RES	0x0A
42 
43 #define DIGITAL_CMD_SENSF_REQ	0x00
44 #define DIGITAL_CMD_SENSF_RES	0x01
45 
46 #define DIGITAL_SENSF_RES_MIN_LENGTH 17
47 #define DIGITAL_SENSF_RES_RD_AP_B1   0x00
48 #define DIGITAL_SENSF_RES_RD_AP_B2   0x8F
49 
50 #define DIGITAL_SENSF_REQ_RC_NONE 0
51 #define DIGITAL_SENSF_REQ_RC_SC   1
52 #define DIGITAL_SENSF_REQ_RC_AP   2
53 
54 struct digital_sdd_res {
55 	u8 nfcid1[4];
56 	u8 bcc;
57 } __packed;
58 
59 struct digital_sel_req {
60 	u8 sel_cmd;
61 	u8 b2;
62 	u8 nfcid1[4];
63 	u8 bcc;
64 } __packed;
65 
66 struct digital_sensf_req {
67 	u8 cmd;
68 	u8 sc1;
69 	u8 sc2;
70 	u8 rc;
71 	u8 tsn;
72 } __packed;
73 
74 struct digital_sensf_res {
75 	u8 cmd;
76 	u8 nfcid2[8];
77 	u8 pad0[2];
78 	u8 pad1[3];
79 	u8 mrti_check;
80 	u8 mrti_update;
81 	u8 pad2;
82 	u8 rd[2];
83 } __packed;
84 
85 static int digital_in_send_sdd_req(struct nfc_digital_dev *ddev,
86 				   struct nfc_target *target);
87 
88 static void digital_in_recv_sel_res(struct nfc_digital_dev *ddev, void *arg,
89 				    struct sk_buff *resp)
90 {
91 	struct nfc_target *target = arg;
92 	int rc;
93 	u8 sel_res;
94 	u8 nfc_proto;
95 
96 	if (IS_ERR(resp)) {
97 		rc = PTR_ERR(resp);
98 		resp = NULL;
99 		goto exit;
100 	}
101 
102 	if (!DIGITAL_DRV_CAPS_IN_CRC(ddev)) {
103 		rc = digital_skb_check_crc_a(resp);
104 		if (rc) {
105 			PROTOCOL_ERR("4.4.1.3");
106 			goto exit;
107 		}
108 	}
109 
110 	if (!resp->len) {
111 		rc = -EIO;
112 		goto exit;
113 	}
114 
115 	sel_res = resp->data[0];
116 
117 	if (!DIGITAL_SEL_RES_NFCID1_COMPLETE(sel_res)) {
118 		rc = digital_in_send_sdd_req(ddev, target);
119 		if (rc)
120 			goto exit;
121 
122 		goto exit_free_skb;
123 	}
124 
125 	if (DIGITAL_SEL_RES_IS_T2T(sel_res)) {
126 		nfc_proto = NFC_PROTO_MIFARE;
127 	} else if (DIGITAL_SEL_RES_IS_NFC_DEP(sel_res)) {
128 		nfc_proto = NFC_PROTO_NFC_DEP;
129 	} else {
130 		rc = -EOPNOTSUPP;
131 		goto exit;
132 	}
133 
134 	target->sel_res = sel_res;
135 
136 	rc = digital_target_found(ddev, target, nfc_proto);
137 
138 exit:
139 	kfree(target);
140 
141 exit_free_skb:
142 	dev_kfree_skb(resp);
143 
144 	if (rc)
145 		digital_poll_next_tech(ddev);
146 }
147 
148 static int digital_in_send_sel_req(struct nfc_digital_dev *ddev,
149 				   struct nfc_target *target,
150 				   struct digital_sdd_res *sdd_res)
151 {
152 	struct sk_buff *skb;
153 	struct digital_sel_req *sel_req;
154 	u8 sel_cmd;
155 	int rc;
156 
157 	skb = digital_skb_alloc(ddev, sizeof(struct digital_sel_req));
158 	if (!skb)
159 		return -ENOMEM;
160 
161 	skb_put(skb, sizeof(struct digital_sel_req));
162 	sel_req = (struct digital_sel_req *)skb->data;
163 
164 	if (target->nfcid1_len <= 4)
165 		sel_cmd = DIGITAL_CMD_SEL_REQ_CL1;
166 	else if (target->nfcid1_len < 10)
167 		sel_cmd = DIGITAL_CMD_SEL_REQ_CL2;
168 	else
169 		sel_cmd = DIGITAL_CMD_SEL_REQ_CL3;
170 
171 	sel_req->sel_cmd = sel_cmd;
172 	sel_req->b2 = 0x70;
173 	memcpy(sel_req->nfcid1, sdd_res->nfcid1, 4);
174 	sel_req->bcc = sdd_res->bcc;
175 
176 	if (DIGITAL_DRV_CAPS_IN_CRC(ddev)) {
177 		rc = digital_in_configure_hw(ddev, NFC_DIGITAL_CONFIG_FRAMING,
178 				NFC_DIGITAL_FRAMING_NFCA_STANDARD_WITH_CRC_A);
179 		if (rc)
180 			goto exit;
181 	} else {
182 		digital_skb_add_crc_a(skb);
183 	}
184 
185 	rc = digital_in_send_cmd(ddev, skb, 30, digital_in_recv_sel_res,
186 				 target);
187 exit:
188 	if (rc)
189 		kfree_skb(skb);
190 
191 	return rc;
192 }
193 
194 static void digital_in_recv_sdd_res(struct nfc_digital_dev *ddev, void *arg,
195 				    struct sk_buff *resp)
196 {
197 	struct nfc_target *target = arg;
198 	struct digital_sdd_res *sdd_res;
199 	int rc;
200 	u8 offset, size;
201 	u8 i, bcc;
202 
203 	if (IS_ERR(resp)) {
204 		rc = PTR_ERR(resp);
205 		resp = NULL;
206 		goto exit;
207 	}
208 
209 	if (resp->len < DIGITAL_SDD_RES_LEN) {
210 		PROTOCOL_ERR("4.7.2.8");
211 		rc = -EINVAL;
212 		goto exit;
213 	}
214 
215 	sdd_res = (struct digital_sdd_res *)resp->data;
216 
217 	for (i = 0, bcc = 0; i < 4; i++)
218 		bcc ^= sdd_res->nfcid1[i];
219 
220 	if (bcc != sdd_res->bcc) {
221 		PROTOCOL_ERR("4.7.2.6");
222 		rc = -EINVAL;
223 		goto exit;
224 	}
225 
226 	if (sdd_res->nfcid1[0] == DIGITAL_SDD_RES_CT) {
227 		offset = 1;
228 		size = 3;
229 	} else {
230 		offset = 0;
231 		size = 4;
232 	}
233 
234 	memcpy(target->nfcid1 + target->nfcid1_len, sdd_res->nfcid1 + offset,
235 	       size);
236 	target->nfcid1_len += size;
237 
238 	rc = digital_in_send_sel_req(ddev, target, sdd_res);
239 
240 exit:
241 	dev_kfree_skb(resp);
242 
243 	if (rc) {
244 		kfree(target);
245 		digital_poll_next_tech(ddev);
246 	}
247 }
248 
249 static int digital_in_send_sdd_req(struct nfc_digital_dev *ddev,
250 				   struct nfc_target *target)
251 {
252 	int rc;
253 	struct sk_buff *skb;
254 	u8 sel_cmd;
255 
256 	rc = digital_in_configure_hw(ddev, NFC_DIGITAL_CONFIG_FRAMING,
257 				     NFC_DIGITAL_FRAMING_NFCA_STANDARD);
258 	if (rc)
259 		return rc;
260 
261 	skb = digital_skb_alloc(ddev, 2);
262 	if (!skb)
263 		return -ENOMEM;
264 
265 	if (target->nfcid1_len == 0)
266 		sel_cmd = DIGITAL_CMD_SEL_REQ_CL1;
267 	else if (target->nfcid1_len == 3)
268 		sel_cmd = DIGITAL_CMD_SEL_REQ_CL2;
269 	else
270 		sel_cmd = DIGITAL_CMD_SEL_REQ_CL3;
271 
272 	*skb_put(skb, sizeof(u8)) = sel_cmd;
273 	*skb_put(skb, sizeof(u8)) = DIGITAL_SDD_REQ_SEL_PAR;
274 
275 	return digital_in_send_cmd(ddev, skb, 30, digital_in_recv_sdd_res,
276 				   target);
277 }
278 
279 static void digital_in_recv_sens_res(struct nfc_digital_dev *ddev, void *arg,
280 				     struct sk_buff *resp)
281 {
282 	struct nfc_target *target = NULL;
283 	int rc;
284 
285 	if (IS_ERR(resp)) {
286 		rc = PTR_ERR(resp);
287 		resp = NULL;
288 		goto exit;
289 	}
290 
291 	if (resp->len < sizeof(u16)) {
292 		rc = -EIO;
293 		goto exit;
294 	}
295 
296 	target = kzalloc(sizeof(struct nfc_target), GFP_KERNEL);
297 	if (!target) {
298 		rc = -ENOMEM;
299 		goto exit;
300 	}
301 
302 	target->sens_res = __le16_to_cpu(*(__le16 *)resp->data);
303 
304 	if (!DIGITAL_SENS_RES_IS_VALID(target->sens_res)) {
305 		PROTOCOL_ERR("4.6.3.3");
306 		rc = -EINVAL;
307 		goto exit;
308 	}
309 
310 	if (DIGITAL_SENS_RES_IS_T1T(target->sens_res))
311 		rc = digital_target_found(ddev, target, NFC_PROTO_JEWEL);
312 	else
313 		rc = digital_in_send_sdd_req(ddev, target);
314 
315 exit:
316 	dev_kfree_skb(resp);
317 
318 	if (rc) {
319 		kfree(target);
320 		digital_poll_next_tech(ddev);
321 	}
322 }
323 
324 int digital_in_send_sens_req(struct nfc_digital_dev *ddev, u8 rf_tech)
325 {
326 	struct sk_buff *skb;
327 	int rc;
328 
329 	rc = digital_in_configure_hw(ddev, NFC_DIGITAL_CONFIG_RF_TECH,
330 				     NFC_DIGITAL_RF_TECH_106A);
331 	if (rc)
332 		return rc;
333 
334 	rc = digital_in_configure_hw(ddev, NFC_DIGITAL_CONFIG_FRAMING,
335 				     NFC_DIGITAL_FRAMING_NFCA_SHORT);
336 	if (rc)
337 		return rc;
338 
339 	skb = digital_skb_alloc(ddev, 1);
340 	if (!skb)
341 		return -ENOMEM;
342 
343 	*skb_put(skb, sizeof(u8)) = DIGITAL_CMD_SENS_REQ;
344 
345 	rc = digital_in_send_cmd(ddev, skb, 30, digital_in_recv_sens_res, NULL);
346 	if (rc)
347 		kfree_skb(skb);
348 
349 	return rc;
350 }
351 
352 int digital_in_recv_mifare_res(struct sk_buff *resp)
353 {
354 	/* Successful READ command response is 16 data bytes + 2 CRC bytes long.
355 	 * Since the driver can't differentiate a ACK/NACK response from a valid
356 	 * READ response, the CRC calculation must be handled at digital level
357 	 * even if the driver supports it for this technology.
358 	 */
359 	if (resp->len == DIGITAL_MIFARE_READ_RES_LEN + DIGITAL_CRC_LEN) {
360 		if (digital_skb_check_crc_a(resp)) {
361 			PROTOCOL_ERR("9.4.1.2");
362 			return -EIO;
363 		}
364 
365 		return 0;
366 	}
367 
368 	/* ACK response (i.e. successful WRITE). */
369 	if (resp->len == 1 && resp->data[0] == DIGITAL_MIFARE_ACK_RES) {
370 		resp->data[0] = 0;
371 		return 0;
372 	}
373 
374 	/* NACK and any other responses are treated as error. */
375 	return -EIO;
376 }
377 
378 static void digital_in_recv_sensf_res(struct nfc_digital_dev *ddev, void *arg,
379 				   struct sk_buff *resp)
380 {
381 	int rc;
382 	u8 proto;
383 	struct nfc_target target;
384 	struct digital_sensf_res *sensf_res;
385 
386 	if (IS_ERR(resp)) {
387 		rc = PTR_ERR(resp);
388 		resp = NULL;
389 		goto exit;
390 	}
391 
392 	if (resp->len < DIGITAL_SENSF_RES_MIN_LENGTH) {
393 		rc = -EIO;
394 		goto exit;
395 	}
396 
397 	if (!DIGITAL_DRV_CAPS_IN_CRC(ddev)) {
398 		rc = digital_skb_check_crc_f(resp);
399 		if (rc) {
400 			PROTOCOL_ERR("6.4.1.8");
401 			goto exit;
402 		}
403 	}
404 
405 	skb_pull(resp, 1);
406 
407 	memset(&target, 0, sizeof(struct nfc_target));
408 
409 	sensf_res = (struct digital_sensf_res *)resp->data;
410 
411 	memcpy(target.sensf_res, sensf_res, resp->len);
412 	target.sensf_res_len = resp->len;
413 
414 	memcpy(target.nfcid2, sensf_res->nfcid2, NFC_NFCID2_MAXSIZE);
415 	target.nfcid2_len = NFC_NFCID2_MAXSIZE;
416 
417 	if (target.nfcid2[0] == DIGITAL_SENSF_NFCID2_NFC_DEP_B1 &&
418 	    target.nfcid2[1] == DIGITAL_SENSF_NFCID2_NFC_DEP_B2)
419 		proto = NFC_PROTO_NFC_DEP;
420 	else
421 		proto = NFC_PROTO_FELICA;
422 
423 	rc = digital_target_found(ddev, &target, proto);
424 
425 exit:
426 	dev_kfree_skb(resp);
427 
428 	if (rc)
429 		digital_poll_next_tech(ddev);
430 }
431 
432 int digital_in_send_sensf_req(struct nfc_digital_dev *ddev, u8 rf_tech)
433 {
434 	struct digital_sensf_req *sensf_req;
435 	struct sk_buff *skb;
436 	int rc;
437 	u8 size;
438 
439 	rc = digital_in_configure_hw(ddev, NFC_DIGITAL_CONFIG_RF_TECH, rf_tech);
440 	if (rc)
441 		return rc;
442 
443 	rc = digital_in_configure_hw(ddev, NFC_DIGITAL_CONFIG_FRAMING,
444 				     NFC_DIGITAL_FRAMING_NFCF);
445 	if (rc)
446 		return rc;
447 
448 	size = sizeof(struct digital_sensf_req);
449 
450 	skb = digital_skb_alloc(ddev, size);
451 	if (!skb)
452 		return -ENOMEM;
453 
454 	skb_put(skb, size);
455 
456 	sensf_req = (struct digital_sensf_req *)skb->data;
457 	sensf_req->cmd = DIGITAL_CMD_SENSF_REQ;
458 	sensf_req->sc1 = 0xFF;
459 	sensf_req->sc2 = 0xFF;
460 	sensf_req->rc = 0;
461 	sensf_req->tsn = 0;
462 
463 	*skb_push(skb, 1) = size + 1;
464 
465 	if (!DIGITAL_DRV_CAPS_IN_CRC(ddev))
466 		digital_skb_add_crc_f(skb);
467 
468 	rc = digital_in_send_cmd(ddev, skb, 30, digital_in_recv_sensf_res,
469 				 NULL);
470 	if (rc)
471 		kfree_skb(skb);
472 
473 	return rc;
474 }
475 
476 static int digital_tg_send_sel_res(struct nfc_digital_dev *ddev)
477 {
478 	struct sk_buff *skb;
479 	int rc;
480 
481 	skb = digital_skb_alloc(ddev, 1);
482 	if (!skb)
483 		return -ENOMEM;
484 
485 	*skb_put(skb, 1) = DIGITAL_SEL_RES_NFC_DEP;
486 
487 	if (!DIGITAL_DRV_CAPS_TG_CRC(ddev))
488 		digital_skb_add_crc_a(skb);
489 
490 	rc = digital_tg_send_cmd(ddev, skb, 300, digital_tg_recv_atr_req,
491 				 NULL);
492 	if (rc)
493 		kfree_skb(skb);
494 
495 	return rc;
496 }
497 
498 static void digital_tg_recv_sel_req(struct nfc_digital_dev *ddev, void *arg,
499 				    struct sk_buff *resp)
500 {
501 	int rc;
502 
503 	if (IS_ERR(resp)) {
504 		rc = PTR_ERR(resp);
505 		resp = NULL;
506 		goto exit;
507 	}
508 
509 	if (!DIGITAL_DRV_CAPS_TG_CRC(ddev)) {
510 		rc = digital_skb_check_crc_a(resp);
511 		if (rc) {
512 			PROTOCOL_ERR("4.4.1.3");
513 			goto exit;
514 		}
515 	}
516 
517 	/* Silently ignore SEL_REQ content and send a SEL_RES for NFC-DEP */
518 
519 	rc = digital_tg_send_sel_res(ddev);
520 
521 exit:
522 	if (rc)
523 		digital_poll_next_tech(ddev);
524 
525 	dev_kfree_skb(resp);
526 }
527 
528 static int digital_tg_send_sdd_res(struct nfc_digital_dev *ddev)
529 {
530 	struct sk_buff *skb;
531 	struct digital_sdd_res *sdd_res;
532 	int rc, i;
533 
534 	skb = digital_skb_alloc(ddev, sizeof(struct digital_sdd_res));
535 	if (!skb)
536 		return -ENOMEM;
537 
538 	skb_put(skb, sizeof(struct digital_sdd_res));
539 	sdd_res = (struct digital_sdd_res *)skb->data;
540 
541 	sdd_res->nfcid1[0] = 0x08;
542 	get_random_bytes(sdd_res->nfcid1 + 1, 3);
543 
544 	sdd_res->bcc = 0;
545 	for (i = 0; i < 4; i++)
546 		sdd_res->bcc ^= sdd_res->nfcid1[i];
547 
548 	rc = digital_tg_send_cmd(ddev, skb, 300, digital_tg_recv_sel_req,
549 				 NULL);
550 	if (rc)
551 		kfree_skb(skb);
552 
553 	return rc;
554 }
555 
556 static void digital_tg_recv_sdd_req(struct nfc_digital_dev *ddev, void *arg,
557 				    struct sk_buff *resp)
558 {
559 	u8 *sdd_req;
560 	int rc;
561 
562 	if (IS_ERR(resp)) {
563 		rc = PTR_ERR(resp);
564 		resp = NULL;
565 		goto exit;
566 	}
567 
568 	sdd_req = resp->data;
569 
570 	if (resp->len < 2 || sdd_req[0] != DIGITAL_CMD_SEL_REQ_CL1 ||
571 	    sdd_req[1] != DIGITAL_SDD_REQ_SEL_PAR) {
572 		rc = -EINVAL;
573 		goto exit;
574 	}
575 
576 	rc = digital_tg_send_sdd_res(ddev);
577 
578 exit:
579 	if (rc)
580 		digital_poll_next_tech(ddev);
581 
582 	dev_kfree_skb(resp);
583 }
584 
585 static int digital_tg_send_sens_res(struct nfc_digital_dev *ddev)
586 {
587 	struct sk_buff *skb;
588 	u8 *sens_res;
589 	int rc;
590 
591 	skb = digital_skb_alloc(ddev, 2);
592 	if (!skb)
593 		return -ENOMEM;
594 
595 	sens_res = skb_put(skb, 2);
596 
597 	sens_res[0] = (DIGITAL_SENS_RES_NFC_DEP >> 8) & 0xFF;
598 	sens_res[1] = DIGITAL_SENS_RES_NFC_DEP & 0xFF;
599 
600 	rc = digital_tg_send_cmd(ddev, skb, 300, digital_tg_recv_sdd_req,
601 				 NULL);
602 	if (rc)
603 		kfree_skb(skb);
604 
605 	return rc;
606 }
607 
608 void digital_tg_recv_sens_req(struct nfc_digital_dev *ddev, void *arg,
609 			      struct sk_buff *resp)
610 {
611 	u8 sens_req;
612 	int rc;
613 
614 	if (IS_ERR(resp)) {
615 		rc = PTR_ERR(resp);
616 		resp = NULL;
617 		goto exit;
618 	}
619 
620 	sens_req = resp->data[0];
621 
622 	if (!resp->len || (sens_req != DIGITAL_CMD_SENS_REQ &&
623 	    sens_req != DIGITAL_CMD_ALL_REQ)) {
624 		rc = -EINVAL;
625 		goto exit;
626 	}
627 
628 	rc = digital_tg_send_sens_res(ddev);
629 
630 exit:
631 	if (rc)
632 		digital_poll_next_tech(ddev);
633 
634 	dev_kfree_skb(resp);
635 }
636 
637 static int digital_tg_send_sensf_res(struct nfc_digital_dev *ddev,
638 			      struct digital_sensf_req *sensf_req)
639 {
640 	struct sk_buff *skb;
641 	u8 size;
642 	int rc;
643 	struct digital_sensf_res *sensf_res;
644 
645 	size = sizeof(struct digital_sensf_res);
646 
647 	if (sensf_req->rc != DIGITAL_SENSF_REQ_RC_NONE)
648 		size -= sizeof(sensf_res->rd);
649 
650 	skb = digital_skb_alloc(ddev, size);
651 	if (!skb)
652 		return -ENOMEM;
653 
654 	skb_put(skb, size);
655 
656 	sensf_res = (struct digital_sensf_res *)skb->data;
657 
658 	memset(sensf_res, 0, size);
659 
660 	sensf_res->cmd = DIGITAL_CMD_SENSF_RES;
661 	sensf_res->nfcid2[0] = DIGITAL_SENSF_NFCID2_NFC_DEP_B1;
662 	sensf_res->nfcid2[1] = DIGITAL_SENSF_NFCID2_NFC_DEP_B2;
663 	get_random_bytes(&sensf_res->nfcid2[2], 6);
664 
665 	switch (sensf_req->rc) {
666 	case DIGITAL_SENSF_REQ_RC_SC:
667 		sensf_res->rd[0] = sensf_req->sc1;
668 		sensf_res->rd[1] = sensf_req->sc2;
669 		break;
670 	case DIGITAL_SENSF_REQ_RC_AP:
671 		sensf_res->rd[0] = DIGITAL_SENSF_RES_RD_AP_B1;
672 		sensf_res->rd[1] = DIGITAL_SENSF_RES_RD_AP_B2;
673 		break;
674 	}
675 
676 	*skb_push(skb, sizeof(u8)) = size + 1;
677 
678 	if (!DIGITAL_DRV_CAPS_TG_CRC(ddev))
679 		digital_skb_add_crc_f(skb);
680 
681 	rc = digital_tg_send_cmd(ddev, skb, 300,
682 				 digital_tg_recv_atr_req, NULL);
683 	if (rc)
684 		kfree_skb(skb);
685 
686 	return rc;
687 }
688 
689 void digital_tg_recv_sensf_req(struct nfc_digital_dev *ddev, void *arg,
690 			       struct sk_buff *resp)
691 {
692 	struct digital_sensf_req *sensf_req;
693 	int rc;
694 
695 	if (IS_ERR(resp)) {
696 		rc = PTR_ERR(resp);
697 		resp = NULL;
698 		goto exit;
699 	}
700 
701 	if (!DIGITAL_DRV_CAPS_TG_CRC(ddev)) {
702 		rc = digital_skb_check_crc_f(resp);
703 		if (rc) {
704 			PROTOCOL_ERR("6.4.1.8");
705 			goto exit;
706 		}
707 	}
708 
709 	if (resp->len != sizeof(struct digital_sensf_req) + 1) {
710 		rc = -EINVAL;
711 		goto exit;
712 	}
713 
714 	skb_pull(resp, 1);
715 	sensf_req = (struct digital_sensf_req *)resp->data;
716 
717 	if (sensf_req->cmd != DIGITAL_CMD_SENSF_REQ) {
718 		rc = -EINVAL;
719 		goto exit;
720 	}
721 
722 	rc = digital_tg_send_sensf_res(ddev, sensf_req);
723 
724 exit:
725 	if (rc)
726 		digital_poll_next_tech(ddev);
727 
728 	dev_kfree_skb(resp);
729 }
730 
731 int digital_tg_listen_nfca(struct nfc_digital_dev *ddev, u8 rf_tech)
732 {
733 	int rc;
734 
735 	rc = digital_tg_configure_hw(ddev, NFC_DIGITAL_CONFIG_RF_TECH, rf_tech);
736 	if (rc)
737 		return rc;
738 
739 	rc = digital_tg_configure_hw(ddev, NFC_DIGITAL_CONFIG_FRAMING,
740 				     NFC_DIGITAL_FRAMING_NFCA_NFC_DEP);
741 	if (rc)
742 		return rc;
743 
744 	return digital_tg_listen(ddev, 300, digital_tg_recv_sens_req, NULL);
745 }
746 
747 int digital_tg_listen_nfcf(struct nfc_digital_dev *ddev, u8 rf_tech)
748 {
749 	int rc;
750 	u8 *nfcid2;
751 
752 	rc = digital_tg_configure_hw(ddev, NFC_DIGITAL_CONFIG_RF_TECH, rf_tech);
753 	if (rc)
754 		return rc;
755 
756 	rc = digital_tg_configure_hw(ddev, NFC_DIGITAL_CONFIG_FRAMING,
757 				     NFC_DIGITAL_FRAMING_NFCF_NFC_DEP);
758 	if (rc)
759 		return rc;
760 
761 	nfcid2 = kzalloc(NFC_NFCID2_MAXSIZE, GFP_KERNEL);
762 	if (!nfcid2)
763 		return -ENOMEM;
764 
765 	nfcid2[0] = DIGITAL_SENSF_NFCID2_NFC_DEP_B1;
766 	nfcid2[1] = DIGITAL_SENSF_NFCID2_NFC_DEP_B2;
767 	get_random_bytes(nfcid2 + 2, NFC_NFCID2_MAXSIZE - 2);
768 
769 	return digital_tg_listen(ddev, 300, digital_tg_recv_sensf_req, nfcid2);
770 }
771