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Commit 49dbb14e authored by Mark A. Greer's avatar Mark A. Greer Committed by Samuel Ortiz
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NFC: digital: Add NFC-DEP Target-side NACK Support 



When an NFC-DEP Target receives a NACK PDU with
a PNI equal to 1 less than the current PNI, it
is supposed to re-send the last PDU.  This is
implied in section 14.12.5.4 of the NFC Digital
Protocol Spec.

The digital layer's NFC-DEP code doesn't implement
Target-side NACK handing so add it.  The last PDU
that was sent is saved in the 'nfc_digital_dev'
structure's 'saved_skb' member.  The skb will have
an additional reference taken to ensure that the skb
isn't freed when the driver performs a kfree_skb()
on the skb.  The length of the skb/PDU is also saved
so the length can be restored when re-sending the PDU
in the skb (the driver will perform an skb_pull() so
an skb_push() needs to be done to restore the skb's
data pointer/length).

Reviewed-by: default avatarThierry Escande <thierry.escande@linux.intel.com>
Tested-by: default avatarThierry Escande <thierry.escande@linux.intel.com>
Signed-off-by: default avatarMark A. Greer <mgreer@animalcreek.com>
Signed-off-by: default avatarSamuel Ortiz <sameo@linux.intel.com>
parent a80509c7

include/net/nfc/digital.h

+3 −0
Original line number Diff line number Diff line
@@ -235,6 +235,9 @@ struct nfc_digital_dev { 


	int nack_count;



	struct sk_buff *saved_skb;

	unsigned int saved_skb_len;



	u16 target_fsc;



	int (*skb_check_crc)(struct sk_buff *skb);

net/nfc/digital_dep.c

+51 −11
Original line number Diff line number Diff line
@@ -864,14 +864,29 @@ static int digital_tg_send_ack(struct nfc_digital_dev *ddev, 


	ddev->skb_add_crc(skb);



	ddev->saved_skb = skb_get(skb);

	ddev->saved_skb_len = skb->len;



	rc = digital_tg_send_cmd(ddev, skb, 1500, digital_tg_recv_dep_req,

				 data_exch);

	if (rc)

	if (rc) {

		kfree_skb(skb);

		kfree_skb(ddev->saved_skb);

		ddev->saved_skb = NULL;

	}



	return rc;

}



static int digital_tg_send_saved_skb(struct nfc_digital_dev *ddev)

{

	skb_get(ddev->saved_skb);

	skb_push(ddev->saved_skb, ddev->saved_skb_len);



	return digital_tg_send_cmd(ddev, ddev->saved_skb, 1500,

				   digital_tg_recv_dep_req, NULL);

}



static void digital_tg_recv_dep_req(struct nfc_digital_dev *ddev, void *arg,

				    struct sk_buff *resp)

{
@@ -948,6 +963,9 @@ static void digital_tg_recv_dep_req(struct nfc_digital_dev *ddev, void *arg, 
			goto exit;

		}



		kfree_skb(ddev->saved_skb);

		ddev->saved_skb = NULL;



		resp = digital_recv_dep_data_gather(ddev, pfb, resp,

						    digital_tg_send_ack, NULL);

		if (IS_ERR(resp)) {
@@ -966,23 +984,36 @@ static void digital_tg_recv_dep_req(struct nfc_digital_dev *ddev, void *arg, 
		rc = 0;

		break;

	case DIGITAL_NFC_DEP_PFB_ACK_NACK_PDU:

		if (DIGITAL_NFC_DEP_PFB_PNI(pfb) != ddev->curr_nfc_dep_pni) {

			PROTOCOL_ERR("14.12.3.4");

		if (!DIGITAL_NFC_DEP_NACK_BIT_SET(pfb)) { /* ACK */

			if ((DIGITAL_NFC_DEP_PFB_PNI(pfb) !=

						ddev->curr_nfc_dep_pni) ||

			    !ddev->chaining_skb || !ddev->saved_skb) {

				rc = -EIO;

				goto exit;

			}



		if (ddev->chaining_skb && !DIGITAL_NFC_DEP_NACK_BIT_SET(pfb)) {

			kfree_skb(ddev->saved_skb);

			ddev->saved_skb = NULL;



			rc = digital_tg_send_dep_res(ddev, ddev->chaining_skb);

			if (rc)

				goto exit;



			return;

		} else { /* NACK */

			if ((DIGITAL_NFC_DEP_PFB_PNI(pfb + 1) !=

						ddev->curr_nfc_dep_pni) ||

			    !ddev->saved_skb) {

				rc = -EIO;

				goto exit;

			}



		pr_err("Received a ACK/NACK PDU\n");

		rc = -EINVAL;

			rc = digital_tg_send_saved_skb(ddev);

			if (rc) {

				kfree_skb(ddev->saved_skb);

				goto exit;

			}

		}



		return;

	case DIGITAL_NFC_DEP_PFB_SUPERVISOR_PDU:

		pr_err("Received a SUPERVISOR PDU\n");

		rc = -EINVAL;
@@ -995,6 +1026,9 @@ static void digital_tg_recv_dep_req(struct nfc_digital_dev *ddev, void *arg, 
	kfree_skb(ddev->chaining_skb);

	ddev->chaining_skb = NULL;



	kfree_skb(ddev->saved_skb);

	ddev->saved_skb = NULL;



	if (rc)

		kfree_skb(resp);

}
@@ -1033,6 +1067,9 @@ int digital_tg_send_dep_res(struct nfc_digital_dev *ddev, struct sk_buff *skb) 


	ddev->skb_add_crc(tmp_skb);



	ddev->saved_skb = skb_get(tmp_skb);

	ddev->saved_skb_len = tmp_skb->len;



	rc = digital_tg_send_cmd(ddev, tmp_skb, 1500, digital_tg_recv_dep_req,

				 NULL);

	if (rc) {
@@ -1041,6 +1078,9 @@ int digital_tg_send_dep_res(struct nfc_digital_dev *ddev, struct sk_buff *skb) 


		kfree_skb(chaining_skb);

		ddev->chaining_skb = NULL;



		kfree_skb(ddev->saved_skb);

		ddev->saved_skb = NULL;

	}



	return rc;