From 49dbb14e30c3249f98fe243c3e21b91d10c5c59b Mon Sep 17 00:00:00 2001 From: "Mark A. Greer" Date: Tue, 23 Sep 2014 16:38:12 -0700 Subject: 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: Thierry Escande Tested-by: Thierry Escande Signed-off-by: Mark A. Greer Signed-off-by: Samuel Ortiz --- net/nfc/digital_dep.c | 62 ++++++++++++++++++++++++++++++++++++++++++--------- 1 file changed, 51 insertions(+), 11 deletions(-) (limited to 'net/nfc/digital_dep.c') diff --git a/net/nfc/digital_dep.c b/net/nfc/digital_dep.c index 9840e858ec5b..31418edbe78e 100644 --- a/net/nfc/digital_dep.c +++ b/net/nfc/digital_dep.c @@ -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"); - rc = -EIO; - goto exit; - } + 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; + } + + kfree_skb(ddev->saved_skb); + ddev->saved_skb = NULL; - if (ddev->chaining_skb && !DIGITAL_NFC_DEP_NACK_BIT_SET(pfb)) { rc = digital_tg_send_dep_res(ddev, ddev->chaining_skb); if (rc) goto exit; + } else { /* NACK */ + if ((DIGITAL_NFC_DEP_PFB_PNI(pfb + 1) != + ddev->curr_nfc_dep_pni) || + !ddev->saved_skb) { + rc = -EIO; + goto exit; + } - return; + rc = digital_tg_send_saved_skb(ddev); + if (rc) { + kfree_skb(ddev->saved_skb); + goto exit; + } } - pr_err("Received a ACK/NACK PDU\n"); - rc = -EINVAL; - goto exit; + return; case DIGITAL_NFC_DEP_PFB_SUPERVISOR_PDU: pr_err("Received a SUPERVISOR PDU\n"); rc = -EINVAL; @@ -995,6 +1026,9 @@ exit: 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; -- cgit v1.2.3