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NFC: digital: Add NFC-DEP Target-side NACK Support

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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 <thierry.escande@linux.intel.com>
Tested-by: Thierry Escande <thierry.escande@linux.intel.com>
Signed-off-by: Mark A. Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
This commit is contained in:
Mark A. Greer 2014-09-23 16:38:12 -07:00 committed by Samuel Ortiz
parent a80509c76b
commit 49dbb14e30
2 changed files with 54 additions and 11 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
include/net/nfc/digital.h
View File

@ -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);

56
net/nfc/digital_dep.c
View File

@ -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 @@ 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;