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 <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>
diff --git a/net/nfc/digital_dep.c b/net/nfc/digital_dep.c
index 9840e85..31418ed 100644
--- a/net/nfc/digital_dep.c
+++ b/net/nfc/digital_dep.c
@@ -864,14 +864,29 @@
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 @@
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 @@
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;
+ }
- 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;
+ } 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 @@
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 @@
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 @@
kfree_skb(chaining_skb);
ddev->chaining_skb = NULL;
+
+ kfree_skb(ddev->saved_skb);
+ ddev->saved_skb = NULL;
}
return rc;
