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

When an NFC-DEP target receives an ATN PDU, its
supposed to respond with a similar ATN PDU.
When the Target receives an I PDU with the PNI
one less than the current PNI and the last PDU
sent was an ATN PDU, the Target is to resend the
last non-ATN PDU that it has sent.  This is
described in section 14.12.3.4 of the NFC Digital
Protocol Spec.

The digital layer's NFC-DEP code doesn't implement
this so add that support.

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>

1 files changed, 83 insertions, 5 deletions

diff --git a/net/nfc/digital_dep.c b/net/nfc/digital_dep.c
index 8f1fefd2ed14..f72be7433df3 100644
--- a/net/nfc/digital_dep.c
+++ b/net/nfc/digital_dep.c
@@ -970,6 +970,43 @@ static int digital_tg_send_ack(struct nfc_digital_dev *ddev,
         return rc;
 }
 
+static int digital_tg_send_atn(struct nfc_digital_dev *ddev)
+{
+        struct digital_dep_req_res *dep_res;
+        struct sk_buff *skb;
+        int rc;
+
+        skb = digital_skb_alloc(ddev, 1);
+        if (!skb)
+                return -ENOMEM;
+
+        skb_push(skb, sizeof(struct digital_dep_req_res));
+
+        dep_res = (struct digital_dep_req_res *)skb->data;
+
+        dep_res->dir = DIGITAL_NFC_DEP_FRAME_DIR_IN;
+        dep_res->cmd = DIGITAL_CMD_DEP_RES;
+        dep_res->pfb = DIGITAL_NFC_DEP_PFB_SUPERVISOR_PDU;
+
+        if (ddev->did) {
+                dep_res->pfb |= DIGITAL_NFC_DEP_PFB_DID_BIT;
+
+                memcpy(skb_put(skb, sizeof(ddev->did)), &ddev->did,
+                       sizeof(ddev->did));
+        }
+
+        digital_skb_push_dep_sod(ddev, skb);
+
+        ddev->skb_add_crc(skb);
+
+        rc = digital_tg_send_cmd(ddev, skb, 1500, digital_tg_recv_dep_req,
+                                 NULL);
+        if (rc)
+                kfree_skb(skb);
+
+        return rc;
+}
+
 static int digital_tg_send_saved_skb(struct nfc_digital_dev *ddev)
 {
         skb_get(ddev->saved_skb);
@@ -1049,12 +1086,24 @@ static void digital_tg_recv_dep_req(struct nfc_digital_dev *ddev, void *arg,
         case DIGITAL_NFC_DEP_PFB_I_PDU:
                 pr_debug("DIGITAL_NFC_DEP_PFB_I_PDU\n");
 
-                if (DIGITAL_NFC_DEP_PFB_PNI(pfb) != ddev->curr_nfc_dep_pni) {
+                if ((ddev->atn_count && (DIGITAL_NFC_DEP_PFB_PNI(pfb - 1) !=
+                                                ddev->curr_nfc_dep_pni)) ||
+                    (DIGITAL_NFC_DEP_PFB_PNI(pfb) != ddev->curr_nfc_dep_pni)) {
                         PROTOCOL_ERR("14.12.3.4");
                         rc = -EIO;
                         goto exit;
                 }
 
+                if (ddev->atn_count) {
+                        ddev->atn_count = 0;
+
+                        rc = digital_tg_send_saved_skb(ddev);
+                        if (rc)
+                                goto exit;
+
+                        return;
+                }
+
                 kfree_skb(ddev->saved_skb);
                 ddev->saved_skb = NULL;
 
@@ -1077,13 +1126,26 @@ static void digital_tg_recv_dep_req(struct nfc_digital_dev *ddev, void *arg,
                 break;
         case DIGITAL_NFC_DEP_PFB_ACK_NACK_PDU:
                 if (!DIGITAL_NFC_DEP_NACK_BIT_SET(pfb)) { /* ACK */
-                        if ((DIGITAL_NFC_DEP_PFB_PNI(pfb) !=
+                        if ((ddev->atn_count &&
+                             (DIGITAL_NFC_DEP_PFB_PNI(pfb - 1) !=
+                                                ddev->curr_nfc_dep_pni)) ||
+                            (DIGITAL_NFC_DEP_PFB_PNI(pfb) !=
                                                 ddev->curr_nfc_dep_pni) ||
                             !ddev->chaining_skb || !ddev->saved_skb) {
                                 rc = -EIO;
                                 goto exit;
                         }
 
+                        if (ddev->atn_count) {
+                                ddev->atn_count = 0;
+
+                                rc = digital_tg_send_saved_skb(ddev);
+                                if (rc)
+                                        goto exit;
+
+                                return;
+                        }
+
                         kfree_skb(ddev->saved_skb);
                         ddev->saved_skb = NULL;
 
@@ -1098,6 +1160,8 @@ static void digital_tg_recv_dep_req(struct nfc_digital_dev *ddev, void *arg,
                                 goto exit;
                         }
 
+                        ddev->atn_count = 0;
+
                         rc = digital_tg_send_saved_skb(ddev);
                         if (rc) {
                                 kfree_skb(ddev->saved_skb);
@@ -1107,9 +1171,19 @@ static void digital_tg_recv_dep_req(struct nfc_digital_dev *ddev, void *arg,
 
                 return;
         case DIGITAL_NFC_DEP_PFB_SUPERVISOR_PDU:
-                pr_err("Received a SUPERVISOR PDU\n");
-                rc = -EINVAL;
-                goto exit;
+                if (DIGITAL_NFC_DEP_PFB_IS_TIMEOUT(pfb)) {
+                        rc = -EINVAL;
+                        goto exit;
+                }
+
+                rc = digital_tg_send_atn(ddev);
+                if (rc)
+                        goto exit;
+
+                ddev->atn_count++;
+
+                kfree_skb(resp);
+                return;
         }
 
         rc = nfc_tm_data_received(ddev->nfc_dev, resp);
@@ -1118,6 +1192,8 @@ exit:
         kfree_skb(ddev->chaining_skb);
         ddev->chaining_skb = NULL;
 
+        ddev->atn_count = 0;
+
         kfree_skb(ddev->saved_skb);
         ddev->saved_skb = NULL;
 
@@ -1311,6 +1387,8 @@ static void digital_tg_send_atr_res_complete(struct nfc_digital_dev *ddev,
         if (resp->data[0] == DIGITAL_NFC_DEP_NFCA_SOD_SB)
                 offset++;
 
+        ddev->atn_count = 0;
+
         if (resp->data[offset] == DIGITAL_CMD_PSL_REQ)
                 digital_tg_recv_psl_req(ddev, arg, resp);
         else