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

When an NFC-DEP Initiator times out when waiting for
a DEP_RES from the Target, its supposed to send an
ATN to the Target.  The Target should respond to the
ATN with a similar ATN PDU and the Initiator can then
resend the last non-ATN PDU that it sent.  No more
than 'N(retry,atn)' are to be send where
2 <= 'N(retry,atn)' <= 5.  If the Initiator had just
sent a NACK PDU when the timeout occurred, it is to
continue sending NACKs until 'N(retry,nack)' NACKs
have been send.  This is described in section
14.12.5.6 of the NFC-DEP Digital Protocol Spec.

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

The value chosen for 'N(retry,atn)' is 2.

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/include/net/nfc/digital.h b/include/net/nfc/digital.h
index 7400a81..0ae101e 100644 (file)
--- a/include/net/nfc/digital.h
+++ b/include/net/nfc/digital.h
@@ -233,6 +233,7 @@ struct nfc_digital_dev {
        struct sk_buff *chaining_skb;
        struct digital_data_exch *data_exch;
 
+       int atn_count;
        int nack_count;
 
        struct sk_buff *saved_skb;

diff --git a/net/nfc/digital_dep.c b/net/nfc/digital_dep.c
index 31418ed..8f1fefd 100644 (file)
--- a/net/nfc/digital_dep.c
+++ b/net/nfc/digital_dep.c
@@ -18,6 +18,7 @@
 #include "digital.h"
 
 #define DIGITAL_NFC_DEP_N_RETRY_NACK   2
+#define DIGITAL_NFC_DEP_N_RETRY_ATN    2
 
 #define DIGITAL_NFC_DEP_FRAME_DIR_OUT 0xD4
 #define DIGITAL_NFC_DEP_FRAME_DIR_IN  0xD5
@@ -523,10 +524,16 @@ static int digital_in_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_in_send_cmd(ddev, skb, 1500, digital_in_recv_dep_res,
                                 data_exch);
-       if (rc)
+       if (rc) {
                kfree_skb(skb);
+               kfree_skb(ddev->saved_skb);
+               ddev->saved_skb = NULL;
+       }
 
        return rc;
 }
@@ -563,6 +570,37 @@ static int digital_in_send_nack(struct nfc_digital_dev *ddev,
        return rc;
 }
 
+static int digital_in_send_atn(struct nfc_digital_dev *ddev,
+                              struct digital_data_exch *data_exch)
+{
+       struct digital_dep_req_res *dep_req;
+       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_req = (struct digital_dep_req_res *)skb->data;
+
+       dep_req->dir = DIGITAL_NFC_DEP_FRAME_DIR_OUT;
+       dep_req->cmd = DIGITAL_CMD_DEP_REQ;
+       dep_req->pfb = DIGITAL_NFC_DEP_PFB_SUPERVISOR_PDU;
+
+       digital_skb_push_dep_sod(ddev, skb);
+
+       ddev->skb_add_crc(skb);
+
+       rc = digital_in_send_cmd(ddev, skb, 1500, digital_in_recv_dep_res,
+                                data_exch);
+       if (rc)
+               kfree_skb(skb);
+
+       return rc;
+}
+
 static int digital_in_send_rtox(struct nfc_digital_dev *ddev,
                                struct digital_data_exch *data_exch, u8 rtox)
 {
@@ -589,14 +627,30 @@ static int digital_in_send_rtox(struct nfc_digital_dev *ddev,
 
        ddev->skb_add_crc(skb);
 
+       ddev->saved_skb = skb_get(skb);
+       ddev->saved_skb_len = skb->len;
+
        rc = digital_in_send_cmd(ddev, skb, 1500, digital_in_recv_dep_res,
                                 data_exch);
-       if (rc)
+       if (rc) {
                kfree_skb(skb);
+               kfree_skb(ddev->saved_skb);
+               ddev->saved_skb = NULL;
+       }
 
        return rc;
 }
 
+static int digital_in_send_saved_skb(struct nfc_digital_dev *ddev,
+                                    struct digital_data_exch *data_exch)
+{
+       skb_get(ddev->saved_skb);
+       skb_push(ddev->saved_skb, ddev->saved_skb_len);
+
+       return digital_in_send_cmd(ddev, ddev->saved_skb, 1500,
+                                  digital_in_recv_dep_res, data_exch);
+}
+
 static void digital_in_recv_dep_res(struct nfc_digital_dev *ddev, void *arg,
                                    struct sk_buff *resp)
 {
@@ -610,13 +664,24 @@ static void digital_in_recv_dep_res(struct nfc_digital_dev *ddev, void *arg,
                rc = PTR_ERR(resp);
                resp = NULL;
 
-               if ((rc != -ETIMEDOUT) &&
+               if (((rc != -ETIMEDOUT) || ddev->nack_count) &&
                    (ddev->nack_count++ < DIGITAL_NFC_DEP_N_RETRY_NACK)) {
+                       ddev->atn_count = 0;
+
                        rc = digital_in_send_nack(ddev, data_exch);
                        if (rc)
                                goto error;
 
                        return;
+               } else if ((rc == -ETIMEDOUT) &&
+                          (ddev->atn_count++ < DIGITAL_NFC_DEP_N_RETRY_ATN)) {
+                       ddev->nack_count = 0;
+
+                       rc = digital_in_send_atn(ddev, data_exch);
+                       if (rc)
+                               goto error;
+
+                       return;
                }
 
                goto exit;
@@ -632,6 +697,8 @@ static void digital_in_recv_dep_res(struct nfc_digital_dev *ddev, void *arg,
        if (rc) {
                if ((resp->len >= 4) &&
                    (ddev->nack_count++ < DIGITAL_NFC_DEP_N_RETRY_NACK)) {
+                       ddev->atn_count = 0;
+
                        rc = digital_in_send_nack(ddev, data_exch);
                        if (rc)
                                goto error;
@@ -645,6 +712,7 @@ static void digital_in_recv_dep_res(struct nfc_digital_dev *ddev, void *arg,
                goto error;
        }
 
+       ddev->atn_count = 0;
        ddev->nack_count = 0;
 
        if (resp->len > ddev->local_payload_max) {
@@ -692,6 +760,9 @@ static void digital_in_recv_dep_res(struct nfc_digital_dev *ddev, void *arg,
                ddev->curr_nfc_dep_pni =
                        DIGITAL_NFC_DEP_PFB_PNI(ddev->curr_nfc_dep_pni + 1);
 
+               kfree_skb(ddev->saved_skb);
+               ddev->saved_skb = NULL;
+
                resp = digital_recv_dep_data_gather(ddev, pfb, resp,
                                                    digital_in_send_ack,
                                                    data_exch);
@@ -722,6 +793,9 @@ static void digital_in_recv_dep_res(struct nfc_digital_dev *ddev, void *arg,
                        DIGITAL_NFC_DEP_PFB_PNI(ddev->curr_nfc_dep_pni + 1);
 
                if (ddev->chaining_skb && !DIGITAL_NFC_DEP_NACK_BIT_SET(pfb)) {
+                       kfree_skb(ddev->saved_skb);
+                       ddev->saved_skb = NULL;
+
                        rc = digital_in_send_dep_req(ddev, NULL,
                                                     ddev->chaining_skb,
                                                     ddev->data_exch);
@@ -736,11 +810,19 @@ static void digital_in_recv_dep_res(struct nfc_digital_dev *ddev, void *arg,
                goto exit;
 
        case DIGITAL_NFC_DEP_PFB_SUPERVISOR_PDU:
-               if (!DIGITAL_NFC_DEP_PFB_IS_TIMEOUT(pfb)) {
-                       rc = -EINVAL;
-                       goto error;
+               if (!DIGITAL_NFC_DEP_PFB_IS_TIMEOUT(pfb)) { /* ATN */
+                       rc = digital_in_send_saved_skb(ddev, data_exch);
+                       if (rc) {
+                               kfree_skb(ddev->saved_skb);
+                               goto error;
+                       }
+
+                       return;
                }
 
+               kfree_skb(ddev->saved_skb);
+               ddev->saved_skb = NULL;
+
                rc = digital_in_send_rtox(ddev, data_exch, resp->data[0]);
                if (rc)
                        goto error;
@@ -758,6 +840,9 @@ error:
        kfree_skb(ddev->chaining_skb);
        ddev->chaining_skb = NULL;
 
+       kfree_skb(ddev->saved_skb);
+       ddev->saved_skb = NULL;
+
        if (rc)
                kfree_skb(resp);
 }
@@ -778,6 +863,7 @@ int digital_in_send_dep_req(struct nfc_digital_dev *ddev,
        dep_req->cmd = DIGITAL_CMD_DEP_REQ;
        dep_req->pfb = ddev->curr_nfc_dep_pni;
 
+       ddev->atn_count = 0;
        ddev->nack_count = 0;
 
        chaining_skb = ddev->chaining_skb;
@@ -790,6 +876,9 @@ int digital_in_send_dep_req(struct nfc_digital_dev *ddev,
 
        ddev->skb_add_crc(tmp_skb);
 
+       ddev->saved_skb = skb_get(tmp_skb);
+       ddev->saved_skb_len = tmp_skb->len;
+
        rc = digital_in_send_cmd(ddev, tmp_skb, 1500, digital_in_recv_dep_res,
                                 data_exch);
        if (rc) {
@@ -798,6 +887,9 @@ int digital_in_send_dep_req(struct nfc_digital_dev *ddev,
 
                kfree_skb(chaining_skb);
                ddev->chaining_skb = NULL;
+
+               kfree_skb(ddev->saved_skb);
+               ddev->saved_skb = NULL;
        }
 
        return rc;