NFC: digital: Fix RTOX supervisor PDU handling

When the target needs more time to process the received PDU, it sends
Response Timeout Extension (RTOX) PDU.

When the initiator receives a RTOX PDU, it must reply with a RTOX PDU
and extends the current rwt value with the formula:
 rwt_int = rwt * rtox

This patch takes care of the rtox value passed by the target in the RTOX
PDU and extends the timeout for the next response accordingly.

Signed-off-by: Thierry Escande <thierry.escande@collabora.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

1 files changed, 24 insertions, 2 deletions

diff --git a/net/nfc/digital_dep.c b/net/nfc/digital_dep.c
index 6cf2eeb2e865..f864ce19e13d 100644
--- a/net/nfc/digital_dep.c
+++ b/net/nfc/digital_dep.c
@@ -65,6 +65,9 @@
 #define DIGITAL_NFC_DEP_DID_BIT_SET(pfb) ((pfb) & DIGITAL_NFC_DEP_PFB_DID_BIT)
 #define DIGITAL_NFC_DEP_PFB_PNI(pfb)     ((pfb) & 0x03)
 
+#define DIGITAL_NFC_DEP_RTOX_VALUE(data) ((data) & 0x3F)
+#define DIGITAL_NFC_DEP_RTOX_MAX         59
+
 #define DIGITAL_NFC_DEP_PFB_I_PDU          0x00
 #define DIGITAL_NFC_DEP_PFB_ACK_NACK_PDU   0x40
 #define DIGITAL_NFC_DEP_PFB_SUPERVISOR_PDU 0x80
@@ -643,6 +646,11 @@ static int digital_in_send_rtox(struct nfc_digital_dev *ddev,
         struct digital_dep_req_res *dep_req;
         struct sk_buff *skb;
         int rc;
+        u16 rwt_int;
+
+        rwt_int = ddev->dep_rwt * rtox;
+        if (rwt_int > digital_rwt_map[DIGITAL_NFC_DEP_IN_MAX_WT])
+                rwt_int = digital_rwt_map[DIGITAL_NFC_DEP_IN_MAX_WT];
 
         skb = digital_skb_alloc(ddev, 1);
         if (!skb)
@@ -663,7 +671,7 @@ static int digital_in_send_rtox(struct nfc_digital_dev *ddev,
 
         ddev->skb_add_crc(skb);
 
-        rc = digital_in_send_cmd(ddev, skb, ddev->dep_rwt,
+        rc = digital_in_send_cmd(ddev, skb, rwt_int,
                                  digital_in_recv_dep_res, data_exch);
         if (rc)
                 kfree_skb(skb);
@@ -697,6 +705,7 @@ static void digital_in_recv_dep_res(struct nfc_digital_dev *ddev, void *arg,
         u8 pfb;
         uint size;
         int rc;
+        u8 rtox;
 
         if (IS_ERR(resp)) {
                 rc = PTR_ERR(resp);
@@ -865,7 +874,20 @@ static void digital_in_recv_dep_res(struct nfc_digital_dev *ddev, void *arg,
                         goto free_resp;
                 }
 
-                rc = digital_in_send_rtox(ddev, data_exch, resp->data[0]);
+                if (ddev->atn_count || ddev->nack_count) {
+                        PROTOCOL_ERR("14.12.4.4");
+                        rc = -EIO;
+                        goto error;
+                }
+
+                rtox = DIGITAL_NFC_DEP_RTOX_VALUE(resp->data[0]);
+                if (!rtox || rtox > DIGITAL_NFC_DEP_RTOX_MAX) {
+                        PROTOCOL_ERR("14.8.4.1");
+                        rc = -EIO;
+                        goto error;
+                }
+
+                rc = digital_in_send_rtox(ddev, data_exch, rtox);
                 if (rc)
                         goto error;