NFC: digital: Add ISO-DEP support for data exchange

When a type 4A target is activated, this change adds the ISO-DEP SoD
when sending frames and removes it when receiving responses. Chaining
is not supported so sent frames are rejected if they exceed remote FSC
bytes.

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

1 files changed, 57 insertions, 0 deletions

diff --git a/net/nfc/digital_technology.c b/net/nfc/digital_technology.c
index 6649d9461dff..278c3fed27e0 100644
--- a/net/nfc/digital_technology.c
+++ b/net/nfc/digital_technology.c
@@ -61,6 +61,15 @@
 #define DIGITAL_ISO15693_RES_IS_VALID(flags) \
         (!((flags) & DIGITAL_ISO15693_RES_FLAG_ERROR))
 
+#define DIGITAL_ISO_DEP_I_PCB    0x02
+#define DIGITAL_ISO_DEP_PNI(pni) ((pni) & 0x01)
+
+#define DIGITAL_ISO_DEP_PCB_TYPE(pcb) ((pcb) & 0xC0)
+
+#define DIGITAL_ISO_DEP_I_BLOCK 0x00
+
+#define DIGITAL_ISO_DEP_BLOCK_HAS_DID(pcb) ((pcb) & 0x08)
+
 static const u8 digital_ats_fsc[] = {
          16,  24,  32,  40,  48,  64,  96, 128,
 };
@@ -118,6 +127,54 @@ struct digital_iso15693_inv_res {
 static int digital_in_send_sdd_req(struct nfc_digital_dev *ddev,
                                    struct nfc_target *target);
 
+int digital_in_iso_dep_pull_sod(struct nfc_digital_dev *ddev,
+                                struct sk_buff *skb)
+{
+        u8 pcb;
+        u8 block_type;
+
+        if (skb->len < 1)
+                return -EIO;
+
+        pcb = *skb->data;
+        block_type = DIGITAL_ISO_DEP_PCB_TYPE(pcb);
+
+        /* No support fo R-block nor S-block */
+        if (block_type != DIGITAL_ISO_DEP_I_BLOCK) {
+                pr_err("ISO_DEP R-block and S-block not supported\n");
+                return -EIO;
+        }
+
+        if (DIGITAL_ISO_DEP_BLOCK_HAS_DID(pcb)) {
+                pr_err("DID field in ISO_DEP PCB not supported\n");
+                return -EIO;
+        }
+
+        skb_pull(skb, 1);
+
+        return 0;
+}
+
+int digital_in_iso_dep_push_sod(struct nfc_digital_dev *ddev,
+                                struct sk_buff *skb)
+{
+        /*
+         * Chaining not supported so skb->len + 1 PCB byte + 2 CRC bytes must
+         * not be greater than remote FSC
+         */
+        if (skb->len + 3 > ddev->target_fsc)
+                return -EIO;
+
+        skb_push(skb, 1);
+
+        *skb->data = DIGITAL_ISO_DEP_I_PCB | ddev->curr_nfc_dep_pni;
+
+        ddev->curr_nfc_dep_pni =
+                DIGITAL_ISO_DEP_PNI(ddev->curr_nfc_dep_pni + 1);
+
+        return 0;
+}
+
 static void digital_in_recv_ats(struct nfc_digital_dev *ddev, void *arg,
                                 struct sk_buff *resp)
 {