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>

3 files changed, 83 insertions, 4 deletions

diff --git a/net/nfc/digital.h b/net/nfc/digital.h
index 3c757dc7d44f..3759add68b1b 100644
--- a/net/nfc/digital.h
+++ b/net/nfc/digital.h
@@ -74,6 +74,11 @@ int digital_in_send_sens_req(struct nfc_digital_dev *ddev, u8 rf_tech);
 int digital_in_send_sensf_req(struct nfc_digital_dev *ddev, u8 rf_tech);
 int digital_in_send_iso15693_inv_req(struct nfc_digital_dev *ddev, u8 rf_tech);
 
+int digital_in_iso_dep_pull_sod(struct nfc_digital_dev *ddev,
+                                struct sk_buff *skb);
+int digital_in_iso_dep_push_sod(struct nfc_digital_dev *ddev,
+                                struct sk_buff *skb);
+
 int digital_target_found(struct nfc_digital_dev *ddev,
                          struct nfc_target *target, u8 protocol);
 
diff --git a/net/nfc/digital_core.c b/net/nfc/digital_core.c
index e1f240266adf..5b440e7d9598 100644
--- a/net/nfc/digital_core.c
+++ b/net/nfc/digital_core.c
@@ -624,20 +624,30 @@ static void digital_in_send_complete(struct nfc_digital_dev *ddev, void *arg,
 
         if (IS_ERR(resp)) {
                 rc = PTR_ERR(resp);
+                resp = NULL;
                 goto done;
         }
 
-        if (ddev->curr_protocol == NFC_PROTO_MIFARE)
+        if (ddev->curr_protocol == NFC_PROTO_MIFARE) {
                 rc = digital_in_recv_mifare_res(resp);
-        else
-                rc = ddev->skb_check_crc(resp);
+                /* crc check is done in digital_in_recv_mifare_res() */
+                goto done;
+        }
+
+        if (ddev->curr_protocol == NFC_PROTO_ISO14443) {
+                rc = digital_in_iso_dep_pull_sod(ddev, resp);
+                if (rc)
+                        goto done;
+        }
+
+        rc = ddev->skb_check_crc(resp);
 
+done:
         if (rc) {
                 kfree_skb(resp);
                 resp = NULL;
         }
 
-done:
         data_exch->cb(data_exch->cb_context, resp, rc);
 
         kfree(data_exch);
@@ -649,6 +659,7 @@ static int digital_in_send(struct nfc_dev *nfc_dev, struct nfc_target *target,
 {
         struct nfc_digital_dev *ddev = nfc_get_drvdata(nfc_dev);
         struct digital_data_exch *data_exch;
+        int rc;
 
         data_exch = kzalloc(sizeof(struct digital_data_exch), GFP_KERNEL);
         if (!data_exch) {
@@ -662,6 +673,12 @@ static int digital_in_send(struct nfc_dev *nfc_dev, struct nfc_target *target,
         if (ddev->curr_protocol == NFC_PROTO_NFC_DEP)
                 return digital_in_send_dep_req(ddev, target, skb, data_exch);
 
+        if (ddev->curr_protocol == NFC_PROTO_ISO14443) {
+                rc = digital_in_iso_dep_push_sod(ddev, skb);
+                if (rc)
+                        return rc;
+        }
+
         ddev->skb_add_crc(skb);
 
         return digital_in_send_cmd(ddev, skb, 500, digital_in_send_complete,
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)
 {