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

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);
 

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,

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)
 {