NFC: Set and get DEP general bytes

Without an API for setting and getting the local and remote general bytes,
drivers won't be able to properly establish a DEP link.
This API also allows them to propagate the remote general bytes they get
from the DEP link establishment up to the LLCP layer.
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/nfc/pn533.c

@@ -1121,6 +1121,7 @@ static int pn533_activate_target_nfcdep(struct pn533 *dev)
 {
 	struct pn533_cmd_activate_param param;
 	struct pn533_cmd_activate_response *resp;
+	u16 gt_len;
 	int rc;
 
 	nfc_dev_dbg(&dev->interface->dev, "%s", __func__);
@@ -1146,7 +1147,11 @@ static int pn533_activate_target_nfcdep(struct pn533 *dev)
 	if (rc != PN533_CMD_RET_SUCCESS)
 		return -EIO;
 
-	return 0;
+	/* ATR_RES general bytes are located at offset 16 */
+	gt_len = PN533_FRAME_CMD_PARAMS_LEN(dev->in_frame) - 16;
+	rc = nfc_set_remote_general_bytes(dev->nfc_dev, resp->gt, gt_len);
+
+	return rc;
 }
 
 static int pn533_activate_target(struct nfc_dev *nfc_dev, u32 target_idx,

include/net/nfc/nfc.h

@@ -170,6 +170,11 @@ struct sk_buff *nfc_alloc_send_skb(struct nfc_dev *dev, struct sock *sk,
 					unsigned int *err);
 struct sk_buff *nfc_alloc_recv_skb(unsigned int size, gfp_t gfp);
 
+int nfc_set_remote_general_bytes(struct nfc_dev *dev,
+					u8 *gt, u8 gt_len);
+
+u8 *nfc_get_local_general_bytes(struct nfc_dev *dev, u8 *gt_len);
+
 int nfc_targets_found(struct nfc_dev *dev, struct nfc_target *targets,
 							int ntargets);
 

net/nfc/core.c

@@ -352,6 +352,24 @@ int nfc_data_exchange(struct nfc_dev *dev, u32 target_idx,
 	return rc;
 }
 
+int nfc_set_remote_general_bytes(struct nfc_dev *dev, u8 *gb, u8 gb_len)
+{
+	pr_debug("dev_name=%s gb_len=%d\n",
+			dev_name(&dev->dev), gb_len);
+
+	if (gb_len > NFC_MAX_GT_LEN)
+		return -EINVAL;
+
+	return 0;
+}
+EXPORT_SYMBOL(nfc_set_remote_general_bytes);
+
+u8 *nfc_get_local_general_bytes(struct nfc_dev *dev, u8 *gt_len)
+{
+	return NULL;
+}
+EXPORT_SYMBOL(nfc_get_local_general_bytes);
+
 /**
  * nfc_alloc_send_skb - allocate a skb for data exchange responses
  *