Introduce new eth_receive routine

The purpose of this routine is receiving a single network frame, outside of
U-Boot's NetLoop(). Exporting it to standalone programs that run on top of
U-Boot will let them utilise networking facilities. For sending a raw frame
the already existing eth_send() can be used.

The direct consumer of this routine is the newly introduced API layer for
external applications (enabled with CONFIG_API).

Signed-off-by: Rafal Jaworowski <raj@semihalf.com>
Signed-off-by: Piotr Kruszynski <ppk@semihalf.com>
Signed-off-by: Ben Warren <biggerbadderben@gmail.com>
diff --git a/net/net.c b/net/net.c
index c719bc4..cac3e09 100644
--- a/net/net.c
+++ b/net/net.c
@@ -137,6 +137,9 @@
 			{ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff };
 uchar		NetEtherNullAddr[6] =
 			{ 0, 0, 0, 0, 0, 0 };
+#ifdef CONFIG_API
+void		(*push_packet)(volatile void *, int len) = 0;
+#endif
 #if defined(CONFIG_CMD_CDP)
 uchar		NetCDPAddr[6] =		/* Ethernet bcast address		*/
 			{ 0x01, 0x00, 0x0c, 0xcc, 0xcc, 0xcc };
@@ -1161,6 +1164,13 @@
 	if (len < ETHER_HDR_SIZE)
 		return;
 
+#ifdef CONFIG_API
+	if (push_packet) {
+		(*push_packet)(inpkt, len);
+		return;
+	}
+#endif
+
 #if defined(CONFIG_CMD_CDP)
 	/* keep track if packet is CDP */
 	iscdp = memcmp(et->et_dest, NetCDPAddr, 6) == 0;