net: Add link-local addressing support

Code based on networking/zcip.c in busybox
commit 8531d76a15890c2c535908ce888b2e2aed35b172

Signed-off-by: Joe Hershberger <joe.hershberger@ni.com>

common/cmd_net.c

@@ -428,3 +428,34 @@ U_BOOT_CMD(
 );
 
 #endif	/* CONFIG_CMD_DNS */
+
+#if defined(CONFIG_CMD_LINK_LOCAL)
+static int do_link_local(cmd_tbl_t *cmdtp, int flag, int argc,
+			char * const argv[])
+{
+	char tmp[22];
+
+	if (NetLoop(LINKLOCAL) < 0)
+		return 1;
+
+	NetOurGatewayIP = 0;
+	ip_to_string(NetOurGatewayIP, tmp);
+	setenv("gatewayip", tmp);
+
+	ip_to_string(NetOurSubnetMask, tmp);
+	setenv("netmask", tmp);
+
+	ip_to_string(NetOurIP, tmp);
+	setenv("ipaddr", tmp);
+	setenv("llipaddr", tmp); /* store this for next time */
+
+	return 0;
+}
+
+U_BOOT_CMD(
+	linklocal,	1,	1,	do_link_local,
+	"acquire a network IP address using the link-local protocol",
+	""
+);
+
+#endif  /* CONFIG_CMD_LINK_LOCAL */