google/gru: Add a stub rk3399 mainboard

Most things still need to be filled in, but this will allow
us to build boards which use this SOC.

[pg: separated out from the combined commit that added both SoC and
board. Added board_info.txt that will be added downstream, too.]

Change-Id: I7facce7b98a5d19fb77746b1aee67fff74da8150
Signed-off-by: Patrick Georgi <pgeorgi@chromium.org>
Original-Commit-Id: 27dfc39efe95025be2271e2e00e9df93b7907840
Original-Change-Id: I6f2407ff578dcd3d0daed86dd03d8f5f4edcac53
Original-Signed-off-by: huang lin <hl@rock-chips.com>
Original-Signed-off-by: Vadim Bendebury <vbendeb@chromium.org>
Original-Reviewed-on: https://chromium-review.googlesource.com/332385
Reviewed-on: https://review.coreboot.org/14279
Tested-by: build bot (Jenkins)
Reviewed-by: Martin Roth <martinroth@google.com>
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
diff --git a/src/mainboard/google/gru/mainboard.c b/src/mainboard/google/gru/mainboard.c
new file mode 100644
index 0000000..1641838
--- /dev/null
+++ b/src/mainboard/google/gru/mainboard.c
@@ -0,0 +1,36 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright 2016 Rockchip Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#include <arch/cache.h>
+#include <arch/io.h>
+#include <boardid.h>
+#include <boot/coreboot_tables.h>
+#include <device/device.h>
+#include <console/console.h>
+
+static void mainboard_init(device_t dev)
+{
+}
+
+static void mainboard_enable(device_t dev)
+{
+	dev->ops->init = &mainboard_init;
+}
+
+struct chip_operations mainboard_ops = {
+	.name = CONFIG_MAINBOARD_PART_NUMBER,
+	.enable_dev = mainboard_enable,
+};