arm: rockchip: Add RK3308 SOC support

RK3308 is a quad Cortex A35 based SOC with rich audio
interfaces(I2S/PCM/TDM/PDM/SPDIF/VAD/HDMI ARC), which
designed for intelligent voice interaction and audio
input/output processing.

Signed-off-by: Andy Yan <andy.yan@rock-chips.com>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>
diff --git a/arch/arm/mach-rockchip/rk3308/syscon_rk3308.c b/arch/arm/mach-rockchip/rk3308/syscon_rk3308.c
new file mode 100644
index 0000000..b380ff5
--- /dev/null
+++ b/arch/arm/mach-rockchip/rk3308/syscon_rk3308.c
@@ -0,0 +1,20 @@
+// SPDX-License-Identifier:     GPL-2.0+
+/*
+ * (C) Copyright 2018 Rockchip Electronics Co., Ltd
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <syscon.h>
+#include <asm/arch-rockchip/clock.h>
+
+static const struct udevice_id rk3308_syscon_ids[] = {
+	{ .compatible = "rockchip,rk3308-grf", .data = ROCKCHIP_SYSCON_GRF },
+	{ }
+};
+
+U_BOOT_DRIVER(syscon_rk3308) = {
+	.name = "rk3308_syscon",
+	.id = UCLASS_SYSCON,
+	.of_match = rk3308_syscon_ids,
+};