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/clk_rk3308.c b/arch/arm/mach-rockchip/rk3308/clk_rk3308.c
new file mode 100644
index 0000000..51b4315
--- /dev/null
+++ b/arch/arm/mach-rockchip/rk3308/clk_rk3308.c
@@ -0,0 +1,31 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2018 Fuzhou Rockchip Electronics Co., Ltd
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <syscon.h>
+#include <asm/arch-rockchip/clock.h>
+#include <asm/arch/cru_rk3308.h>
+
+int rockchip_get_clk(struct udevice **devp)
+{
+	return uclass_get_device_by_driver(UCLASS_CLK,
+			DM_GET_DRIVER(rockchip_rk3308_cru), devp);
+}
+
+void *rockchip_get_cru(void)
+{
+	struct rk3308_clk_priv *priv;
+	struct udevice *dev;
+	int ret;
+
+	ret = rockchip_get_clk(&dev);
+	if (ret)
+		return ERR_PTR(ret);
+
+	priv = dev_get_priv(dev);
+
+	return priv->cru;
+}