Documentation: arm64: add SCU dts binding documentation to linux kernel

This add documentation for the SCU system clock unit device tree binding
to the kernel.

Signed-off-by: Feng Kan <fkan@apm.com>

diff --git a/Documentation/devicetree/bindings/arm/apm/scu.txt b/Documentation/devicetree/bindings/arm/apm/scu.txt
new file mode 100644 (file)
index 0000000..b45be06
--- /dev/null
+++ b/Documentation/devicetree/bindings/arm/apm/scu.txt
@@ -0,0 +1,17 @@
+APM X-GENE SoC series SCU Registers
+
+This system clock unit contain various register that control block resets,
+clock enable/disables, clock divisors and other deepsleep registers.
+
+Properties:
+ - compatible : should contain two values. First value must be:
+                  - "apm,xgene-scu"
+               second value must be always "syscon".
+
+ - reg : offset and length of the register set.
+
+Example :
+       scu: system-clk-controller@17000000 {
+               compatible = "apm,xgene-scu","syscon";
+               reg = <0x0 0x17000000 0x0 0x400>;
+       };