new file mode 100644
@@ -0,0 +1,55 @@
+Aspeed SGPIO controller Device Tree Bindings
+-------------------------------------------
+
+This SGPIO controller is for ASPEED AST2500 SoC, it supports up to 80 full
+featured Serial GPIOs. Each of the Serial GPIO pins can be programmed to
+support the following options:
+- Support interrupt option for each input port and various interrupt
+ sensitivity option (level-high, level-low, edge-high, edge-low)
+- Support reset tolerance option for each output port
+- Directly connected to APB bus and its shift clock is from APB bus clock
+ divided by a programmable value.
+- Co-work with external signal-chained TTL components (74LV165/74LV595)
+
+
+Required properties:
+
+- compatible : Either "aspeed,ast2400-sgpio" or "aspeed,ast2500-sgpio"
+
+- #gpio-cells : Should be two
+ - First cell is the GPIO line number
+ - Second cell is used to specify optional
+ parameters (unused)
+
+- reg : Address and length of the register set for the device
+- gpio-controller : Marks the device node as a GPIO controller
+- interrupts : Interrupt specifier (see interrupt bindings for
+ details)
+
+- interrupt-controller : Mark the GPIO controller as an interrupt-controller
+
+- ngpios : number of GPIO pins to serialise.
+ (should be multiple of 8, up to 80 pins)
+
+- clocks : A phandle to the APB clock for SGPM clock division
+
+- bus-frequency : SGPM CLK frequency
+
+
+The sgpio and interrupt properties are further described in their respective bindings documentation:
+
+- Documentation/devicetree/bindings/gpio/gpio.txt
+- Documentation/devicetree/bindings/interrupt-controller/interrupts.txt
+
+ Example:
+ sgpio: sgpio@1e780200 {
+ #gpio-cells = <2>;
+ compatible = "aspeed,ast2500-sgpio";
+ gpio-controller;
+ interrupts = <40>;
+ reg = <0x1e780200 0x0100>;
+ clocks = <&syscon ASPEED_CLK_APB>;
+ interrupt-controller;
+ ngpios = <8>;
+ bus-frequency = <12000000>;
+ };