ARM: dts: at91: shdwc binding: add new shutdown controller documentation

		clocks = <&clk32k>;

	};

SHDWC SAMA5D2-Compatible Shutdown Controller

1) shdwc node

required properties:

- compatible: should be "atmel,sama5d2-shdwc".

- reg: should contain registers location and length

- clocks: phandle to input clock.

- #address-cells: should be one. The cell is the wake-up input index.

- #size-cells: should be zero.

optional properties:

- debounce-delay-us: minimum wake-up inputs debouncer period in

  microseconds. It's usually a board-related property.

- atmel,wakeup-rtc-timer: boolean to enable Real-Time Clock wake-up.

The node contains child nodes for each wake-up input that the platform uses.

2) input nodes

Wake-up input nodes are usually described in the "board" part of the Device

Tree. Note also that input 0 is linked to the wake-up pin and is frequently

used.

Required properties:

- reg: should contain the wake-up input index [0 - 15].

Optional properties:

- atmel,wakeup-active-high: boolean, the corresponding wake-up input described

  by the child, forces the wake-up of the core power supply on a high level.

  The default is to be active low.

Example:

On the SoC side:

	shdwc@f8048010 {

		compatible = "atmel,sama5d2-shdwc";

		reg = <0xf8048010 0x10>;

		clocks = <&clk32k>;

		#address-cells = <1>;

		#size-cells = <0>;

		atmel,wakeup-rtc-timer;

	};

On the board side:

	shdwc@f8048010 {

		debounce-delay-us = <976>;

		input@0 {

			reg = <0>;

		};

		input@1 {

			reg = <1>;

			atmel,wakeup-active-high;

		};

	};

Special Function Registers (SFR)

Special Function Registers (SFR) manage specific aspects of the integrated