mtd: nand: vf610_nfc: add device tree bindings

Freescale's NAND flash controller (NFC)

This variant of the Freescale NAND flash controller (NFC) can be found on

Vybrid (vf610), MPC5125, MCF54418 and Kinetis K70.

Required properties:

- compatible: Should be set to "fsl,vf610-nfc".

- reg: address range of the NFC.

- interrupts: interrupt of the NFC.

- #address-cells: shall be set to 1. Encode the nand CS.

- #size-cells : shall be set to 0.

- assigned-clocks: main clock from the SoC, for Vybrid <&clks VF610_CLK_NFC>;

- assigned-clock-rates: The NAND bus timing is derived from this clock

    rate and should not exceed maximum timing for any NAND memory chip

    in a board stuffing. Typical NAND memory timings derived from this

    clock are found in the SoC hardware reference manual. Furthermore,

    there might be restrictions on maximum rates when using hardware ECC.

- #address-cells, #size-cells : Must be present if the device has sub-nodes

  representing partitions.

Required children nodes:

Children nodes represent the available nand chips. Currently the driver can

only handle one NAND chip.

Required properties:

- compatible: Should be set to "fsl,vf610-nfc-cs".

- nand-bus-width: see nand.txt

- nand-ecc-mode: see nand.txt

Required properties for hardware ECC:

- nand-ecc-strength: supported strengths are 24 and 32 bit (see nand.txt)

- nand-ecc-step-size: step size equals page size, currently only 2k pages are

    supported

- nand-on-flash-bbt: see nand.txt

Example:

	nfc: nand@400e0000 {

		compatible = "fsl,vf610-nfc";

		#address-cells = <1>;

		#size-cells = <0>;

		reg = <0x400e0000 0x4000>;

		interrupts = <GIC_SPI 83 IRQ_TYPE_LEVEL_HIGH>;

		clocks = <&clks VF610_CLK_NFC>;

		clock-names = "nfc";

		assigned-clocks = <&clks VF610_CLK_NFC>;

		assigned-clock-rates = <33000000>;

		nand@0 {

			compatible = "fsl,vf610-nfc-nandcs";

			reg = <0>;

			nand-bus-width = <8>;

			nand-ecc-mode = "hw";

			nand-ecc-strength = <32>;

			nand-ecc-step-size = <2048>;

			nand-on-flash-bbt;

		};

	};