Device tree bindings for Texas instruments Davinci/Keystone NAND controller

This file provides information, what the device node for the davinci/keystone
NAND interface contains.

Documentation:
Davinci DM646x - https://www.ti.com/lit/ug/sprueq7c/sprueq7c.pdf
Kestone - https://www.ti.com/lit/ug/sprugz3a/sprugz3a.pdf

Required properties:

- compatible:			"ti,davinci-nand"
				"ti,keystone-nand"

- reg:				Contains 2 offset/length values:
				- offset and length for the access window.
				- offset and length for accessing the AEMIF
				control registers.

- ti,davinci-chipselect:	number of chipselect. Indicates on the
				davinci_nand driver which chipselect is used
				for accessing the nand.
				Can be in the range [0-3].

Recommended properties :

- ti,davinci-mask-ale:		mask for ALE. Needed for executing address
				phase. These offset will be added to the base
				address for the chip select space the NAND Flash
				device is connected to.
				If not set equal to 0x08.

- ti,davinci-mask-cle:		mask for CLE. Needed for executing command
				phase. These offset will be added to the base
				address for the chip select space the NAND Flash
				device is connected to.
				If not set equal to 0x10.

- ti,davinci-mask-chipsel:	mask for chipselect address. Needed to mask
				addresses for given chipselect.

- nand-ecc-mode:		operation mode of the NAND ecc mode. ECC mode
				valid values for davinci driver:
				- "none"
				- "soft"
				- "hw"

- ti,davinci-ecc-bits:		used ECC bits, currently supported 1 or 4.

- nand-bus-width:		buswidth 8 or 16. If not present 8.

- nand-on-flash-bbt:		use flash based bad block table support. OOB
				identifier is saved in OOB area. If not present
				false.

Deprecated properties:

- ti,davinci-ecc-mode:		operation mode of the NAND ecc mode. ECC mode
				valid values for davinci driver:
				- "none"
				- "soft"
				- "hw"

- ti,davinci-nand-buswidth:	buswidth 8 or 16. If not present 8.

- ti,davinci-nand-use-bbt:	use flash based bad block table support. OOB
				identifier is saved in OOB area. If not present
				false.

Nand device bindings may contain additional sub-nodes describing partitions of
the address space. See mtd.yaml for more detail. The NAND Flash timing
values must be programmed in the chip select’s node of AEMIF
memory-controller (see Documentation/devicetree/bindings/memory-controllers/
davinci-aemif.txt).

Example(da850 EVM ):

nand_cs3@62000000 {
	compatible = "ti,davinci-nand";
	reg = <0x62000000 0x807ff
	       0x68000000 0x8000>;
	ti,davinci-chipselect = <1>;
	ti,davinci-mask-ale = <0>;
	ti,davinci-mask-cle = <0>;
	ti,davinci-mask-chipsel = <0>;
	nand-ecc-mode = "hw";
	ti,davinci-ecc-bits = <4>;
	nand-on-flash-bbt;

	partition@180000 {
		label = "ubifs";
		reg = <0x180000 0x7e80000>;
	};
};