Representing flash partitions in devicetree

Partitions can be represented by sub-nodes of an mtd device. This can be used
on platforms which have strong conventions about which portions of a flash are
used for what purposes, but which don't use an on-flash partition table such
as RedBoot.

The partition table should be a subnode of the mtd node and should be named
'partitions'. This node should have the following property:
- compatible : (required) must be "fixed-partitions"
Partitions are then defined in subnodes of the partitions node.

For backwards compatibility partitions as direct subnodes of the mtd device are
supported. This use is discouraged.
NOTE: also for backwards compatibility, direct subnodes that have a compatible
string are not considered partitions, as they may be used for other bindings.

#address-cells & #size-cells must both be present in the partitions subnode of the
mtd device. There are two valid values for both:
<1>: for partitions that require a single 32-bit cell to represent their
     size/address (aka the value is below 4 GiB)
<2>: for partitions that require two 32-bit cells to represent their
     size/address (aka the value is 4 GiB or greater).

Required properties:
- reg : The partition's offset and size within the mtd bank.

Optional properties:
- label : The label / name for this partition.  If omitted, the label is taken
  from the node name (excluding the unit address).
- read-only : This parameter, if present, is a hint to Linux that this
  partition should only be mounted read-only. This is usually used for flash
  partitions containing early-boot firmware images or data which should not be
  clobbered.
- lock : Do not unlock the partition at initialization time (not supported on
  all devices)
- encrypted : This parameter flags a partition as encrypted. All accesses to
  and from this partition will be encrypted/decrypted.
- encryption-keyblob-size : Size in bytes of the encryption key blob defined
  above. The size of the key blob is the size of the key itself plus 48 bytes
  of blob overhead. The maximum key size is 64 bytes so the maximum key blob
  size is 112 bytes.
- encryption-keyblob-part : Partition number where the CAAM encrypted crypto
  key is stored. Defauls to 1.
- encryption-keyblob-offset : Offset in the encryption-keyblob-part where the
  CAAM encrypted crypto key is stored.

Examples:


flash@0 {
	partitions {
		compatible = "fixed-partitions";
		#address-cells = <1>;
		#size-cells = <1>;

		partition@0 {
			label = "u-boot";
			reg = <0x0000000 0x100000>;
			read-only;
		};

		uimage@100000 {
			reg = <0x0100000 0x200000>;
		};
	};
};

flash@1 {
	partitions {
		compatible = "fixed-partitions";
		#address-cells = <1>;
		#size-cells = <2>;

		/* a 4 GiB partition */
		partition@0 {
			label = "filesystem";
			reg = <0x00000000 0x1 0x00000000>;
		};
	};
};

flash@2 {
	partitions {
		compatible = "fixed-partitions";
		#address-cells = <2>;
		#size-cells = <2>;

		/* an 8 GiB partition */
		partition@0 {
			label = "filesystem #1";
			reg = <0x0 0x00000000 0x2 0x00000000>;
		};

		/* a 4 GiB partition */
		partition@200000000 {
			label = "filesystem #2";
			reg = <0x2 0x00000000 0x1 0x00000000>;
			encrypted;
			encryption-keyblob-size = <80>;
			encryption-keyblob-offset = <0x40000>;
			encryption-keyblob-part = <1>;
		};
	};
};
