dt-bindings: mtd: Add Documentation for qpic nand

Qualcomm Technologies, Inc. Parallel Interface controller (QPIC) for NAND devices

Required properties:

- compatible : "qcom,msm-nand".

- reg : should specify QPIC NANDc and BAM physical address range.

- reg-names : should specify relevant names to each reg property defined.

- interrupts : should specify QPIC/BAM interrupt numbers.

- interrupt-names : should specify relevant names to each interrupts property

  defined.

- qcom,reg-adjustment-offset : Specify the base adjustment offset value for the

  version registers

- qcom,qpic-clk-rpmh: Indicates whether QPIC clock is RPMH controlled clock or

  not.

MTD flash partition layout for NAND devices -

Each partition is represented as a sub-node of the qcom,mtd-partitions device.

Each node's name represents the name of the corresponding partition.

This is now completely optional as the partition information is avaialble from

bootloader.

Optional properties:

- reg : boot_cfg. This is needed only on the targets where both NAND and eMMC

  devices are supported. On eMMC based builds, NAND cannot be enabled by

  default due to the absence of some of its required resources.

- reg : The partition offset and size

- label : The label / name for this partition.

- read-only: This parameter, if present, indicates that this partition

  should only be mounted read-only.

- Refer to "Documentation/devicetree/bindings/arm/msm/msm_bus.txt" for

below optional properties:

	- qcom,msm-bus,name

	- qcom,msm-bus,num-cases

	- qcom,msm-bus,active-only

	- qcom,msm-bus,num-paths

	- qcom,msm-bus,vectors-KBps

Examples:

	qcom,nand@f9af0000 {

		compatible = "qcom,msm-nand";

		reg = <0xf9af0000 0x1000>,

		      <0xf9ac4000 0x8000>,

		      <0x5e02c 0x4>;

		reg-names = "nand_phys",

			    "bam_phys",

			    "boot_cfg";

		qcom,reg-adjustment-offset = <0x4000>;

		interrupts = <0 279 0>;

		interrupt-names = "bam_irq";

		qcom,msm-bus,name = "qpic_nand";

		qcom,msm-bus,num-cases = <1>;

		qcom,msm-bus,num-paths = <1>;

		qcom,msm-bus,vectors-KBps = <91 512 0 0>,

		qcom,qpic-clk-rpmh;

	};

       qcom,mtd-partitions {

	       #address-cells = <1>;

	       #size-cells = <1>;

               partition@0 {

                       label = "boot";

                       reg = <0x0 0x1000>;

		       read-only;

               };

               partition@20000 {

                       label = "userdata";

                       reg = <0x20000 0x1000>;

               };

               partition@40000 {

                       label = "system";

                       reg = <0x40000 0x1000>;

               };

       };