ARM: msm: Documentation: Add device tree binding for LLCC

== Introduction==

LLCC (Last Level Cache Controller) driver is implemented as simple-mfd. The

driver is classified into four drivers based on the hw block that provide

different functionality.

1. LLCC Core Driver:

LLCC core driver takes care of initialization of the LLCC required to enable LLCC,

ECC (Error Correction Code) & AMON (Activity Monitor) drivers.

2. LLCC driver:

Programs the SCT (system configuration table). The SCT programming divides the

system cache into slices. Each slice is assigned an ID A.K.A SCID(Sub-cache ID).

HW modules that are designated to use the system cache are known as clients.

Each client must also be represented as a node in the device tree just like

any other hw module.

One client can have multiple SCID's assigned meaning each client could get

multiple slices in the cache. Client can use the slices for various pre-defined

usecases. Each client defines a set of names for these usecases in its

device tree binding.

Client makes a request to LLCC device to get cache-slices properties for each

of its usecase. Client gets the information like cache slice ID and size of the

cache slice.

3. LLCC ECC Driver:

Reports single and double bit errors in the data and tag ram of LLCC.

4. LLCC AMON Driver:

Keeps track of the data progress within the internal channels of LLCC.

== llcc device ==

Require Properties:

- compatible:

	Usage: required

	Value type: <string>

	Definition: must be "qcom,llcc-core"

- reg:

	Usage: required

	Value Type: <prop-encoded-array>

	Definition: must be addresses and sizes of the LLCC registers

- reg-names:

	Usage: required

	Value Type: <stringlist>

	Definition: Address names. Must be "llcc"

- #cache-cells:

	Usage: required

	Value Type: <u32>

	Definition: Number of cache cells, must be 1

- max-slices:

	usage: required

	Value Type: <u32>

	Definition: Number of cache slices supported by hardware

Optional Properties:

- status:

	Usage: optional

	Value type: <string>

	Definition: Property to enable or disable the driver

Example:

	qcom,llcc@01300000 {

		compatible = "llcc-core", "syscon", "simple-mfd";

		reg = <0x1300000 0x50000>;

		reg-names = "llcc_base";

		status = "disabled";

		llcc: qcom,msmskunk-llcc {

			compatible = "qcom,msmskunk-llcc";

			#cache-cells = <1>;

			max-slices = <32>;

		};

		qcom,llcc-erp {

			compatible = "qcom,llcc-erp";

		};

		qcom,llcc-amon {

			compatible = "qcom,llcc-amon";

		};

	};

== Client ==

Required properties:

- cache-slice-names:

	Usage: required

	Value type: <stringlist>

	Definition: A set of names that identify the usecase names of a client that uses

		    cache slice. These strings are used to look up the cache slice

		    entries by name.

- cache-slices:

	Usage: required

	Value type: <prop-encoded-array>

	Definition: The tuple has phandle to llcc device as the first argument and the

		    second argument is the usecase id of the client.

For Example:

	venus {

		cache-slice-names = "vidsc0", "vidsc1";

		cache-slices = <&llcc 2>, <&llcc 3>;

	};