Amlogic Meson MHU Mailbox Driver
================================

The Amlogic's Meson SoCs Message-Handling-Unit (MHU) is a mailbox controller
that has 3 independent channels/links to communicate with remote processor(s).
MHU links are hardwired on a platform. A link raises interrupt for any
received data. However, there is no specified way of knowing if the sent
data has been read by the remote. This driver assumes the sender polls
STAT register and the remote clears it after having read the data.

Mailbox Device Node:
====================

Required properties:
--------------------
- compatible:		Shall be "amlogic,meson-gxbb-mhu"
- reg:			Contains the mailbox register address range (base
			address and length)
- #mbox-cells		Shall be 1 - the index of the channel needed.
- interrupts:		Contains the interrupt information corresponding to
			each of the 2 links of MHU.

Example:
--------

	mailbox: mailbox@c883c404 {
		#mbox-cells = <1>;
		compatible = "amlogic,meson-gxbb-mhu";
		reg = <0 0xc883c404 0 0x4c>;
		interrupts = <0 208 IRQ_TYPE_EDGE_RISING>,
			     <0 209 IRQ_TYPE_EDGE_RISING>,
			     <0 210 IRQ_TYPE_EDGE_RISING>;
		#mbox-cells = <1>;
	};