[PATCH v2 2/4] dt-bindings: mailbox: provide imx-mailbox documentation

@@ -0,0 +1,35 @@
+i.MX Messaging Unit
+===================
+
+The i.MX Messaging Unit (MU) contains two register sets: "A" and "B". In most
+cases they are accessible from all Processor Units. On one hand, at least for
+mailbox functionality, it makes no difference which application or processor is
+using which set of the MU. On other hand, the register sets for each of the MU
+parts are not identical.
+
+Required properties:
+- compatible :	Shell be one of:
+                    "fsl,imx7s-mu-a" and "fsl,imx7s-mu-b" for i.MX7S or i.MX7D
+- reg :		physical base address of the mailbox and length of
+		memory mapped region.
+- #mbox-cells:	Common mailbox binding property to identify the number
+		of cells required for the mailbox specifier. Should be 1.
+- interrupts :	The interrupt number
+- clocks     :  phandle to the input clock.
+
+Example:
+	mu0a: mailbox@30aa0000 {
+		compatible = "fsl,imx7s-mu-a";
+		reg = <0x30aa0000 0x28>;
+		interrupts = <GIC_SPI 88 IRQ_TYPE_LEVEL_HIGH>;
+		clocks = <&clks IMX7D_MU_ROOT_CLK>;
+		#mbox-cells = <1>;
+	};
+
+	mu0b: mailbox@30ab0000 {
+		compatible = "fsl,imx7s-mu-b";
+		reg = <0x30ab0000 0x28>;
+		interrupts = <GIC_SPI 97 IRQ_TYPE_LEVEL_HIGH>;
+		clocks = <&clks IMX7D_MU_ROOT_CLK>;
+		#mbox-cells = <1>;
+	};