[PATCH 2/4] dt-bindings: arm: fsl: add mu binding doc

[Dong Aisheng <aisheng.dong@nxp.com>]

The Messaging Unit module enables two processors within
the SoC to communicate and coordinate by passing messages
(e.g. data, status and control) through the MU interface.

Cc: Shawn Guo <shawnguo@kernel.org>
Cc: Sascha Hauer <kernel@pengutronix.de>
Cc: Fabio Estevam <fabio.estevam@nxp.com>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: devicetree@vger.kernel.org
Signed-off-by: Dong Aisheng <aisheng.dong@nxp.com>
---
 .../devicetree/bindings/arm/freescale/fsl,mu.txt   | 33 ++++++++++++++++++++++
 1 file changed, 33 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/arm/freescale/fsl,mu.txt

diff --git a/Documentation/devicetree/bindings/arm/freescale/fsl,mu.txt b/Documentation/devicetree/bindings/arm/freescale/fsl,mu.txt
new file mode 100644
index 0000000..a7ceb1f
--- /dev/null
+++ b/Documentation/devicetree/bindings/arm/freescale/fsl,mu.txt
@@ -0,0 +1,33 @@
+NXP i.MX Messaging Unit (MU)
+--------------------------------------------------------------------
+
+The Messaging Unit module enables two processors within the SoC to
+communicate and coordinate by passing messages (e.g. data, status
+and control) through the MU interface. The MU also provides the ability
+for one processor to signal the other processor using interrupts.
+
+Because the MU manages the messaging between processors, the MU uses
+different clocks (from each side of the different peripheral buses).
+Therefore, the MU must synchronize the accesses from one side to the
+other. The MU accomplishes synchronization using two sets of matching
+registers (Processor A-facing, Processor Bfacing).
+
+Messaging Unit Device Node:
+=============================
+
+Required properties:
+-------------------
+- compatible :	should be "fsl,<chip>-mu", the supported chips include
+		imx6sx, imx7d, imx7ulp, imx8qxp, imx8qm, imx8mq.
+- reg :		Should contain the registers location and length
+- interrupts :	Interrupt number. The interrupt specifier format depends
+		on the interrupt controller parent.
+
+Examples:
+--------
+lsio_mu0: mu@5d1b0000 {
+	compatible = "fsl,imx8qxp-mu", "fsl,imx6sx-mu";
+	reg = <0x0 0x5d1b0000 0x0 0x10000>;
+	interrupts = <GIC_SPI 176 IRQ_TYPE_LEVEL_HIGH>;
+	status = "okay";
+};
-- 
2.7.4