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+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 B-facing).
+
+Messaging Unit Device Node:
+=============================
+
+Required properties:
+-------------------
+- compatible : should be "fsl,<chip>-mu", the supported chips include
+ imx6sx, imx7s, imx8qxp, imx8qm.
+ The "fsl,imx6sx-mu" compatible is seen as generic and should
+ be included together with SoC specific compatible.
+- reg : Should contain the registers location and length
+- interrupts : Interrupt number. The interrupt specifier format depends
+ on the interrupt controller parent.
+- #mbox-cells: Must be 2.
+ <&phandle type channel>
+ phandle : Label name of controller
+ type : Channel type
+ channel : Channel number
+
+ This MU support 4 type of unidirectional channels, each type
+ has 4 channels. A total of 16 channels. Following types are
+ supported:
+ 0 - TX channel with 32bit transmit register and IRQ transmit
+ acknowledgment support.
+ 1 - RX channel with 32bit receive register and IRQ support
+ 2 - TX doorbell channel. Without own register and no ACK support.
+ 3 - RX doorbell channel.
+
+Optional properties:
+-------------------
+- clocks : phandle to the input clock.
+- fsl,mu-side-b : Should be set for side B MU.
+
+Examples:
+--------
+lsio_mu0: mailbox@5d1b0000 {
+ compatible = "fsl,imx8qxp-mu";
+ reg = <0x0 0x5d1b0000 0x0 0x10000>;
+ interrupts = <GIC_SPI 176 IRQ_TYPE_LEVEL_HIGH>;
+ #mbox-cells = <2>;
+};