new file mode 100644
@@ -0,0 +1,74 @@
+Hisilicon Hi6220 Mailbox Driver
+===============================
+
+Hisilicon Hi6220 mailbox supports up to 32 channels. Each channel
+is unidirectional with a maximum message size of 8 words. I/O is
+performed using register access (there is no DMA) and the cell
+raises an interrupt when messages are received.
+
+Mailbox Device Node:
+====================
+
+Required properties:
+--------------------
+- compatible: Shall be "hisilicon,hi6220-mbox"
+- reg: Contains the mailbox register address range (base
+ address and length); the first item is for IPC
+ registers, the second item is shared buffer for
+ slots.
+- #mbox-cells: Common mailbox binding property to identify the number
+ of cells required for the mailbox specifier. Must be 3.
+ <&phandle slot_id dst_irq ack_irq>
+ phandle: Label name of mailbox controller
+ slot_id: Slot id used either for TX or RX
+ dst_irq: IRQ identifier index number which used by MCU
+ ack_irq: IRQ identifier index number with generating a
+ TX/RX interrupt to application processor,
+ mailbox driver uses it to acknowledge interrupt
+- interrupts: Contains the interrupt information for the mailbox
+ device. The format is dependent on which interrupt
+ controller the SoCs use.
+
+Optional Properties:
+--------------------
+- hi6220,mbox-tx-noirq: Property of MCU firmware's feature, so mailbox driver
+ use this flag to ask MCU to enable "automatic idle
+ flag" mode or IRQ generated mode to acknowledge a TX
+ completion.
+
+Example:
+--------
+
+ mailbox: mailbox@f7510000 {
+ compatible = "hisilicon,hi6220-mbox";
+ reg = <0x0 0xf7510000 0x0 0x1000>, /* IPC_S */
+ <0x0 0x06dff800 0x0 0x0800>; /* Mailbox */
+ interrupt-parent = <&gic>;
+ interrupts = <GIC_SPI 94 IRQ_TYPE_LEVEL_HIGH>;
+ #mbox-cells = <3>;
+ };
+
+
+Mailbox client
+===============
+
+Required properties:
+--------------------
+- compatible: Many (See the client docs).
+- mboxes: Standard property to specify a Mailbox (See ./mailbox.txt)
+ Cells must match 'mbox-cells' (See Mailbox Device Node above).
+
+Optional Properties:
+--------------------
+- mbox-names: Name given to channels seen in the 'mboxes' property.
+
+Example:
+--------
+
+ stub_clock: stub_clock {
+ compatible = "hisilicon,hi6220-stub-clk";
+ hisilicon,hi6220-clk-sram = <&sram>;
+ #clock-cells = <1>;
+ mbox-names = "mbox-tx", "mbox-rx";
+ mboxes = <&mailbox 1 0 11>, <&mailbox 0 1 10>;
+ };