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diff --git a/Documentation/devicetree/bindings/arm/fw-cfg.txt b/Documentation/devicetree/bindings/arm/fw-cfg.txt
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+* QEMU Firmware Configuration bindings for ARM
+
+QEMU's arm-softmmu and aarch64-softmmu emulation / virtualization targets
+provide the following Firmware Configuration interface on the "virt" machine
+type:
+
+- A write-only, 16-bit wide selector (or control) register,
+- a read-write, 64-bit wide data register.
+
+QEMU exposes the control and data register to ARM guests as memory mapped
+registers; their location is communicated to the guest's UEFI firmware in the
+DTB that QEMU places at the bottom of the guest's DRAM.
+
+The authoritative guest-side hardware interface documentation to the fw_cfg
+device can be found in "docs/specs/fw_cfg.txt" in the QEMU source tree.
+
+
+Required properties:
+
+- compatible: "qemu,fw-cfg-mmio".
+
+- reg: the MMIO region used by the device.
+  * Bytes 0x0 to 0x7 cover the data register.
+  * Bytes 0x8 to 0x9 cover the selector register.
+  * Further registers may be appended to the region in case of future interface
+    revisions / feature bits.
+
+Example:
+
+/ {
+	#size-cells = <0x2>;
+	#address-cells = <0x2>;
+
+	fw-cfg@9020000 {
+		compatible = "qemu,fw-cfg-mmio";
+		reg = <0x0 0x9020000 0x0 0xa>;
+	};
+};