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diff --git a/Documentation/devicetree/bindings/virtio/iommu.txt b/Documentation/devicetree/bindings/virtio/iommu.txt
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+* virtio IOMMU PCI device
+
+When virtio-iommu uses the PCI transport, its programming interface is
+discovered dynamically by the PCI probing infrastructure. However the
+device tree statically describes the relation between IOMMU and DMA
+masters. Therefore, the PCI root complex that hosts the virtio-iommu
+contains a child node representing the IOMMU device explicitly.
+
+Required properties:
+
+- compatible:	Should be "virtio,pci-iommu"
+- reg:		PCI address of the IOMMU. As defined in the PCI Bus
+		Binding reference [1], the reg property is a five-cell
+		address encoded as (phys.hi phys.mid phys.lo size.hi
+		size.lo). phys.hi should contain the device's BDF as
+		0b00000000 bbbbbbbb dddddfff 00000000. The other cells
+		should be zero.
+- #iommu-cells:	Each platform DMA master managed by the IOMMU is assigned
+		an endpoint ID, described by the "iommus" property [2].
+		For virtio-iommu, #iommu-cells must be 1.
+
+Notes:
+
+- DMA from the IOMMU device isn't managed by another IOMMU. Therefore the
+  virtio-iommu node doesn't have an "iommus" property, and is omitted from
+  the iommu-map property of the root complex.
+
+Example:
+
+pcie@10000000 {
+	compatible = "pci-host-ecam-generic";
+	...
+
+	/* The IOMMU programming interface uses slot 00:01.0 */
+	iommu0: iommu@0008 {
+		compatible = "virtio,pci-iommu";
+		reg = <0x00000800 0 0 0 0>;
+		#iommu-cells = <1>;
+	};
+
+	/*
+	 * The IOMMU manages all functions in this PCI domain except
+	 * itself. Omit BDF 00:01.0.
+	 */
+	iommu-map = <0x0 &iommu0 0x0 0x8>
+		    <0x9 &iommu0 0x9 0xfff7>;
+};
+
+pcie@20000000 {
+	compatible = "pci-host-ecam-generic";
+	...
+	/*
+	 * The IOMMU also manages all functions from this domain,
+	 * with endpoint IDs 0x10000 - 0x1ffff
+	 */
+	iommu-map = <0x0 &iommu0 0x10000 0x10000>;
+};
+
+ethernet@fe001000 {
+	...
+	/* The IOMMU manages this platform device with endpoint ID 0x20000 */
+	iommus = <&iommu0 0x20000>;
+};
+
+[1] Documentation/devicetree/bindings/pci/pci.txt
+[2] Documentation/devicetree/bindings/iommu/iommu.txt
diff --git a/Documentation/devicetree/bindings/virtio/mmio.txt b/Documentation/devicetree/bindings/virtio/mmio.txt
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+* virtio memory mapped device
+
+See https://ozlabs.org/~rusty/virtio-spec/ for more details.
+
+Required properties:
+
+- compatible:	"virtio,mmio" compatibility string
+- reg:		control registers base address and size including configuration space
+- interrupts:	interrupt generated by the device
+
+Required properties for virtio-iommu:
+
+- #iommu-cells:	When the node corresponds to a virtio-iommu device, it is
+		linked to DMA masters using the "iommus" or "iommu-map"
+		properties [1][2]. #iommu-cells specifies the size of the
+		"iommus" property. For virtio-iommu #iommu-cells must be
+		1, each cell describing a single endpoint ID.
+
+Optional properties:
+
+- iommus:	If the device accesses memory through an IOMMU, it should
+		have an "iommus" property [1]. Since virtio-iommu itself
+		does not access memory through an IOMMU, the "virtio,mmio"
+		node cannot have both an "#iommu-cells" and an "iommus"
+		property.
+
+Example:
+
+	virtio_block@3000 {
+		compatible = "virtio,mmio";
+		reg = <0x3000 0x100>;
+		interrupts = <41>;
+
+		/* Device has endpoint ID 23 */
+		iommus = <&viommu 23>
+	}
+
+	viommu: iommu@3100 {
+		compatible = "virtio,mmio";
+		reg = <0x3100 0x100>;
+		interrupts = <42>;
+
+		#iommu-cells = <1>
+	}
+
+[1] Documentation/devicetree/bindings/iommu/iommu.txt
+[2] Documentation/devicetree/bindings/pci/pci-iommu.txt