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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