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| author | Jean-Philippe Brucker <jean-philippe.brucker@arm.com> | 2019-01-15 15:19:54 +0300 |
|---|---|---|
| committer | Michael S. Tsirkin <mst@redhat.com> | 2019-06-07 00:32:13 +0300 |
| commit | 6c9e92ef8bdde13398caae1989b0292524d6475e (patch) | |
| tree | 545a30050b7453b7d7dea7d4273f54c24a963590 /Documentation/devicetree/bindings/virtio | |
| parent | 8447d84e35f2c3b2e76f80319d0b547a9521bafa (diff) | |
| download | linux-6c9e92ef8bdde13398caae1989b0292524d6475e.tar.xz | |
dt-bindings: virtio: Add virtio-pci-iommu node
Some systems implement virtio-iommu as a PCI endpoint. The operating
system needs to discover the relationship between IOMMU and masters long
before the PCI endpoint gets probed. Add a PCI child node to describe the
virtio-iommu device.
The virtio-pci-iommu is conceptually split between a PCI programming
interface and a translation component on the parent bus. The latter
doesn't have a node in the device tree. The virtio-pci-iommu node
describes both, by linking the PCI endpoint to "iommus" property of DMA
master nodes and to "iommu-map" properties of bus nodes.
Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Jean-Philippe Brucker <jean-philippe.brucker@arm.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Diffstat (limited to 'Documentation/devicetree/bindings/virtio')
| -rw-r--r-- | Documentation/devicetree/bindings/virtio/iommu.txt | 66 |
1 files changed, 66 insertions, 0 deletions
diff --git a/Documentation/devicetree/bindings/virtio/iommu.txt b/Documentation/devicetree/bindings/virtio/iommu.txt new file mode 100644 index 000000000000..2407fea0651c --- /dev/null +++ b/Documentation/devicetree/bindings/virtio/iommu.txt @@ -0,0 +1,66 @@ +* 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 |