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Diffstat (limited to 'Documentation/devicetree/bindings/pci/pci-iommu.txt')
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diff --git a/Documentation/devicetree/bindings/pci/pci-iommu.txt b/Documentation/devicetree/bindings/pci/pci-iommu.txt new file mode 100644 index 000000000..0def586fd --- /dev/null +++ b/Documentation/devicetree/bindings/pci/pci-iommu.txt @@ -0,0 +1,171 @@ +This document describes the generic device tree binding for describing the +relationship between PCI(e) devices and IOMMU(s). + +Each PCI(e) device under a root complex is uniquely identified by its Requester +ID (AKA RID). A Requester ID is a triplet of a Bus number, Device number, and +Function number. + +For the purpose of this document, when treated as a numeric value, a RID is +formatted such that: + +* Bits [15:8] are the Bus number. +* Bits [7:3] are the Device number. +* Bits [2:0] are the Function number. +* Any other bits required for padding must be zero. + +IOMMUs may distinguish PCI devices through sideband data derived from the +Requester ID. While a given PCI device can only master through one IOMMU, a +root complex may split masters across a set of IOMMUs (e.g. with one IOMMU per +bus). + +The generic 'iommus' property is insufficient to describe this relationship, +and a mechanism is required to map from a PCI device to its IOMMU and sideband +data. + +For generic IOMMU bindings, see +Documentation/devicetree/bindings/iommu/iommu.txt. + + +PCI root complex +================ + +Optional properties +------------------- + +- iommu-map: Maps a Requester ID to an IOMMU and associated IOMMU specifier + data. + + The property is an arbitrary number of tuples of + (rid-base,iommu,iommu-base,length). + + Any RID r in the interval [rid-base, rid-base + length) is associated with + the listed IOMMU, with the IOMMU specifier (r - rid-base + iommu-base). + +- iommu-map-mask: A mask to be applied to each Requester ID prior to being + mapped to an IOMMU specifier per the iommu-map property. + + +Example (1) +=========== + +/ { + #address-cells = <1>; + #size-cells = <1>; + + iommu: iommu@a { + reg = <0xa 0x1>; + compatible = "vendor,some-iommu"; + #iommu-cells = <1>; + }; + + pci: pci@f { + reg = <0xf 0x1>; + compatible = "vendor,pcie-root-complex"; + device_type = "pci"; + + /* + * The sideband data provided to the IOMMU is the RID, + * identity-mapped. + */ + iommu-map = <0x0 &iommu 0x0 0x10000>; + }; +}; + + +Example (2) +=========== + +/ { + #address-cells = <1>; + #size-cells = <1>; + + iommu: iommu@a { + reg = <0xa 0x1>; + compatible = "vendor,some-iommu"; + #iommu-cells = <1>; + }; + + pci: pci@f { + reg = <0xf 0x1>; + compatible = "vendor,pcie-root-complex"; + device_type = "pci"; + + /* + * The sideband data provided to the IOMMU is the RID with the + * function bits masked out. + */ + iommu-map = <0x0 &iommu 0x0 0x10000>; + iommu-map-mask = <0xfff8>; + }; +}; + + +Example (3) +=========== + +/ { + #address-cells = <1>; + #size-cells = <1>; + + iommu: iommu@a { + reg = <0xa 0x1>; + compatible = "vendor,some-iommu"; + #iommu-cells = <1>; + }; + + pci: pci@f { + reg = <0xf 0x1>; + compatible = "vendor,pcie-root-complex"; + device_type = "pci"; + + /* + * The sideband data provided to the IOMMU is the RID, + * but the high bits of the bus number are flipped. + */ + iommu-map = <0x0000 &iommu 0x8000 0x8000>, + <0x8000 &iommu 0x0000 0x8000>; + }; +}; + + +Example (4) +=========== + +/ { + #address-cells = <1>; + #size-cells = <1>; + + iommu_a: iommu@a { + reg = <0xa 0x1>; + compatible = "vendor,some-iommu"; + #iommu-cells = <1>; + }; + + iommu_b: iommu@b { + reg = <0xb 0x1>; + compatible = "vendor,some-iommu"; + #iommu-cells = <1>; + }; + + iommu_c: iommu@c { + reg = <0xc 0x1>; + compatible = "vendor,some-iommu"; + #iommu-cells = <1>; + }; + + pci: pci@f { + reg = <0xf 0x1>; + compatible = "vendor,pcie-root-complex"; + device_type = "pci"; + + /* + * Devices with bus number 0-127 are mastered via IOMMU + * a, with sideband data being RID[14:0]. + * Devices with bus number 128-255 are mastered via + * IOMMU b, with sideband data being RID[14:0]. + * No devices master via IOMMU c. + */ + iommu-map = <0x0000 &iommu_a 0x0000 0x8000>, + <0x8000 &iommu_b 0x0000 0x8000>; + }; +}; |