[PATCH 0/3] Enable PCIe ATS for devicetree boot

[Jean-Philippe Brucker]

Before enabling Address Translation Support (ATS) in endpoints, the OS
needs to confirm that the Root Complex supports it. Obtain this
information from the firmware description since there is no architected
method. ACPI provides a bit via IORT tables, so add the devicetree
equivalent.

It was discussed a while ago [1], but at the time only a software model
supported it. Respin it now that hardware is available [2].

To test this with the Arm RevC model, enable ATS in the endpoint and
note that ATS is enabled. Address translation is transparent to the OS.

	-C pci.pcie_rc.ahci0.endpoint.ats_supported=1

    $ lspci -s 00:1f.0 -vv
    	Capabilities: [100 v1] Address Translation Service (ATS)
		ATSCap: Invalidate Queue Depth: 00
    		ATSCtl: Enable+, Smallest Translation Unit: 00


[1] https://lore.kernel.org/linux-iommu/20200213165049.508908-1-jean-philippe@linaro.org/
[2] https://lore.kernel.org/linux-arm-kernel/ZeJP6CwrZ2FSbTYm@Asurada-Nvidia/

Jean-Philippe Brucker (3):
  dt-bindings: PCI: generic: Add ats-supported property
  iommu/of: Support ats-supported device-tree property
  arm64: dts: fvp: Enable PCIe ATS for Base RevC FVP

 .../devicetree/bindings/pci/host-generic-pci.yaml        | 6 ++++++
 drivers/iommu/of_iommu.c                                 | 9 +++++++++
 arch/arm64/boot/dts/arm/fvp-base-revc.dts                | 1 +
 3 files changed, 16 insertions(+)

-- 
2.44.0