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Diffstat (limited to 'arch/arm/cpu/armv8/fsl-layerscape/doc/README.pci_iommu_extra')
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diff --git a/arch/arm/cpu/armv8/fsl-layerscape/doc/README.pci_iommu_extra b/arch/arm/cpu/armv8/fsl-layerscape/doc/README.pci_iommu_extra new file mode 100644 index 0000000000..43db4d8e94 --- /dev/null +++ b/arch/arm/cpu/armv8/fsl-layerscape/doc/README.pci_iommu_extra @@ -0,0 +1,67 @@ +# +# Copyright 2020 NXP +# +# SPDX-License-Identifier: GPL-2.0+ +# + +Specifying extra IOMMU mappings for PCI controllers + +This feature can be enabled through the PCI_IOMMU_EXTRA_MAPPINGS Kconfig option. + +The "pci_iommu_extra" env var or "pci-iommu-extra" device tree property (to be +used for example in more static scenarios such as hardwired PCI endpoints that +get initialized later in the system setup) allows two things: + - for a SRIOV capable PCI EP identified by its B.D.F specify the maximum number + of VFs that will ever be created for it + - for hot-plug case, specify the B.D.F with which the device will show up on + the PCI bus + +The env var consists of a list of <bdf>,<action> pairs for a certain pci bus +identified by its controller's base register address, as defined in the "reg" +property in the device tree. + +pci_iommu_extra = pci@<addr1>,<bdf>,<action>,<bdf>,<action>, + pci@<addr2>,<bdf>,<action>,<bdf>,<action>,... + +where: + <addr> is the base register address of the pci controller for which the + subsequent <bdf>,<action> pairs apply + <bdf> identifies to which B.D.F the action applies to + <action> can be: + - "vfs=<number>" to specify that for the PCI EP identified previously by + the <bdf> to include mappings for <number> of VFs. + The variant "noari_vfs=<number>" is available to disable taking ARI into + account. + - "hp" to specify that on this <bdf> there will be a hot-plugged device so + it needs a mapping +The device tree property must be placed under the correct pci controller node +and only the bdf and action pairs need to be specified, like this: + +pci-iommu-extra = "<bdf>,<action>,<bdf>,<action>,..."; + +Note: the env var has priority over the device tree property. + +For example, given this configuration on bus 6: + +=> pci 6 +Scanning PCI devices on bus 6 +BusDevFun VendorId DeviceId Device Class Sub-Class +_____________________________________________________________ +06.00.00 0x8086 0x1572 Network controller 0x00 +06.00.01 0x8086 0x1572 Network controller 0x00 + +The following u-boot env var will create iommu mappings for 3 VFs for each PF: + +=> setenv pci_iommu_extra pci@0x3800000,6.0.0,vfs=3,6.0.1,vfs=3 + +For the device tree case, this would be specified like this: + +pci-iommu-extra = "6.0.0,vfs=3,6.0.1,vfs=3"; + +To add an iommu mapping for a hot-plugged device, please see following example: + +=> setenv pci_iommu_extra pci@0x3800000,2.16.0,hp + +For the device tree case, this would be specified like this: + +pci-iommu-extra = "2.16.0,hp"; |