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DtBindings.md

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FdtBusPkg-Specific Devicetree Bindings

Note

See FdtBusPkg Documentation Style and Terms Definitions first.

These apply on top of Devicetree Specification, Chapter 4 and use terms and definitions from that spec.

PCIe Root Complex and PCI Host Bridge Properties

fdtbuspkg,pci-keep-config

Property Value Type Description
fdtbuspkg,pci-keep-config Keep existing PCI(e) BAR configuration.

When set, UEFI PCI bus driver will perform a lightweight enumeration, that skips resource (re)assignment. This requires the resource assignment to be performed elsewhere (e.g. before UEFI).

Miscellaneous Properties

fdtbuspkg,critical

Property Value Type Description
fdtbuspkg,critical Marks a DT controller as critical.

A critical controller is always connected at End-of-DXE event (gEfiEndOfDxeEventGroupGuid). This facility allows device to be always initialized, even under rapid boot conditions.

Note

This property is parsed by FdtBusDxe during processing of child DT controllers. Thus, a DT device with fdtbuspkg,critical must be a child of a controller supported by an existing driver, and this controller needs to have a fdtbuspkg,critical property as well.

Note

Devices of type memory are implicitly treated as having fdtbuspkg,critical.

fdtbuspkg,unit-test-device

Property Value Type Description
fdtbuspkg,unit-test-device Marks a DT controller as being used by internal unit tests.

Note

Only supported in the special testing Devicetree with a DEBUG build of FdtBusDxe. Don't use it.

fdtbuspkg,reg-attrs and fdtbuspkg,range-attrs

Provides optional EFI_DT_IO_REG_TYPE and mapping attribute information for CPU-accessible regions. When not provided, reg and ranges memory regions returned from DtIo default to memory type EfiDtIoRegTypeMemoryMappedIo and and attributes EFI_MEMORY_UC.

The EFI_DT_IO_REG_TYPE is encoded as a <u32>. The EFI memory attributes are encoded as a <u64>.

Property Value Type Description
fdtbuspkg,reg-attrs <prop-encoded-array> Consist of a number of (EFI_DT_IO_REG_TYPE, EFI_MEMORY* attributes_) pairs, matching the number of entries in a reg property.
fdtbuspkg,ranges-attrs <prop-encoded-array> Consist of a number of (EFI_DT_IO_REG_TYPE, EFI_MEMORY* attributes_) pairs, matching the number of entries in a ranges property.

Note

The attributes are not inherited and do not stack. reg does not inherit the parent's ranges type and attribute information.