PCI bus bridges have standardized Device Tree bindings: PCI Bus Binding to: IEEE Std 1275-1994 http://www.openfirmware.org/ofwg/bindings/pci/pci2_1.pdf And for the interrupt mapping part: Open Firmware Recommended Practice: Interrupt Mapping http://www.openfirmware.org/1275/practice/imap/imap0_9d.pdf Additionally to the properties specified in the above standards a host bridge driver implementation may support the following properties: - linux,pci-domain: If present this property assigns a fixed PCI domain number to a host bridge, otherwise an unstable (across boots) unique number will be assigned. It is required to either not set this property at all or set it for all host bridges in the system, otherwise potentially conflicting domain numbers may be assigned to root buses behind different host bridges. The domain number for each host bridge in the system must be unique.