| PCI bus bridges have standardized Device Tree bindings: |
| |
| PCI Bus Binding to: IEEE Std 1275-1994 |
| http://www.devicetree.org/open-firmware/bindings/pci/pci2_1.pdf |
| |
| And for the interrupt mapping part: |
| |
| Open Firmware Recommended Practice: Interrupt Mapping |
| http://www.devicetree.org/open-firmware/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. |
| - max-link-speed: |
| If present this property specifies PCI gen for link capability. Host |
| drivers could add this as a strategy to avoid unnecessary operation for |
| unsupported link speed, for instance, trying to do training for |
| unsupported link speed, etc. Must be '4' for gen4, '3' for gen3, '2' |
| for gen2, and '1' for gen1. Any other values are invalid. |
