bus number 1 in domain 1 has the devices we're looking for.
For the busses that are present, the SAL call returns an
non-NULL value for the addr parameter so use that as well
as the status code to determine whether to create a child.
Save the domain, bus number and PROM address in the softc
after assigning the driver to the new device.
This yields:
...
pcib0: <SGI PCI-X host controller> on motherboard
pci0: <PCI bus> on pcib0
pci0: domain=1, physical bus=1
...
pcib1: <SGI PCI-X host controller> on motherboard
pci1: <PCI bus> on pcib1
pci1: domain=2, physical bus=1
...