bindings/pci/pci.txt

3 PCI Bus Binding to: IEEE Std 1275-1994
4 https://www.devicetree.org/open-firmware/bindings/pci/pci2_1.pdf
9 https://www.devicetree.org/open-firmware/practice/imap/imap0_9d.pdf
11 Additionally to the properties specified in the above standards a host bridge
14 - linux,pci-domain:
15    If present this property assigns a fixed PCI domain number to a host bridge,
18    host bridges in the system, otherwise potentially conflicting domain numbers
19    may be assigned to root buses behind different host bridges.  The domain
20    number for each host bridge in the system must be unique.
21 - max-link-speed:
22    If present this property specifies PCI gen for link capability.  Host
27 - reset-gpios:
28    If present this property specifies PERST# GPIO. Host drivers can parse the
30 - supports-clkreq:
32    root port to downstream device and host bridge drivers can do programming
33    which depends on CLKREQ signal existence. For example, programming root port
34    not to advertise ASPM L1 Sub-States support if there is no CLKREQ signal.
36 PCI-PCI Bridge properties
37 -------------------------
40 tree, as children of the host bridge node. Even though those devices are
46 - reg:
47    Identifies the PCI-PCI bridge. As defined in the IEEE Std 1275-1994
48    document, it is a five-cell address encoded as (phys.hi phys.mid
53    configuration mechanism. If this port is a switch port, then firmware
55    register of the bridge directly above this port. Otherwise, the bus
56    number of a root port is the first number in the bus-range property,
60    above this port, then phys.hi contains the 8-bit function number as
63    OS is ARI-aware.
67 - external-facing:
68    When present, the port is external-facing. All bridges and endpoints
69    downstream of this port are external to the machine. The OS can, for
72    malicious devices to this port.
77 	compatible = "pci-host-ecam-generic";
80 		/* Root port 00:01.0 is external-facing */
82 		external-facing;