[PATCH v2] PCI: add missing DT binding for linux,pci-domain property

[Lucas Stach <l.stach@pengutronix.de>]

This property was added by 41e5c0f81d3e
(of/pci: Add pci_get_new_domain_nr() and of_get_pci_domain_nr())
without the required binding documentation. As this property
will be supported by a number of host bridge drivers going forward,
add it to the common PCI binding doc.

Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
---
This is a non-critical fix, but may still qualify for 3.18-rc as
the property was added in this release cycle.

v2:
- emphasize that the property must be present and unique systemwide
  if used
---
 Documentation/devicetree/bindings/pci/pci.txt | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/Documentation/devicetree/bindings/pci/pci.txt b/Documentation/devicetree/bindings/pci/pci.txt
index 41aeed38926d..68c364e2f5e5 100644
--- a/Documentation/devicetree/bindings/pci/pci.txt
+++ b/Documentation/devicetree/bindings/pci/pci.txt
@@ -7,3 +7,14 @@ 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.
-- 
2.1.1