Adding upstream version 4.19.249.upstream/4.19.249upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 26 insertions, 0 deletions

diff --git a/Documentation/devicetree/bindings/pci/pci.txt b/Documentation/devicetree/bindings/pci/pci.txt
new file mode 100644
index 000000000..c77981c5d
--- /dev/null
+++ b/Documentation/devicetree/bindings/pci/pci.txt
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+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.