[PATCH v2 0/3] PCI: of: update endpoint ranges dynamically

[Alex Elder]

A PCI endpoint bus is a devicetree construct that allows a PCI
endpoint (function) to have sub-devices defined that are accessible
in an SoC via the PCI endpoint's BARs.  Such a bus is represented as
a devicetree sub-node for a PCI function having the name "pci-ep-bus".
There can be one or more pci-ep-bus nodes.

A PCI function with a pci-ep-bus devicetree node must also define
"#address-cells", "#size-cells", and "ranges" properties, to specify
how endpoint bus addresses are translated to the PCI parent bus.

An endpoint bus address has three cells; the first indicates which of
the function's BARs the address is associated with, and the other two
specify a 64-bit (2 cell) offset within the BAR's region.

BAR base addresses are determined dynamically by the PCI enumeration
process, so generally it's not possible to include them in a static
devicetree file.  When this addressing scheme was introduced, this
was not a problem because the devicetree content was generated
dynamically--after booting--based on the information (including BAR
addresses) available following PCI enumeration.

It is possible (and in some cases, necessary) to define the devicetree
nodes that represent PCI devices ahead of time, in a statically-defined
devicetree file.  In order to support the PCI endpoint bus model in this
case it is necessary to dynamically update the static devicetree so that
the BAR base addresses assigned during enumeration are reflected in the
endpoint's "ranges" property.

This series implements that dynamic update, leveraging the same code
used to create the "ranges" property when PCI_DYNAMIC_OF_NODES is
enabled.  The first patch makes an argument to of_pci_get_addr_flags()
optional.  The second patch separates the code that dynamically builds
the property value into a helper function, and the last arranges for a
statically-defined devicetree node for a PCI endpoint to have its
"ranges" property updated (if it includes a "pci-ep-bus" sub-node)..

					-Alex

Note: this series is built upon these patches:
  https://lore.kernel.org/lkml/20260908213459.2519059-1-elder@xxxxxxxxxxxx/

The entire series (based on v7.3-rc2 and including those prerequisites)
is available here:
  https://github.com/riscstar/linux/tree/outgoing/dynamic_ranges-v2


Between version 1 and version 2:
- Included the first patch (which was previously posted in a different
  series)
- Modified the last patch so the ranges property is updated only for
  PCI endpoints having at least one "pci-ep-bus" node
- Rebased on v7.3-rc2 (and the prerequisite series)


Version 1 is available here:
  https://lore.kernel.org/lkml/20260813220717.1394644-1-elder@xxxxxxxxxxxx/


Alex Elder (3):
  PCI: of: make a flags argument optional
  PCI: of: introduce of_pci_build_prop_ranges()
  PCI: of: introduce of_pci_update_endpoint_node_ranges()

 drivers/pci/of.c          |  89 ++++++++++++++++++++++---
 drivers/pci/of_property.c | 137 +++++++++++++++++++++++++-------------
 drivers/pci/pci.h         |   1 +
 3 files changed, 173 insertions(+), 54 deletions(-)


base-commit: 857c3561ea9f2c3107b5c6d830d3b3face159cbc
-- 
2.53.0