PCI: endpoint: BAR subrange mapping support

This series proposes support for mapping subranges within a PCIe endpoint
BAR and enables controllers to program inbound address translation for
those subranges.

- Patch 1/5 introduces generic BAR subrange mapping support in the PCI
  endpoint core.

- Patch 2/5 changes dw_pcie_ep_ops.get_features() to return a mutable
  struct pci_epc_features * and updates all DWC-based glue drivers
  accordingly. This is preparatory work for subsequent patches.

- Patch 3/5 introduces dynamic_inbound_mapping feature bit. This can be
  used as a safeguard to check whether a BAR can really be reconfigured
  without clearing/resetting it.

- Patch 4/5 adds an implementation for the DesignWare PCIe endpoint
  controller using Address Match Mode IB iATU. It also advertises
  subrange_mapping support from the DWC EP midlayer.

- Patch 5/5 updates a documentation for pci_epc_set_bar().

This series is originally a spin-off from a larger RFC series posted
earlier:
https://lore.kernel.org/all/20251217151609.3162665-4-den@...
The first user will likely be Remote eDMA-backed NTB transport,
demonstrated in that RFC series.

Kernel base:
  - repo: git://git.kernel.org/pub/scm/linux/kernel/git/pci/pci.git
  - branch: controller/dwc
  - commit: 68ac85fb42cf ("PCI: dwc: Use cfg0_base as iMSI-RX target address
                           to support 32-bit MSI devices")

Changelog:
* v5->v6 changes:
  - Added a new feature bit dynamic_inbound_mapping and set it centrally
    in dw_pcie_ep_get_features() for all DWC-based glue drivers.
  - Updated documentation for pci_epc_set_bar().
  - Dropped a needless and harmful dw_pcie_ep_clear_bar() call on the error
    path.
  - Fixed "Bar Match Mode" to "BAR Match Mode" in a source code comment.

* v4->v5 changes:
  - Added subrange_mapping to struct pci_epc_features and enforced a
    strict capability check in pci_epc_set_bar() (reject use_submap when
    unsupported).
  - Changed DWC-based glue drivers to return a mutable features pointer
    and set subrange_mapping centrally at the DWC midlayer.
  - Split the series into 3 patches accordingly.

* v3->v4 changes:
  - Drop unused includes that should have been removed in v3

* v2->v3 changes:
  - Remove submap copying and sorting from dw_pcie_ep_ib_atu_addr(), and
    require callers to pass a sorted submap. The related source code
    comments are updated accordingly.
  - Refine source code comments and commit messages, including normalizing
    "Address Match Mode" wording.
  - Add const qualifiers where applicable.

* v1->v2 changes:
  - Introduced stricter submap validation: no holes/overlaps and the
    subranges must exactly cover the whole BAR. Added
    dw_pcie_ep_validate_submap() to enforce alignment and full-coverage
    constraints.
  - Enforced one-shot (all-or-nothing) submap programming to avoid leaving
    half-programmed BAR state:
    * Dropped incremental/overwrite logic that is no longer needed with the
      one-shot design.
    * Added dw_pcie_ep_clear_ib_maps() and used it from multiple places to
      tear down BAR match / address match inbound mappings without code
      duplication.
  - Updated kernel source code comments and commit messages, including a
    small refinement made along the way.
  - Changed num_submap type to unsigned int.

v5: https://lore.kernel.org/all/20260108172403.2629671-1-den@...
v4: https://lore.kernel.org/all/20260108044148.2352800-1-den@...
v3: https://lore.kernel.org/all/20260108024829.2255501-1-den@...
v2: https://lore.kernel.org/all/20260107041358.1986701-1-den@...
v1: https://lore.kernel.org/all/20260105080214.1254325-1-den@...


Thank you for reviewing,


Koichiro Den (5):
  PCI: endpoint: Add BAR subrange mapping support
  PCI: dwc: Allow glue drivers to return mutable EPC features
  PCI: endpoint: Add dynamic_inbound_mapping EPC feature
  PCI: dwc: ep: Support BAR subrange inbound mapping via Address Match
    Mode iATU
  Documentation: PCI: endpoint: Clarify pci_epc_set_bar() usage

 Documentation/PCI/endpoint/pci-endpoint.rst   |  22 ++
 drivers/pci/controller/dwc/pci-dra7xx.c       |   4 +-
 drivers/pci/controller/dwc/pci-imx6.c         |  10 +-
 drivers/pci/controller/dwc/pci-keystone.c     |   4 +-
 .../pci/controller/dwc/pci-layerscape-ep.c    |   2 +-
 drivers/pci/controller/dwc/pcie-artpec6.c     |   4 +-
 .../pci/controller/dwc/pcie-designware-ep.c   | 240 +++++++++++++++++-
 .../pci/controller/dwc/pcie-designware-plat.c |   4 +-
 drivers/pci/controller/dwc/pcie-designware.h  |   4 +-
 drivers/pci/controller/dwc/pcie-dw-rockchip.c |   8 +-
 drivers/pci/controller/dwc/pcie-keembay.c     |   4 +-
 drivers/pci/controller/dwc/pcie-qcom-ep.c     |   4 +-
 drivers/pci/controller/dwc/pcie-rcar-gen4.c   |   4 +-
 drivers/pci/controller/dwc/pcie-stm32-ep.c    |   4 +-
 drivers/pci/controller/dwc/pcie-tegra194.c    |   4 +-
 drivers/pci/controller/dwc/pcie-uniphier-ep.c |  58 +++--
 drivers/pci/endpoint/pci-epc-core.c           |   3 +
 include/linux/pci-epc.h                       |   8 +
 include/linux/pci-epf.h                       |  31 +++
 19 files changed, 355 insertions(+), 67 deletions(-)

-- 
2.51.0