[PATCH v6 0/5] PCI: endpoint: BAR subrange mapping support

Koichiro Den
2026-01-13T02:38:34Z

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

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(-)

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2.51.0