[PATCH v2 0/5] PCI: endpoint: Remote DMA support via vNTB

[Koichiro Den <den@valinux.co.jp>]

Hi,

This series lets an RC use endpoint-local DesignWare eDMA read channels
through vNTB.

It is intended to supersede the separate PCI DMA EPF v7 approach (see
the link below). Since no consumer outside the vNTB/ntb_hw_epf path is
currently known, this rework keeps the DMA export there instead of
maintaining a generic ABI for one use case. It also removes the need for
a second PCI function, allowing this setup on EPCs without
multi-function support.

On the endpoint, pci-epf-vntb reserves the complete eDMA read direction
and exposes those channels as a group. HDMA is not yet supported,
keeping the series minimal.

The DMA feature is opt-in through the pci-epf-vntb configfs attribute
'use_dma'. Without it, no DMA extension is exported. pci-epf-ntb is
unchanged.

Base and dependency
===================

This series is currently based on next-20260827 (3d83758432b5) plus:

  [PATCH v2 0/3] dmaengine: dw-edma: Prepare channels for remote use
  https://lore.kernel.org/r/20260828163611.2691264-1-den@valinux.co.jp/

The prerequisite is for the dmaengine tree and is not part of
pci/endpoint. linux-next provides a common buildable base for both
series. Once the prerequisite lands, this series can be rebased onto
pci/endpoint.

Best regards,
Koichiro
---
Changes in v2:
  - Rewrite most of v1 and move the dw-edma preparation into the
    companion series. Drop the generic pci-ep-dma API, auxiliary-bus
    child/frontend, test ntb client, and preparatory MW-state
    refactoring.
    See individual patch trailers for provenance.
  - Replace v1's post-registration channel-ID cache with driver-supplied
    static IDs. (Frank)
    https://lore.kernel.org/r/abMcgQOHDD55Yv0e@lizhi-Precision-Tower-5810/
  - Let pci-epf-vntb reserve channels with dma_request_channel() and
    configure interrupt routing with dmaengine_slave_config(). This
    removes the PCI EPC DMA delegation API. (Frank)
    https://lore.kernel.org/r/ao2nHoCwfTEEiFSr@SMW015318/
  - Drop v1's dma_offset and dma_num_chans attributes. use_dma now enables
    export of the complete eDMA read direction as a group.

v1:
  https://lore.kernel.org/r/20260312165005.1148676-1-den@valinux.co.jp/

Related PCI DMA EPF v7:
  https://lore.kernel.org/r/20260813063757.3131865-1-den@valinux.co.jp/


Koichiro Den (5):
  PCI: endpoint: Add DMA auxiliary resource metadata
  PCI: dwc: Expose endpoint DMA resources
  PCI: endpoint: pci-epf-vntb: Move epf_ntb_is_bar_used() up
  PCI: endpoint: pci-epf-vntb: Export endpoint DMA channels
  NTB: ntb_hw_epf: Discover vNTB-embedded DMA

 Documentation/PCI/endpoint/pci-vntb-howto.rst |  23 +-
 drivers/ntb/hw/epf/ntb_hw_epf.c               | 360 ++++++++-
 .../pci/controller/dwc/pcie-designware-ep.c   | 107 ++-
 drivers/pci/endpoint/functions/pci-epf-vntb.c | 692 +++++++++++++++++-
 include/linux/pci-epc.h                       |  34 +-
 5 files changed, 1154 insertions(+), 62 deletions(-)

-- 
2.51.0