Re: [PATCH 0/2] PCI: dwc: Expose integrated DesignWare eDMA windows

[Koichiro Den]

On Mon, Jan 26, 2026 at 04:15:48PM +0900, Koichiro Den wrote:
> This series adds small, query-only helper APIs to the DesignWare PCIe
> endpoint controller driver to expose resources of an integrated
> DesignWare eDMA instance. Specifically, it allows querying:
> 
>   - the physical base address and size of the integrated eDMA register
>     aperture, and
>   - the per-channel linked-list (LL) region base and size, keyed by
>     transfer direction and hardware channel identifier.
> 
> The motivation is that some DesignWare PCIe endpoint platforms integrate
> an eDMA engine that can be driven either locally by the endpoint or
> remotely by the host. Remote eDMA use cases (e.g. [1]) need to expose
> the eDMA register block and LL regions to the host through PCIe BARs,
> while still allowing the endpoint to boot with a standard EP settings,
> without DT changes to hide the eDMA instance from the endpoint itself.
> 
> The hardware channel identifier used by the LL-region helper can be
> obtained via dma_get_slave_caps().hw_id, introduced by a dmaengine
> series posted separately.

For reference, the series has been submitted here:

  [PATCH 0/5] dmaengine: dw-edma: Add helpers for remote eDMA use scenarios
  https://lore.kernel.org/dmaengine/20260126073652.3293564-1-den@xxxxxxxxxxxxx/

Kind regards,
Koichiro

> 
> [1] [RFC PATCH v4 00/38] NTB transport backed by PCI EP embedded DMA
>     https://lore.kernel.org/linux-pci/20260118135440.1958279-1-den@xxxxxxxxxxxxx/
> 
> Developed on PCI controller/dwc:
>   commit 0ecd890e3cf5 ("PCI: dwc: Rename dw_pcie_rp::has_msi_ctrl to
>                         dw_pcie_rp::use_imsi_rx for clarity")
> 
> Kind regards,
> 
> Koichiro Den (2):
>   PCI: dwc: Add helper to query integrated dw-edma register window
>   PCI: dwc: Add helper to query integrated dw-edma linked-list region
> 
>  MAINTAINERS                                  |  2 +-
>  drivers/pci/controller/dwc/pcie-designware.c | 74 ++++++++++++++++++++
>  drivers/pci/controller/dwc/pcie-designware.h |  2 +
>  include/linux/pcie-dwc-edma.h                | 72 +++++++++++++++++++
>  4 files changed, 149 insertions(+), 1 deletion(-)
>  create mode 100644 include/linux/pcie-dwc-edma.h
> 
> -- 
> 2.51.0
>