On Wed, Jan 14, 2026 at 01:27:15AM +0900, Koichiro Den wrote:
> Extend the PCI endpoint core to support mapping subranges within a BAR.
> Introduce a new 'submap' field and a 'use_submap' flag in struct
> pci_epf_bar so an endpoint function driver can request inbound mappings
> that fully cover the BAR.
>
> Add a subrange_mapping feature bit to struct pci_epc_features so EPC
> drivers can explicitly advertise support. Make pci_epc_set_bar() reject
> use_submap requests (-EINVAL) when the EPC does not advertise
> subrange_mapping, to avoid silently accepting a configuration that the
> controller cannot implement.
>
> The submap array describes the complete BAR layout (no overlaps and no
> gaps are allowed to avoid exposing untranslated address ranges). This
> provides the generic infrastructure needed to map multiple logical
> regions into a single BAR at different offsets, without assuming a
> controller-specific inbound address translation mechanism. Also, the
> array must be sorted in ascending order by offset.
>
> Reviewed-by: Niklas Cassel <[email protected]>
> Signed-off-by: Koichiro Den <[email protected]>
> ---
...
>
> #define to_pci_epf_driver(drv) container_of_const((drv), struct
> pci_epf_driver, driver)
>
> +/**
> + * struct pci_epf_bar_submap - BAR subrange for inbound mapping
> + * @phys_addr: target physical/DMA address for this subrange
> + * @size: the size of the subrange to be mapped
> + * @offset: byte offset within the BAR base
> + *
> + * When pci_epf_bar.use_submap is set, pci_epf_bar.submap describes the
> + * complete BAR layout. This allows an EPC driver to program multiple
> + * inbound translation windows for a single BAR when supported by the
> + * controller.
> + *
> + * Note that the subranges:
> + * - must be non-overlapping
> + * - must exactly cover the BAR (i.e. no holes)
> + * - must be sorted (in ascending order by offset)
> + */
> +struct pci_epf_bar_submap {
> + dma_addr_t phys_addr;
> + size_t size;
> + size_t offset;
> +};
I suppose offset is sum of previous all submap's size? If yes, needn't
offset.
> +
> /**
> * struct pci_epf_bar - represents the BAR of EPF device
> * @phys_addr: physical address that should be mapped to the BAR
> @@ -119,6 +141,10 @@ struct pci_epf_driver {
> * requirement
> * @barno: BAR number
> * @flags: flags that are set for the BAR
> + * @use_submap: set true to request subrange mappings within this BAR
> + * @num_submap: number of entries in @submap
> + * @submap: array of subrange descriptors allocated by the caller. See
> + * struct pci_epf_bar_submap for the restrictions in detail.
> */
> struct pci_epf_bar {
> dma_addr_t phys_addr;
> @@ -127,6 +153,11 @@ struct pci_epf_bar {
> size_t mem_size;
> enum pci_barno barno;
> int flags;
> +
> + /* Optional sub-range mapping */
> + bool use_submap;
> + unsigned int num_submap;
can we use num_submap != 0 as use_submap?
Frank
> + struct pci_epf_bar_submap *submap;
> };
>
> /**
> --
> 2.51.0
>
