Re: [PATCH v2 1/5] PCI: endpoint: Add DMA auxiliary resource metadata

[Frank Li]

On Sat, Aug 29, 2026 at 02:09:28AM +0900, Koichiro Den wrote:
> Endpoint functions that export controller-local DMA channels need the
> controller register and descriptor-memory layout.
>
> Add DMA control and descriptor-memory resource types. The control resource
> carries the register layout and channel counts. Each descriptor region is
> associated with the static channel ID assigned by the local DMA driver.
>
> Signed-off-by: Koichiro Den <den@xxxxxxxxxxxxx>
> ---

Reviewed-by: Frank Li <Frank.Li@xxxxxxx>

> Changes in v2:
>   - Rework PCI DMA EPF v7 patch 3 with only the metadata needed by vNTB.
>     https://lore.kernel.org/r/20260813063757.3131865-4-den@xxxxxxxxxxxxx/
>   - Keep descriptor metadata keyed only by static channel IDs. (Frank)
>     https://lore.kernel.org/r/lm7tadnxsyrypu4mypptlkx5qkytex4qxsijdr5ydud2n3anvf@yakjfjg5ng4u/
>
>  include/linux/pci-epc.h | 34 +++++++++++++++++++++++++++++++---
>  1 file changed, 31 insertions(+), 3 deletions(-)
>
> diff --git a/include/linux/pci-epc.h b/include/linux/pci-epc.h
> index f247cf9bcf1a..e0348e7bc534 100644
> --- a/include/linux/pci-epc.h
> +++ b/include/linux/pci-epc.h
> @@ -65,6 +65,8 @@ struct pci_epc_map {
>   * enum pci_epc_aux_resource_type - auxiliary resource type identifiers
>   * @PCI_EPC_AUX_DOORBELL_MMIO: Doorbell MMIO, that might be outside the DMA
>   *                             controller register window
> + * @PCI_EPC_AUX_DMA_CTRL_MMIO: DMA controller MMIO register window
> + * @PCI_EPC_AUX_DMA_DESC_MEM: DMA descriptor memory
>   *
>   * EPC backends may expose auxiliary blocks (e.g. DMA engines) by mapping their
>   * register windows and descriptor memories into BAR space. This enum
> @@ -72,13 +74,25 @@ struct pci_epc_map {
>   */
>  enum pci_epc_aux_resource_type {
>  	PCI_EPC_AUX_DOORBELL_MMIO,
> +	PCI_EPC_AUX_DMA_CTRL_MMIO,
> +	PCI_EPC_AUX_DMA_DESC_MEM,
>  };
>
>  /**
> - * struct pci_epc_aux_resource - a physical auxiliary resource that may be
> - *                               exposed for peer use
> + * enum pci_epc_aux_dma_reg_layout - DMA controller register layout
> + * @PCI_EPC_AUX_DMA_REG_LAYOUT_UNKNOWN: unknown or uninitialized layout
> + * @PCI_EPC_AUX_DMA_REG_LAYOUT_DW_EDMA: Synopsys DesignWare eDMA/HDMA layout
> + */
> +enum pci_epc_aux_dma_reg_layout {
> +	PCI_EPC_AUX_DMA_REG_LAYOUT_UNKNOWN = 0,
> +	PCI_EPC_AUX_DMA_REG_LAYOUT_DW_EDMA,
> +};
> +
> +/**
> + * struct pci_epc_aux_resource - an auxiliary resource that may be exposed for
> + *                               peer use
>   * @type:       resource type, see enum pci_epc_aux_resource_type
> - * @phys_addr:  physical base address of the resource
> + * @phys_addr:  CPU physical base address of an MMIO resource
>   * @size:       size of the resource in bytes
>   * @bar:        BAR number where this resource is already exposed to the RC
>   *              (NO_BAR if not)
> @@ -99,6 +113,20 @@ struct pci_epc_aux_resource {
>  			int irq; /* IRQ number for the doorbell handler */
>  			u32 data; /* write value to ring the doorbell */
>  		} db_mmio;
> +
> +		/* PCI_EPC_AUX_DMA_CTRL_MMIO */
> +		struct {
> +			enum pci_epc_aux_dma_reg_layout reg_layout;
> +			u32 reg_layout_data;
> +			u16 ep_to_rc_ch_cnt;
> +			u16 rc_to_ep_ch_cnt;
> +		} dma_ctrl;
> +
> +		/* PCI_EPC_AUX_DMA_DESC_MEM */
> +		struct {
> +			dma_addr_t dma_addr; /* Endpoint-local DMA address */
> +			u16 chan_id;
> +		} dma_desc;
>  	} u;
>  };
>
> --
> 2.51.0
>