Re: [PATCH v7 5/9] PCI: dwc: ep: Expose integrated eDMA resources via EPC aux-resource API

[Niklas Cassel <cassel@kernel.org>]

On Mon, Feb 16, 2026 at 01:38:43AM +0900, Koichiro Den wrote:
> Implement the EPC aux-resource API for DesignWare endpoint controllers
> with integrated eDMA.
> 
> Report:
>   - DMA controller MMIO window (PCI_EPC_AUX_DMA_CTRL_MMIO)
>   - interrupt-emulation doorbell register (PCI_EPC_AUX_DOORBELL_MMIO),
>     including its Linux IRQ
>   - per-channel LL descriptor regions (PCI_EPC_AUX_DMA_CHAN_DESC)
> 
> If the DMA controller MMIO window is already exposed via a
> platform-owned fixed BAR subregion, also provide the BAR number and
> offset so EPF drivers can reuse it without reprogramming the BAR.
> 
> Signed-off-by: Koichiro Den <den@valinux.co.jp>
> ---
>  .../pci/controller/dwc/pcie-designware-ep.c   | 149 ++++++++++++++++++
>  1 file changed, 149 insertions(+)
> 
> diff --git a/drivers/pci/controller/dwc/pcie-designware-ep.c b/drivers/pci/controller/dwc/pcie-designware-ep.c
> index 7e7844ff0f7e..ffd2797b7b81 100644
> --- a/drivers/pci/controller/dwc/pcie-designware-ep.c
> +++ b/drivers/pci/controller/dwc/pcie-designware-ep.c
> @@ -808,6 +808,154 @@ dw_pcie_ep_get_features(struct pci_epc *epc, u8 func_no, u8 vfunc_no)
>  	return ep->ops->get_features(ep);
>  }
>  
> +static const struct pci_epc_bar_rsvd_region *
> +dw_pcie_ep_find_bar_rsvd_region(struct dw_pcie_ep *ep,
> +				enum pci_epc_bar_rsvd_region_type type,
> +				enum pci_barno *bar,
> +				resource_size_t *bar_offset)
> +{
> +	const struct pci_epc_features *features;
> +	const struct pci_epc_bar_desc *bar_desc;
> +	const struct pci_epc_bar_rsvd_region *r;
> +	int i, j;
> +
> +	if (!ep->ops->get_features)
> +		return NULL;
> +
> +	features = ep->ops->get_features(ep);
> +	if (!features)
> +		return NULL;
> +
> +	for (i = BAR_0; i <= BAR_5; i++) {
> +		bar_desc = &features->bar[i];
> +
> +		if (!bar_desc->nr_rsvd_regions || !bar_desc->rsvd_regions)
> +			continue;
> +
> +		for (j = 0; j < bar_desc->nr_rsvd_regions; j++) {
> +			r = &bar_desc->rsvd_regions[j];
> +
> +			if (r->type != type)
> +				continue;
> +
> +			if (bar)
> +				*bar = i;
> +			if (bar_offset)
> +				*bar_offset = r->offset;
> +			return r;
> +		}
> +	}
> +
> +	return NULL;
> +}
> +
> +static int
> +dw_pcie_ep_get_aux_resources(struct pci_epc *epc, u8 func_no, u8 vfunc_no,
> +			     struct pci_epc_aux_resource *resources,
> +			     int num_resources)
> +{
> +	struct dw_pcie_ep *ep = epc_get_drvdata(epc);
> +	struct dw_pcie *pci = to_dw_pcie_from_ep(ep);
> +	const struct pci_epc_bar_rsvd_region *rsvd;
> +	struct dw_edma_chip *edma = &pci->edma;
> +	enum pci_barno dma_ctrl_bar = NO_BAR;
> +	int ll_cnt = 0, needed, idx = 0;
> +	resource_size_t db_offset = edma->db_offset;
> +	resource_size_t dma_ctrl_bar_offset = 0;
> +	resource_size_t dma_reg_size;
> +	unsigned int i;
> +
> +	if (!pci->edma_reg_size)
> +		return 0;
> +
> +	dma_reg_size = pci->edma_reg_size;
> +
> +	for (i = 0; i < edma->ll_wr_cnt; i++)
> +		if (edma->ll_region_wr[i].sz)
> +			ll_cnt++;
> +
> +	for (i = 0; i < edma->ll_rd_cnt; i++)
> +		if (edma->ll_region_rd[i].sz)
> +			ll_cnt++;
> +
> +	needed = 1 + ll_cnt + (db_offset != ~0 ? 1 : 0);
> +
> +	/* Count query mode */
> +	if (!resources || !num_resources)
> +		return needed;
> +
> +	if (num_resources < needed)
> +		return -ENOSPC;
> +
> +	rsvd = dw_pcie_ep_find_bar_rsvd_region(ep,
> +					       PCI_EPC_BAR_RSVD_DMA_CTRL_MMIO,
> +					       &dma_ctrl_bar,
> +					       &dma_ctrl_bar_offset);
> +	if (rsvd && rsvd->size < dma_reg_size)
> +		dma_reg_size = rsvd->size;
> +
> +	/* DMA register block */
> +	resources[idx++] = (struct pci_epc_aux_resource) {
> +		.type = PCI_EPC_AUX_DMA_CTRL_MMIO,
> +		.phys_addr = pci->edma_reg_phys,
> +		.size = dma_reg_size,
> +		.bar = dma_ctrl_bar,
> +		.bar_offset = dma_ctrl_bar_offset,
> +	};
> +
> +	/*
> +	 * For interrupt-emulation doorbells, report a standalone resource
> +	 * instead of bundling it into the DMA controller MMIO resource.
> +	 */
> +	if (db_offset != ~0) {
> +		if (dma_reg_size < sizeof(u32) ||
> +		    db_offset > dma_reg_size - sizeof(u32))

In your other patch, you used:

	if (size_add(offset, sizeof(u32)) > epf->bar[bar].size)

For consistency, do you perhaps want to use the same here?

size_add(db_offset, sizeof(u32)) > dma_reg_size ?




Kind regards,
Niklas