On Sat, Feb 07, 2026 at 02:26:43AM +0900, Koichiro Den wrote:
> Implement pci_epc_ops.get_remote_resources() for DesignWare PCIe
> endpoint controllers with integrated eDMA.
>
> Report:
> - the eDMA controller MMIO window (physical base + size),
> - each non-empty per-channel linked-list region, along with
> per-channel metadata such as the Linux IRQ number and the
> interrupt-emulation doorbell register offset.
>
> This allows endpoint function drivers (e.g. pci-epf-test) to discover
> the eDMA resources and map a suitable doorbell target into BAR space.
>
> Signed-off-by: Koichiro Den <[email protected]>
> ---
> .../pci/controller/dwc/pcie-designware-ep.c | 85 +++++++++++++++++++
> 1 file changed, 85 insertions(+)
>
> diff --git a/drivers/pci/controller/dwc/pcie-designware-ep.c
> b/drivers/pci/controller/dwc/pcie-designware-ep.c
> index 7e7844ff0f7e..29dedac86190 100644
> --- a/drivers/pci/controller/dwc/pcie-designware-ep.c
> +++ b/drivers/pci/controller/dwc/pcie-designware-ep.c
> @@ -8,6 +8,7 @@
>
> #include <linux/align.h>
> #include <linux/bitfield.h>
> +#include <linux/dma/edma.h>
> #include <linux/of.h>
> #include <linux/platform_device.h>
>
> @@ -808,6 +809,89 @@ dw_pcie_ep_get_features(struct pci_epc *epc, u8 func_no,
> u8 vfunc_no)
> return ep->ops->get_features(ep);
> }
>
> +static int
> +dw_pcie_ep_get_remote_resources(struct pci_epc *epc, u8 func_no, u8 vfunc_no,
> + struct pci_epc_remote_resource *resources,
> + int num_resources)
> +{
> + struct dw_pcie_ep *ep = epc_get_drvdata(epc);
> + struct dw_pcie *pci = to_dw_pcie_from_ep(ep);
> + struct dw_edma_chip *edma = &pci->edma;
> + struct dw_edma_chan_info info;
> + int ll_cnt = 0, needed, idx = 0;
> + resource_size_t dma_size;
> + phys_addr_t dma_phys;
> + unsigned int i;
> + int ret;
> +
> + if (!pci->edma_reg_size)
> + return 0;
> +
> + dma_phys = pci->edma_reg_phys;
> + dma_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;
> +
> + /* Count query mode */
> + if (!resources || !num_resources)
> + return needed;
> +
> + if (num_resources < needed)
> + return -ENOSPC;
> +
> + resources[idx++] = (struct pci_epc_remote_resource) {
> + .type = PCI_EPC_RR_DMA_CTRL_MMIO,
> + .phys_addr = dma_phys,
> + .size = dma_size,
> + };
> +
> + /* One LL region per write channel */
> + for (i = 0; i < edma->ll_wr_cnt; i++) {
> + if (!edma->ll_region_wr[i].sz)
> + continue;
> +
> + ret = dw_edma_chan_info(edma, i, &info);
> + if (ret)
> + return ret;
> +
> + resources[idx++] = (struct pci_epc_remote_resource) {
> + .type = PCI_EPC_RR_DMA_CHAN_DESC,
> + .phys_addr = edma->ll_region_wr[i].paddr,
> + .size = edma->ll_region_wr[i].sz,
> + .u.dma_chan_desc.irq = info.irq,
> + .u.dma_chan_desc.db_offset = info.db_offset,
> + };
> + }
> +
> + /* One LL region per read channel */
> + for (i = 0; i < edma->ll_rd_cnt; i++) {
> + if (!edma->ll_region_rd[i].sz)
> + continue;
> +
> + ret = dw_edma_chan_info(edma, i + edma->ll_wr_cnt, &info);
edma's information is what dw-EP pass to edma driver, supposed dw-ep know
irq and HDMI or EDMA's information, I think needn't go around to EDMA again
to fetch this information back.
Frank
> + if (ret)
> + return ret;
> +
> + resources[idx++] = (struct pci_epc_remote_resource) {
> + .type = PCI_EPC_RR_DMA_CHAN_DESC,
> + .phys_addr = edma->ll_region_rd[i].paddr,
> + .size = edma->ll_region_rd[i].sz,
> + .u.dma_chan_desc.irq = info.irq,
> + .u.dma_chan_desc.db_offset = info.db_offset,
> + };
> + }
> +
> + return idx;
> +}
> +
> static const struct pci_epc_ops epc_ops = {
> .write_header = dw_pcie_ep_write_header,
> .set_bar = dw_pcie_ep_set_bar,
> @@ -823,6 +907,7 @@ static const struct pci_epc_ops epc_ops = {
> .start = dw_pcie_ep_start,
> .stop = dw_pcie_ep_stop,
> .get_features = dw_pcie_ep_get_features,
> + .get_remote_resources = dw_pcie_ep_get_remote_resources,
> };
>
> /**
> --
> 2.51.0
>
