On Mon, Feb 16, 2026 at 03:12:53PM +0100, Niklas Cassel wrote:

On Mon, Feb 16, 2026 at 01:38:43AM +0900, Koichiro Den wrote:

quoted

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 <redacted>
---
 .../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 ?

db_offset and dma_reg_size are resource_size_t, not size_t. resource_size_t can
be wider than size_t on some 32-bit builds with CONFIG_PHYS_ADDR_T_64BIT, so
using size_add() would potentially introduce a narrowing conversion. For that
reason, I avoided it.

If that would be preferable, I'm happy to switch this part to something like:

        if (db_offset != ~0) {
                if (range_end_overflows_t(resource_size_t, db_offset,
                                          sizeof(u32), dma_reg_size))
                        return -EINVAL;

or alternatively use check_add_overflow().

Best regards,
Koichiro

Kind regards,
Niklas