Implement pci_epc_ops.get_aux_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 <den@valinux.co.jp>
---
 .../pci/controller/dwc/pcie-designware-ep.c   | 78 +++++++++++++++++++
 1 file changed, 78 insertions(+)

diff --git a/drivers/pci/controller/dwc/pcie-designware-ep.c b/drivers/pci/controller/dwc/pcie-designware-ep.c
index 7e7844ff0f7e..c99ba1b85da4 100644
--- a/drivers/pci/controller/dwc/pcie-designware-ep.c
+++ b/drivers/pci/controller/dwc/pcie-designware-ep.c
@@ -808,6 +808,83 @@ 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_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);
+	struct dw_edma_chip *edma = &pci->edma;
+	int ll_cnt = 0, needed, idx = 0;
+	resource_size_t dma_size;
+	phys_addr_t dma_phys;
+	unsigned int i;
+
+	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_aux_resource) {
+		.type = PCI_EPC_AUX_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;
+
+		resources[idx++] = (struct pci_epc_aux_resource) {
+			.type = PCI_EPC_AUX_DMA_CHAN_DESC,
+			.phys_addr = edma->ll_region_wr[i].paddr,
+			.size = edma->ll_region_wr[i].sz,
+			.u.dma_chan_desc = {
+				.irq = edma->ch_info_wr[i].irq,
+				.db_offset = edma->ch_info_wr[i].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;
+
+		resources[idx++] = (struct pci_epc_aux_resource) {
+			.type = PCI_EPC_AUX_DMA_CHAN_DESC,
+			.phys_addr = edma->ll_region_rd[i].paddr,
+			.size = edma->ll_region_rd[i].sz,
+			.u.dma_chan_desc = {
+				.irq = edma->ch_info_rd[i].irq,
+				.db_offset = edma->ch_info_rd[i].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 +900,7 @@ 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_aux_resources	= dw_pcie_ep_get_aux_resources,
 };
 
 /**
-- 
2.51.0