[PATCH v5 4/6] PCI: dwc: Expose endpoint DMA resources

[Koichiro Den]

Expose the DesignWare endpoint-integrated eDMA register window, logical
DMA channels, and linked-list descriptor memories through the EPC
auxiliary resource API. This lets endpoint functions decide which
channels to publish to the host.

When the DMA register window is already visible through a reserved BAR
region, report its BAR and offset. Otherwise report it as a normal
physical resource so an endpoint function can map it. DMA channel
resources carry hardware channel selectors and refer to linked-list
descriptor memory by ID.

Expose DMA controller and channel resources only after the local DW eDMA
provider has been registered, and only expose channels whose linked-list
descriptor memory is available. The interrupt-emulation doorbell remains
reported when the local DW eDMA provider is registered and its offset is
valid, even if linked-list resources are unavailable. DWC non-LL exposure
needs a metadata ABI and host parser extension, so leave it unsupported
for now. Reject VF auxiliary resource queries because the
RC-programmable DWC eDMA/HDMA register window is assigned to a PF BAR
only.

Signed-off-by: Koichiro Den <den@xxxxxxxxxxxxx>
---
Changes in v5:
  - Keep reporting the standalone doorbell for a registered provider when
    linked-list DMA resources are unavailable. (Sashiko)

 .../pci/controller/dwc/pcie-designware-ep.c   | 120 +++++++++++++++++-
 1 file changed, 116 insertions(+), 4 deletions(-)

diff --git a/drivers/pci/controller/dwc/pcie-designware-ep.c b/drivers/pci/controller/dwc/pcie-designware-ep.c
index 7d2794945704..ef1e2b6d85cf 100644
--- a/drivers/pci/controller/dwc/pcie-designware-ep.c
+++ b/drivers/pci/controller/dwc/pcie-designware-ep.c
@@ -858,6 +858,36 @@ dw_pcie_ep_find_bar_rsvd_region(struct dw_pcie_ep *ep,
 	return NULL;
 }
 
+static bool dw_pcie_ep_has_edma_ll_resources(struct dw_edma_chip *edma)
+{
+	unsigned int i;
+
+	if (!edma->dw)
+		return false;
+
+	for (i = 0; i < edma->ll_wr_cnt; i++)
+		if (!edma->ll_region_wr[i].sz)
+			return false;
+
+	for (i = 0; i < edma->ll_rd_cnt; i++)
+		if (!edma->ll_region_rd[i].sz)
+			return false;
+
+	return true;
+}
+
+static int dw_pcie_ep_check_edma_vfunc(u8 vfunc_no)
+{
+	/*
+	 * The DWC endpoint databook says it is not possible to assign the
+	 * DMA/HDMA registers to any Virtual Function.
+	 */
+	if (vfunc_no)
+		return -EOPNOTSUPP;
+
+	return 0;
+}
+
 static int
 dw_pcie_ep_get_aux_resources_count(struct pci_epc *epc, u8 func_no,
 				   u8 vfunc_no)
@@ -865,14 +895,23 @@ dw_pcie_ep_get_aux_resources_count(struct pci_epc *epc, u8 func_no,
 	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 ret;
+	int count = 0;
 
 	if (!pci->edma_reg_size)
 		return 0;
 
-	if (edma->db_offset == ~0)
-		return 0;
+	ret = dw_pcie_ep_check_edma_vfunc(vfunc_no);
+	if (ret)
+		return ret;
 
-	return 1;
+	if (dw_pcie_ep_has_edma_ll_resources(edma))
+		count += 1 + 2 * (edma->ll_wr_cnt + edma->ll_rd_cnt);
+
+	if (edma->dw && edma->db_offset != ~0)
+		count++;
+
+	return count;
 }
 
 static int
@@ -888,6 +927,8 @@ dw_pcie_ep_get_aux_resources(struct pci_epc *epc, u8 func_no, u8 vfunc_no,
 	resource_size_t db_offset = edma->db_offset;
 	resource_size_t dma_ctrl_bar_offset = 0;
 	resource_size_t dma_reg_size;
+	bool has_edma_ll_resources;
+	unsigned int i;
 	int count;
 
 	count = dw_pcie_ep_get_aux_resources_count(epc, func_no, vfunc_no);
@@ -901,6 +942,7 @@ dw_pcie_ep_get_aux_resources(struct pci_epc *epc, u8 func_no, u8 vfunc_no,
 		return 0;
 
 	dma_reg_size = pci->edma_reg_size;
+	has_edma_ll_resources = dw_pcie_ep_has_edma_ll_resources(edma);
 
 	rsvd = dw_pcie_ep_find_bar_rsvd_region(ep,
 					       PCI_EPC_BAR_RSVD_DMA_CTRL_MMIO,
@@ -909,6 +951,76 @@ dw_pcie_ep_get_aux_resources(struct pci_epc *epc, u8 func_no, u8 vfunc_no,
 	if (rsvd && rsvd->size < dma_reg_size)
 		dma_reg_size = rsvd->size;
 
+	count = 0;
+	if (has_edma_ll_resources) {
+		resources[count++] = (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,
+			.u.dma_ctrl = {
+				.reg_layout = PCI_EPC_AUX_DMA_REG_LAYOUT_DW_EDMA,
+				.reg_layout_data = edma->mf,
+				.ep_to_rc_ch_cnt = edma->ll_wr_cnt,
+				.rc_to_ep_ch_cnt = edma->ll_rd_cnt,
+			},
+		};
+
+		for (i = 0; i < edma->ll_wr_cnt; i++) {
+			struct dw_edma_region *ll = &edma->ll_region_wr[i];
+			u16 desc_mem_id = i;
+
+			resources[count++] = (struct pci_epc_aux_resource) {
+				.type = PCI_EPC_AUX_DMA_CHAN,
+				.bar = NO_BAR,
+				.u.dma_chan = {
+					.dir = PCI_EPC_AUX_DMA_EP_TO_RC,
+					.hw_ch = i,
+					.desc_mem_id = desc_mem_id,
+				},
+			};
+
+			resources[count++] = (struct pci_epc_aux_resource) {
+				.type = PCI_EPC_AUX_DMA_DESC_MEM,
+				.phys_addr = ll->paddr,
+				.size = ll->sz,
+				.bar = NO_BAR,
+				.u.dma_desc = {
+					.id = desc_mem_id,
+				},
+			};
+		}
+
+		for (i = 0; i < edma->ll_rd_cnt; i++) {
+			struct dw_edma_region *ll = &edma->ll_region_rd[i];
+			u16 desc_mem_id = edma->ll_wr_cnt + i;
+
+			resources[count++] = (struct pci_epc_aux_resource) {
+				.type = PCI_EPC_AUX_DMA_CHAN,
+				.bar = NO_BAR,
+				.u.dma_chan = {
+					.dir = PCI_EPC_AUX_DMA_RC_TO_EP,
+					.hw_ch = i,
+					.desc_mem_id = desc_mem_id,
+				},
+			};
+
+			resources[count++] = (struct pci_epc_aux_resource) {
+				.type = PCI_EPC_AUX_DMA_DESC_MEM,
+				.phys_addr = ll->paddr,
+				.size = ll->sz,
+				.bar = NO_BAR,
+				.u.dma_desc = {
+					.id = desc_mem_id,
+				},
+			};
+		}
+	}
+
+	if (db_offset == ~0)
+		return 0;
+
 	/*
 	 * For interrupt-emulation doorbells, report a standalone resource
 	 * instead of bundling it into the DMA controller MMIO resource.
@@ -917,7 +1029,7 @@ dw_pcie_ep_get_aux_resources(struct pci_epc *epc, u8 func_no, u8 vfunc_no,
 				  sizeof(u32), dma_reg_size))
 		return -EINVAL;
 
-	resources[0] = (struct pci_epc_aux_resource) {
+	resources[count] = (struct pci_epc_aux_resource) {
 		.type = PCI_EPC_AUX_DOORBELL_MMIO,
 		.phys_addr = pci->edma_reg_phys + db_offset,
 		.size = sizeof(u32),
-- 
2.51.0