PCI: qcom-ep: Add HDMA support for SA8775P SoC

SA8775P SoC supports the new Hyper DMA (HDMA) DMA Engine inside the DWC IP,
so add support for it by passing the mapping format and the number of
read/write channels count.

The PCIe EP controller used on this SoC is of version 1.34.0, so a separate
config struct is introduced for the sake of enabling HDMA conditionally.

It should be noted that for the eDMA support (predecessor of HDMA), there
are no mapping format and channels count specified. That is because eDMA
supports auto detection of both parameters, whereas HDMA doesn't.

[mani: reworded commit message, added kdoc, and minor cleanups]
Link: https://lore.kernel.org/linux-pci/[email protected]
Signed-off-by: Mrinmay Sarkar <[email protected]>
Signed-off-by: Manivannan Sadhasivam <[email protected]>
Signed-off-by: Krzysztof Wilczyński <[email protected]>
Signed-off-by: Bjorn Helgaas <[email protected]>
Reviewed-by: Frank Li <[email protected]>
Reviewed-by: Siddharth Vadapalli <[email protected]>

Author: Mrinmay Sarkar

drivers/pci/controller/dwc/pcie-qcom-ep.c

@@ -149,6 +149,14 @@ enum qcom_pcie_ep_link_status {
 	QCOM_PCIE_EP_LINK_DOWN,
 };
 
+/**
+ * struct qcom_pcie_ep_cfg - Per SoC config struct
+ * @hdma_support: HDMA support on this SoC
+ */
+struct qcom_pcie_ep_cfg {
+	bool hdma_support;
+};
+
 /**
  * struct qcom_pcie_ep - Qualcomm PCIe Endpoint Controller
  * @pci: Designware PCIe controller struct
@@ -803,6 +811,7 @@ static const struct dw_pcie_ep_ops pci_ep_ops = {
 
 static int qcom_pcie_ep_probe(struct platform_device *pdev)
 {
+	const struct qcom_pcie_ep_cfg *cfg;
 	struct device *dev = &pdev->dev;
 	struct qcom_pcie_ep *pcie_ep;
 	char *name;
@@ -816,6 +825,14 @@ static int qcom_pcie_ep_probe(struct platform_device *pdev)
 	pcie_ep->pci.ops = &pci_ops;
 	pcie_ep->pci.ep.ops = &pci_ep_ops;
 	pcie_ep->pci.edma.nr_irqs = 1;
+
+	cfg = of_device_get_match_data(dev);
+	if (cfg && cfg->hdma_support) {
+		pcie_ep->pci.edma.ll_wr_cnt = 8;
+		pcie_ep->pci.edma.ll_rd_cnt = 8;
+		pcie_ep->pci.edma.mf = EDMA_MF_HDMA_NATIVE;
+	}
+
 	platform_set_drvdata(pdev, pcie_ep);
 
 	ret = qcom_pcie_ep_get_resources(pdev, pcie_ep);
@@ -874,8 +891,12 @@ static void qcom_pcie_ep_remove(struct platform_device *pdev)
 	qcom_pcie_disable_resources(pcie_ep);
 }
 
+static const struct qcom_pcie_ep_cfg cfg_1_34_0 = {
+	.hdma_support = true,
+};
+
 static const struct of_device_id qcom_pcie_ep_match[] = {
-	{ .compatible = "qcom,sa8775p-pcie-ep", },
+	{ .compatible = "qcom,sa8775p-pcie-ep", .data = &cfg_1_34_0},
 	{ .compatible = "qcom,sdx55-pcie-ep", },
 	{ .compatible = "qcom,sm8450-pcie-ep", },
 	{ }