PCI: imx6: Add i.MX PCIe EP mode support

i.MX PCIe is one dual mode PCIe controller.

Add i.MX PCIe EP mode support here, and split the PCIe modes to the Root
Complex mode and Endpoint mode.

Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Richard Zhu <[e-mail]>
Signed-off-by: Lorenzo Pieralisi <[e-mail]>

drivers/pci/controller/dwc/Kconfig

···
 	  functions to implement the driver.
 
 config PCI_IMX6
-	bool "Freescale i.MX6/7/8 PCIe controller"
+	bool
+
+config PCI_IMX6_HOST
+	bool "Freescale i.MX6/7/8 PCIe controller host mode"
 	depends on ARCH_MXC || COMPILE_TEST
 	depends on PCI_MSI
 	select PCIE_DW_HOST
+	select PCI_IMX6
+	help
+	  Enables support for the PCIe controller in the i.MX SoCs to
+	  work in Root Complex mode. The PCI controller on i.MX is based
+	  on DesignWare hardware and therefore the driver re-uses the
+	  DesignWare core functions to implement the driver.
+
+config PCI_IMX6_EP
+	bool "Freescale i.MX6/7/8 PCIe controller endpoint mode"
+	depends on ARCH_MXC || COMPILE_TEST
+	depends on PCI_ENDPOINT
+	select PCIE_DW_EP
+	select PCI_IMX6
+	help
+	  Enables support for the PCIe controller in the i.MX SoCs to
+	  work in endpoint mode. The PCI controller on i.MX is based
+	  on DesignWare hardware and therefore the driver re-uses the
+	  DesignWare core functions to implement the driver.
 
 config PCIE_SPEAR13XX
 	bool "STMicroelectronics SPEAr PCIe controller"

drivers/pci/controller/dwc/pci-imx6.c

···
 
 struct imx6_pcie_drvdata {
 	enum imx6_pcie_variants variant;
+	enum dw_pcie_device_mode mode;
 	u32 flags;
 	int dbi_length;
 	const char *gpr;
···
 
 static void imx6_pcie_configure_type(struct imx6_pcie *imx6_pcie)
 {
-	unsigned int mask, val;
+	unsigned int mask, val, mode;
+
+	if (imx6_pcie->drvdata->mode == DW_PCIE_EP_TYPE)
+		mode = PCI_EXP_TYPE_ENDPOINT;
+	else
+		mode = PCI_EXP_TYPE_ROOT_PORT;
 
 	if (imx6_pcie->drvdata->variant == IMX8MQ &&
 	    imx6_pcie->controller_id == 1) {
 		mask = IMX8MQ_GPR12_PCIE2_CTRL_DEVICE_TYPE;
-		val  = FIELD_PREP(IMX8MQ_GPR12_PCIE2_CTRL_DEVICE_TYPE,
-				  PCI_EXP_TYPE_ROOT_PORT);
+		val  = FIELD_PREP(IMX8MQ_GPR12_PCIE2_CTRL_DEVICE_TYPE, mode);
 	} else {
 		mask = IMX6Q_GPR12_DEVICE_TYPE;
-		val  = FIELD_PREP(IMX6Q_GPR12_DEVICE_TYPE,
-				  PCI_EXP_TYPE_ROOT_PORT);
+		val  = FIELD_PREP(IMX6Q_GPR12_DEVICE_TYPE, mode);
 	}
 
 	regmap_update_bits(imx6_pcie->iomuxc_gpr, IOMUXC_GPR12, mask, val);
···
 
 static const struct dw_pcie_ops dw_pcie_ops = {
 	.start_link = imx6_pcie_start_link,
+	.stop_link = imx6_pcie_stop_link,
 };
+
+static void imx6_pcie_ep_init(struct dw_pcie_ep *ep)
+{
+	enum pci_barno bar;
+	struct dw_pcie *pci = to_dw_pcie_from_ep(ep);
+
+	for (bar = BAR_0; bar <= BAR_5; bar++)
+		dw_pcie_ep_reset_bar(pci, bar);
+}
+
+static int imx6_pcie_ep_raise_irq(struct dw_pcie_ep *ep, u8 func_no,
+				  enum pci_epc_irq_type type,
+				  u16 interrupt_num)
+{
+	struct dw_pcie *pci = to_dw_pcie_from_ep(ep);
+
+	switch (type) {
+	case PCI_EPC_IRQ_LEGACY:
+		return dw_pcie_ep_raise_legacy_irq(ep, func_no);
+	case PCI_EPC_IRQ_MSI:
+		return dw_pcie_ep_raise_msi_irq(ep, func_no, interrupt_num);
+	case PCI_EPC_IRQ_MSIX:
+		return dw_pcie_ep_raise_msix_irq(ep, func_no, interrupt_num);
+	default:
+		dev_err(pci->dev, "UNKNOWN IRQ type\n");
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static const struct pci_epc_features imx8m_pcie_epc_features = {
+	.linkup_notifier = false,
+	.msi_capable = true,
+	.msix_capable = false,
+	.reserved_bar = 1 << BAR_1 | 1 << BAR_3,
+	.align = SZ_64K,
+};
+
+static const struct pci_epc_features*
+imx6_pcie_ep_get_features(struct dw_pcie_ep *ep)
+{
+	return &imx8m_pcie_epc_features;
+}
+
+static const struct dw_pcie_ep_ops pcie_ep_ops = {
+	.ep_init = imx6_pcie_ep_init,
+	.raise_irq = imx6_pcie_ep_raise_irq,
+	.get_features = imx6_pcie_ep_get_features,
+};
+
+static int imx6_add_pcie_ep(struct imx6_pcie *imx6_pcie,
+			   struct platform_device *pdev)
+{
+	int ret;
+	unsigned int pcie_dbi2_offset;
+	struct dw_pcie_ep *ep;
+	struct resource *res;
+	struct dw_pcie *pci = imx6_pcie->pci;
+	struct dw_pcie_rp *pp = &pci->pp;
+	struct device *dev = pci->dev;
+
+	imx6_pcie_host_init(pp);
+	ep = &pci->ep;
+	ep->ops = &pcie_ep_ops;
+
+	switch (imx6_pcie->drvdata->variant) {
+	default:
+		pcie_dbi2_offset = SZ_4K;
+		break;
+	}
+	pci->dbi_base2 = pci->dbi_base + pcie_dbi2_offset;
+	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "addr_space");
+	if (!res)
+		return -EINVAL;
+
+	ep->phys_base = res->start;
+	ep->addr_size = resource_size(res);
+	ep->page_size = SZ_64K;
+
+	ret = dw_pcie_ep_init(ep);
+	if (ret) {
+		dev_err(dev, "failed to initialize endpoint\n");
+		return ret;
+	}
+	/* Start LTSSM. */
+	imx6_pcie_ltssm_enable(dev);
+
+	return 0;
+}
 
 static void imx6_pcie_pm_turnoff(struct imx6_pcie *imx6_pcie)
 {
···
 	if (ret)
 		return ret;
 
-	ret = dw_pcie_host_init(&pci->pp);
-	if (ret < 0)
-		return ret;
+	if (imx6_pcie->drvdata->mode == DW_PCIE_EP_TYPE) {
+		ret = imx6_add_pcie_ep(imx6_pcie, pdev);
+		if (ret < 0)
+			return ret;
+	} else {
+		ret = dw_pcie_host_init(&pci->pp);
+		if (ret < 0)
+			return ret;
 
-	if (pci_msi_enabled()) {
-		u8 offset = dw_pcie_find_capability(pci, PCI_CAP_ID_MSI);
-		val = dw_pcie_readw_dbi(pci, offset + PCI_MSI_FLAGS);
-		val |= PCI_MSI_FLAGS_ENABLE;
-		dw_pcie_writew_dbi(pci, offset + PCI_MSI_FLAGS, val);
+		if (pci_msi_enabled()) {
+			u8 offset = dw_pcie_find_capability(pci, PCI_CAP_ID_MSI);
+
+			val = dw_pcie_readw_dbi(pci, offset + PCI_MSI_FLAGS);
+			val |= PCI_MSI_FLAGS_ENABLE;
+			dw_pcie_writew_dbi(pci, offset + PCI_MSI_FLAGS, val);
+		}
 	}
 
 	return 0;