diff --git a/Documentation/devicetree/bindings/pci/designware-pcie.txt b/Documentation/devicetree/bindings/pci/designware-pcie.txt
index ed0d9b9fff2b..9f4faa8e8d00 100644
--- a/Documentation/devicetree/bindings/pci/designware-pcie.txt
+++ b/Documentation/devicetree/bindings/pci/designware-pcie.txt
@@ -23,3 +23,6 @@ Required properties:
 
 Optional properties:
 - reset-gpio: gpio pin number of power good signal
+- bus-range: PCI bus numbers covered (it is recommended for new devicetrees to
+  specify this property, to keep backwards compatibility a range of 0x00-0xff
+  is assumed if not present)
diff --git a/drivers/pci/host/pcie-designware.c b/drivers/pci/host/pcie-designware.c
index 52bd3a143563..538bbf310e44 100644
--- a/drivers/pci/host/pcie-designware.c
+++ b/drivers/pci/host/pcie-designware.c
@@ -425,7 +425,7 @@ int __init dw_pcie_host_init(struct pcie_port *pp)
 	struct resource *cfg_res;
 	u32 val, na, ns;
 	const __be32 *addrp;
-	int i, index;
+	int i, index, ret;
 
 	/* Find the address cell size and the number of cells in order to get
 	 * the untranslated address.
@@ -500,6 +500,16 @@ int __init dw_pcie_host_init(struct pcie_port *pp)
 		}
 	}
 
+	ret = of_pci_parse_bus_range(np, &pp->busn);
+	if (ret < 0) {
+		pp->busn.name = np->name;
+		pp->busn.start = 0;
+		pp->busn.end = 0xff;
+		pp->busn.flags = IORESOURCE_BUS;
+		dev_dbg(pp->dev, "failed to parse bus-range property: %d, using default %pR\n",
+			ret, &pp->busn);
+	}
+
 	if (!pp->dbi_base) {
 		pp->dbi_base = devm_ioremap(pp->dev, pp->cfg.start,
 					resource_size(&pp->cfg));
@@ -511,17 +521,24 @@ int __init dw_pcie_host_init(struct pcie_port *pp)
 
 	pp->mem_base = pp->mem.start;
 
-	pp->va_cfg0_base = devm_ioremap(pp->dev, pp->cfg0_base,
-					pp->config.cfg0_size);
 	if (!pp->va_cfg0_base) {
-		dev_err(pp->dev, "error with ioremap in function\n");
-		return -ENOMEM;
+		pp->cfg0_base = pp->cfg.start;
+		pp->va_cfg0_base = devm_ioremap(pp->dev, pp->cfg0_base,
+						pp->config.cfg0_size);
+		if (!pp->va_cfg0_base) {
+			dev_err(pp->dev, "error with ioremap in function\n");
+			return -ENOMEM;
+		}
 	}
-	pp->va_cfg1_base = devm_ioremap(pp->dev, pp->cfg1_base,
-					pp->config.cfg1_size);
+
 	if (!pp->va_cfg1_base) {
-		dev_err(pp->dev, "error with ioremap\n");
-		return -ENOMEM;
+		pp->cfg1_base = pp->cfg.start + pp->config.cfg0_size;
+		pp->va_cfg1_base = devm_ioremap(pp->dev, pp->cfg1_base,
+						pp->config.cfg1_size);
+		if (!pp->va_cfg1_base) {
+			dev_err(pp->dev, "error with ioremap\n");
+			return -ENOMEM;
+		}
 	}
 
 	if (of_property_read_u32(np, "num-lanes", &pp->lanes)) {
@@ -530,16 +547,22 @@ int __init dw_pcie_host_init(struct pcie_port *pp)
 	}
 
 	if (IS_ENABLED(CONFIG_PCI_MSI)) {
-		pp->irq_domain = irq_domain_add_linear(pp->dev->of_node,
-					MAX_MSI_IRQS, &msi_domain_ops,
-					&dw_pcie_msi_chip);
-		if (!pp->irq_domain) {
-			dev_err(pp->dev, "irq domain init failed\n");
-			return -ENXIO;
-		}
+		if (!pp->ops->msi_host_init) {
+			pp->irq_domain = irq_domain_add_linear(pp->dev->of_node,
+						MAX_MSI_IRQS, &msi_domain_ops,
+						&dw_pcie_msi_chip);
+			if (!pp->irq_domain) {
+				dev_err(pp->dev, "irq domain init failed\n");
+				return -ENXIO;
+			}
 
-		for (i = 0; i < MAX_MSI_IRQS; i++)
-			irq_create_mapping(pp->irq_domain, i);
+			for (i = 0; i < MAX_MSI_IRQS; i++)
+				irq_create_mapping(pp->irq_domain, i);
+		} else {
+			ret = pp->ops->msi_host_init(pp, &dw_pcie_msi_chip);
+			if (ret < 0)
+				return ret;
+		}
 	}
 
 	if (pp->ops->host_init)
@@ -558,7 +581,6 @@ int __init dw_pcie_host_init(struct pcie_port *pp)
 	dw_pci.private_data = (void **)&pp;
 
 	pci_common_init_dev(pp->dev, &dw_pci);
-	pci_assign_unassigned_resources();
 #ifdef CONFIG_PCI_DOMAINS
 	dw_pci.domain++;
 #endif
@@ -781,6 +803,7 @@ static int dw_pcie_setup(int nr, struct pci_sys_data *sys)
 
 	sys->mem_offset = pp->mem.start - pp->config.mem_bus_addr;
 	pci_add_resource_offset(&sys->resources, &pp->mem, sys->mem_offset);
+	pci_add_resource(&sys->resources, &pp->busn);
 
 	return 1;
 }
@@ -790,14 +813,16 @@ static struct pci_bus *dw_pcie_scan_bus(int nr, struct pci_sys_data *sys)
 	struct pci_bus *bus;
 	struct pcie_port *pp = sys_to_pcie(sys);
 
-	if (pp) {
-		pp->root_bus_nr = sys->busnr;
-		bus = pci_scan_root_bus(pp->dev, sys->busnr, &dw_pcie_ops,
-					sys, &sys->resources);
-	} else {
-		bus = NULL;
-		BUG();
-	}
+	pp->root_bus_nr = sys->busnr;
+	bus = pci_create_root_bus(pp->dev, sys->busnr,
+				  &dw_pcie_ops, sys, &sys->resources);
+	if (!bus)
+		return NULL;
+
+	pci_scan_child_bus(bus);
+
+	if (bus && pp->ops->scan_bus)
+		pp->ops->scan_bus(pp);
 
 	return bus;
 }
diff --git a/drivers/pci/host/pcie-designware.h b/drivers/pci/host/pcie-designware.h
index daf81f922cda..a476e60993cb 100644
--- a/drivers/pci/host/pcie-designware.h
+++ b/drivers/pci/host/pcie-designware.h
@@ -48,6 +48,7 @@ struct pcie_port {
 	struct resource		cfg;
 	struct resource		io;
 	struct resource		mem;
+	struct resource		busn;
 	struct pcie_port_info	config;
 	int			irq;
 	u32			lanes;
@@ -74,6 +75,8 @@ struct pcie_host_ops {
 	void (*msi_set_irq)(struct pcie_port *pp, int irq);
 	void (*msi_clear_irq)(struct pcie_port *pp, int irq);
 	u32 (*get_msi_data)(struct pcie_port *pp);
+	void (*scan_bus)(struct pcie_port *pp);
+	int (*msi_host_init)(struct pcie_port *pp, struct msi_chip *chip);
 };
 
 int dw_pcie_cfg_read(void __iomem *addr, int where, int size, u32 *val);