diff --git a/drivers/pci/controller/pci-mvebu.c b/drivers/pci/controller/pci-mvebu.c
index 4edce441901c..36fbdc4f0e06 100644
--- a/drivers/pci/controller/pci-mvebu.c
+++ b/drivers/pci/controller/pci-mvebu.c
@@ -127,6 +127,11 @@ static bool mvebu_pcie_link_up(struct mvebu_pcie_port *port)
 	return !(mvebu_readl(port, PCIE_STAT_OFF) & PCIE_STAT_LINK_DOWN);
 }
 
+static u8 mvebu_pcie_get_local_bus_nr(struct mvebu_pcie_port *port)
+{
+	return (mvebu_readl(port, PCIE_STAT_OFF) & PCIE_STAT_BUS) >> 8;
+}
+
 static void mvebu_pcie_set_local_bus_nr(struct mvebu_pcie_port *port, int nr)
 {
 	u32 stat;
@@ -490,6 +495,20 @@ mvebu_pci_bridge_emul_base_conf_read(struct pci_bridge_emul *bridge,
 		*value = mvebu_readl(port, PCIE_CMD_OFF);
 		break;
 
+	case PCI_PRIMARY_BUS: {
+		/*
+		 * From the whole 32bit register we support reading from HW only
+		 * secondary bus number which is mvebu local bus number.
+		 * Other bits are retrieved only from emulated config buffer.
+		 */
+		__le32 *cfgspace = (__le32 *)&bridge->conf;
+		u32 val = le32_to_cpu(cfgspace[PCI_PRIMARY_BUS / 4]);
+		val &= ~0xff00;
+		val |= mvebu_pcie_get_local_bus_nr(port) << 8;
+		*value = val;
+		break;
+	}
+
 	default:
 		return PCI_BRIDGE_EMUL_NOT_HANDLED;
 	}
@@ -594,7 +613,8 @@ mvebu_pci_bridge_emul_base_conf_write(struct pci_bridge_emul *bridge,
 		break;
 
 	case PCI_PRIMARY_BUS:
-		mvebu_pcie_set_local_bus_nr(port, conf->secondary_bus);
+		if (mask & 0xff00)
+			mvebu_pcie_set_local_bus_nr(port, conf->secondary_bus);
 		break;
 
 	default:
@@ -1186,8 +1206,84 @@ static int mvebu_pcie_probe(struct platform_device *pdev)
 			continue;
 		}
 
+		/*
+		 * PCIe topology exported by mvebu hw is quite complicated. In
+		 * reality has something like N fully independent host bridges
+		 * where each host bridge has one PCIe Root Port (which acts as
+		 * PCI Bridge device). Each host bridge has its own independent
+		 * internal registers, independent access to PCI config space,
+		 * independent interrupt lines, independent window and memory
+		 * access configuration. But additionally there is some kind of
+		 * peer-to-peer support between PCIe devices behind different
+		 * host bridges limited just to forwarding of memory and I/O
+		 * transactions (forwarding of error messages and config cycles
+		 * is not supported). So we could say there are N independent
+		 * PCIe Root Complexes.
+		 *
+		 * For this kind of setup DT should have been structured into
+		 * N independent PCIe controllers / host bridges. But instead
+		 * structure in past was defined to put PCIe Root Ports of all
+		 * host bridges into one bus zero, like in classic multi-port
+		 * Root Complex setup with just one host bridge.
+		 *
+		 * This means that pci-mvebu.c driver provides "virtual" bus 0
+		 * on which registers all PCIe Root Ports (PCI Bridge devices)
+		 * specified in DT by their BDF addresses and virtually routes
+		 * PCI config access of each PCI bridge device to specific PCIe
+		 * host bridge.
+		 *
+		 * Normally PCI Bridge should choose between Type 0 and Type 1
+		 * config requests based on primary and secondary bus numbers
+		 * configured on the bridge itself. But because mvebu PCI Bridge
+		 * does not have registers for primary and secondary bus numbers
+		 * in its config space, it determinates type of config requests
+		 * via its own custom way.
+		 *
+		 * There are two options how mvebu determinate type of config
+		 * request.
+		 *
+		 * 1. If Secondary Bus Number Enable bit is not set or is not
+		 * available (applies for pre-XP PCIe controllers) then Type 0
+		 * is used if target bus number equals Local Bus Number (bits
+		 * [15:8] in register 0x1a04) and target device number differs
+		 * from Local Device Number (bits [20:16] in register 0x1a04).
+		 * Type 1 is used if target bus number differs from Local Bus
+		 * Number. And when target bus number equals Local Bus Number
+		 * and target device equals Local Device Number then request is
+		 * routed to Local PCI Bridge (PCIe Root Port).
+		 *
+		 * 2. If Secondary Bus Number Enable bit is set (bit 7 in
+		 * register 0x1a2c) then mvebu hw determinate type of config
+		 * request like compliant PCI Bridge based on primary bus number
+		 * which is configured via Local Bus Number (bits [15:8] in
+		 * register 0x1a04) and secondary bus number which is configured
+		 * via Secondary Bus Number (bits [7:0] in register 0x1a2c).
+		 * Local PCI Bridge (PCIe Root Port) is available on primary bus
+		 * as device with Local Device Number (bits [20:16] in register
+		 * 0x1a04).
+		 *
+		 * Secondary Bus Number Enable bit is disabled by default and
+		 * option 2. is not available on pre-XP PCIe controllers. Hence
+		 * this driver always use option 1.
+		 *
+		 * Basically it means that primary and secondary buses shares
+		 * one virtual number configured via Local Bus Number bits and
+		 * Local Device Number bits determinates if accessing primary
+		 * or secondary bus. Set Local Device Number to 1 and redirect
+		 * all writes of PCI Bridge Secondary Bus Number register to
+		 * Local Bus Number (bits [15:8] in register 0x1a04).
+		 *
+		 * So when accessing devices on buses behind secondary bus
+		 * number it would work correctly. And also when accessing
+		 * device 0 at secondary bus number via config space would be
+		 * correctly routed to secondary bus. Due to issues described
+		 * in mvebu_pcie_setup_hw(), PCI Bridges at primary bus (zero)
+		 * are not accessed directly via PCI config space but rarher
+		 * indirectly via kernel emulated PCI bridge driver.
+		 */
 		mvebu_pcie_setup_hw(port);
 		mvebu_pcie_set_local_dev_nr(port, 1);
+		mvebu_pcie_set_local_bus_nr(port, 0);
 	}
 
 	bridge->sysdata = pcie;
