PCI: Export pcie_find_root_port

Export pcie_find_root_port() so we can use it outside of PCIe-AER error
injection.

Signed-off-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 0e49f70..a38772a 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -1928,6 +1928,20 @@ static inline int pci_pcie_type(const struct pci_dev *dev)
 	return (pcie_caps_reg(dev) & PCI_EXP_FLAGS_TYPE) >> 4;
 }
 
+static inline struct pci_dev *pcie_find_root_port(struct pci_dev *dev)
+{
+	while (1) {
+		if (!pci_is_pcie(dev))
+			break;
+		if (pci_pcie_type(dev) == PCI_EXP_TYPE_ROOT_PORT)
+			return dev;
+		if (!dev->bus->self)
+			break;
+		dev = dev->bus->self;
+	}
+	return NULL;
+}
+
 void pci_request_acs(void);
 bool pci_acs_enabled(struct pci_dev *pdev, u16 acs_flags);
 bool pci_acs_path_enabled(struct pci_dev *start,