+/*
+ * find the upstream PCIE-to-PCI bridge of a PCI device
+ * if the device is PCIE, return NULL
+ * if the device isn't connected to a PCIE bridge (that is its parent is a
+ * legacy PCI bridge and the bridge is directly connected to bus 0), return its
+ * parent
+ */
+struct pci_dev *
+pci_find_upstream_pcie_bridge(struct pci_dev *pdev)
+{
+ struct pci_dev *tmp = NULL;
+
+ if (pdev->is_pcie)
+ return NULL;
+ while (1) {
+ if (!pdev->bus->self)
+ break;
+ pdev = pdev->bus->self;
+ /* a p2p bridge */
+ if (!pdev->is_pcie) {
+ tmp = pdev;
+ continue;
+ }
+ /* PCI device should connect to a PCIE bridge */
+ if (pdev->pcie_type != PCI_EXP_TYPE_PCI_BRIDGE) {
+ /* Busted hardware? */
+ WARN_ON_ONCE(1);
+ return NULL;
+ }
+ return pdev;
+ }
+
+ return tmp;
+}