PCI: Make rescan bus increase bridge resource size if needed

Current rescan will not touch bridge MMIO and IO.

Try to reuse pci_assign_unassigned_bridge_resources(bridge) to update bridge
resources, if child devices need more resources.

Only do that for bridges whose children are all removed already; i.e. don't
release resources that could already be in use by drivers on child devices.

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

drivers/pci/probe.c

@@ -1666,6 +1666,31 @@ struct pci_bus * __devinit pci_scan_bus(int bus, struct pci_ops *ops,
 EXPORT_SYMBOL(pci_scan_bus);
 
 #ifdef CONFIG_HOTPLUG
+/**
+ * pci_rescan_bus_bridge_resize - scan a PCI bus for devices.
+ * @bridge: PCI bridge for the bus to scan
+ *
+ * Scan a PCI bus and child buses for new devices, add them,
+ * and enable them, resizing bridge mmio/io resource if necessary
+ * and possible.  The caller must ensure the child devices are already
+ * removed for resizing to occur.
+ *
+ * Returns the max number of subordinate bus discovered.
+ */
+unsigned int __ref pci_rescan_bus_bridge_resize(struct pci_dev *bridge)
+{
+	unsigned int max;
+	struct pci_bus *bus = bridge->subordinate;
+
+	max = pci_scan_child_bus(bus);
+
+	pci_assign_unassigned_bridge_resources(bridge);
+
+	pci_bus_add_devices(bus);
+
+	return max;
+}
+
 /**
  * pci_rescan_bus - scan a PCI bus for devices.
  * @bus: PCI bus to scan