PCI: add pci_bridge_release_resources and pci_bus_release_bridge_resources

We use this in later patches to free resrouce ranges for reassignment in
an effort to support a wider variety of PCI topologies.
Signed-off-by: NYinghai Lu <yinghai@kernel.org>
Reviewed-by: NAlex Chiang <achiang@hp.com>
Signed-off-by: NJesse Barnes <jbarnes@virtuousgeek.org>

drivers/pci/setup-bus.c

@@ -604,6 +604,88 @@ void __ref pci_bus_assign_resources(const struct pci_bus *bus)
 }
 EXPORT_SYMBOL(pci_bus_assign_resources);
 
+static void pci_bridge_release_resources(struct pci_bus *bus,
+					  unsigned long type)
+{
+	int idx;
+	bool changed = false;
+	struct pci_dev *dev;
+	struct resource *r;
+	unsigned long type_mask = IORESOURCE_IO | IORESOURCE_MEM |
+				  IORESOURCE_PREFETCH;
+
+	dev = bus->self;
+	for (idx = PCI_BRIDGE_RESOURCES; idx <= PCI_BRIDGE_RESOURCE_END;
+	     idx++) {
+		r = &dev->resource[idx];
+		if ((r->flags & type_mask) != type)
+			continue;
+		if (!r->parent)
+			continue;
+		/*
+		 * if there are children under that, we should release them
+		 *  all
+		 */
+		release_child_resources(r);
+		if (!release_resource(r)) {
+			dev_printk(KERN_DEBUG, &dev->dev,
+				 "resource %d %pR released\n", idx, r);
+			/* keep the old size */
+			r->end = resource_size(r) - 1;
+			r->start = 0;
+			r->flags = 0;
+			changed = true;
+		}
+	}
+
+	if (changed) {
+		/* avoiding touch the one without PREF */
+		if (type & IORESOURCE_PREFETCH)
+			type = IORESOURCE_PREFETCH;
+		__pci_setup_bridge(bus, type);
+	}
+}
+
+enum release_type {
+	leaf_only,
+	whole_subtree,
+};
+/*
+ * try to release pci bridge resources that is from leaf bridge,
+ * so we can allocate big new one later
+ */
+static void __ref pci_bus_release_bridge_resources(struct pci_bus *bus,
+						   unsigned long type,
+						   enum release_type rel_type)
+{
+	struct pci_dev *dev;
+	bool is_leaf_bridge = true;
+
+	list_for_each_entry(dev, &bus->devices, bus_list) {
+		struct pci_bus *b = dev->subordinate;
+		if (!b)
+			continue;
+
+		is_leaf_bridge = false;
+
+		if ((dev->class >> 8) != PCI_CLASS_BRIDGE_PCI)
+			continue;
+
+		if (rel_type == whole_subtree)
+			pci_bus_release_bridge_resources(b, type,
+						 whole_subtree);
+	}
+
+	if (pci_is_root_bus(bus))
+		return;
+
+	if ((bus->self->class >> 8) != PCI_CLASS_BRIDGE_PCI)
+		return;
+
+	if ((rel_type == whole_subtree) || is_leaf_bridge)
+		pci_bridge_release_resources(bus, type);
+}
+
 static void pci_bus_dump_res(struct pci_bus *bus)
 {
         int i;