3 files changed, 159 insertions, 0 deletions

diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c
index 73dda0d59bbc..6826a893288a 100644
--- a/drivers/pci/setup-bus.c
+++ b/drivers/pci/setup-bus.c
@@ -1913,6 +1913,104 @@ enable_all:
 }
 EXPORT_SYMBOL_GPL(pci_assign_unassigned_bridge_resources);
 
+int pci_reassign_bridge_resources(struct pci_dev *bridge, unsigned long type)
+{
+	struct pci_dev_resource *dev_res;
+	struct pci_dev *next;
+	LIST_HEAD(saved);
+	LIST_HEAD(added);
+	LIST_HEAD(failed);
+	unsigned int i;
+	int ret;
+
+	/* Walk to the root hub, releasing bridge BARs when possible */
+	next = bridge;
+	do {
+		bridge = next;
+		for (i = PCI_BRIDGE_RESOURCES; i < PCI_BRIDGE_RESOURCE_END;
+		     i++) {
+			struct resource *res = &bridge->resource[i];
+
+			if ((res->flags ^ type) & PCI_RES_TYPE_MASK)
+				continue;
+
+			/* Ignore BARs which are still in use */
+			if (res->child)
+				continue;
+
+			ret = add_to_list(&saved, bridge, res, 0, 0);
+			if (ret)
+				goto cleanup;
+
+			dev_info(&bridge->dev, "BAR %d: releasing %pR\n",
+				 i, res);
+
+			if (res->parent)
+				release_resource(res);
+			res->start = 0;
+			res->end = 0;
+			break;
+		}
+		if (i == PCI_BRIDGE_RESOURCE_END)
+			break;
+
+		next = bridge->bus ? bridge->bus->self : NULL;
+	} while (next);
+
+	if (list_empty(&saved))
+		return -ENOENT;
+
+	__pci_bus_size_bridges(bridge->subordinate, &added);
+	__pci_bridge_assign_resources(bridge, &added, &failed);
+	BUG_ON(!list_empty(&added));
+
+	if (!list_empty(&failed)) {
+		ret = -ENOSPC;
+		goto cleanup;
+	}
+
+	list_for_each_entry(dev_res, &saved, list) {
+		/* Skip the bridge we just assigned resources for. */
+		if (bridge == dev_res->dev)
+			continue;
+
+		bridge = dev_res->dev;
+		pci_setup_bridge(bridge->subordinate);
+	}
+
+	free_list(&saved);
+	return 0;
+
+cleanup:
+	/* restore size and flags */
+	list_for_each_entry(dev_res, &failed, list) {
+		struct resource *res = dev_res->res;
+
+		res->start = dev_res->start;
+		res->end = dev_res->end;
+		res->flags = dev_res->flags;
+	}
+	free_list(&failed);
+
+	/* Revert to the old configuration */
+	list_for_each_entry(dev_res, &saved, list) {
+		struct resource *res = dev_res->res;
+
+		bridge = dev_res->dev;
+		i = res - bridge->resource;
+
+		res->start = dev_res->start;
+		res->end = dev_res->end;
+		res->flags = dev_res->flags;
+
+		pci_claim_resource(bridge, i);
+		pci_setup_bridge(bridge->subordinate);
+	}
+	free_list(&saved);
+
+	return ret;
+}
+
 void pci_assign_unassigned_bus_resources(struct pci_bus *bus)
 {
 	struct pci_dev *dev;
diff --git a/drivers/pci/setup-res.c b/drivers/pci/setup-res.c
index e576e1a8d978..bf0089ef2177 100644
--- a/drivers/pci/setup-res.c
+++ b/drivers/pci/setup-res.c
@@ -396,6 +396,64 @@ int pci_reassign_resource(struct pci_dev *dev, int resno, resource_size_t addsiz
 	return 0;
 }
 
+void pci_release_resource(struct pci_dev *dev, int resno)
+{
+	struct resource *res = dev->resource + resno;
+
+	dev_info(&dev->dev, "BAR %d: releasing %pR\n", resno, res);
+	release_resource(res);
+	res->end = resource_size(res) - 1;
+	res->start = 0;
+	res->flags |= IORESOURCE_UNSET;
+}
+EXPORT_SYMBOL(pci_release_resource);
+
+int pci_resize_resource(struct pci_dev *dev, int resno, int size)
+{
+	struct resource *res = dev->resource + resno;
+	int old, ret;
+	u32 sizes;
+	u16 cmd;
+
+	/* Make sure the resource isn't assigned before resizing it. */
+	if (!(res->flags & IORESOURCE_UNSET))
+		return -EBUSY;
+
+	pci_read_config_word(dev, PCI_COMMAND, &cmd);
+	if (cmd & PCI_COMMAND_MEMORY)
+		return -EBUSY;
+
+	sizes = pci_rebar_get_possible_sizes(dev, resno);
+	if (!sizes)
+		return -ENOTSUPP;
+
+	if (!(sizes & BIT(size)))
+		return -EINVAL;
+
+	old = pci_rebar_get_current_size(dev, resno);
+	if (old < 0)
+		return old;
+
+	ret = pci_rebar_set_size(dev, resno, size);
+	if (ret)
+		return ret;
+
+	res->end = res->start + pci_rebar_size_to_bytes(size) - 1;
+
+	/* Check if the new config works by trying to assign everything. */
+	ret = pci_reassign_bridge_resources(dev->bus->self, res->flags);
+	if (ret)
+		goto error_resize;
+
+	return 0;
+
+error_resize:
+	pci_rebar_set_size(dev, resno, old);
+	res->end = res->start + pci_rebar_size_to_bytes(old) - 1;
+	return ret;
+}
+EXPORT_SYMBOL(pci_resize_resource);
+
 int pci_enable_resources(struct pci_dev *dev, int mask)
 {
 	u16 cmd, old_cmd;
diff --git a/include/linux/pci.h b/include/linux/pci.h
index f4f8ee5a7362..55e9fe6dd577 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -1106,6 +1106,8 @@ void pci_reset_bridge_secondary_bus(struct pci_dev *dev);
 void pci_update_resource(struct pci_dev *dev, int resno);
 int __must_check pci_assign_resource(struct pci_dev *dev, int i);
 int __must_check pci_reassign_resource(struct pci_dev *dev, int i, resource_size_t add_size, resource_size_t align);
+void pci_release_resource(struct pci_dev *dev, int resno);
+int __must_check pci_resize_resource(struct pci_dev *dev, int i, int size);
 int pci_select_bars(struct pci_dev *dev, unsigned long flags);
 bool pci_device_is_present(struct pci_dev *pdev);
 void pci_ignore_hotplug(struct pci_dev *dev);
@@ -1185,6 +1187,7 @@ void pci_assign_unassigned_resources(void);
 void pci_assign_unassigned_bridge_resources(struct pci_dev *bridge);
 void pci_assign_unassigned_bus_resources(struct pci_bus *bus);
 void pci_assign_unassigned_root_bus_resources(struct pci_bus *bus);
+int pci_reassign_bridge_resources(struct pci_dev *bridge, unsigned long type);
 void pdev_enable_device(struct pci_dev *);
 int pci_enable_resources(struct pci_dev *, int mask);
 void pci_assign_irq(struct pci_dev *dev);