[PATCH v7 06/26] PCI: hotplug: Recalculate every bridge window during rescan

[Sergei Miroshnichenko <s.miroshnichenko@yadro.com>]

When the movable BARs feature is enabled and a rescan has been requested,
release all the bridge windows and recalculate them from scratch, taking
into account all kinds for BARs: immovable+fixed, movable, new.

Comparing to simply trying to expand bridge windows, this also employs the
PCI ability to shuffle BARs within a bridge, increasing the chances to find
a memory space to fit BARs for newly hotplugged devices, especially if no
(not enough) gaps were reserved by the BIOS/bootloader/firmware.

The last step of writing the recalculated windows to the bridges is done
by the new pci_setup_bridges() function.

Signed-off-by: Sergei Miroshnichenko <s.miroshnichenko@yadro.com>
---
 drivers/pci/pci.h       |  1 +
 drivers/pci/probe.c     | 22 ++++++++++++++++++++++
 drivers/pci/setup-bus.c | 16 ++++++++++++++++
 3 files changed, 39 insertions(+)

diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index ce8c53ca7a1e..fe995993b481 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -283,6 +283,7 @@ void __pci_bus_assign_resources(const struct pci_bus *bus,
 				struct list_head *realloc_head,
 				struct list_head *fail_head);
 bool pci_bus_clip_resource(struct pci_dev *dev, int idx);
+void pci_bus_release_root_bridge_resources(struct pci_bus *bus);
 
 void pci_reassigndev_resource_alignment(struct pci_dev *dev);
 void pci_disable_bridge_window(struct pci_dev *dev);
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 9b6d15587f5d..daaaebdfd4c4 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -3190,6 +3190,25 @@ static void pci_bus_rescan_done(struct pci_bus *bus)
 		pci_config_pm_runtime_put(bus->self);
 }
 
+static void pci_setup_bridges(struct pci_bus *bus)
+{
+	struct pci_dev *dev;
+
+	list_for_each_entry(dev, &bus->devices, bus_list) {
+		struct pci_bus *child;
+
+		if (!pci_dev_is_added(dev))
+			continue;
+
+		child = dev->subordinate;
+		if (child)
+			pci_setup_bridges(child);
+	}
+
+	if (bus->self)
+		pci_setup_bridge(bus);
+}
+
 /**
  * pci_rescan_bus - Scan a PCI bus for devices
  * @bus: PCI bus to scan
@@ -3211,8 +3230,11 @@ unsigned int pci_rescan_bus(struct pci_bus *bus)
 		pci_bus_rescan_prepare(root);
 
 		max = pci_scan_child_bus(root);
+
+		pci_bus_release_root_bridge_resources(root);
 		pci_assign_unassigned_root_bus_resources(root);
 
+		pci_setup_bridges(root);
 		pci_bus_rescan_done(root);
 	} else {
 		max = pci_scan_child_bus(bus);
diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c
index 2cf07003d5fc..7a9bf979908d 100644
--- a/drivers/pci/setup-bus.c
+++ b/drivers/pci/setup-bus.c
@@ -1654,6 +1654,22 @@ static void pci_bus_release_bridge_resources(struct pci_bus *bus,
 		pci_bridge_release_resources(bus, type);
 }
 
+void pci_bus_release_root_bridge_resources(struct pci_bus *root_bus)
+{
+	int i;
+	struct resource *r;
+
+	pci_bus_release_bridge_resources(root_bus, IORESOURCE_IO, whole_subtree);
+	pci_bus_release_bridge_resources(root_bus, IORESOURCE_MEM, whole_subtree);
+	pci_bus_release_bridge_resources(root_bus,
+					 IORESOURCE_MEM_64 | IORESOURCE_PREFETCH,
+					 whole_subtree);
+
+	pci_bus_for_each_resource(root_bus, r, i) {
+		pci_release_child_resources(root_bus, r);
+	}
+}
+
 static void pci_bus_dump_res(struct pci_bus *bus)
 {
 	struct resource *res;
-- 
2.24.1