[PATCH RFC v4 11/21] PCI: Release and reassign the root bridge resources during rescan

[Sergey Miroshnichenko]

When the movable BARs feature is enabled, don't rely on the memory gaps
reserved by the BIOS/bootloader/firmware, but instead rearrange the BARs
and bridge windows starting from the root.

Endpoint device's BARs, after being released, are resorted and written
back by the pci_assign_unassigned_root_bus_resources().

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

Signed-off-by: Sergey Miroshnichenko <s.miroshniche...@yadro.com>
---
 drivers/pci/pci.h       |  1 +
 drivers/pci/probe.c     | 22 ++++++++++++++++++++++
 drivers/pci/setup-bus.c | 11 ++++++++++-
 3 files changed, 33 insertions(+), 1 deletion(-)

diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index 224d88634115..e06e8692a7b1 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -248,6 +248,7 @@ 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 1cf6ec960236..692752c71f71 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -3299,6 +3299,25 @@ static void pci_bus_rescan_done(struct pci_bus *bus)
        pm_runtime_put(&bus->dev);
 }
 
+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) || pci_dev_is_ignored(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
@@ -3321,8 +3340,11 @@ 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 be7d4e6d7b65..36a1907d9509 100644
--- a/drivers/pci/setup-bus.c
+++ b/drivers/pci/setup-bus.c
@@ -1584,7 +1584,7 @@ static void pci_bridge_release_resources(struct pci_bus 
*bus,
                pci_printk(KERN_DEBUG, dev, "resource %d %pR released\n",
                                        PCI_BRIDGE_RESOURCES + idx, r);
                /* keep the old size */
-               r->end = resource_size(r) - 1;
+               r->end = pci_movable_bars_enabled() ? 0 : (resource_size(r) - 
1);
                r->start = 0;
                r->flags = 0;
 
@@ -1637,6 +1637,15 @@ 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)
+{
+       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);
+}
+
 static void pci_bus_dump_res(struct pci_bus *bus)
 {
        struct resource *res;
-- 
2.20.1