PCI: add pci_create_root_bus() that accepts resource list

pci_create_bus() assigns ioport_resource and iomem_resource as the default
bus resources, i.e., the entire address space.  Architectures fix these
later, typically in pcibios_fixup_bus() or after pci_scan_bus_parented()
returns, but code that runs in the interim sees incorrect resource
information.

This patch adds a new pci_create_root_bus() that sets the bus resources
correctly from a supplied list of resources.

I intend to remove pci_create_bus() after changing all callers.

Based on original patch by Deng-Cheng Zhu.

Reference: http://www.spinics.net/lists/mips/msg41654.html
Reference: https://lkml.org/lkml/2011/8/26/88
Signed-off-by: Deng-Cheng Zhu <dczhu@mips.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

2 files changed, 24 insertions, 4 deletions

diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 2f0b14451d9d..89ecded0581b 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -1522,12 +1522,13 @@ unsigned int __devinit pci_scan_child_bus(struct pci_bus *bus)
         return max;
 }
 
-struct pci_bus * pci_create_bus(struct device *parent,
-                int bus, struct pci_ops *ops, void *sysdata)
+struct pci_bus *pci_create_root_bus(struct device *parent, int bus,
+                struct pci_ops *ops, void *sysdata, struct list_head *resources)
 {
         int error, i;
         struct pci_bus *b, *b2;
         struct device *dev;
+        struct pci_bus_resource *bus_res, *n;
         struct resource *res;
 
         b = pci_alloc_bus();
@@ -1578,8 +1579,10 @@ struct pci_bus * pci_create_bus(struct device *parent,
         pci_create_legacy_files(b);
 
         b->number = b->secondary = bus;
-        b->resource[0] = &ioport_resource;
-        b->resource[1] = &iomem_resource;
+
+        /* Add initial resources to the bus */
+        list_for_each_entry_safe(bus_res, n, resources, list)
+                list_move_tail(&bus_res->list, &b->resources);
 
         if (parent)
                 dev_info(parent, "PCI host bridge to bus %s\n", dev_name(&b->dev));
@@ -1605,6 +1608,20 @@ err_out:
         return NULL;
 }
 
+struct pci_bus *pci_create_bus(struct device *parent,
+                int bus, struct pci_ops *ops, void *sysdata)
+{
+        LIST_HEAD(resources);
+        struct pci_bus *b;
+
+        pci_add_resource(&resources, &ioport_resource);
+        pci_add_resource(&resources, &iomem_resource);
+        b = pci_create_root_bus(parent, bus, ops, sysdata, &resources);
+        if (!b)
+                pci_free_resource_list(&resources);
+        return b;
+}
+
 struct pci_bus * __devinit pci_scan_bus_parented(struct device *parent,
                 int bus, struct pci_ops *ops, void *sysdata)
 {
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 9daa79901122..eacb1e51e11b 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -670,6 +670,9 @@ static inline struct pci_bus * __devinit pci_scan_bus(int bus, struct pci_ops *o
                 pci_bus_add_devices(root_bus);
         return root_bus;
 }
+struct pci_bus *pci_create_root_bus(struct device *parent, int bus,
+                                    struct pci_ops *ops, void *sysdata,
+                                    struct list_head *resources);
 struct pci_bus *pci_create_bus(struct device *parent, int bus,
                                struct pci_ops *ops, void *sysdata);
 struct pci_bus *pci_add_new_bus(struct pci_bus *parent, struct pci_dev *dev,