ACPI: Optimize acpi_get_pci_rootbridge_handle() to boot faster

Move acpi_get_pci_rootbridge_handle() from glue.c to pci_root.c and get the
root bridge ACPI handles by searching the &acpi_pci_roots list instead of
walking through the ACPI name space.  This significantly reduces boot time
on large I/O systems.

Signed-off-by: Justin Chen <justin.chen@hp.com>
Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
Signed-off-by: Len Brown <len.brown@intel.com>

1 files changed, 13 insertions, 0 deletions

diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
index a860efa2c562..1f06229040ac 100644
--- a/drivers/acpi/pci_root.c
+++ b/drivers/acpi/pci_root.c
@@ -117,6 +117,19 @@ void acpi_pci_unregister_driver(struct acpi_pci_driver *driver)
 
 EXPORT_SYMBOL(acpi_pci_unregister_driver);
 
+acpi_handle acpi_get_pci_rootbridge_handle(unsigned int seg, unsigned int bus)
+{
+        struct acpi_pci_root *tmp;
+        
+        list_for_each_entry(tmp, &acpi_pci_roots, node) {
+                if ((tmp->id.segment == (u16) seg) && (tmp->id.bus == (u16) bus))
+                        return tmp->device->handle;
+        }
+        return NULL;            
+}
+
+EXPORT_SYMBOL_GPL(acpi_get_pci_rootbridge_handle);
+
 static acpi_status
 get_root_bridge_busnr_callback(struct acpi_resource *resource, void *data)
 {