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>

2 files changed, 13 insertions, 123 deletions

diff --git a/drivers/acpi/glue.c b/drivers/acpi/glue.c
index 8a0324b43e53..7b6c9ff9bebe 100644
--- a/drivers/acpi/glue.c
+++ b/drivers/acpi/glue.c
@@ -86,129 +86,6 @@ static int acpi_find_bridge_device(struct device *dev, acpi_handle * handle)
         return ret;
 }
 
-/* Get PCI root bridge's handle from its segment and bus number */
-struct acpi_find_pci_root {
-        unsigned int seg;
-        unsigned int bus;
-        acpi_handle handle;
-};
-
-static acpi_status
-do_root_bridge_busnr_callback(struct acpi_resource *resource, void *data)
-{
-        unsigned long *busnr = data;
-        struct acpi_resource_address64 address;
-
-        if (resource->type != ACPI_RESOURCE_TYPE_ADDRESS16 &&
-            resource->type != ACPI_RESOURCE_TYPE_ADDRESS32 &&
-            resource->type != ACPI_RESOURCE_TYPE_ADDRESS64)
-                return AE_OK;
-
-        acpi_resource_to_address64(resource, &address);
-        if ((address.address_length > 0) &&
-            (address.resource_type == ACPI_BUS_NUMBER_RANGE))
-                *busnr = address.minimum;
-
-        return AE_OK;
-}
-
-static int get_root_bridge_busnr(acpi_handle handle)
-{
-        acpi_status status;
-        unsigned long bus, bbn;
-        struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
-
-        acpi_get_name(handle, ACPI_FULL_PATHNAME, &buffer);
-
-        status = acpi_evaluate_integer(handle, METHOD_NAME__BBN, NULL,
-                                       &bbn);
-        if (status == AE_NOT_FOUND) {
-                /* Assume bus = 0 */
-                printk(KERN_INFO PREFIX
-                       "Assume root bridge [%s] bus is 0\n",
-                       (char *)buffer.pointer);
-                status = AE_OK;
-                bbn = 0;
-        }
-        if (ACPI_FAILURE(status)) {
-                bbn = -ENODEV;
-                goto exit;
-        }
-        if (bbn > 0)
-                goto exit;
-
-        /* _BBN in some systems return 0 for all root bridges */
-        bus = -1;
-        status = acpi_walk_resources(handle, METHOD_NAME__CRS,
-                                     do_root_bridge_busnr_callback, &bus);
-        /* If _CRS failed, we just use _BBN */
-        if (ACPI_FAILURE(status) || (bus == -1))
-                goto exit;
-        /* We select _CRS */
-        if (bbn != bus) {
-                printk(KERN_INFO PREFIX
-                       "_BBN and _CRS returns different value for %s. Select _CRS\n",
-                       (char *)buffer.pointer);
-                bbn = bus;
-        }
-      exit:
-        kfree(buffer.pointer);
-        return (int)bbn;
-}
-
-static acpi_status
-find_pci_rootbridge(acpi_handle handle, u32 lvl, void *context, void **rv)
-{
-        struct acpi_find_pci_root *find = (struct acpi_find_pci_root *)context;
-        unsigned long seg, bus;
-        acpi_status status;
-        int tmp;
-        struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
-
-        acpi_get_name(handle, ACPI_FULL_PATHNAME, &buffer);
-
-        status = acpi_evaluate_integer(handle, METHOD_NAME__SEG, NULL, &seg);
-        if (status == AE_NOT_FOUND) {
-                /* Assume seg = 0 */
-                status = AE_OK;
-                seg = 0;
-        }
-        if (ACPI_FAILURE(status)) {
-                status = AE_CTRL_DEPTH;
-                goto exit;
-        }
-
-        tmp = get_root_bridge_busnr(handle);
-        if (tmp < 0) {
-                printk(KERN_ERR PREFIX
-                       "Find root bridge failed for %s\n",
-                       (char *)buffer.pointer);
-                status = AE_CTRL_DEPTH;
-                goto exit;
-        }
-        bus = tmp;
-
-        if (seg == find->seg && bus == find->bus)
-        {
-                find->handle = handle;
-                status = AE_CTRL_TERMINATE;
-        }
-        else
-                status = AE_OK;
-      exit:
-        kfree(buffer.pointer);
-        return status;
-}
-
-acpi_handle acpi_get_pci_rootbridge_handle(unsigned int seg, unsigned int bus)
-{
-        struct acpi_find_pci_root find = { seg, bus, NULL };
-
-        acpi_get_devices(PCI_ROOT_HID_STRING, find_pci_rootbridge, &find, NULL);
-        return find.handle;
-}
-EXPORT_SYMBOL_GPL(acpi_get_pci_rootbridge_handle);
-
 /* Get device's handler per its address under its parent */
 struct acpi_find_child {
         acpi_handle handle;
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)
 {