PCI/ACPI: Use acpi_pci_root info rather than looking it up again

This patch changes the function signature of walk_root_bridge().

We can omit _STA, _SEG, and _BBN evaluation by passing not acpi_handle
but acpi_pci_root.  Now that acpi_pci_slot_add() which is the only
caller of walk_root_bridge() gets acpi_pci_root structure, changing
signature of walk_root_bridge() is reasonable.

[bhelgaas: changelog]
Signed-off-by: Taku Izumi <izumi.taku@jp.fujitsu.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

drivers/acpi/pci_slot.c

@@ -233,45 +233,20 @@ out:
 
 /*
  * walk_root_bridge - generic root bridge walker
- * @handle: points to an acpi_pci_root
+ * @root: poiner of an acpi_pci_root
  * @user_function: user callback for slot objects
  *
  * Call user_function for all objects underneath this root bridge.
  * Walk p2p bridges underneath us and call user_function on those too.
  */
 static int
-walk_root_bridge(acpi_handle handle, acpi_walk_callback user_function)
+walk_root_bridge(struct acpi_pci_root *root, acpi_walk_callback user_function)
 {
-	int seg, bus;
-	unsigned long long tmp;
 	acpi_status status;
-	acpi_handle dummy_handle;
-	struct pci_bus *pci_bus;
+	acpi_handle handle = root->device->handle;
+	struct pci_bus *pci_bus = root->bus;
 	struct callback_args context;
 
-	/* If the bridge doesn't have _STA, we assume it is always there */
-	status = acpi_get_handle(handle, "_STA", &dummy_handle);
-	if (ACPI_SUCCESS(status)) {
-		status = acpi_evaluate_integer(handle, "_STA", NULL, &tmp);
-		if (ACPI_FAILURE(status)) {
-			info("%s: _STA evaluation failure\n", __func__);
-			return 0;
-		}
-		if ((tmp & ACPI_STA_DEVICE_FUNCTIONING) == 0)
-			/* don't register this object */
-			return 0;
-	}
-
-	status = acpi_evaluate_integer(handle, "_SEG", NULL, &tmp);
-	seg = ACPI_SUCCESS(status) ? tmp : 0;
-
-	status = acpi_evaluate_integer(handle, "_BBN", NULL, &tmp);
-	bus = ACPI_SUCCESS(status) ? tmp : 0;
-
-	pci_bus = pci_find_bus(seg, bus);
-	if (!pci_bus)
-		return 0;
-
 	context.pci_bus = pci_bus;
 	context.user_function = user_function;
 	context.root_handle = handle;
@@ -299,7 +274,7 @@ acpi_pci_slot_add(struct acpi_pci_root *root)
 {
 	acpi_status status;
 
-	status = walk_root_bridge(root->device->handle, register_slot);
+	status = walk_root_bridge(root, register_slot);
 	if (ACPI_FAILURE(status))
 		err("%s: register_slot failure - %d\n", __func__, status);