[PATCH 20/140] ACPI: Optimize acpi_get_pci_rootbridge_handle() to boot faster

Len Brown
2007-02-07T18:53:23Z

From: Justin Chen <justin.chen@hp.com>

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>
---
drivers/acpi/glue.c | 123 -----------------------------------------------
drivers/acpi/pci_root.c | 13 +++++
2 files changed, 13 insertions(+), 123 deletions(-)

diff --git a/drivers/acpi/glue.c b/drivers/acpi/glue.c
index 8a0324b..7b6c9ff 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 a860efa..1f06229 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)
{
--
1.5.0.rc3.39.gec804