[AGPGART] add agp_find_bridge function

From: Michael Werner <werner@mrcoffee.engr.sgi.com>

This patch gives non-generic platforms a method for using platform specific
agp_find_bridge functions.
Signed-off-by: Mike Werner <werner@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Dave Jones <davej@redhat.com>

drivers/char/agp/backend.c

@@ -50,6 +50,9 @@ static struct agp_version agp_current_version =
 	.minor = AGPGART_VERSION_MINOR,
 };
 
+struct agp_bridge_data *(*agp_find_bridge)(struct pci_dev *) =
+	&agp_generic_find_bridge;
+
 struct agp_bridge_data *agp_bridge;
 LIST_HEAD(agp_bridges);
 EXPORT_SYMBOL(agp_bridge);
@@ -63,7 +66,7 @@ struct agp_bridge_data *agp_backend_acquire(struct pci_dev *pdev)
 {
 	struct agp_bridge_data *bridge;
 
-	bridge = agp_generic_find_bridge(pdev);
+	bridge = agp_find_bridge(pdev);
 
 	if (!bridge)
 		return NULL;

include/linux/agp_backend.h

@@ -94,6 +94,8 @@ struct agp_memory {
 extern struct agp_bridge_data *agp_bridge;
 extern struct list_head agp_bridges;
 
+extern struct agp_bridge_data *(*agp_find_bridge)(struct pci_dev *);
+
 extern void agp_free_memory(struct agp_memory *);
 extern struct agp_memory *agp_allocate_memory(struct agp_bridge_data *, size_t, u32);
 extern int agp_copy_info(struct agp_bridge_data *, struct agp_kern_info *);