[SCSI] add wrapper to access and set scsi_bus_type in struct acpi_bus_type

For being able to bind ata devices against acpi devices, scsi_bus_type
needs to be set as bus in struct acpi_bus_type. So add wrapper to
scsi_lib to accomplish that.
Signed-off-by: Holger Macht <holger@homac.de>
Signed-off-by: Lin Ming <ming.m.lin@intel.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

drivers/scsi/scsi_lib.c

@@ -68,6 +68,23 @@ static struct scsi_host_sg_pool scsi_sg_pools[] = {
 
 struct kmem_cache *scsi_sdb_cache;
 
+#ifdef CONFIG_ACPI
+#include <acpi/acpi_bus.h>
+
+int scsi_register_acpi_bus_type(struct acpi_bus_type *bus)
+{
+        bus->bus = &scsi_bus_type;
+        return register_acpi_bus_type(bus);
+}
+EXPORT_SYMBOL_GPL(scsi_register_acpi_bus_type);
+
+void scsi_unregister_acpi_bus_type(struct acpi_bus_type *bus)
+{
+	unregister_acpi_bus_type(bus);
+}
+EXPORT_SYMBOL_GPL(scsi_unregister_acpi_bus_type);
+#endif
+
 /*
  * When to reinvoke queueing after a resource shortage. It's 3 msecs to
  * not change behaviour from the previous unplug mechanism, experimentation

include/scsi/scsi.h

@@ -214,6 +214,16 @@ scsi_command_size(const unsigned char *cmnd)
 		scsi_varlen_cdb_length(cmnd) : COMMAND_SIZE(cmnd[0]);
 }
 
+#ifdef CONFIG_ACPI
+struct acpi_bus_type;
+
+extern int
+scsi_register_acpi_bus_type(struct acpi_bus_type *bus);
+
+extern void
+scsi_unregister_acpi_bus_type(struct acpi_bus_type *bus);
+#endif
+
 /*
  *  SCSI Architecture Model (SAM) Status codes. Taken from SAM-3 draft
  *  T10/1561-D Revision 4 Draft dated 7th November 2002.