add disk device class

drivers/block/genhd.c

@@ -209,6 +209,10 @@ extern int soc_probe(void);
 extern int atmdev_init(void);
 extern int cpqarray_init(void);
 
+struct device_class disk_devclass = {
+	.name		= "disk",
+};
+
 int __init device_init(void)
 {
 	int i;
@@ -226,7 +230,11 @@ int __init device_init(void)
 #ifdef CONFIG_ATM
 	(void) atmdev_init();
 #endif
+
+	devclass_register(&disk_devclass);
 	return 0;
 }
 
 __initcall(device_init);
+
+EXPORT_SYMBOL(disk_devclass);

include/linux/genhd.h

@@ -109,6 +109,8 @@ static inline void set_capacity(struct gendisk *disk, sector_t size)
 	disk->capacity = size;
 }
 
+extern struct device_class disk_devclass;
+
 #endif  /*  __KERNEL__  */
 
 #ifdef CONFIG_SOLARIS_X86_PARTITION