diff --git a/include/linux/const.h b/include/linux/const.h
index 07b300bfe34b..c22c707c455d 100644
--- a/include/linux/const.h
+++ b/include/linux/const.h
@@ -7,13 +7,18 @@
  * C code.  Therefore we cannot annotate them always with
  * 'UL' and other type specifiers unilaterally.  We
  * use the following macros to deal with this.
+ *
+ * Similarly, _AT() will cast an expression with a type in C, but
+ * leave it unchanged in asm.
  */
 
 #ifdef __ASSEMBLY__
 #define _AC(X,Y)	X
+#define _AT(T,X)	X
 #else
 #define __AC(X,Y)	(X##Y)
 #define _AC(X,Y)	__AC(X,Y)
+#define _AT(T,X)	((T)(X))
 #endif
 
 #endif /* !(_LINUX_CONST_H) */