linux/const.h: import from kernel

Combine the uapi/linux/const.h header into the kernel linux/const.h. The
next commit will use the _AC macro this header instead of the common.h
definition.

Based on Linux kernel version 4.19.

Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Reviewed-by: Tom Rini <trini@konsulko.com>
Signed-off-by: Stefan Roese <sr@denx.de>

include/linux/const.h

@@ -0,0 +1,34 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+#ifndef _LINUX_CONST_H
+#define _LINUX_CONST_H
+
+/* const.h: Macros for dealing with constants.  */
+
+/* Some constant macros are used in both assembler and
+ * 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
+
+#define _UL(x)		(_AC(x, UL))
+#define _ULL(x)		(_AC(x, ULL))
+
+#define _BITUL(x)	(_UL(1) << (x))
+#define _BITULL(x)	(_ULL(1) << (x))
+
+#define UL(x)		(_UL(x))
+#define ULL(x)		(_ULL(x))
+
+#endif /* _LINUX_CONST_H */