1/* Generic barrier definitions, based on MN10300 definitions.
 2 *
 3 * It should be possible to use these on really simple architectures,
 4 * but it serves more as a starting point for new ports.
 5 *
 6 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
 7 * Written by David Howells (dhowells@redhat.com)
 8 *
 9 * This program is free software; you can redistribute it and/or
10 * modify it under the terms of the GNU General Public Licence
11 * as published by the Free Software Foundation; either version
12 * 2 of the Licence, or (at your option) any later version.
13 */
14#ifndef __ASM_GENERIC_BARRIER_H
15#define __ASM_GENERIC_BARRIER_H
16
17#ifndef __ASSEMBLY__
18
19#define nop() asm volatile ("nop")
20
21/*
22 * Force strict CPU ordering.
23 * And yes, this is required on UP too when we're talking
24 * to devices.
25 *
26 * This implementation only contains a compiler barrier.
27 */
28
29#define mb()	asm volatile ("": : :"memory")
30#define rmb()	mb()
31#define wmb()	asm volatile ("": : :"memory")
32
33#ifdef CONFIG_SMP
34#define smp_mb()	mb()
35#define smp_rmb()	rmb()
36#define smp_wmb()	wmb()
37#else
38#define smp_mb()	barrier()
39#define smp_rmb()	barrier()
40#define smp_wmb()	barrier()
41#endif
42
43#define set_mb(var, value)  do { var = value;  mb(); } while (0)
44#define set_wmb(var, value) do { var = value; wmb(); } while (0)
45
46#define read_barrier_depends()		do {} while (0)
47#define smp_read_barrier_depends()	do {} while (0)
48
49#endif /* !__ASSEMBLY__ */
50#endif /* __ASM_GENERIC_BARRIER_H */