/*
   * Generic barrier definitions, originally based on MN10300 definitions.
   *
   * It should be possible to use these on really simple architectures,
   * but it serves more as a starting point for new ports.
   *
   * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
   * Written by David Howells (dhowells@redhat.com)
   *
   * This program is free software; you can redistribute it and/or
   * modify it under the terms of the GNU General Public Licence
   * as published by the Free Software Foundation; either version
   * 2 of the Licence, or (at your option) any later version.
   */
  #ifndef __ASM_GENERIC_BARRIER_H
  #define __ASM_GENERIC_BARRIER_H
  
  #ifndef __ASSEMBLY__
  
  #include <linux/compiler.h>
  
  #ifndef nop
  #define nop()	asm volatile ("nop")
  #endif
  
  /*
   * Force strict CPU ordering. And yes, this is required on UP too when we're
   * talking to devices.
   *
   * Fall back to compiler barriers if nothing better is provided.
   */
  
  #ifndef mb
  #define mb()	barrier()
  #endif
  
  #ifndef rmb
  #define rmb()	mb()
  #endif
  
  #ifndef wmb
  #define wmb()	mb()
  #endif
  
  #ifndef read_barrier_depends
  #define read_barrier_depends()		do { } while (0)
  #endif
  
  #ifdef CONFIG_SMP
  #define smp_mb()	mb()
  #define smp_rmb()	rmb()
  #define smp_wmb()	wmb()
  #define smp_read_barrier_depends()	read_barrier_depends()
  #else
  #define smp_mb()	barrier()
  #define smp_rmb()	barrier()
  #define smp_wmb()	barrier()
  #define smp_read_barrier_depends()	do { } while (0)
  #endif
  
  #ifndef set_mb
  #define set_mb(var, value)  do { (var) = (value); mb(); } while (0)
  #endif
  
  #define smp_store_release(p, v)						\
  do {									\
  	compiletime_assert_atomic_type(*p);				\
  	smp_mb();							\
  	ACCESS_ONCE(*p) = (v);						\
  } while (0)
  
  #define smp_load_acquire(p)						\
  ({									\
  	typeof(*p) ___p1 = ACCESS_ONCE(*p);				\
  	compiletime_assert_atomic_type(*p);				\
  	smp_mb();							\
  	___p1;								\
  })
  
  #endif /* !__ASSEMBLY__ */
  #endif /* __ASM_GENERIC_BARRIER_H */