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/*
* Copyright 2004-2009 Analog Devices Inc.
* Tony Kou (tonyko@lineo.ca)
*
* Licensed under the GPL-2 or later
*/
#ifndef _BLACKFIN_BARRIER_H
#define _BLACKFIN_BARRIER_H
#include <asm/cache.h>
#define nop() __asm__ __volatile__ ("nop;\n\t" : : )
/*
* Force strict CPU ordering.
*/
#ifdef CONFIG_SMP
#ifdef __ARCH_SYNC_CORE_DCACHE
/* Force Core data cache coherence */
# define mb() do { barrier(); smp_check_barrier(); smp_mark_barrier(); } while (0)
# define rmb() do { barrier(); smp_check_barrier(); } while (0)
# define wmb() do { barrier(); smp_mark_barrier(); } while (0)
/*
* read_barrier_depends - Flush all pending reads that subsequents reads
* depend on.
*
* No data-dependent reads from memory-like regions are ever reordered
* over this barrier. All reads preceding this primitive are guaranteed
* to access memory (but not necessarily other CPUs' caches) before any
* reads following this primitive that depend on the data return by
* any of the preceding reads. This primitive is much lighter weight than
* rmb() on most CPUs, and is never heavier weight than is
* rmb().
*
* These ordering constraints are respected by both the local CPU
* and the compiler.
*
* Ordering is not guaranteed by anything other than these primitives,
* not even by data dependencies. See the documentation for
* memory_barrier() for examples and URLs to more information.
*
* For example, the following code would force ordering (the initial
* value of "a" is zero, "b" is one, and "p" is "&a"):
*
* <programlisting>
* CPU 0 CPU 1
*
* b = 2;
* memory_barrier();
* p = &b; q = p;
* read_barrier_depends();
* d = *q;
* </programlisting>
*
* because the read of "*q" depends on the read of "p" and these
* two reads are separated by a read_barrier_depends(). However,
* the following code, with the same initial values for "a" and "b":
*
* <programlisting>
* CPU 0 CPU 1
*
* a = 2;
* memory_barrier();
* b = 3; y = b;
* read_barrier_depends();
* x = a;
* </programlisting>
*
* does not enforce ordering, since there is no data dependency between
* the read of "a" and the read of "b". Therefore, on some CPUs, such
* as Alpha, "y" could be set to 3 and "x" to 0. Use rmb()
* in cases like this where there are no data dependencies.
*/
# define read_barrier_depends() do { barrier(); smp_check_barrier(); } while (0)
#endif
#endif /* !CONFIG_SMP */
#define __smp_mb__before_atomic() barrier()
#define __smp_mb__after_atomic() barrier()
#include <asm-generic/barrier.h>
#endif /* _BLACKFIN_BARRIER_H */
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