-/*
- * 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 thiswhere there are no data dependencies.
- */
-
-#define read_barrier_depends() do { } while(0)
-
-#ifdef CONFIG_CPU_HAS_SYNC
-#define __sync() \
- __asm__ __volatile__( \
- ".set push\n\t" \
- ".set noreorder\n\t" \
- ".set mips2\n\t" \
- "sync\n\t" \
- ".set pop" \
- : /* no output */ \
- : /* no input */ \
- : "memory")
-#else
-#define __sync() do { } while(0)
-#endif
-
-#define __fast_iob() \
- __asm__ __volatile__( \
- ".set push\n\t" \
- ".set noreorder\n\t" \
- "lw $0,%0\n\t" \
- "nop\n\t" \
- ".set pop" \
- : /* no output */ \
- : "m" (*(int *)CKSEG1) \
- : "memory")
-
-#define fast_wmb() __sync()
-#define fast_rmb() __sync()
-#define fast_mb() __sync()
-#define fast_iob() \
- do { \
- __sync(); \
- __fast_iob(); \
- } while (0)
-
-#ifdef CONFIG_CPU_HAS_WB
-
-#include <asm/wbflush.h>
-
-#define wmb() fast_wmb()
-#define rmb() fast_rmb()
-#define mb() wbflush()
-#define iob() wbflush()
-
-#else /* !CONFIG_CPU_HAS_WB */
-
-#define wmb() fast_wmb()
-#define rmb() fast_rmb()
-#define mb() fast_mb()
-#define iob() fast_iob()
-
-#endif /* !CONFIG_CPU_HAS_WB */
-
-#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
-
-#define set_mb(var, value) \
-do { var = value; mb(); } while (0)
-
-#define set_wmb(var, value) \
-do { var = value; wmb(); } while (0)