atomic.h

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#ifndef __ASM_SH_ATOMIC_H
#define __ASM_SH_ATOMIC_H

/*
 * Atomic operations that C can't guarantee us.  Useful for
 * resource counting etc..
 *
 */

#include <linux/compiler.h>
#include <linux/types.h>
#include <asm/cmpxchg.h>

#define ATOMIC_INIT(i)  { (i) }

#define atomic_read(v)      (*(volatile int *)&(v)->counter)
#define atomic_set(v,i)     ((v)->counter = (i))

#if defined(CONFIG_GUSA_RB)
#include <asm/atomic-grb.h>
#elif defined(CONFIG_CPU_SH4A)
#include <asm/atomic-llsc.h>
#else
#include <asm/atomic-irq.h>
#endif

#define atomic_add_negative(a, v)   (atomic_add_return((a), (v)) < 0)
#define atomic_dec_return(v)        atomic_sub_return(1, (v))
#define atomic_inc_return(v)        atomic_add_return(1, (v))
#define atomic_inc_and_test(v)      (atomic_inc_return(v) == 0)
#define atomic_sub_and_test(i,v)    (atomic_sub_return((i), (v)) == 0)
#define atomic_dec_and_test(v)      (atomic_sub_return(1, (v)) == 0)

#define atomic_inc(v)           atomic_add(1, (v))
#define atomic_dec(v)           atomic_sub(1, (v))

#define atomic_xchg(v, new)     (xchg(&((v)->counter), new))
#define atomic_cmpxchg(v, o, n)     (cmpxchg(&((v)->counter), (o), (n)))

static inline int __atomic_add_unless(atomic_t *v, int a, int u)
{
    int c, old;
    c = atomic_read(v);
    for (;;) {
        if (unlikely(c == (u)))
            break;
        old = atomic_cmpxchg((v), c, c + (a));
        if (likely(old == c))
            break;
        c = old;
    }

    return c;
}

#define smp_mb__before_atomic_dec() smp_mb()
#define smp_mb__after_atomic_dec()  smp_mb()
#define smp_mb__before_atomic_inc() smp_mb()
#define smp_mb__after_atomic_inc()  smp_mb()

#endif /* __ASM_SH_ATOMIC_H */