cmpxchg.h

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/*
 * Copyright 2004-2011 Analog Devices Inc.
 *
 * Licensed under the GPL-2 or later.
 */

#ifndef __ARCH_BLACKFIN_CMPXCHG__
#define __ARCH_BLACKFIN_CMPXCHG__

#ifdef CONFIG_SMP

#include <linux/linkage.h>

asmlinkage unsigned long __raw_xchg_1_asm(volatile void *ptr, unsigned long value);
asmlinkage unsigned long __raw_xchg_2_asm(volatile void *ptr, unsigned long value);
asmlinkage unsigned long __raw_xchg_4_asm(volatile void *ptr, unsigned long value);
asmlinkage unsigned long __raw_cmpxchg_1_asm(volatile void *ptr,
                    unsigned long new, unsigned long old);
asmlinkage unsigned long __raw_cmpxchg_2_asm(volatile void *ptr,
                    unsigned long new, unsigned long old);
asmlinkage unsigned long __raw_cmpxchg_4_asm(volatile void *ptr,
                    unsigned long new, unsigned long old);

static inline unsigned long __xchg(unsigned long x, volatile void *ptr,
                   int size)
{
    unsigned long tmp;

    switch (size) {
    case 1:
        tmp = __raw_xchg_1_asm(ptr, x);
        break;
    case 2:
        tmp = __raw_xchg_2_asm(ptr, x);
        break;
    case 4:
        tmp = __raw_xchg_4_asm(ptr, x);
        break;
    }

    return tmp;
}

/*
 * Atomic compare and exchange.  Compare OLD with MEM, if identical,
 * store NEW in MEM.  Return the initial value in MEM.  Success is
 * indicated by comparing RETURN with OLD.
 */
static inline unsigned long __cmpxchg(volatile void *ptr, unsigned long old,
                      unsigned long new, int size)
{
    unsigned long tmp;

    switch (size) {
    case 1:
        tmp = __raw_cmpxchg_1_asm(ptr, new, old);
        break;
    case 2:
        tmp = __raw_cmpxchg_2_asm(ptr, new, old);
        break;
    case 4:
        tmp = __raw_cmpxchg_4_asm(ptr, new, old);
        break;
    }

    return tmp;
}
#define cmpxchg(ptr, o, n) \
    ((__typeof__(*(ptr)))__cmpxchg((ptr), (unsigned long)(o), \
        (unsigned long)(n), sizeof(*(ptr))))

#else /* !CONFIG_SMP */

#include <mach/blackfin.h>
#include <asm/irqflags.h>

struct __xchg_dummy {
    unsigned long a[100];
};
#define __xg(x) ((volatile struct __xchg_dummy *)(x))

static inline unsigned long __xchg(unsigned long x, volatile void *ptr,
                   int size)
{
    unsigned long tmp = 0;
    unsigned long flags;

    flags = hard_local_irq_save();

    switch (size) {
    case 1:
        __asm__ __volatile__
            ("%0 = b%2 (z);\n\t"
             "b%2 = %1;\n\t"
             : "=&d" (tmp) : "d" (x), "m" (*__xg(ptr)) : "memory");
        break;
    case 2:
        __asm__ __volatile__
            ("%0 = w%2 (z);\n\t"
             "w%2 = %1;\n\t"
             : "=&d" (tmp) : "d" (x), "m" (*__xg(ptr)) : "memory");
        break;
    case 4:
        __asm__ __volatile__
            ("%0 = %2;\n\t"
             "%2 = %1;\n\t"
             : "=&d" (tmp) : "d" (x), "m" (*__xg(ptr)) : "memory");
        break;
    }
    hard_local_irq_restore(flags);
    return tmp;
}

#include <asm-generic/cmpxchg-local.h>

/*
 * cmpxchg_local and cmpxchg64_local are atomic wrt current CPU. Always make
 * them available.
 */
#define cmpxchg_local(ptr, o, n)                           \
    ((__typeof__(*(ptr)))__cmpxchg_local_generic((ptr), (unsigned long)(o),\
            (unsigned long)(n), sizeof(*(ptr))))
#define cmpxchg64_local(ptr, o, n) __cmpxchg64_local_generic((ptr), (o), (n))

#define cmpxchg(ptr, o, n)  cmpxchg_local((ptr), (o), (n))
#define cmpxchg64(ptr, o, n)    cmpxchg64_local((ptr), (o), (n))

#endif /* !CONFIG_SMP */

#define xchg(ptr, x) ((__typeof__(*(ptr)))__xchg((unsigned long)(x), (ptr), sizeof(*(ptr))))
#define tas(ptr) ((void)xchg((ptr), 1))

#endif /* __ARCH_BLACKFIN_CMPXCHG__ */