cmpxchg.h

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/*
 * Atomic operations that C can't guarantee us.  Useful for
 * resource counting etc.
 *
 * But use these as seldom as possible since they are slower than
 * regular operations.
 *
 * Copyright (C) 2004-2006 Atmel Corporation
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */
#ifndef __ASM_AVR32_CMPXCHG_H
#define __ASM_AVR32_CMPXCHG_H

#define xchg(ptr,x) \
    ((__typeof__(*(ptr)))__xchg((unsigned long)(x),(ptr),sizeof(*(ptr))))

extern void __xchg_called_with_bad_pointer(void);

static inline unsigned long xchg_u32(u32 val, volatile u32 *m)
{
    u32 ret;

    asm volatile("xchg %[ret], %[m], %[val]"
            : [ret] "=&r"(ret), "=m"(*m)
            : "m"(*m), [m] "r"(m), [val] "r"(val)
            : "memory");
    return ret;
}

static inline unsigned long __xchg(unsigned long x,
                       volatile void *ptr,
                       int size)
{
    switch(size) {
    case 4:
        return xchg_u32(x, ptr);
    default:
        __xchg_called_with_bad_pointer();
        return x;
    }
}

static inline unsigned long __cmpxchg_u32(volatile int *m, unsigned long old,
                      unsigned long new)
{
    __u32 ret;

    asm volatile(
        "1: ssrf    5\n"
        "   ld.w    %[ret], %[m]\n"
        "   cp.w    %[ret], %[old]\n"
        "   brne    2f\n"
        "   stcond  %[m], %[new]\n"
        "   brne    1b\n"
        "2:\n"
        : [ret] "=&r"(ret), [m] "=m"(*m)
        : "m"(m), [old] "ir"(old), [new] "r"(new)
        : "memory", "cc");
    return ret;
}

extern unsigned long __cmpxchg_u64_unsupported_on_32bit_kernels(
        volatile int * m, unsigned long old, unsigned long new);
#define __cmpxchg_u64 __cmpxchg_u64_unsupported_on_32bit_kernels

/* This function doesn't exist, so you'll get a linker error
   if something tries to do an invalid cmpxchg().  */
extern void __cmpxchg_called_with_bad_pointer(void);

#define __HAVE_ARCH_CMPXCHG 1

static inline unsigned long __cmpxchg(volatile void *ptr, unsigned long old,
                      unsigned long new, int size)
{
    switch (size) {
    case 4:
        return __cmpxchg_u32(ptr, old, new);
    case 8:
        return __cmpxchg_u64(ptr, old, new);
    }

    __cmpxchg_called_with_bad_pointer();
    return old;
}

#define cmpxchg(ptr, old, new)                  \
    ((typeof(*(ptr)))__cmpxchg((ptr), (unsigned long)(old), \
                   (unsigned long)(new),    \
                   sizeof(*(ptr))))

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

static inline unsigned long __cmpxchg_local(volatile void *ptr,
                      unsigned long old,
                      unsigned long new, int size)
{
    switch (size) {
    case 4:
        return __cmpxchg_u32(ptr, old, new);
    default:
        return __cmpxchg_local_generic(ptr, old, new, size);
    }

    return old;
}

#define cmpxchg_local(ptr, old, new)                    \
    ((typeof(*(ptr)))__cmpxchg_local((ptr), (unsigned long)(old),   \
                   (unsigned long)(new),        \
                   sizeof(*(ptr))))

#define cmpxchg64_local(ptr, o, n) __cmpxchg64_local_generic((ptr), (o), (n))

#endif /* __ASM_AVR32_CMPXCHG_H */