mutex.h

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/*
 * Optimised mutex implementation of include/asm-generic/mutex-dec.h algorithm
 */
#ifndef _ASM_POWERPC_MUTEX_H
#define _ASM_POWERPC_MUTEX_H

static inline int __mutex_cmpxchg_lock(atomic_t *v, int old, int new)
{
    int t;

    __asm__ __volatile__ (
"1: lwarx   %0,0,%1     # mutex trylock\n\
    cmpw    0,%0,%2\n\
    bne-    2f\n"
    PPC405_ERR77(0,%1)
"   stwcx.  %3,0,%1\n\
    bne-    1b"
    PPC_ACQUIRE_BARRIER
    "\n\
2:"
    : "=&r" (t)
    : "r" (&v->counter), "r" (old), "r" (new)
    : "cc", "memory");

    return t;
}

static inline int __mutex_dec_return_lock(atomic_t *v)
{
    int t;

    __asm__ __volatile__(
"1: lwarx   %0,0,%1     # mutex lock\n\
    addic   %0,%0,-1\n"
    PPC405_ERR77(0,%1)
"   stwcx.  %0,0,%1\n\
    bne-    1b"
    PPC_ACQUIRE_BARRIER
    : "=&r" (t)
    : "r" (&v->counter)
    : "cc", "memory");

    return t;
}

static inline int __mutex_inc_return_unlock(atomic_t *v)
{
    int t;

    __asm__ __volatile__(
    PPC_RELEASE_BARRIER
"1: lwarx   %0,0,%1     # mutex unlock\n\
    addic   %0,%0,1\n"
    PPC405_ERR77(0,%1)
"   stwcx.  %0,0,%1 \n\
    bne-    1b"
    : "=&r" (t)
    : "r" (&v->counter)
    : "cc", "memory");

    return t;
}

static inline void
__mutex_fastpath_lock(atomic_t *count, void (*fail_fn)(atomic_t *))
{
    if (unlikely(__mutex_dec_return_lock(count) < 0))
        fail_fn(count);
}

static inline int
__mutex_fastpath_lock_retval(atomic_t *count, int (*fail_fn)(atomic_t *))
{
    if (unlikely(__mutex_dec_return_lock(count) < 0))
        return fail_fn(count);
    return 0;
}

static inline void
__mutex_fastpath_unlock(atomic_t *count, void (*fail_fn)(atomic_t *))
{
    if (unlikely(__mutex_inc_return_unlock(count) <= 0))
        fail_fn(count);
}

#define __mutex_slowpath_needs_to_unlock()      1

static inline int
__mutex_fastpath_trylock(atomic_t *count, int (*fail_fn)(atomic_t *))
{
    if (likely(__mutex_cmpxchg_lock(count, 1, 0) == 1))
        return 1;
    return 0;
}

#endif