oro_atomic.h

/***************************************************************************
  tag: FMTC  Tue Mar 11 21:49:19 CET 2008  oro_atomic.h

                        oro_atomic.h -  description
                           -------------------
    begin                : Tue March 11 2008
    copyright            : (C) 2008 FMTC
    email                : peter.soetens@fmtc.be

 ***************************************************************************
 *   This library is free software; you can redistribute it and/or         *
 *   modify it under the terms of the GNU General Public                   *
 *   License as published by the Free Software Foundation;                 *
 *   version 2 of the License.                                             *
 *                                                                         *
 *   As a special exception, you may use this file as part of a free       *
 *   software library without restriction.  Specifically, if other files   *
 *   instantiate templates or use macros or inline functions from this     *
 *   file, or you compile this file and link it with other files to        *
 *   produce an executable, this file does not by itself cause the         *
 *   resulting executable to be covered by the GNU General Public          *
 *   License.  This exception does not however invalidate any other        *
 *   reasons why the executable file might be covered by the GNU General   *
 *   Public License.                                                       *
 *                                                                         *
 *   This library is distributed in the hope that it will be useful,       *
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU     *
 *   Lesser General Public License for more details.                       *
 *                                                                         *
 *   You should have received a copy of the GNU General Public             *
 *   License along with this library; if not, write to the Free Software   *
 *   Foundation, Inc., 59 Temple Place,                                    *
 *   Suite 330, Boston, MA  02111-1307  USA                                *
 *                                                                         *
 ***************************************************************************/


#ifndef __ARCH_powerpc_ORO_ATOMIC__
#define __ARCH_powerpc_ORO_ATOMIC__

/* Klaas Gadeyne, copied the 32 bit part from
 * /usr/src/linux-2.6.16/include/asm-powerpc/atomic.h
 * /usr/src/linux-2.6.16/include/asm-powerpc/asm-compat.h
 * /usr/src/linux-2.6.16/include/asm-powerpc/synch.h
 * So will currently only work for 32 bit ppc
 */

// ==================================================
// asm/synch.h
#ifdef _cplusplus
extern "C"
{
#endif // _cplusplus

#ifdef __SUBARCH_HAS_LWSYNC
#    define LWSYNC  lwsync
#else
#    define LWSYNC  sync
#endif

#define ISYNC_ON_SMP
#define LWSYNC_ON_SMP

static inline void eieio(void)
{
    __asm__ __volatile__ ("eieio" : : : "memory");
}

static inline void isync(void)
{
    __asm__ __volatile__ ("isync" : : : "memory");
}

// ==================================================
// asm/asm-compat.h

#ifdef __ASSEMBLY__
#  define stringify_in_c(...)   __VA_ARGS__
#  define ASM_CONST(x)          x
#else
/* This version of stringify will deal with commas... */
#  define __stringify_in_c(...) #__VA_ARGS__
#  define stringify_in_c(...)   __stringify_in_c(__VA_ARGS__) " "
#  define __ASM_CONST(x)        x##UL
#  define ASM_CONST(x)          __ASM_CONST(x)
#endif

/* operations for longs and pointers */
#define PPC_LL          stringify_in_c(lwz)
#define PPC_STL         stringify_in_c(stw)
#define PPC_LCMPI       stringify_in_c(cmpwi)
#define PPC_LONG        stringify_in_c(.long)
#define PPC_TLNEI       stringify_in_c(twnei)
#define PPC_LLARX       stringify_in_c(lwarx)
#define PPC_STLCX       stringify_in_c(stwcx.)
#define PPC_CNTLZL      stringify_in_c(cntlzw)

#ifdef CONFIG_IBM405_ERR77
/* Erratum #77 on the 405 means we need a sync or dcbt before every
 * stwcx.  The old ATOMIC_SYNC_FIX covered some but not all of this.
 */
#define PPC405_ERR77(ra,rb)     stringify_in_c(dcbt     ra, rb;)
#define PPC405_ERR77_SYNC       stringify_in_c(sync;)
#else
#define PPC405_ERR77(ra,rb)
#define PPC405_ERR77_SYNC
#endif

// ==================================================
// asm/atomic.h

/*
 * PowerPC atomic operations
 */

typedef struct { volatile int counter; } oro_atomic_t;

#define ORO_ATOMIC_INIT(i)      { (i) }
#define ORO_ATOMIC_SETUP    oro_atomic_set
#define ORO_ATOMIC_CLEANUP(v)   

#define oro_atomic_read(v)      ((v)->counter)
#define oro_atomic_set(v,i)     (((v)->counter) = (i))

static __inline__ void oro_atomic_add(int a, oro_atomic_t *v)
{
    int t;

    __asm__ __volatile__(
"1: lwarx   %0,0,%3     # oro_atomic_add\n\
    add %0,%2,%0\n"
    PPC405_ERR77(0,%3)
"   stwcx.  %0,0,%3 \n\
    bne-    1b"
    : "=&r" (t), "=m" (v->counter)
    : "r" (a), "r" (&v->counter), "m" (v->counter)
    : "cc");
}

static __inline__ int oro_atomic_add_return(int a, oro_atomic_t *v)
{
    int t;

    __asm__ __volatile__(
    LWSYNC_ON_SMP
"1: lwarx   %0,0,%2     # oro_atomic_add_return\n\
    add %0,%1,%0\n"
    PPC405_ERR77(0,%2)
"   stwcx.  %0,0,%2 \n\
    bne-    1b"
    ISYNC_ON_SMP
    : "=&r" (t)
    : "r" (a), "r" (&v->counter)
    : "cc", "memory");

    return t;
}

#define oro_atomic_add_negative(a, v)   (oro_atomic_add_return((a), (v)) < 0)

static __inline__ void oro_atomic_sub(int a, oro_atomic_t *v)
{
    int t;

    __asm__ __volatile__(
"1: lwarx   %0,0,%3     # oro_atomic_sub\n\
    subf    %0,%2,%0\n"
    PPC405_ERR77(0,%3)
"   stwcx.  %0,0,%3 \n\
    bne-    1b"
    : "=&r" (t), "=m" (v->counter)
    : "r" (a), "r" (&v->counter), "m" (v->counter)
    : "cc");
}

static __inline__ int oro_atomic_sub_return(int a, oro_atomic_t *v)
{
    int t;

    __asm__ __volatile__(
    LWSYNC_ON_SMP
"1: lwarx   %0,0,%2     # oro_atomic_sub_return\n\
    subf    %0,%1,%0\n"
    PPC405_ERR77(0,%2)
"   stwcx.  %0,0,%2 \n\
    bne-    1b"
    ISYNC_ON_SMP
    : "=&r" (t)
    : "r" (a), "r" (&v->counter)
    : "cc", "memory");

    return t;
}

static __inline__ void oro_atomic_inc(oro_atomic_t *v)
{
    int t;

    __asm__ __volatile__(
"1: lwarx   %0,0,%2     # oro_atomic_inc\n\
    addic   %0,%0,1\n"
    PPC405_ERR77(0,%2)
"   stwcx.  %0,0,%2 \n\
    bne-    1b"
    : "=&r" (t), "=m" (v->counter)
    : "r" (&v->counter), "m" (v->counter)
    : "cc");
}

static __inline__ int oro_atomic_inc_return(oro_atomic_t *v)
{
    int t;

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

    return t;
}

/*
 * oro_atomic_inc_and_test - increment and test
 * @v: pointer of type oro_atomic_t
 *
 * Atomically increments @v by 1
 * and returns true if the result is zero, or false for all
 * other cases.
 */
#define oro_atomic_inc_and_test(v) (oro_atomic_inc_return(v) == 0)

static __inline__ void oro_atomic_dec(oro_atomic_t *v)
{
    int t;

    __asm__ __volatile__(
"1: lwarx   %0,0,%2     # oro_atomic_dec\n\
    addic   %0,%0,-1\n"
    PPC405_ERR77(0,%2)\
"   stwcx.  %0,0,%2\n\
    bne-    1b"
    : "=&r" (t), "=m" (v->counter)
    : "r" (&v->counter), "m" (v->counter)
    : "cc");
}

static __inline__ int oro_atomic_dec_return(oro_atomic_t *v)
{
    int t;

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

    return t;
}

#define oro_atomic_oro_cmpxchg(v, o, n) ((int)oro_cmpxchg(&((v)->counter), (o), (n)))
#define oro_atomic_xchg(v, new) (xchg(&((v)->counter), new))

#define oro_atomic_add_unless(v, a, u)          \
({                          \
    int c, old;                 \
    c = oro_atomic_read(v);             \
    for (;;) {                  \
        if (unlikely(c == (u)))         \
            break;              \
        old = oro_atomic_oro_cmpxchg((v), c, c + (a));  \
        if (likely(old == c))           \
            break;              \
        c = old;                \
    }                       \
    c != (u);                   \
})
#define oro_atomic_inc_not_zero(v) oro_atomic_add_unless((v), 1, 0)

#define oro_atomic_sub_and_test(a, v)   (oro_atomic_sub_return((a), (v)) == 0)
#define oro_atomic_dec_and_test(v)      (oro_atomic_dec_return((v)) == 0)

/*
 * Atomically test *v and decrement if it is greater than 0.
 * The function returns the old value of *v minus 1.
 */
static __inline__ int oro_atomic_dec_if_positive(oro_atomic_t *v)
{
    int t;

    __asm__ __volatile__(
    LWSYNC_ON_SMP
"1: lwarx   %0,0,%1     # oro_atomic_dec_if_positive\n\
    addic.  %0,%0,-1\n\
    blt-    2f\n"
    PPC405_ERR77(0,%1)
"   stwcx.  %0,0,%1\n\
    bne-    1b"
    ISYNC_ON_SMP
    "\n\
2:" : "=&r" (t)
    : "r" (&v->counter)
    : "cc", "memory");

    return t;
}

#define smp_mb__before_oro_atomic_dec()     smp_mb()
#define smp_mb__after_oro_atomic_dec()      smp_mb()
#define smp_mb__before_oro_atomic_inc()     smp_mb()
#define smp_mb__after_oro_atomic_inc()      smp_mb()

#undef ORO_LOCK

#ifdef _cplusplus
} // end extern "C"
#endif // _cplusplus

#endif // __ARCH_powerpc_ORO_ATOMIC__