/*      $NetBSD: lock.h,v 1.17 2022/02/12 17:17:53 riastradh Exp $      */

/*-
* Copyright (c) 2000, 2007 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Jason R. Thorpe and Andrew Doran.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
*    notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
*    notice, this list of conditions and the following disclaimer in the
*    documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/

/*
* Machine-dependent spin lock operations.
*/

#ifndef _POWERPC_LOCK_H_
#define _POWERPC_LOCK_H_

static __inline int
__SIMPLELOCK_LOCKED_P(const __cpu_simple_lock_t *__ptr)
{
       return *__ptr == __SIMPLELOCK_LOCKED;
}

static __inline int
__SIMPLELOCK_UNLOCKED_P(const __cpu_simple_lock_t *__ptr)
{
       return *__ptr == __SIMPLELOCK_UNLOCKED;
}

static __inline void
__cpu_simple_lock_clear(__cpu_simple_lock_t *__ptr)
{
       *__ptr = __SIMPLELOCK_UNLOCKED;
}

static __inline void
__cpu_simple_lock_set(__cpu_simple_lock_t *__ptr)
{
       *__ptr = __SIMPLELOCK_LOCKED;
}

static __inline void
__cpu_simple_lock_init(__cpu_simple_lock_t *alp)
{
       *alp = __SIMPLELOCK_UNLOCKED;
}

static __inline void
__cpu_simple_lock(__cpu_simple_lock_t *alp)
{
       int old;

       __asm volatile ("       \
                               \n\
1:      lwarx   %0,0,%1         \n\
       cmpwi   %0,%2           \n\
       beq+    3f              \n\
2:      lwzx    %0,0,%1         \n\
       cmpwi   %0,%2           \n\
       beq+    1b              \n\
       b       2b              \n\
3:                              \n"
#ifdef IBM405_ERRATA77
       "dcbt   0,%1            \n"
#endif
       "stwcx. %3,0,%1         \n\
       bne-    1b              \n\
       isync                   \n\
                               \n"
       : "=&r"(old)
       : "r"(alp), "I"(__SIMPLELOCK_UNLOCKED), "r"(__SIMPLELOCK_LOCKED)
       : "memory");
}

static __inline int
__cpu_simple_lock_try(__cpu_simple_lock_t *alp)
{
       int old, dummy;

       __asm volatile ("       \
                               \n\
1:      lwarx   %0,0,%1         \n\
       cmpwi   %0,%2           \n\
       bne     2f              \n"
#ifdef IBM405_ERRATA77
       "dcbt   0,%1            \n"
#endif
       "stwcx. %3,0,%1         \n\
       bne-    1b              \n\
2:                              \n"
#ifdef IBM405_ERRATA77
       "dcbt   0,%4            \n"
#endif
       "stwcx. %3,0,%4         \n\
       isync                   \n\
                               \n"
       : "=&r"(old)
       : "r"(alp), "I"(__SIMPLELOCK_UNLOCKED), "r"(__SIMPLELOCK_LOCKED),
         "r"(&dummy)
       : "memory");

       return (old == __SIMPLELOCK_UNLOCKED);
}

static __inline void
__cpu_simple_unlock(__cpu_simple_lock_t *alp)
{
       __asm volatile ("sync");
       *alp = __SIMPLELOCK_UNLOCKED;
}

#endif /* _POWERPC_LOCK_H_ */