/*      $NetBSD: mutex.h,v 1.20 2023/07/12 12:50:13 riastradh Exp $     */

/*-
* Copyright (c) 2002, 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.
*/

#ifndef _VAX_MUTEX_H_
#define _VAX_MUTEX_H_

/*
* The VAX mutex implementation is troublesome, because VAX lacks a
* compare-and-swap operation.
*
* So we emulate compare-and-swap by raising IPL to lock out interrupts
* and (if MP) using BBSSI/BBCCI to lock out the other processors.
*/

#include <sys/types.h>

#ifndef __MUTEX_PRIVATE

struct kmutex {
       uintptr_t       mtx_pad1;
};

#else   /* __MUTEX_PRIVATE */

#include <machine/intr.h>

struct kmutex {
       union {
               /* Adaptive mutex */
               volatile uintptr_t      mtxa_owner;     /* 0-3 */

               /* Spin mutex */
               struct {
                       volatile uint8_t        mtxs_dummy;
                       ipl_cookie_t            mtxs_ipl;
                       __cpu_simple_lock_t     mtxs_lock;
                       volatile uint8_t        mtxs_unused;
               } s;
       } u;
};

#define mtx_owner               u.mtxa_owner
#define mtx_ipl                 u.s.mtxs_ipl
#define mtx_lock                u.s.mtxs_lock

#define __HAVE_MUTEX_STUBS              1
#define __HAVE_SPIN_MUTEX_STUBS         1
#define __HAVE_SIMPLE_MUTEXES           1

#endif  /* __MUTEX_PRIVATE */

#endif /* _VAX_MUTEX_H_ */