/*      $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_ */