sys/arch/vax/include/mutex.h

   1 /*      $NetBSD: mutex.h,v 1.11 2008/02/22 03:16:01 matt Exp $  */
   2
   3 /*-
   4  * Copyright (c) 2002, 2007 The NetBSD Foundation, Inc.
   5  * All rights reserved.
   6  *
   7  * This code is derived from software contributed to The NetBSD Foundation
   8  * by Jason R. Thorpe and Andrew Doran.
   9  *
  10  * Redistribution and use in source and binary forms, with or without
  11  * modification, are permitted provided that the following conditions
  12  * are met:
  13  * 1. Redistributions of source code must retain the above copyright
  14  *    notice, this list of conditions and the following disclaimer.
  15  * 2. Redistributions in binary form must reproduce the above copyright
  16  *    notice, this list of conditions and the following disclaimer in the
  17  *    documentation and/or other materials provided with the distribution.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
  20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
  21  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
  23  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  29  * POSSIBILITY OF SUCH DAMAGE.
  30  */
  31
  32 #ifndef _VAX_MUTEX_H_
  33 #define _VAX_MUTEX_H_
  34
  35 /*
  36  * The VAX mutex implementation is troublesome, because VAX lacks a
  37  * compare-and-swap operation.
  38  *
  39  * So we emulate compare-and-swap by raising IPL to lock out interrupts
  40  * and (if MP) using BBSSI/BBCCI to lock out the other processors.
  41  */
  42
  43 #ifndef __MUTEX_PRIVATE
  44
  45 struct kmutex {
  46         uintptr_t       mtx_pad1;
  47 };
  48
  49 #else   /* __MUTEX_PRIVATE */
  50
  51 struct kmutex {
  52         union {
  53                 /* Adaptive mutex */
  54                 volatile uintptr_t      mtxa_owner;     /* 0-3 */
  55
  56                 /* Spin mutex */
  57                 struct {
  58                         volatile uint8_t        mtxs_dummy;
  59                         ipl_cookie_t            mtxs_ipl;
  60                         __cpu_simple_lock_t     mtxs_lock;
  61                         volatile uint8_t        mtxs_unused;
  62                 } s;
  63         } u;
  64 };
  65
  66 #define mtx_owner               u.mtxa_owner
  67 #define mtx_ipl                 u.s.mtxs_ipl
  68 #define mtx_lock                u.s.mtxs_lock
  69
  70 #define __HAVE_MUTEX_STUBS              1
  71 #define __HAVE_SPIN_MUTEX_STUBS         1
  72 #define __HAVE_SIMPLE_MUTEXES           1
  73
  74 /*
  75  * MUTEX_RECEIVE: no memory barrier required; we're synchronizing against
  76  * interrupts, not multiple processors.
  77  */
  78 #define MUTEX_RECEIVE(mtx)      /* nothing */
  79
  80 /*
  81  * MUTEX_GIVE: no memory barrier required; same reason.
  82  */
  83 #define MUTEX_GIVE(mtx)         /* nothing */
  84
  85 #define MUTEX_CAS(p, o, n)      (atomic_cas_ulong((p), (o), (n)) == (o))
  86
  87 #endif  /* __MUTEX_PRIVATE */
  88
  89 #endif /* _VAX_MUTEX_H_ */