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lock.h revision 1.7
      1  1.7  thorpej /*	$NetBSD: lock.h,v 1.7 2000/04/29 03:31:55 thorpej Exp $ */
      2  1.1       pk 
      3  1.1       pk /*-
      4  1.4  thorpej  * Copyright (c) 1998, 1999 The NetBSD Foundation, Inc.
      5  1.1       pk  * All rights reserved.
      6  1.1       pk  *
      7  1.1       pk  * This code is derived from software contributed to The NetBSD Foundation
      8  1.1       pk  * by Paul Kranenburg.
      9  1.1       pk  *
     10  1.1       pk  * Redistribution and use in source and binary forms, with or without
     11  1.1       pk  * modification, are permitted provided that the following conditions
     12  1.1       pk  * are met:
     13  1.1       pk  * 1. Redistributions of source code must retain the above copyright
     14  1.1       pk  *    notice, this list of conditions and the following disclaimer.
     15  1.1       pk  * 2. Redistributions in binary form must reproduce the above copyright
     16  1.1       pk  *    notice, this list of conditions and the following disclaimer in the
     17  1.1       pk  *    documentation and/or other materials provided with the distribution.
     18  1.1       pk  * 3. All advertising materials mentioning features or use of this software
     19  1.1       pk  *    must display the following acknowledgement:
     20  1.1       pk  *        This product includes software developed by the NetBSD
     21  1.1       pk  *        Foundation, Inc. and its contributors.
     22  1.1       pk  * 4. Neither the name of The NetBSD Foundation nor the names of its
     23  1.1       pk  *    contributors may be used to endorse or promote products derived
     24  1.1       pk  *    from this software without specific prior written permission.
     25  1.1       pk  *
     26  1.1       pk  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     27  1.1       pk  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     28  1.1       pk  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     29  1.1       pk  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     30  1.1       pk  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     31  1.1       pk  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     32  1.1       pk  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     33  1.1       pk  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     34  1.1       pk  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     35  1.1       pk  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     36  1.1       pk  * POSSIBILITY OF SUCH DAMAGE.
     37  1.1       pk  */
     38  1.1       pk 
     39  1.1       pk #ifndef _MACHINE_LOCK_H
     40  1.1       pk #define _MACHINE_LOCK_H
     41  1.1       pk 
     42  1.1       pk /*
     43  1.1       pk  * Machine dependent spin lock operations.
     44  1.1       pk  */
     45  1.1       pk 
     46  1.5  thorpej /*
     47  1.7  thorpej  * The value for __SIMPLELOCK_LOCKED is what ldstub() naturally stores
     48  1.5  thorpej  * `lock_data' given its address (and the fact that SPARC is big-endian).
     49  1.5  thorpej  */
     50  1.7  thorpej #define	__SIMPLELOCK_LOCKED	0xff000000
     51  1.7  thorpej #define	__SIMPLELOCK_UNLOCKED	0
     52  1.5  thorpej 
     53  1.7  thorpej /* XXX So we can expose this to userland. */
     54  1.7  thorpej #define	__ldstub(__addr)						\
     55  1.7  thorpej ({									\
     56  1.7  thorpej 	__v;								\
     57  1.7  thorpej 									\
     58  1.7  thorpej 	__asm __volatile("ldstub [%1],%0"				\
     59  1.7  thorpej 	    : "=r" (__v)						\
     60  1.7  thorpej 	    : "r" (__addr)						\
     61  1.7  thorpej 	    : "memory");						\
     62  1.7  thorpej 									\
     63  1.7  thorpej 	__v;								\
     64  1.7  thorpej })
     65  1.7  thorpej 
     66  1.7  thorpej static __inline void __cpu_simple_lock_init __P((__volatile int *))
     67  1.7  thorpej 	__attribute__((__unused__));
     68  1.7  thorpej static __inline void __cpu_simple_lock __P((__volatile int *))
     69  1.7  thorpej 	__attribute__((__unused__));
     70  1.7  thorpej static __inline int __cpu_simple_lock_try __P((__volatile int *))
     71  1.7  thorpej 	__attribute__((__unused__));
     72  1.7  thorpej static __inline void __cpu_simple_unlock __P((__volatile int *))
     73  1.7  thorpej 	__attribute__((__unused__));
     74  1.7  thorpej 
     75  1.7  thorpej static __inline void
     76  1.7  thorpej __cpu_simple_lock_init(__volatile int *alp)
     77  1.1       pk {
     78  1.2       pk 
     79  1.7  thorpej 	*alp = __SIMPLELOCK_UNLOCKED;
     80  1.1       pk }
     81  1.1       pk 
     82  1.7  thorpej static __inline void
     83  1.7  thorpej __cpu_simple_lock(__volatile int *alp)
     84  1.1       pk {
     85  1.2       pk 
     86  1.2       pk 	/*
     87  1.7  thorpej 	 * If someone else holds the lock use simple reads until it
     88  1.7  thorpej 	 * is released, then retry the atomic operation. This reduces
     89  1.7  thorpej 	 * memory bus contention because the cache-coherency logic
     90  1.7  thorpej 	 * does not have to broadcast invalidates on the lock while
     91  1.7  thorpej 	 * we spin on it.
     92  1.2       pk 	 */
     93  1.7  thorpej 	while (__ldstub(alp) != __SIMPLELOCK_UNLOCKED) {
     94  1.7  thorpej 		while (*alp != __SIMPLELOCK_UNLOCKED)
     95  1.7  thorpej 			/* spin */ ;
     96  1.2       pk 	}
     97  1.1       pk }
     98  1.1       pk 
     99  1.7  thorpej static __inline int
    100  1.7  thorpej __cpu_simple_lock_try(__volatile int *alp)
    101  1.1       pk {
    102  1.2       pk 
    103  1.7  thorpej 	return (__ldstub(alp) == __SIMPLELOCK_UNLOCKED);
    104  1.1       pk }
    105  1.1       pk 
    106  1.7  thorpej static __inline void
    107  1.7  thorpej __cpu_simple_unlock(__volatile int *alp)
    108  1.1       pk {
    109  1.2       pk 
    110  1.7  thorpej 	*alp = __SIMPLELOCK_UNLOCKED;
    111  1.1       pk }
    112  1.1       pk 
    113  1.1       pk #endif /* _MACHINE_LOCK_H */
    114