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lock.h revision 1.14 
      1 /*	$NetBSD: lock.h,v 1.14 2007/09/10 11:34:07 skrll Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 2000, 2001 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.
      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  * 3. All advertising materials mentioning features or use of this software
     19  *    must display the following acknowledgement:
     20  *	This product includes software developed by the NetBSD
     21  *	Foundation, Inc. and its contributors.
     22  * 4. Neither the name of The NetBSD Foundation nor the names of its
     23  *    contributors may be used to endorse or promote products derived
     24  *    from this software without specific prior written permission.
     25  *
     26  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     27  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     28  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     29  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     30  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     31  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     32  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     33  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     34  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     35  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     36  * POSSIBILITY OF SUCH DAMAGE.
     37  */
     38 
     39 /*
     40  * Machine-dependent spin lock operations.
     41  *
     42  * NOTE: The SWP insn used here is available only on ARM architecture
     43  * version 3 and later (as well as 2a).  What we are going to do is
     44  * expect that the kernel will trap and emulate the insn.  That will
     45  * be slow, but give us the atomicity that we need.
     46  */
     47 
     48 #ifndef _ARM_LOCK_H_
     49 #define	_ARM_LOCK_H_
     50 
     51 static __inline int
     52 __SIMPLELOCK_LOCKED_P(__cpu_simple_lock_t *__ptr)
     53 {
     54 	return *__ptr == __SIMPLELOCK_LOCKED;
     55 }
     56 
     57 static __inline int
     58 __SIMPLELOCK_UNLOCKED_P(__cpu_simple_lock_t *__ptr)
     59 {
     60 	return *__ptr == __SIMPLELOCK_UNLOCKED;
     61 }
     62 
     63 static __inline void
     64 __cpu_simple_lock_clear(__cpu_simple_lock_t *__ptr)
     65 {
     66 	*__ptr = __SIMPLELOCK_UNLOCKED;
     67 }
     68 
     69 static __inline void
     70 __cpu_simple_lock_set(__cpu_simple_lock_t *__ptr)
     71 {
     72 	*__ptr = __SIMPLELOCK_LOCKED;
     73 }
     74 
     75 #ifdef _KERNEL
     76 #include <arm/cpufunc.h>
     77 
     78 #define	mb_read		drain_writebuf		/* in cpufunc.h */
     79 #define	mb_write	drain_writebuf		/* in cpufunc.h */
     80 #define	mb_memory	drain_writebuf		/* in cpufunc.h */
     81 #endif
     82 
     83 #if defined(_KERNEL)
     84 static __inline int
     85 __swp(int __val, volatile unsigned char *__ptr)
     86 {
     87 
     88 	__asm volatile("swpb %0, %1, [%2]"
     89 	    : "=r" (__val) : "r" (__val), "r" (__ptr) : "memory");
     90 	return __val;
     91 }
     92 #else
     93 static __inline int
     94 __swp(int __val, volatile int *__ptr)
     95 {
     96 
     97 	__asm volatile("swp %0, %1, [%2]"
     98 	    : "=r" (__val) : "r" (__val), "r" (__ptr) : "memory");
     99 	return __val;
    100 }
    101 #endif /* _KERNEL */
    102 
    103 static __inline void __attribute__((__unused__))
    104 __cpu_simple_lock_init(__cpu_simple_lock_t *alp)
    105 {
    106 
    107 	*alp = __SIMPLELOCK_UNLOCKED;
    108 }
    109 
    110 static __inline void __attribute__((__unused__))
    111 __cpu_simple_lock(__cpu_simple_lock_t *alp)
    112 {
    113 
    114 	while (__swp(__SIMPLELOCK_LOCKED, alp) != __SIMPLELOCK_UNLOCKED)
    115 		continue;
    116 }
    117 
    118 static __inline int __attribute__((__unused__))
    119 __cpu_simple_lock_try(__cpu_simple_lock_t *alp)
    120 {
    121 
    122 	return (__swp(__SIMPLELOCK_LOCKED, alp) == __SIMPLELOCK_UNLOCKED);
    123 }
    124 
    125 static __inline void __attribute__((__unused__))
    126 __cpu_simple_unlock(__cpu_simple_lock_t *alp)
    127 {
    128 
    129 	*alp = __SIMPLELOCK_UNLOCKED;
    130 }
    131 
    132 #endif /* _ARM_LOCK_H_ */
    133