1 /* $NetBSD: lock.h,v 1.3 2002/10/07 23:19:49 bjh21 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 typedef __volatile int __cpu_simple_lock_t; 52 53 #define __SIMPLELOCK_LOCKED 1 54 #define __SIMPLELOCK_UNLOCKED 0 55 56 static __inline int 57 __swp(int __val, __volatile int *__ptr) 58 { 59 60 __asm __volatile("swp %0, %1, [%2]" 61 : "=r" (__val) : "r" (__val), "r" (__ptr) : "memory"); 62 return __val; 63 } 64 65 static __inline void __attribute__((__unused__)) 66 __cpu_simple_lock_init(__cpu_simple_lock_t *alp) 67 { 68 69 *alp = __SIMPLELOCK_UNLOCKED; 70 } 71 72 static __inline void __attribute__((__unused__)) 73 __cpu_simple_lock(__cpu_simple_lock_t *alp) 74 { 75 76 while (__swp(__SIMPLELOCK_LOCKED, alp) != __SIMPLELOCK_UNLOCKED) 77 continue; 78 } 79 80 static __inline int __attribute__((__unused__)) 81 __cpu_simple_lock_try(__cpu_simple_lock_t *alp) 82 { 83 84 return (__swp(__SIMPLELOCK_LOCKED, alp) == __SIMPLELOCK_UNLOCKED); 85 } 86 87 static __inline void __attribute__((__unused__)) 88 __cpu_simple_unlock(__cpu_simple_lock_t *alp) 89 { 90 91 *alp = __SIMPLELOCK_UNLOCKED; 92 } 93 94 #endif /* _ARM_LOCK_H_ */ 95