| /* $NetBSD: lock.h,v 1.7 2005/12/28 19:09:29 perry Exp $ */ | |
| /*- | |
| * Copyright (c) 2000, 2001 The NetBSD Foundation, Inc. | |
| * All rights reserved. | |
| * | |
| * This code is derived from software contributed to The NetBSD Foundation | |
| * by Jason R. Thorpe. | |
| * | |
| * 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. | |
| * 3. All advertising materials mentioning features or use of this software | |
| * must display the following acknowledgement: | |
| * This product includes software developed by the NetBSD | |
| * Foundation, Inc. and its contributors. | |
| * 4. Neither the name of The NetBSD Foundation nor the names of its | |
| * contributors may be used to endorse or promote products derived | |
| * from this software without specific prior written permission. | |
| * | |
| * 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. | |
| */ | |
| /* | |
| * Machine-dependent spin lock operations. | |
| * | |
| * NOTE: The SWP insn used here is available only on ARM architecture | |
| * version 3 and later (as well as 2a). What we are going to do is | |
| * expect that the kernel will trap and emulate the insn. That will | |
| * be slow, but give us the atomicity that we need. | |
| */ | |
| #ifndef _ARM_LOCK_H_ | |
| #define _ARM_LOCK_H_ | |
| static __inline int | |
| __swp(int __val, volatile int *__ptr) | |
| { | |
| __asm volatile("swp %0, %1, [%2]" | |
| : "=r" (__val) : "r" (__val), "r" (__ptr) : "memory"); | |
| return __val; | |
| } | |
| static __inline void __attribute__((__unused__)) | |
| __cpu_simple_lock_init(__cpu_simple_lock_t *alp) | |
| { | |
| *alp = __SIMPLELOCK_UNLOCKED; | |
| } | |
| static __inline void __attribute__((__unused__)) | |
| __cpu_simple_lock(__cpu_simple_lock_t *alp) | |
| { | |
| while (__swp(__SIMPLELOCK_LOCKED, alp) != __SIMPLELOCK_UNLOCKED) | |
| continue; | |
| } | |
| static __inline int __attribute__((__unused__)) | |
| __cpu_simple_lock_try(__cpu_simple_lock_t *alp) | |
| { | |
| return (__swp(__SIMPLELOCK_LOCKED, alp) == __SIMPLELOCK_UNLOCKED); | |
| } | |
| static __inline void __attribute__((__unused__)) | |
| __cpu_simple_unlock(__cpu_simple_lock_t *alp) | |
| { | |
| *alp = __SIMPLELOCK_UNLOCKED; | |
| } | |
| #endif /* _ARM_LOCK_H_ */ |