1 /* $NetBSD: lock.h,v 1.2 2001/11/15 19:22:32 thorpej 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 void __attribute__((__unused__)) 57 __cpu_simple_lock_init(__cpu_simple_lock_t *alp) 58 { 59 60 *alp = __SIMPLELOCK_UNLOCKED; 61 } 62 63 static __inline void __attribute__((__unused__)) 64 __cpu_simple_lock(__cpu_simple_lock_t *alp) 65 { 66 int __val = __SIMPLELOCK_LOCKED; 67 68 do { 69 __asm __volatile("swp %0, %1, [%2]" 70 : "=r" (__val) 71 : "0" (__val), "r" (alp) 72 : "memory"); 73 } while (__val != __SIMPLELOCK_UNLOCKED); 74 } 75 76 static __inline int __attribute__((__unused__)) 77 __cpu_simple_lock_try(__cpu_simple_lock_t *alp) 78 { 79 int __val = __SIMPLELOCK_LOCKED; 80 81 __asm __volatile("swp %0, %1, [%2]" 82 : "=r" (__val) 83 : "0" (__val), "r" (alp) 84 : "memory"); 85 86 return ((__val == __SIMPLELOCK_UNLOCKED) ? 1 : 0); 87 } 88 89 static __inline void __attribute__((__unused__)) 90 __cpu_simple_unlock(__cpu_simple_lock_t *alp) 91 { 92 93 *alp = __SIMPLELOCK_UNLOCKED; 94 } 95 96 #endif /* _ARM_LOCK_H_ */ 97