1 /* $NetBSD: lock.h,v 1.15 2007/10/17 19:53:41 garbled 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