1 /* $NetBSD: lock.h,v 1.17 2008/04/28 20:23:14 martin 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 * 19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 29 * POSSIBILITY OF SUCH DAMAGE. 30 */ 31 32 /* 33 * Machine-dependent spin lock operations. 34 * 35 * NOTE: The SWP insn used here is available only on ARM architecture 36 * version 3 and later (as well as 2a). What we are going to do is 37 * expect that the kernel will trap and emulate the insn. That will 38 * be slow, but give us the atomicity that we need. 39 */ 40 41 #ifndef _ARM_LOCK_H_ 42 #define _ARM_LOCK_H_ 43 44 static __inline int 45 __SIMPLELOCK_LOCKED_P(__cpu_simple_lock_t *__ptr) 46 { 47 return *__ptr == __SIMPLELOCK_LOCKED; 48 } 49 50 static __inline int 51 __SIMPLELOCK_UNLOCKED_P(__cpu_simple_lock_t *__ptr) 52 { 53 return *__ptr == __SIMPLELOCK_UNLOCKED; 54 } 55 56 static __inline void 57 __cpu_simple_lock_clear(__cpu_simple_lock_t *__ptr) 58 { 59 *__ptr = __SIMPLELOCK_UNLOCKED; 60 } 61 62 static __inline void 63 __cpu_simple_lock_set(__cpu_simple_lock_t *__ptr) 64 { 65 *__ptr = __SIMPLELOCK_LOCKED; 66 } 67 68 #ifdef _KERNEL 69 #include <arm/cpufunc.h> 70 71 #define mb_read drain_writebuf /* in cpufunc.h */ 72 #define mb_write drain_writebuf /* in cpufunc.h */ 73 #define mb_memory drain_writebuf /* in cpufunc.h */ 74 #endif 75 76 #if defined(_KERNEL) 77 static __inline int 78 __swp(int __val, volatile unsigned char *__ptr) 79 { 80 81 __asm volatile("swpb %0, %1, [%2]" 82 : "=&r" (__val) : "r" (__val), "r" (__ptr) : "memory"); 83 return __val; 84 } 85 #else 86 static __inline int 87 __swp(int __val, volatile int *__ptr) 88 { 89 90 __asm volatile("swp %0, %1, [%2]" 91 : "=&r" (__val) : "r" (__val), "r" (__ptr) : "memory"); 92 return __val; 93 } 94 #endif /* _KERNEL */ 95 96 static __inline void __attribute__((__unused__)) 97 __cpu_simple_lock_init(__cpu_simple_lock_t *alp) 98 { 99 100 *alp = __SIMPLELOCK_UNLOCKED; 101 } 102 103 static __inline void __attribute__((__unused__)) 104 __cpu_simple_lock(__cpu_simple_lock_t *alp) 105 { 106 107 while (__swp(__SIMPLELOCK_LOCKED, alp) != __SIMPLELOCK_UNLOCKED) 108 continue; 109 } 110 111 static __inline int __attribute__((__unused__)) 112 __cpu_simple_lock_try(__cpu_simple_lock_t *alp) 113 { 114 115 return (__swp(__SIMPLELOCK_LOCKED, alp) == __SIMPLELOCK_UNLOCKED); 116 } 117 118 static __inline void __attribute__((__unused__)) 119 __cpu_simple_unlock(__cpu_simple_lock_t *alp) 120 { 121 122 *alp = __SIMPLELOCK_UNLOCKED; 123 } 124 125 #endif /* _ARM_LOCK_H_ */ 126