Annotation of src/sys/arch/sparc/include/lock.h, Revision 1.7
1.7 ! thorpej 1: /* $NetBSD: lock.h,v 1.6 1999/07/27 23:45:14 thorpej Exp $ */
1.1 pk 2:
3: /*-
1.4 thorpej 4: * Copyright (c) 1998, 1999 The NetBSD Foundation, Inc.
1.1 pk 5: * All rights reserved.
6: *
7: * This code is derived from software contributed to The NetBSD Foundation
8: * by Paul Kranenburg.
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: #ifndef _MACHINE_LOCK_H
40: #define _MACHINE_LOCK_H
41:
42: /*
43: * Machine dependent spin lock operations.
44: */
45:
1.5 thorpej 46: /*
1.7 ! thorpej 47: * The value for __SIMPLELOCK_LOCKED is what ldstub() naturally stores
1.5 thorpej 48: * `lock_data' given its address (and the fact that SPARC is big-endian).
49: */
1.7 ! thorpej 50: #define __SIMPLELOCK_LOCKED 0xff000000
! 51: #define __SIMPLELOCK_UNLOCKED 0
1.5 thorpej 52:
1.7 ! thorpej 53: /* XXX So we can expose this to userland. */
! 54: #define __ldstub(__addr) \
! 55: ({ \
! 56: __v; \
! 57: \
! 58: __asm __volatile("ldstub [%1],%0" \
! 59: : "=r" (__v) \
! 60: : "r" (__addr) \
! 61: : "memory"); \
! 62: \
! 63: __v; \
! 64: })
! 65:
! 66: static __inline void __cpu_simple_lock_init __P((__volatile int *))
! 67: __attribute__((__unused__));
! 68: static __inline void __cpu_simple_lock __P((__volatile int *))
! 69: __attribute__((__unused__));
! 70: static __inline int __cpu_simple_lock_try __P((__volatile int *))
! 71: __attribute__((__unused__));
! 72: static __inline void __cpu_simple_unlock __P((__volatile int *))
! 73: __attribute__((__unused__));
! 74:
! 75: static __inline void
! 76: __cpu_simple_lock_init(__volatile int *alp)
1.1 pk 77: {
1.2 pk 78:
1.7 ! thorpej 79: *alp = __SIMPLELOCK_UNLOCKED;
1.1 pk 80: }
81:
1.7 ! thorpej 82: static __inline void
! 83: __cpu_simple_lock(__volatile int *alp)
1.1 pk 84: {
1.2 pk 85:
86: /*
1.7 ! thorpej 87: * If someone else holds the lock use simple reads until it
! 88: * is released, then retry the atomic operation. This reduces
! 89: * memory bus contention because the cache-coherency logic
! 90: * does not have to broadcast invalidates on the lock while
! 91: * we spin on it.
1.2 pk 92: */
1.7 ! thorpej 93: while (__ldstub(alp) != __SIMPLELOCK_UNLOCKED) {
! 94: while (*alp != __SIMPLELOCK_UNLOCKED)
! 95: /* spin */ ;
1.2 pk 96: }
1.1 pk 97: }
98:
1.7 ! thorpej 99: static __inline int
! 100: __cpu_simple_lock_try(__volatile int *alp)
1.1 pk 101: {
1.2 pk 102:
1.7 ! thorpej 103: return (__ldstub(alp) == __SIMPLELOCK_UNLOCKED);
1.1 pk 104: }
105:
1.7 ! thorpej 106: static __inline void
! 107: __cpu_simple_unlock(__volatile int *alp)
1.1 pk 108: {
1.2 pk 109:
1.7 ! thorpej 110: *alp = __SIMPLELOCK_UNLOCKED;
1.1 pk 111: }
112:
113: #endif /* _MACHINE_LOCK_H */
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