lock.h revision 1.7 
1/* $NetBSD: lock.h,v 1.7 2000/06/07 01:49:13 simonb Exp $ */
2
3/*-
4 * Copyright (c) 1998, 1999 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 of the Numerical Aerospace Simulation Facility,
9 * NASA Ames Research Center.
10 *
11 * Redistribution and use in source and binary forms, with or without
12 * modification, are permitted provided that the following conditions
13 * are met:
14 * 1. Redistributions of source code must retain the above copyright
15 *    notice, this list of conditions and the following disclaimer.
16 * 2. Redistributions in binary form must reproduce the above copyright
17 *    notice, this list of conditions and the following disclaimer in the
18 *    documentation and/or other materials provided with the distribution.
19 * 3. All advertising materials mentioning features or use of this software
20 *    must display the following acknowledgement:
21 *	This product includes software developed by the NetBSD
22 *	Foundation, Inc. and its contributors.
23 * 4. Neither the name of The NetBSD Foundation nor the names of its
24 *    contributors may be used to endorse or promote products derived
25 *    from this software without specific prior written permission.
26 *
27 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
28 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
29 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
30 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
31 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
32 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
33 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
34 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
35 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
36 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
37 * POSSIBILITY OF SUCH DAMAGE.
38 */
39
40/*
41 * Machine-dependent spin lock operations.
42 */
43
44#ifndef _ALPHA_LOCK_H_
45#define	_ALPHA_LOCK_H_
46
47typedef	__volatile int		__cpu_simple_lock_t;
48
49#define	__SIMPLELOCK_LOCKED	1
50#define	__SIMPLELOCK_UNLOCKED	0
51
52static __inline void __cpu_simple_lock_init __P((__cpu_simple_lock_t *))
53	__attribute__((__unused__));
54static __inline void __cpu_simple_lock __P((__cpu_simple_lock_t *))
55	__attribute__((__unused__));
56static __inline int __cpu_simple_lock_try __P((__cpu_simple_lock_t *))
57	__attribute__((__unused__));
58static __inline void __cpu_simple_unlock __P((__cpu_simple_lock_t *))
59	__attribute__((__unused__));
60
61static __inline void
62__cpu_simple_lock_init(__cpu_simple_lock_t *alp)
63{
64
65	__asm __volatile(
66		"# BEGIN __cpu_simple_lock_init\n"
67		"	stl	$31, %0		\n"
68		"	mb			\n"
69		"	# END __cpu_simple_lock_init"
70		: "=m" (*alp));
71}
72
73static __inline void
74__cpu_simple_lock(__cpu_simple_lock_t *alp)
75{
76	unsigned long t0;
77
78	/*
79	 * Note, if we detect that the lock is held when
80	 * we do the initial load-locked, we spin using
81	 * a non-locked load to save the coherency logic
82	 * some work.
83	 */
84
85	__asm __volatile(
86		"# BEGIN __cpu_simple_lock\n"
87		"1:	ldl_l	%0, %3		\n"
88		"	bne	%0, 2f		\n"
89		"	bis	$31, %2, %0	\n"
90		"	stl_c	%0, %1		\n"
91		"	beq	%0, 3f		\n"
92		"	mb			\n"
93		"	br	4f		\n"
94		"2:	ldl	%0, %3		\n"
95		"	beq	%0, 1b		\n"
96		"	br	2b		\n"
97		"3:	br	1b		\n"
98		"4:				\n"
99		"	# END __cpu_simple_lock\n"
100		: "=r" (t0), "=m" (*alp)
101		: "i" (__SIMPLELOCK_LOCKED), "1" (*alp));
102}
103
104static __inline int
105__cpu_simple_lock_try(__cpu_simple_lock_t *alp)
106{
107	unsigned long t0, v0;
108
109	__asm __volatile(
110		"# BEGIN __cpu_simple_lock_try\n"
111		"1:	ldl_l	%0, %4		\n"
112		"	bne	%0, 2f		\n"
113		"	bis	$31, %3, %0	\n"
114		"	stl_c	%0, %2		\n"
115		"	beq	%0, 3f		\n"
116		"	mb			\n"
117		"	bis	$31, 1, %1	\n"
118		"	br	4f		\n"
119		"2:	bis	$31, $31, %1	\n"
120		"	br	4f		\n"
121		"3:	br	1b		\n"
122		"4:				\n"
123		"	# END __cpu_simple_lock_try"
124		: "=r" (t0), "=r" (v0), "=m" (*alp)
125		: "i" (__SIMPLELOCK_LOCKED), "2" (*alp));
126
127	return (v0 != 0);
128}
129
130static __inline void
131__cpu_simple_unlock(__cpu_simple_lock_t *alp)
132{
133
134	__asm __volatile(
135		"# BEGIN __cpu_simple_unlock\n"
136		"	stl	$31, %0		\n"
137		"	mb			\n"
138		"	# END __cpu_simple_unlock"
139		: "=m" (*alp));
140}
141
142#endif /* _ALPHA_LOCK_H_ */
143