lock.h revision 1.16 
1/*	$NetBSD: lock.h,v 1.16 2008/04/28 20:23:28 martin Exp $	*/
2
3/*-
4 * Copyright (c) 2001, 2007 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * This code is derived from software contributed to The NetBSD Foundation
8 * by Wayne Knowles and Andrew Doran.
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 for MIPS processors.
34 *
35 * Note: R2000/R3000 doesn't have any atomic update instructions; this
36 * will cause problems for user applications using this header.
37 */
38
39#ifndef _MIPS_LOCK_H_
40#define	_MIPS_LOCK_H_
41
42static __inline int
43__SIMPLELOCK_LOCKED_P(__cpu_simple_lock_t *__ptr)
44{
45	return *__ptr == __SIMPLELOCK_LOCKED;
46}
47
48static __inline int
49__SIMPLELOCK_UNLOCKED_P(__cpu_simple_lock_t *__ptr)
50{
51	return *__ptr == __SIMPLELOCK_UNLOCKED;
52}
53
54static __inline void
55__cpu_simple_lock_clear(__cpu_simple_lock_t *__ptr)
56{
57	*__ptr = __SIMPLELOCK_UNLOCKED;
58}
59
60static __inline void
61__cpu_simple_lock_set(__cpu_simple_lock_t *__ptr)
62{
63	*__ptr = __SIMPLELOCK_LOCKED;
64}
65
66#ifndef _KERNEL
67
68static __inline int
69__cpu_simple_lock_try(__cpu_simple_lock_t *lp)
70{
71	unsigned long t0, v0;
72
73	__asm volatile(
74		"# -- BEGIN __cpu_simple_lock_try\n"
75		"	.set push		\n"
76		"	.set mips2		\n"
77		"1:	ll	%0, %4		\n"
78		"	bnez	%0, 2f		\n"
79		"	nop	       # BDslot	\n"
80		"	li	%0, %3		\n"
81		"	sc	%0, %2		\n"
82		"	beqz	%0, 2f		\n"
83		"	nop	       # BDslot	\n"
84		"	li	%1, 1		\n"
85		"	sync			\n"
86		"	j	3f		\n"
87		"	nop			\n"
88		"	nop			\n"
89		"2:	li	%1, 0		\n"
90		"3:				\n"
91		"	.set pop		\n"
92		"# -- END __cpu_simple_lock_try	\n"
93		: "=r" (t0), "=r" (v0), "+m" (*lp)
94		: "i" (__SIMPLELOCK_LOCKED), "m" (*lp));
95
96	return (v0 != 0);
97}
98
99#ifdef MIPS1
100static __inline void
101mb_read(void)
102{
103	__insn_barrier();
104}
105
106static __inline void
107mb_write(void)
108{
109	__insn_barrier();
110}
111
112static __inline void
113mb_memory(void)
114{
115	__insn_barrier();
116}
117#else	/* MIPS1*/
118static __inline void
119mb_read(void)
120{
121	__asm volatile(
122	    "	.set push\n"
123	    "	.set mips2\n"
124	    "	sync\n"
125	    "	.set pop"
126	    ::: "memory"
127	);
128}
129
130static __inline void
131mb_write(void)
132{
133	mb_read();
134}
135
136static __inline void
137mb_memory(void)
138{
139	mb_read();
140}
141#endif	/* MIPS1 */
142
143#else	/* !_KERNEL */
144
145unsigned _atomic_cas_uint(volatile unsigned *, unsigned, unsigned);
146void	mb_read(void);
147void	mb_write(void);
148void	mb_memory(void);
149
150static __inline int
151__cpu_simple_lock_try(__cpu_simple_lock_t *lp)
152{
153
154	return _atomic_cas_uint((volatile unsigned *)lp,
155	    __SIMPLELOCK_UNLOCKED, __SIMPLELOCK_LOCKED) ==
156	    __SIMPLELOCK_UNLOCKED;
157}
158
159#endif	/* _KERNEL */
160
161static __inline void
162__cpu_simple_lock_init(__cpu_simple_lock_t *lp)
163{
164
165	*lp = __SIMPLELOCK_UNLOCKED;
166	mb_memory();
167}
168
169static __inline void
170__cpu_simple_lock(__cpu_simple_lock_t *lp)
171{
172
173	while (!__cpu_simple_lock_try(lp))
174		while (*lp == __SIMPLELOCK_LOCKED)
175			/* spin */;
176}
177
178static __inline void
179__cpu_simple_unlock(__cpu_simple_lock_t *lp)
180{
181
182	mb_memory();
183	*lp = __SIMPLELOCK_UNLOCKED;
184}
185
186#endif /* _MIPS_LOCK_H_ */
187