lock.h revision 1.20 
1/*	$NetBSD: lock.h,v 1.20 2017/09/17 00:01:07 christos 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
42#include <sys/param.h>
43
44static __inline int
45__SIMPLELOCK_LOCKED_P(const __cpu_simple_lock_t *__ptr)
46{
47	return *__ptr != __SIMPLELOCK_UNLOCKED;
48}
49
50static __inline int
51__SIMPLELOCK_UNLOCKED_P(const __cpu_simple_lock_t *__ptr)
52{
53	return *__ptr == __SIMPLELOCK_UNLOCKED;
54}
55
56static __inline void
57__cpu_simple_lock_clear(__cpu_simple_lock_t *__ptr)
58{
59	*__ptr = __SIMPLELOCK_UNLOCKED;
60}
61
62static __inline void
63__cpu_simple_lock_set(__cpu_simple_lock_t *__ptr)
64{
65	*__ptr = __SIMPLELOCK_LOCKED;
66}
67
68#ifndef _HARDKERNEL
69
70static __inline int
71__cpu_simple_lock_try(__cpu_simple_lock_t *lp)
72{
73	unsigned long t0, v0;
74
75	__asm volatile(
76		"# -- BEGIN __cpu_simple_lock_try\n"
77		"	.set push		\n"
78		"	.set mips2		\n"
79		"1:	ll	%0, %4		\n"
80		"	bnez	%0, 2f		\n"
81		"	nop	       # BDslot	\n"
82		"	li	%0, %3		\n"
83		"	sc	%0, %2		\n"
84		"	beqz	%0, 2f		\n"
85		"	nop	       # BDslot	\n"
86		"	li	%1, 1		\n"
87		"	sync			\n"
88		"	j	3f		\n"
89		"	nop			\n"
90		"	nop			\n"
91		"2:	li	%1, 0		\n"
92		"3:				\n"
93		"	.set pop		\n"
94		"# -- END __cpu_simple_lock_try	\n"
95		: "=r" (t0), "=r" (v0), "+m" (*lp)
96		: "i" (__SIMPLELOCK_LOCKED), "m" (*lp));
97
98	return (v0 != 0);
99}
100
101#ifdef MIPS1
102static __inline void
103mb_read(void)
104{
105	__insn_barrier();
106}
107
108static __inline void
109mb_write(void)
110{
111	__insn_barrier();
112}
113
114static __inline void
115mb_memory(void)
116{
117	__insn_barrier();
118}
119#else	/* MIPS1*/
120static __inline void
121mb_read(void)
122{
123	__asm volatile(
124	    "	.set push\n"
125	    "	.set mips2\n"
126	    "	sync\n"
127	    "	.set pop"
128	    ::: "memory"
129	);
130}
131
132static __inline void
133mb_write(void)
134{
135	mb_read();
136}
137
138static __inline void
139mb_memory(void)
140{
141	mb_read();
142}
143#endif	/* MIPS1 */
144
145#else	/* !_HARDKERNEL */
146
147u_int	_atomic_cas_uint(volatile u_int *, u_int, u_int);
148u_long	_atomic_cas_ulong(volatile u_long *, u_long, u_long);
149void *	_atomic_cas_ptr(volatile void *, void *, void *);
150void	mb_read(void);
151void	mb_write(void);
152void	mb_memory(void);
153
154static __inline int
155__cpu_simple_lock_try(__cpu_simple_lock_t *lp)
156{
157
158	return _atomic_cas_uint(lp,
159	    __SIMPLELOCK_UNLOCKED, __SIMPLELOCK_LOCKED) ==
160	    __SIMPLELOCK_UNLOCKED;
161}
162
163#endif	/* _HARDKERNEL */
164
165static __inline void
166__cpu_simple_lock_init(__cpu_simple_lock_t *lp)
167{
168
169	*lp = __SIMPLELOCK_UNLOCKED;
170	mb_memory();
171}
172
173static __inline void
174__cpu_simple_lock(__cpu_simple_lock_t *lp)
175{
176
177	while (!__cpu_simple_lock_try(lp)) {
178		while (*lp == __SIMPLELOCK_LOCKED)
179			/* spin */;
180	}
181}
182
183static __inline void
184__cpu_simple_unlock(__cpu_simple_lock_t *lp)
185{
186
187#ifndef _MIPS_ARCH_OCTEONP
188	mb_memory();
189#endif
190	*lp = __SIMPLELOCK_UNLOCKED;
191#ifdef _MIPS_ARCH_OCTEONP
192	mb_write();
193#endif
194}
195
196#endif /* _MIPS_LOCK_H_ */
197