1/* $NetBSD: mutex.h,v 1.7 2024/11/25 22:04:14 skrll Exp $ */
2
3/*-
4 * Copyright (c) 2002, 2007 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 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#ifndef _RISCV_MUTEX_H_
33#define _RISCV_MUTEX_H_
34
35#include <sys/types.h>
36
37#ifndef __MUTEX_PRIVATE
38
39struct kmutex {
40 uintptr_t mtx_pad1;
41};
42
43#else /* __MUTEX_PRIVATE */
44
45#include <sys/cdefs.h>
46
47#include <sys/param.h>
48
49#include <machine/intr.h>
50
51struct kmutex {
52 volatile uintptr_t mtx_owner;
53};
54
55#ifdef _KERNEL
56
57#ifdef _LP64
58#define MTX_ASMOP_SFX ".d" // doubleword atomic op
59#else
60#define MTX_ASMOP_SFX ".w" // word atomic op
61#endif
62
63#define MTX_LOCK __BIT(8) // just one bit
64#define MTX_IPL __BITS(7,4) // only need 4 bits
65
66#undef MUTEX_SPIN_IPL // override <sys/mutex.h>
67#define MUTEX_SPIN_IPL(a) riscv_mutex_spin_ipl(a)
68#define MUTEX_INITIALIZE_SPIN_IPL(a,b) riscv_mutex_initialize_spin_ipl(a,b)
69#define MUTEX_SPINBIT_LOCK_INIT(a) riscv_mutex_spinbit_lock_init(a)
70#define MUTEX_SPINBIT_LOCK_TRY(a) riscv_mutex_spinbit_lock_try(a)
71#define MUTEX_SPINBIT_LOCKED_P(a) riscv_mutex_spinbit_locked_p(a)
72#define MUTEX_SPINBIT_LOCK_UNLOCK(a) riscv_mutex_spinbit_lock_unlock(a)
73
74static inline ipl_cookie_t
75riscv_mutex_spin_ipl(kmutex_t *__mtx)
76{
77 return (ipl_cookie_t){._spl = __SHIFTOUT(__mtx->mtx_owner, MTX_IPL)};
78}
79
80static inline void
81riscv_mutex_initialize_spin_ipl(kmutex_t *__mtx, int ipl)
82{
83 __mtx->mtx_owner = (__mtx->mtx_owner & ~MTX_IPL)
84 | __SHIFTIN(ipl, MTX_IPL);
85}
86
87static inline void
88riscv_mutex_spinbit_lock_init(kmutex_t *__mtx)
89{
90 __mtx->mtx_owner &= ~MTX_LOCK;
91}
92
93static inline bool
94riscv_mutex_spinbit_locked_p(const kmutex_t *__mtx)
95{
96 return (__mtx->mtx_owner & MTX_LOCK) != 0;
97}
98
99static inline bool
100riscv_mutex_spinbit_lock_try(kmutex_t *__mtx)
101{
102 uintptr_t __old;
103 __asm __volatile(
104 "amoor" MTX_ASMOP_SFX ".aq\t%0, %1, (%2)"
105 : "=r"(__old)
106 : "r"(MTX_LOCK), "r"(__mtx));
107 return (__old & MTX_LOCK) == 0;
108}
109
110static inline void
111riscv_mutex_spinbit_lock_unlock(kmutex_t *__mtx)
112{
113 __asm __volatile(
114 "amoand" MTX_ASMOP_SFX ".rl\tx0, %0, (%1)"
115 :: "r"(~MTX_LOCK), "r"(__mtx));
116}
117
118#endif /* _KERNEL */
119
120#if 0
121#define __HAVE_MUTEX_STUBS 1
122#define __HAVE_SPIN_MUTEX_STUBS 1
123#endif
124#define __HAVE_SIMPLE_MUTEXES 1
125
126#endif /* __MUTEX_PRIVATE */
127
128#endif /* _RISCV_MUTEX_H_ */