1/*	$NetBSD: mutex.h,v 1.6 2023/07/12 12:50:13 riastradh 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 _LP64
56#define MTX_ASMOP_SFX ".d"		// doubleword atomic op
57#else
58#define MTX_ASMOP_SFX ".w"		// word atomic op
59#endif
60
61#define	MTX_LOCK			__BIT(8)	// just one bit
62#define	MTX_IPL				__BITS(7,4)	// only need 4 bits
63
64#undef MUTEX_SPIN_IPL			// override <sys/mutex.h>
65#define	MUTEX_SPIN_IPL(a)		riscv_mutex_spin_ipl(a)
66#define	MUTEX_INITIALIZE_SPIN_IPL(a,b)	riscv_mutex_initialize_spin_ipl(a,b)
67#define MUTEX_SPINBIT_LOCK_INIT(a)	riscv_mutex_spinbit_lock_init(a)
68#define MUTEX_SPINBIT_LOCK_TRY(a)	riscv_mutex_spinbit_lock_try(a)
69#define MUTEX_SPINBIT_LOCKED_P(a)	riscv_mutex_spinbit_locked_p(a)
70#define MUTEX_SPINBIT_LOCK_UNLOCK(a)	riscv_mutex_spinbit_lock_unlock(a)
71
72static inline ipl_cookie_t
73riscv_mutex_spin_ipl(kmutex_t *__mtx)
74{
75	return (ipl_cookie_t){._spl = __SHIFTOUT(__mtx->mtx_owner, MTX_IPL)};
76}
77
78static inline void
79riscv_mutex_initialize_spin_ipl(kmutex_t *__mtx, int ipl)
80{
81	__mtx->mtx_owner = (__mtx->mtx_owner & ~MTX_IPL)
82	    | __SHIFTIN(ipl, MTX_IPL);
83}
84
85static inline void
86riscv_mutex_spinbit_lock_init(kmutex_t *__mtx)
87{
88	__mtx->mtx_owner &= ~MTX_LOCK;
89}
90
91static inline bool
92riscv_mutex_spinbit_locked_p(const kmutex_t *__mtx)
93{
94	return (__mtx->mtx_owner & MTX_LOCK) != 0;
95}
96
97static inline bool
98riscv_mutex_spinbit_lock_try(kmutex_t *__mtx)
99{
100	uintptr_t __old;
101	__asm __volatile(
102		"amoor" MTX_ASMOP_SFX ".aq\t%0, %1, (%2)"
103	   :	"=r"(__old)
104	   :	"r"(MTX_LOCK), "r"(__mtx));
105	return (__old & MTX_LOCK) == 0;
106}
107
108static inline void
109riscv_mutex_spinbit_lock_unlock(kmutex_t *__mtx)
110{
111	__asm __volatile(
112		"amoand" MTX_ASMOP_SFX ".rl\tx0, %0, (%1)"
113	   ::	"r"(~MTX_LOCK), "r"(__mtx));
114}
115
116#if 0
117#define	__HAVE_MUTEX_STUBS		1
118#define	__HAVE_SPIN_MUTEX_STUBS		1
119#endif
120#define	__HAVE_SIMPLE_MUTEXES		1
121
122#endif	/* __MUTEX_PRIVATE */
123
124#endif /* _RISCV_MUTEX_H_ */
125