summaryrefslogtreecommitdiffstats
path: root/arch/riscv/include/asm/spinlock.h
blob: 04c71d938afdbf40f93d0d5d9d89229fa5f72c56 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
/*
 * Copyright (C) 2015 Regents of the University of California
 * Copyright (C) 2017 SiFive
 *
 *   This program is free software; you can redistribute it and/or
 *   modify it under the terms of the GNU General Public License
 *   as published by the Free Software Foundation, version 2.
 *
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *   GNU General Public License for more details.
 */

#ifndef _ASM_RISCV_SPINLOCK_H
#define _ASM_RISCV_SPINLOCK_H

#include <linux/kernel.h>
#include <asm/current.h>

/*
 * Simple spin lock operations.  These provide no fairness guarantees.
 */

/* FIXME: Replace this with a ticket lock, like MIPS. */

#define arch_spin_is_locked(x)	((x)->lock != 0)

static inline void arch_spin_unlock(arch_spinlock_t *lock)
{
	__asm__ __volatile__ (
		"amoswap.w.rl x0, x0, %0"
		: "=A" (lock->lock)
		:: "memory");
}

static inline int arch_spin_trylock(arch_spinlock_t *lock)
{
	int tmp = 1, busy;

	__asm__ __volatile__ (
		"amoswap.w.aq %0, %2, %1"
		: "=r" (busy), "+A" (lock->lock)
		: "r" (tmp)
		: "memory");

	return !busy;
}

static inline void arch_spin_lock(arch_spinlock_t *lock)
{
	while (1) {
		if (arch_spin_is_locked(lock))
			continue;

		if (arch_spin_trylock(lock))
			break;
	}
}

static inline void arch_spin_unlock_wait(arch_spinlock_t *lock)
{
	smp_rmb();
	do {
		cpu_relax();
	} while (arch_spin_is_locked(lock));
	smp_acquire__after_ctrl_dep();
}

/***********************************************************/

static inline void arch_read_lock(arch_rwlock_t *lock)
{
	int tmp;

	__asm__ __volatile__(
		"1:	lr.w	%1, %0\n"
		"	bltz	%1, 1b\n"
		"	addi	%1, %1, 1\n"
		"	sc.w.aq	%1, %1, %0\n"
		"	bnez	%1, 1b\n"
		: "+A" (lock->lock), "=&r" (tmp)
		:: "memory");
}

static inline void arch_write_lock(arch_rwlock_t *lock)
{
	int tmp;

	__asm__ __volatile__(
		"1:	lr.w	%1, %0\n"
		"	bnez	%1, 1b\n"
		"	li	%1, -1\n"
		"	sc.w.aq	%1, %1, %0\n"
		"	bnez	%1, 1b\n"
		: "+A" (lock->lock), "=&r" (tmp)
		:: "memory");
}

static inline int arch_read_trylock(arch_rwlock_t *lock)
{
	int busy;

	__asm__ __volatile__(
		"1:	lr.w	%1, %0\n"
		"	bltz	%1, 1f\n"
		"	addi	%1, %1, 1\n"
		"	sc.w.aq	%1, %1, %0\n"
		"	bnez	%1, 1b\n"
		"1:\n"
		: "+A" (lock->lock), "=&r" (busy)
		:: "memory");

	return !busy;
}

static inline int arch_write_trylock(arch_rwlock_t *lock)
{
	int busy;

	__asm__ __volatile__(
		"1:	lr.w	%1, %0\n"
		"	bnez	%1, 1f\n"
		"	li	%1, -1\n"
		"	sc.w.aq	%1, %1, %0\n"
		"	bnez	%1, 1b\n"
		"1:\n"
		: "+A" (lock->lock), "=&r" (busy)
		:: "memory");

	return !busy;
}

static inline void arch_read_unlock(arch_rwlock_t *lock)
{
	__asm__ __volatile__(
		"amoadd.w.rl x0, %1, %0"
		: "+A" (lock->lock)
		: "r" (-1)
		: "memory");
}

static inline void arch_write_unlock(arch_rwlock_t *lock)
{
	__asm__ __volatile__ (
		"amoswap.w.rl x0, x0, %0"
		: "=A" (lock->lock)
		:: "memory");
}

#endif /* _ASM_RISCV_SPINLOCK_H */