aboutsummaryrefslogtreecommitdiffstats
path: root/arch/hexagon/include/asm/spinlock.h
blob: 168a920485a85973d1e78ec4406eacbdd6e9a675 (plain) (blame)
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
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
/*
 * Spinlock support for the Hexagon architecture
 *
 * Copyright (c) 2010-2011, Code Aurora Forum. All rights reserved.
 *
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 and
 * only version 2 as published by the Free Software Foundation.
 *
 * 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.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
 * 02110-1301, USA.
 */

#ifndef _ASM_SPINLOCK_H
#define _ASM_SPINLOCK_H

#include <asm/irqflags.h>

/*
 * This file is pulled in for SMP builds.
 * Really need to check all the barrier stuff for "true" SMP
 */

/*
 * Read locks:
 * - load the lock value
 * - increment it
 * - if the lock value is still negative, go back and try again.
 * - unsuccessful store is unsuccessful.  Go back and try again.  Loser.
 * - successful store new lock value if positive -> lock acquired
 */
static inline void arch_read_lock(arch_rwlock_t *lock)
{
	__asm__ __volatile__(
		"1:	R6 = memw_locked(%0);\n"
		"	{ P3 = cmp.ge(R6,#0); R6 = add(R6,#1);}\n"
		"	{ if !P3 jump 1b; }\n"
		"	memw_locked(%0,P3) = R6;\n"
		"	{ if !P3 jump 1b; }\n"
		:
		: "r" (&lock->lock)
		: "memory", "r6", "p3"
	);

}

static inline void arch_read_unlock(arch_rwlock_t *lock)
{
	__asm__ __volatile__(
		"1:	R6 = memw_locked(%0);\n"
		"	R6 = add(R6,#-1);\n"
		"	memw_locked(%0,P3) = R6\n"
		"	if !P3 jump 1b;\n"
		:
		: "r" (&lock->lock)
		: "memory", "r6", "p3"
	);

}

/*  I think this returns 0 on fail, 1 on success.  */
static inline int arch_read_trylock(arch_rwlock_t *lock)
{
	int temp;
	__asm__ __volatile__(
		"	R6 = memw_locked(%1);\n"
		"	{ %0 = #0; P3 = cmp.ge(R6,#0); R6 = add(R6,#1);}\n"
		"	{ if !P3 jump 1f; }\n"
		"	memw_locked(%1,P3) = R6;\n"
		"	{ %0 = P3 }\n"
		"1:\n"
		: "=&r" (temp)
		: "r" (&lock->lock)
		: "memory", "r6", "p3"
	);
	return temp;
}

static inline int arch_read_can_lock(arch_rwlock_t *rwlock)
{
	return rwlock->lock == 0;
}

static inline int arch_write_can_lock(arch_rwlock_t *rwlock)
{
	return rwlock->lock == 0;
}

/*  Stuffs a -1 in the lock value?  */
static inline void arch_write_lock(arch_rwlock_t *lock)
{
	__asm__ __volatile__(
		"1:	R6 = memw_locked(%0)\n"
		"	{ P3 = cmp.eq(R6,#0);  R6 = #-1;}\n"
		"	{ if !P3 jump 1b; }\n"
		"	memw_locked(%0,P3) = R6;\n"
		"	{ if !P3 jump 1b; }\n"
		:
		: "r" (&lock->lock)
		: "memory", "r6", "p3"
	);
}


static inline int arch_write_trylock(arch_rwlock_t *lock)
{
	int temp;
	__asm__ __volatile__(
		"	R6 = memw_locked(%1)\n"
		"	{ %0 = #0; P3 = cmp.eq(R6,#0);  R6 = #-1;}\n"
		"	{ if !P3 jump 1f; }\n"
		"	memw_locked(%1,P3) = R6;\n"
		"	%0 = P3;\n"
		"1:\n"
		: "=&r" (temp)
		: "r" (&lock->lock)
		: "memory", "r6", "p3"
	);
	return temp;

}

static inline void arch_write_unlock(arch_rwlock_t *lock)
{
	smp_mb();
	lock->lock = 0;
}

static inline void arch_spin_lock(arch_spinlock_t *lock)
{
	__asm__ __volatile__(
		"1:	R6 = memw_locked(%0);\n"
		"	P3 = cmp.eq(R6,#0);\n"
		"	{ if !P3 jump 1b; R6 = #1; }\n"
		"	memw_locked(%0,P3) = R6;\n"
		"	{ if !P3 jump 1b; }\n"
		:
		: "r" (&lock->lock)
		: "memory", "r6", "p3"
	);

}

static inline void arch_spin_unlock(arch_spinlock_t *lock)
{
	smp_mb();
	lock->lock = 0;
}

static inline unsigned int arch_spin_trylock(arch_spinlock_t *lock)
{
	int temp;
	__asm__ __volatile__(
		"	R6 = memw_locked(%1);\n"
		"	P3 = cmp.eq(R6,#0);\n"
		"	{ if !P3 jump 1f; R6 = #1; %0 = #0; }\n"
		"	memw_locked(%1,P3) = R6;\n"
		"	%0 = P3;\n"
		"1:\n"
		: "=&r" (temp)
		: "r" (&lock->lock)
		: "memory", "r6", "p3"
	);
	return temp;
}

/*
 * SMP spinlocks are intended to allow only a single CPU at the lock
 */
#define arch_spin_lock_flags(lock, flags) arch_spin_lock(lock)
#define arch_spin_unlock_wait(lock) \
	do {while (arch_spin_is_locked(lock)) cpu_relax(); } while (0)
#define arch_spin_is_locked(x) ((x)->lock != 0)

#define arch_read_lock_flags(lock, flags) arch_read_lock(lock)
#define arch_write_lock_flags(lock, flags) arch_write_lock(lock)

#endif