aboutsummaryrefslogtreecommitdiff
path: root/arch/sh/include/asm/spinlock.h
blob: bdc0f3b6c56afdf23d6b628128e6171cc2552b74 (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
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
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
/*
 * include/asm-sh/spinlock.h
 *
 * Copyright (C) 2002, 2003 Paul Mundt
 * Copyright (C) 2006, 2007 Akio Idehara
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 */
#ifndef __ASM_SH_SPINLOCK_H
#define __ASM_SH_SPINLOCK_H

/*
 * The only locking implemented here uses SH-4A opcodes. For others,
 * split this out as per atomic-*.h.
 */
#ifndef CONFIG_CPU_SH4A
#error "Need movli.l/movco.l for spinlocks"
#endif

/*
 * Your basic SMP spinlocks, allowing only a single CPU anywhere
 */

#define arch_spin_is_locked(x)		((x)->lock <= 0)
#define arch_spin_lock_flags(lock, flags) arch_spin_lock(lock)
#define arch_spin_unlock_wait(x) \
	do { while (arch_spin_is_locked(x)) cpu_relax(); } while (0)

/*
 * Simple spin lock operations.  There are two variants, one clears IRQ's
 * on the local processor, one does not.
 *
 * We make no fairness assumptions.  They have a cost.
 */
static inline void arch_spin_lock(arch_spinlock_t *lock)
{
	unsigned long tmp;
	unsigned long oldval;

	__asm__ __volatile__ (
		"1:						\n\t"
		"movli.l	@%2, %0	! arch_spin_lock	\n\t"
		"mov		%0, %1				\n\t"
		"mov		#0, %0				\n\t"
		"movco.l	%0, @%2				\n\t"
		"bf		1b				\n\t"
		"cmp/pl		%1				\n\t"
		"bf		1b				\n\t"
		: "=&z" (tmp), "=&r" (oldval)
		: "r" (&lock->lock)
		: "t", "memory"
	);
}

static inline void arch_spin_unlock(arch_spinlock_t *lock)
{
	unsigned long tmp;

	__asm__ __volatile__ (
		"mov		#1, %0 ! arch_spin_unlock	\n\t"
		"mov.l		%0, @%1				\n\t"
		: "=&z" (tmp)
		: "r" (&lock->lock)
		: "t", "memory"
	);
}

static inline int arch_spin_trylock(arch_spinlock_t *lock)
{
	unsigned long tmp, oldval;

	__asm__ __volatile__ (
		"1:						\n\t"
		"movli.l	@%2, %0	! arch_spin_trylock	\n\t"
		"mov		%0, %1				\n\t"
		"mov		#0, %0				\n\t"
		"movco.l	%0, @%2				\n\t"
		"bf		1b				\n\t"
		"synco						\n\t"
		: "=&z" (tmp), "=&r" (oldval)
		: "r" (&lock->lock)
		: "t", "memory"
	);

	return oldval;
}

/*
 * Read-write spinlocks, allowing multiple readers but only one writer.
 *
 * NOTE! it is quite common to have readers in interrupts but no interrupt
 * writers. For those circumstances we can "mix" irq-safe locks - any writer
 * needs to get a irq-safe write-lock, but readers can get non-irqsafe
 * read-locks.
 */

/**
 * read_can_lock - would read_trylock() succeed?
 * @lock: the rwlock in question.
 */
#define arch_read_can_lock(x)	((x)->lock > 0)

/**
 * write_can_lock - would write_trylock() succeed?
 * @lock: the rwlock in question.
 */
#define arch_write_can_lock(x)	((x)->lock == RW_LOCK_BIAS)

static inline void arch_read_lock(arch_rwlock_t *rw)
{
	unsigned long tmp;

	__asm__ __volatile__ (
		"1:						\n\t"
		"movli.l	@%1, %0	! arch_read_lock	\n\t"
		"cmp/pl		%0				\n\t"
		"bf		1b				\n\t"
		"add		#-1, %0				\n\t"
		"movco.l	%0, @%1				\n\t"
		"bf		1b				\n\t"
		: "=&z" (tmp)
		: "r" (&rw->lock)
		: "t", "memory"
	);
}

static inline void arch_read_unlock(arch_rwlock_t *rw)
{
	unsigned long tmp;

	__asm__ __volatile__ (
		"1:						\n\t"
		"movli.l	@%1, %0	! arch_read_unlock	\n\t"
		"add		#1, %0				\n\t"
		"movco.l	%0, @%1				\n\t"
		"bf		1b				\n\t"
		: "=&z" (tmp)
		: "r" (&rw->lock)
		: "t", "memory"
	);
}

static inline void arch_write_lock(arch_rwlock_t *rw)
{
	unsigned long tmp;

	__asm__ __volatile__ (
		"1:						\n\t"
		"movli.l	@%1, %0	! arch_write_lock	\n\t"
		"cmp/hs		%2, %0				\n\t"
		"bf		1b				\n\t"
		"sub		%2, %0				\n\t"
		"movco.l	%0, @%1				\n\t"
		"bf		1b				\n\t"
		: "=&z" (tmp)
		: "r" (&rw->lock), "r" (RW_LOCK_BIAS)
		: "t", "memory"
	);
}

static inline void arch_write_unlock(arch_rwlock_t *rw)
{
	__asm__ __volatile__ (
		"mov.l		%1, @%0 ! arch_write_unlock	\n\t"
		:
		: "r" (&rw->lock), "r" (RW_LOCK_BIAS)
		: "t", "memory"
	);
}

static inline int arch_read_trylock(arch_rwlock_t *rw)
{
	unsigned long tmp, oldval;

	__asm__ __volatile__ (
		"1:						\n\t"
		"movli.l	@%2, %0	! arch_read_trylock	\n\t"
		"mov		%0, %1				\n\t"
		"cmp/pl		%0				\n\t"
		"bf		2f				\n\t"
		"add		#-1, %0				\n\t"
		"movco.l	%0, @%2				\n\t"
		"bf		1b				\n\t"
		"2:						\n\t"
		"synco						\n\t"
		: "=&z" (tmp), "=&r" (oldval)
		: "r" (&rw->lock)
		: "t", "memory"
	);

	return (oldval > 0);
}

static inline int arch_write_trylock(arch_rwlock_t *rw)
{
	unsigned long tmp, oldval;

	__asm__ __volatile__ (
		"1:						\n\t"
		"movli.l	@%2, %0	! arch_write_trylock	\n\t"
		"mov		%0, %1				\n\t"
		"cmp/hs		%3, %0				\n\t"
		"bf		2f				\n\t"
		"sub		%3, %0				\n\t"
		"2:						\n\t"
		"movco.l	%0, @%2				\n\t"
		"bf		1b				\n\t"
		"synco						\n\t"
		: "=&z" (tmp), "=&r" (oldval)
		: "r" (&rw->lock), "r" (RW_LOCK_BIAS)
		: "t", "memory"
	);

	return (oldval > (RW_LOCK_BIAS - 1));
}

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

#define arch_spin_relax(lock)	cpu_relax()
#define arch_read_relax(lock)	cpu_relax()
#define arch_write_relax(lock)	cpu_relax()

#endif /* __ASM_SH_SPINLOCK_H */