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1/*
2 * include/asm-s390/spinlock.h
3 *
4 * S390 version
5 * Copyright (C) 1999 IBM Deutschland Entwicklung GmbH, IBM Corporation
6 * Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com)
7 *
8 * Derived from "include/asm-i386/spinlock.h"
9 */
10
11#ifndef __ASM_SPINLOCK_H
12#define __ASM_SPINLOCK_H
13
14#include <linux/smp.h>
15
16#if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ > 2)
17
18static inline int
19_raw_compare_and_swap(volatile unsigned int *lock,
20 unsigned int old, unsigned int new)
21{
22 asm volatile(
23 " cs %0,%3,%1"
24 : "=d" (old), "=Q" (*lock)
25 : "0" (old), "d" (new), "Q" (*lock)
26 : "cc", "memory" );
27 return old;
28}
29
30#else /* __GNUC__ */
31
32static inline int
33_raw_compare_and_swap(volatile unsigned int *lock,
34 unsigned int old, unsigned int new)
35{
36 asm volatile(
37 " cs %0,%3,0(%4)"
38 : "=d" (old), "=m" (*lock)
39 : "0" (old), "d" (new), "a" (lock), "m" (*lock)
40 : "cc", "memory" );
41 return old;
42}
43
44#endif /* __GNUC__ */
45
46/*
47 * Simple spin lock operations. There are two variants, one clears IRQ's
48 * on the local processor, one does not.
49 *
50 * We make no fairness assumptions. They have a cost.
51 *
52 * (the type definitions are in asm/spinlock_types.h)
53 */
54
55#define __raw_spin_is_locked(x) ((x)->owner_cpu != 0)
56#define __raw_spin_unlock_wait(lock) \
57 do { while (__raw_spin_is_locked(lock)) \
58 _raw_spin_relax(lock); } while (0)
59
60extern void _raw_spin_lock_wait(raw_spinlock_t *);
61extern void _raw_spin_lock_wait_flags(raw_spinlock_t *, unsigned long flags);
62extern int _raw_spin_trylock_retry(raw_spinlock_t *);
63extern void _raw_spin_relax(raw_spinlock_t *lock);
64
65static inline void __raw_spin_lock(raw_spinlock_t *lp)
66{
67 int old;
68
69 old = _raw_compare_and_swap(&lp->owner_cpu, 0, ~smp_processor_id());
70 if (likely(old == 0))
71 return;
72 _raw_spin_lock_wait(lp);
73}
74
75static inline void __raw_spin_lock_flags(raw_spinlock_t *lp,
76 unsigned long flags)
77{
78 int old;
79
80 old = _raw_compare_and_swap(&lp->owner_cpu, 0, ~smp_processor_id());
81 if (likely(old == 0))
82 return;
83 _raw_spin_lock_wait_flags(lp, flags);
84}
85
86static inline int __raw_spin_trylock(raw_spinlock_t *lp)
87{
88 int old;
89
90 old = _raw_compare_and_swap(&lp->owner_cpu, 0, ~smp_processor_id());
91 if (likely(old == 0))
92 return 1;
93 return _raw_spin_trylock_retry(lp);
94}
95
96static inline void __raw_spin_unlock(raw_spinlock_t *lp)
97{
98 _raw_compare_and_swap(&lp->owner_cpu, lp->owner_cpu, 0);
99}
100
101/*
102 * Read-write spinlocks, allowing multiple readers
103 * but only one writer.
104 *
105 * NOTE! it is quite common to have readers in interrupts
106 * but no interrupt writers. For those circumstances we
107 * can "mix" irq-safe locks - any writer needs to get a
108 * irq-safe write-lock, but readers can get non-irqsafe
109 * read-locks.
110 */
111
112/**
113 * read_can_lock - would read_trylock() succeed?
114 * @lock: the rwlock in question.
115 */
116#define __raw_read_can_lock(x) ((int)(x)->lock >= 0)
117
118/**
119 * write_can_lock - would write_trylock() succeed?
120 * @lock: the rwlock in question.
121 */
122#define __raw_write_can_lock(x) ((x)->lock == 0)
123
124extern void _raw_read_lock_wait(raw_rwlock_t *lp);
125extern int _raw_read_trylock_retry(raw_rwlock_t *lp);
126extern void _raw_write_lock_wait(raw_rwlock_t *lp);
127extern int _raw_write_trylock_retry(raw_rwlock_t *lp);
128
129static inline void __raw_read_lock(raw_rwlock_t *rw)
130{
131 unsigned int old;
132 old = rw->lock & 0x7fffffffU;
133 if (_raw_compare_and_swap(&rw->lock, old, old + 1) != old)
134 _raw_read_lock_wait(rw);
135}
136
137static inline void __raw_read_unlock(raw_rwlock_t *rw)
138{
139 unsigned int old, cmp;
140
141 old = rw->lock;
142 do {
143 cmp = old;
144 old = _raw_compare_and_swap(&rw->lock, old, old - 1);
145 } while (cmp != old);
146}
147
148static inline void __raw_write_lock(raw_rwlock_t *rw)
149{
150 if (unlikely(_raw_compare_and_swap(&rw->lock, 0, 0x80000000) != 0))
151 _raw_write_lock_wait(rw);
152}
153
154static inline void __raw_write_unlock(raw_rwlock_t *rw)
155{
156 _raw_compare_and_swap(&rw->lock, 0x80000000, 0);
157}
158
159static inline int __raw_read_trylock(raw_rwlock_t *rw)
160{
161 unsigned int old;
162 old = rw->lock & 0x7fffffffU;
163 if (likely(_raw_compare_and_swap(&rw->lock, old, old + 1) == old))
164 return 1;
165 return _raw_read_trylock_retry(rw);
166}
167
168static inline int __raw_write_trylock(raw_rwlock_t *rw)
169{
170 if (likely(_raw_compare_and_swap(&rw->lock, 0, 0x80000000) == 0))
171 return 1;
172 return _raw_write_trylock_retry(rw);
173}
174
175#define _raw_read_relax(lock) cpu_relax()
176#define _raw_write_relax(lock) cpu_relax()
177
178#endif /* __ASM_SPINLOCK_H */