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1da177e4 LT |
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 | ||
951f22d5 MS |
14 | static inline int |
15 | _raw_compare_and_swap(volatile unsigned int *lock, | |
16 | unsigned int old, unsigned int new) | |
17 | { | |
18 | asm volatile ("cs %0,%3,0(%4)" | |
19 | : "=d" (old), "=m" (*lock) | |
20 | : "0" (old), "d" (new), "a" (lock), "m" (*lock) | |
21 | : "cc", "memory" ); | |
22 | return old; | |
23 | } | |
1da177e4 LT |
24 | |
25 | /* | |
26 | * Simple spin lock operations. There are two variants, one clears IRQ's | |
27 | * on the local processor, one does not. | |
28 | * | |
29 | * We make no fairness assumptions. They have a cost. | |
30 | */ | |
31 | ||
32 | typedef struct { | |
33 | volatile unsigned int lock; | |
34 | #ifdef CONFIG_PREEMPT | |
35 | unsigned int break_lock; | |
36 | #endif | |
37 | } __attribute__ ((aligned (4))) spinlock_t; | |
38 | ||
951f22d5 MS |
39 | #define SPIN_LOCK_UNLOCKED (spinlock_t) { 0 } |
40 | #define spin_lock_init(lp) do { (lp)->lock = 0; } while(0) | |
1da177e4 | 41 | #define spin_unlock_wait(lp) do { barrier(); } while(((volatile spinlock_t *)(lp))->lock) |
951f22d5 | 42 | #define spin_is_locked(x) ((x)->lock != 0) |
1da177e4 LT |
43 | #define _raw_spin_lock_flags(lock, flags) _raw_spin_lock(lock) |
44 | ||
951f22d5 MS |
45 | extern void _raw_spin_lock_wait(spinlock_t *lp, unsigned int pc); |
46 | extern int _raw_spin_trylock_retry(spinlock_t *lp, unsigned int pc); | |
47 | ||
48 | static inline void _raw_spin_lock(spinlock_t *lp) | |
1da177e4 | 49 | { |
9513e5e3 | 50 | unsigned long pc = 1 | (unsigned long) __builtin_return_address(0); |
951f22d5 MS |
51 | |
52 | if (unlikely(_raw_compare_and_swap(&lp->lock, 0, pc) != 0)) | |
53 | _raw_spin_lock_wait(lp, pc); | |
1da177e4 LT |
54 | } |
55 | ||
951f22d5 | 56 | static inline int _raw_spin_trylock(spinlock_t *lp) |
1da177e4 | 57 | { |
9513e5e3 | 58 | unsigned long pc = 1 | (unsigned long) __builtin_return_address(0); |
951f22d5 MS |
59 | |
60 | if (likely(_raw_compare_and_swap(&lp->lock, 0, pc) == 0)) | |
61 | return 1; | |
62 | return _raw_spin_trylock_retry(lp, pc); | |
1da177e4 LT |
63 | } |
64 | ||
951f22d5 | 65 | static inline void _raw_spin_unlock(spinlock_t *lp) |
1da177e4 | 66 | { |
951f22d5 | 67 | _raw_compare_and_swap(&lp->lock, lp->lock, 0); |
1da177e4 LT |
68 | } |
69 | ||
70 | /* | |
71 | * Read-write spinlocks, allowing multiple readers | |
72 | * but only one writer. | |
73 | * | |
74 | * NOTE! it is quite common to have readers in interrupts | |
75 | * but no interrupt writers. For those circumstances we | |
76 | * can "mix" irq-safe locks - any writer needs to get a | |
77 | * irq-safe write-lock, but readers can get non-irqsafe | |
78 | * read-locks. | |
79 | */ | |
80 | typedef struct { | |
951f22d5 | 81 | volatile unsigned int lock; |
1da177e4 LT |
82 | volatile unsigned long owner_pc; |
83 | #ifdef CONFIG_PREEMPT | |
84 | unsigned int break_lock; | |
85 | #endif | |
86 | } rwlock_t; | |
87 | ||
88 | #define RW_LOCK_UNLOCKED (rwlock_t) { 0, 0 } | |
89 | ||
90 | #define rwlock_init(x) do { *(x) = RW_LOCK_UNLOCKED; } while(0) | |
91 | ||
92 | /** | |
93 | * read_can_lock - would read_trylock() succeed? | |
94 | * @lock: the rwlock in question. | |
95 | */ | |
96 | #define read_can_lock(x) ((int)(x)->lock >= 0) | |
97 | ||
98 | /** | |
99 | * write_can_lock - would write_trylock() succeed? | |
100 | * @lock: the rwlock in question. | |
101 | */ | |
102 | #define write_can_lock(x) ((x)->lock == 0) | |
103 | ||
951f22d5 MS |
104 | extern void _raw_read_lock_wait(rwlock_t *lp); |
105 | extern int _raw_read_trylock_retry(rwlock_t *lp); | |
106 | extern void _raw_write_lock_wait(rwlock_t *lp); | |
107 | extern int _raw_write_trylock_retry(rwlock_t *lp); | |
108 | ||
109 | static inline void _raw_read_lock(rwlock_t *rw) | |
110 | { | |
111 | unsigned int old; | |
112 | old = rw->lock & 0x7fffffffU; | |
113 | if (_raw_compare_and_swap(&rw->lock, old, old + 1) != old) | |
114 | _raw_read_lock_wait(rw); | |
115 | } | |
116 | ||
117 | static inline void _raw_read_unlock(rwlock_t *rw) | |
118 | { | |
119 | unsigned int old, cmp; | |
120 | ||
121 | old = rw->lock; | |
122 | do { | |
123 | cmp = old; | |
124 | old = _raw_compare_and_swap(&rw->lock, old, old - 1); | |
125 | } while (cmp != old); | |
126 | } | |
127 | ||
128 | static inline void _raw_write_lock(rwlock_t *rw) | |
129 | { | |
130 | if (unlikely(_raw_compare_and_swap(&rw->lock, 0, 0x80000000) != 0)) | |
131 | _raw_write_lock_wait(rw); | |
132 | } | |
133 | ||
134 | static inline void _raw_write_unlock(rwlock_t *rw) | |
135 | { | |
136 | _raw_compare_and_swap(&rw->lock, 0x80000000, 0); | |
137 | } | |
138 | ||
139 | static inline int _raw_read_trylock(rwlock_t *rw) | |
140 | { | |
141 | unsigned int old; | |
142 | old = rw->lock & 0x7fffffffU; | |
143 | if (likely(_raw_compare_and_swap(&rw->lock, old, old + 1) == old)) | |
144 | return 1; | |
145 | return _raw_read_trylock_retry(rw); | |
146 | } | |
147 | ||
148 | static inline int _raw_write_trylock(rwlock_t *rw) | |
1da177e4 | 149 | { |
951f22d5 MS |
150 | if (likely(_raw_compare_and_swap(&rw->lock, 0, 0x80000000) == 0)) |
151 | return 1; | |
152 | return _raw_write_trylock_retry(rw); | |
1da177e4 LT |
153 | } |
154 | ||
155 | #endif /* __ASM_SPINLOCK_H */ |