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1da177e4 LT |
1 | /* $Id: semaphore.h,v 1.3 2001/05/08 13:54:09 bjornw Exp $ */ |
2 | ||
3 | /* On the i386 these are coded in asm, perhaps we should as well. Later.. */ | |
4 | ||
5 | #ifndef _CRIS_SEMAPHORE_H | |
6 | #define _CRIS_SEMAPHORE_H | |
7 | ||
8 | #define RW_LOCK_BIAS 0x01000000 | |
9 | ||
10 | #include <linux/wait.h> | |
11 | #include <linux/spinlock.h> | |
12 | #include <linux/rwsem.h> | |
13 | ||
14 | #include <asm/system.h> | |
15 | #include <asm/atomic.h> | |
16 | ||
17 | /* | |
18 | * CRIS semaphores, implemented in C-only so far. | |
19 | */ | |
20 | ||
1da177e4 LT |
21 | struct semaphore { |
22 | atomic_t count; | |
23 | atomic_t waking; | |
24 | wait_queue_head_t wait; | |
25 | }; | |
26 | ||
27 | #define __SEMAPHORE_INITIALIZER(name, n) \ | |
28 | { \ | |
29 | .count = ATOMIC_INIT(n), \ | |
30 | .waking = ATOMIC_INIT(0), \ | |
31 | .wait = __WAIT_QUEUE_HEAD_INITIALIZER((name).wait) \ | |
32 | } | |
33 | ||
1da177e4 LT |
34 | #define __DECLARE_SEMAPHORE_GENERIC(name,count) \ |
35 | struct semaphore name = __SEMAPHORE_INITIALIZER(name,count) | |
36 | ||
37 | #define DECLARE_MUTEX(name) __DECLARE_SEMAPHORE_GENERIC(name,1) | |
38 | #define DECLARE_MUTEX_LOCKED(name) __DECLARE_SEMAPHORE_GENERIC(name,0) | |
39 | ||
d9b5444e | 40 | static inline void sema_init(struct semaphore *sem, int val) |
1da177e4 LT |
41 | { |
42 | *sem = (struct semaphore)__SEMAPHORE_INITIALIZER((*sem),val); | |
43 | } | |
44 | ||
d9b5444e | 45 | static inline void init_MUTEX (struct semaphore *sem) |
1da177e4 LT |
46 | { |
47 | sema_init(sem, 1); | |
48 | } | |
49 | ||
d9b5444e | 50 | static inline void init_MUTEX_LOCKED (struct semaphore *sem) |
1da177e4 LT |
51 | { |
52 | sema_init(sem, 0); | |
53 | } | |
54 | ||
55 | extern void __down(struct semaphore * sem); | |
56 | extern int __down_interruptible(struct semaphore * sem); | |
57 | extern int __down_trylock(struct semaphore * sem); | |
58 | extern void __up(struct semaphore * sem); | |
59 | ||
60 | /* notice - we probably can do cli/sti here instead of saving */ | |
61 | ||
d9b5444e | 62 | static inline void down(struct semaphore * sem) |
1da177e4 LT |
63 | { |
64 | unsigned long flags; | |
65 | int failed; | |
66 | ||
67 | might_sleep(); | |
68 | ||
69 | /* atomically decrement the semaphores count, and if its negative, we wait */ | |
8d20a541 | 70 | cris_atomic_save(sem, flags); |
1da177e4 | 71 | failed = --(sem->count.counter) < 0; |
8d20a541 | 72 | cris_atomic_restore(sem, flags); |
1da177e4 LT |
73 | if(failed) { |
74 | __down(sem); | |
75 | } | |
76 | } | |
77 | ||
78 | /* | |
79 | * This version waits in interruptible state so that the waiting | |
80 | * process can be killed. The down_interruptible routine | |
81 | * returns negative for signalled and zero for semaphore acquired. | |
82 | */ | |
83 | ||
d9b5444e | 84 | static inline int down_interruptible(struct semaphore * sem) |
1da177e4 LT |
85 | { |
86 | unsigned long flags; | |
87 | int failed; | |
88 | ||
89 | might_sleep(); | |
90 | ||
91 | /* atomically decrement the semaphores count, and if its negative, we wait */ | |
8d20a541 | 92 | cris_atomic_save(sem, flags); |
1da177e4 | 93 | failed = --(sem->count.counter) < 0; |
8d20a541 | 94 | cris_atomic_restore(sem, flags); |
1da177e4 LT |
95 | if(failed) |
96 | failed = __down_interruptible(sem); | |
97 | return(failed); | |
98 | } | |
99 | ||
d9b5444e | 100 | static inline int down_trylock(struct semaphore * sem) |
1da177e4 LT |
101 | { |
102 | unsigned long flags; | |
103 | int failed; | |
104 | ||
8d20a541 | 105 | cris_atomic_save(sem, flags); |
1da177e4 | 106 | failed = --(sem->count.counter) < 0; |
8d20a541 | 107 | cris_atomic_restore(sem, flags); |
1da177e4 LT |
108 | if(failed) |
109 | failed = __down_trylock(sem); | |
110 | return(failed); | |
8d20a541 | 111 | |
1da177e4 LT |
112 | } |
113 | ||
114 | /* | |
115 | * Note! This is subtle. We jump to wake people up only if | |
116 | * the semaphore was negative (== somebody was waiting on it). | |
117 | * The default case (no contention) will result in NO | |
118 | * jumps for both down() and up(). | |
119 | */ | |
d9b5444e | 120 | static inline void up(struct semaphore * sem) |
1da177e4 LT |
121 | { |
122 | unsigned long flags; | |
123 | int wakeup; | |
124 | ||
125 | /* atomically increment the semaphores count, and if it was negative, we wake people */ | |
8d20a541 | 126 | cris_atomic_save(sem, flags); |
1da177e4 | 127 | wakeup = ++(sem->count.counter) <= 0; |
8d20a541 | 128 | cris_atomic_restore(sem, flags); |
1da177e4 LT |
129 | if(wakeup) { |
130 | __up(sem); | |
131 | } | |
132 | } | |
133 | ||
134 | #endif |