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1 | #ifndef _PPC_SEMAPHORE_H |
2 | #define _PPC_SEMAPHORE_H | |
3 | ||
4 | /* | |
5 | * Swiped from asm-sparc/semaphore.h and modified | |
6 | * -- Cort (cort@cs.nmt.edu) | |
7 | * | |
8 | * Stole some rw spinlock-based semaphore stuff from asm-alpha/semaphore.h | |
9 | * -- Ani Joshi (ajoshi@unixbox.com) | |
10 | * | |
11 | * Remove spinlock-based RW semaphores; RW semaphore definitions are | |
12 | * now in rwsem.h and we use the generic lib/rwsem.c implementation. | |
13 | * Rework semaphores to use atomic_dec_if_positive. | |
14 | * -- Paul Mackerras (paulus@samba.org) | |
15 | */ | |
16 | ||
17 | #ifdef __KERNEL__ | |
18 | ||
19 | #include <asm/atomic.h> | |
20 | #include <asm/system.h> | |
21 | #include <linux/wait.h> | |
22 | #include <linux/rwsem.h> | |
23 | ||
24 | struct semaphore { | |
25 | /* | |
26 | * Note that any negative value of count is equivalent to 0, | |
27 | * but additionally indicates that some process(es) might be | |
28 | * sleeping on `wait'. | |
29 | */ | |
30 | atomic_t count; | |
31 | wait_queue_head_t wait; | |
32 | }; | |
33 | ||
34 | #define __SEMAPHORE_INITIALIZER(name, n) \ | |
35 | { \ | |
36 | .count = ATOMIC_INIT(n), \ | |
37 | .wait = __WAIT_QUEUE_HEAD_INITIALIZER((name).wait) \ | |
38 | } | |
39 | ||
40 | #define __MUTEX_INITIALIZER(name) \ | |
41 | __SEMAPHORE_INITIALIZER(name, 1) | |
42 | ||
43 | #define __DECLARE_SEMAPHORE_GENERIC(name, count) \ | |
44 | struct semaphore name = __SEMAPHORE_INITIALIZER(name,count) | |
45 | ||
46 | #define DECLARE_MUTEX(name) __DECLARE_SEMAPHORE_GENERIC(name, 1) | |
47 | #define DECLARE_MUTEX_LOCKED(name) __DECLARE_SEMAPHORE_GENERIC(name, 0) | |
48 | ||
49 | static inline void sema_init (struct semaphore *sem, int val) | |
50 | { | |
51 | atomic_set(&sem->count, val); | |
52 | init_waitqueue_head(&sem->wait); | |
53 | } | |
54 | ||
55 | static inline void init_MUTEX (struct semaphore *sem) | |
56 | { | |
57 | sema_init(sem, 1); | |
58 | } | |
59 | ||
60 | static inline void init_MUTEX_LOCKED (struct semaphore *sem) | |
61 | { | |
62 | sema_init(sem, 0); | |
63 | } | |
64 | ||
65 | extern void __down(struct semaphore * sem); | |
66 | extern int __down_interruptible(struct semaphore * sem); | |
67 | extern void __up(struct semaphore * sem); | |
68 | ||
69 | extern inline void down(struct semaphore * sem) | |
70 | { | |
71 | might_sleep(); | |
72 | ||
73 | /* | |
74 | * Try to get the semaphore, take the slow path if we fail. | |
75 | */ | |
76 | if (atomic_dec_return(&sem->count) < 0) | |
77 | __down(sem); | |
78 | smp_wmb(); | |
79 | } | |
80 | ||
81 | extern inline int down_interruptible(struct semaphore * sem) | |
82 | { | |
83 | int ret = 0; | |
84 | ||
85 | might_sleep(); | |
86 | ||
87 | if (atomic_dec_return(&sem->count) < 0) | |
88 | ret = __down_interruptible(sem); | |
89 | smp_wmb(); | |
90 | return ret; | |
91 | } | |
92 | ||
93 | extern inline int down_trylock(struct semaphore * sem) | |
94 | { | |
95 | int ret; | |
96 | ||
97 | ret = atomic_dec_if_positive(&sem->count) < 0; | |
98 | smp_wmb(); | |
99 | return ret; | |
100 | } | |
101 | ||
102 | extern inline void up(struct semaphore * sem) | |
103 | { | |
104 | smp_wmb(); | |
105 | if (atomic_inc_return(&sem->count) <= 0) | |
106 | __up(sem); | |
107 | } | |
108 | ||
109 | #endif /* __KERNEL__ */ | |
110 | ||
111 | #endif /* !(_PPC_SEMAPHORE_H) */ |