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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 | ||
21 | int printk(const char *fmt, ...); | |
22 | ||
23 | struct semaphore { | |
24 | atomic_t count; | |
25 | atomic_t waking; | |
26 | wait_queue_head_t wait; | |
27 | }; | |
28 | ||
29 | #define __SEMAPHORE_INITIALIZER(name, n) \ | |
30 | { \ | |
31 | .count = ATOMIC_INIT(n), \ | |
32 | .waking = ATOMIC_INIT(0), \ | |
33 | .wait = __WAIT_QUEUE_HEAD_INITIALIZER((name).wait) \ | |
34 | } | |
35 | ||
36 | #define __MUTEX_INITIALIZER(name) \ | |
37 | __SEMAPHORE_INITIALIZER(name,1) | |
38 | ||
39 | #define __DECLARE_SEMAPHORE_GENERIC(name,count) \ | |
40 | struct semaphore name = __SEMAPHORE_INITIALIZER(name,count) | |
41 | ||
42 | #define DECLARE_MUTEX(name) __DECLARE_SEMAPHORE_GENERIC(name,1) | |
43 | #define DECLARE_MUTEX_LOCKED(name) __DECLARE_SEMAPHORE_GENERIC(name,0) | |
44 | ||
45 | extern inline void sema_init(struct semaphore *sem, int val) | |
46 | { | |
47 | *sem = (struct semaphore)__SEMAPHORE_INITIALIZER((*sem),val); | |
48 | } | |
49 | ||
50 | extern inline void init_MUTEX (struct semaphore *sem) | |
51 | { | |
52 | sema_init(sem, 1); | |
53 | } | |
54 | ||
55 | extern inline void init_MUTEX_LOCKED (struct semaphore *sem) | |
56 | { | |
57 | sema_init(sem, 0); | |
58 | } | |
59 | ||
60 | extern void __down(struct semaphore * sem); | |
61 | extern int __down_interruptible(struct semaphore * sem); | |
62 | extern int __down_trylock(struct semaphore * sem); | |
63 | extern void __up(struct semaphore * sem); | |
64 | ||
65 | /* notice - we probably can do cli/sti here instead of saving */ | |
66 | ||
67 | extern inline void down(struct semaphore * sem) | |
68 | { | |
69 | unsigned long flags; | |
70 | int failed; | |
71 | ||
72 | might_sleep(); | |
73 | ||
74 | /* atomically decrement the semaphores count, and if its negative, we wait */ | |
75 | local_save_flags(flags); | |
76 | local_irq_disable(); | |
77 | failed = --(sem->count.counter) < 0; | |
78 | local_irq_restore(flags); | |
79 | if(failed) { | |
80 | __down(sem); | |
81 | } | |
82 | } | |
83 | ||
84 | /* | |
85 | * This version waits in interruptible state so that the waiting | |
86 | * process can be killed. The down_interruptible routine | |
87 | * returns negative for signalled and zero for semaphore acquired. | |
88 | */ | |
89 | ||
90 | extern inline int down_interruptible(struct semaphore * sem) | |
91 | { | |
92 | unsigned long flags; | |
93 | int failed; | |
94 | ||
95 | might_sleep(); | |
96 | ||
97 | /* atomically decrement the semaphores count, and if its negative, we wait */ | |
98 | local_save_flags(flags); | |
99 | local_irq_disable(); | |
100 | failed = --(sem->count.counter) < 0; | |
101 | local_irq_restore(flags); | |
102 | if(failed) | |
103 | failed = __down_interruptible(sem); | |
104 | return(failed); | |
105 | } | |
106 | ||
107 | extern inline int down_trylock(struct semaphore * sem) | |
108 | { | |
109 | unsigned long flags; | |
110 | int failed; | |
111 | ||
112 | local_save_flags(flags); | |
113 | local_irq_disable(); | |
114 | failed = --(sem->count.counter) < 0; | |
115 | local_irq_restore(flags); | |
116 | if(failed) | |
117 | failed = __down_trylock(sem); | |
118 | return(failed); | |
119 | } | |
120 | ||
121 | /* | |
122 | * Note! This is subtle. We jump to wake people up only if | |
123 | * the semaphore was negative (== somebody was waiting on it). | |
124 | * The default case (no contention) will result in NO | |
125 | * jumps for both down() and up(). | |
126 | */ | |
127 | extern inline void up(struct semaphore * sem) | |
128 | { | |
129 | unsigned long flags; | |
130 | int wakeup; | |
131 | ||
132 | /* atomically increment the semaphores count, and if it was negative, we wake people */ | |
133 | local_save_flags(flags); | |
134 | local_irq_disable(); | |
135 | wakeup = ++(sem->count.counter) <= 0; | |
136 | local_irq_restore(flags); | |
137 | if(wakeup) { | |
138 | __up(sem); | |
139 | } | |
140 | } | |
141 | ||
142 | #endif |