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