File: /usr/src/linux/include/asm-cris/semaphore.h
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 int count; /* not atomic_t since we do the atomicity here already */
25 atomic_t waking;
26 wait_queue_head_t wait;
27 #if WAITQUEUE_DEBUG
28 long __magic;
29 #endif
30 };
31
32 #if WAITQUEUE_DEBUG
33 # define __SEM_DEBUG_INIT(name) , (long)&(name).__magic
34 #else
35 # define __SEM_DEBUG_INIT(name)
36 #endif
37
38 #define __SEMAPHORE_INITIALIZER(name,count) \
39 { count, ATOMIC_INIT(0), \
40 __WAIT_QUEUE_HEAD_INITIALIZER((name).wait) \
41 __SEM_DEBUG_INIT(name) }
42
43 #define __MUTEX_INITIALIZER(name) \
44 __SEMAPHORE_INITIALIZER(name,1)
45
46 #define __DECLARE_SEMAPHORE_GENERIC(name,count) \
47 struct semaphore name = __SEMAPHORE_INITIALIZER(name,count)
48
49 #define DECLARE_MUTEX(name) __DECLARE_SEMAPHORE_GENERIC(name,1)
50 #define DECLARE_MUTEX_LOCKED(name) __DECLARE_SEMAPHORE_GENERIC(name,0)
51
52 extern inline void sema_init(struct semaphore *sem, int val)
53 {
54 *sem = (struct semaphore)__SEMAPHORE_INITIALIZER((*sem),val);
55 }
56
57 static inline void init_MUTEX (struct semaphore *sem)
58 {
59 sema_init(sem, 1);
60 }
61
62 static inline void init_MUTEX_LOCKED (struct semaphore *sem)
63 {
64 sema_init(sem, 0);
65 }
66
67 extern void __down(struct semaphore * sem);
68 extern int __down_interruptible(struct semaphore * sem);
69 extern int __down_trylock(struct semaphore * sem);
70 extern void __up(struct semaphore * sem);
71
72 /* notice - we probably can do cli/sti here instead of saving */
73
74 extern inline void down(struct semaphore * sem)
75 {
76 unsigned long flags;
77 int failed;
78
79 #if WAITQUEUE_DEBUG
80 CHECK_MAGIC(sem->__magic);
81 #endif
82
83 /* atomically decrement the semaphores count, and if its negative, we wait */
84 save_flags(flags);
85 cli();
86 failed = --(sem->count) < 0;
87 restore_flags(flags);
88 if(failed) {
89 __down(sem);
90 }
91 }
92
93 /*
94 * This version waits in interruptible state so that the waiting
95 * process can be killed. The down_interruptible routine
96 * returns negative for signalled and zero for semaphore acquired.
97 */
98
99 extern inline int down_interruptible(struct semaphore * sem)
100 {
101 unsigned long flags;
102 int failed;
103
104 #if WAITQUEUE_DEBUG
105 CHECK_MAGIC(sem->__magic);
106 #endif
107
108 /* atomically decrement the semaphores count, and if its negative, we wait */
109 save_flags(flags);
110 cli();
111 failed = --(sem->count) < 0;
112 restore_flags(flags);
113 if(failed)
114 failed = __down_interruptible(sem);
115 return(failed);
116 }
117
118 extern inline int down_trylock(struct semaphore * sem)
119 {
120 unsigned long flags;
121 int failed;
122
123 #if WAITQUEUE_DEBUG
124 CHECK_MAGIC(sem->__magic);
125 #endif
126
127 save_flags(flags);
128 cli();
129 failed = --(sem->count) < 0;
130 restore_flags(flags);
131 if(failed)
132 failed = __down_trylock(sem);
133 return(failed);
134 }
135
136 /*
137 * Note! This is subtle. We jump to wake people up only if
138 * the semaphore was negative (== somebody was waiting on it).
139 * The default case (no contention) will result in NO
140 * jumps for both down() and up().
141 */
142 extern inline void up(struct semaphore * sem)
143 {
144 unsigned long flags;
145 int wakeup;
146
147 #if WAITQUEUE_DEBUG
148 CHECK_MAGIC(sem->__magic);
149 #endif
150
151 /* atomically increment the semaphores count, and if it was negative, we wake people */
152 save_flags(flags);
153 cli();
154 wakeup = ++(sem->count) <= 0;
155 restore_flags(flags);
156 if(wakeup) {
157 __up(sem);
158 }
159 }
160
161 #endif
162