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1da177e4 LT |
1 | /* SMP- and interrupt-safe semaphores. |
2 | * PA-RISC version by Matthew Wilcox | |
3 | * | |
4 | * Linux/PA-RISC Project (http://www.parisc-linux.org/) | |
5 | * Copyright (C) 1996 Linus Torvalds | |
6 | * Copyright (C) 1999-2001 Matthew Wilcox < willy at debian d0T org > | |
7 | * Copyright (C) 2000 Grant Grundler < grundler a debian org > | |
8 | * | |
9 | * This program is free software; you can redistribute it and/or modify | |
10 | * it under the terms of the GNU General Public License as published by | |
11 | * the Free Software Foundation; either version 2 of the License, or | |
12 | * (at your option) any later version. | |
13 | * | |
14 | * This program is distributed in the hope that it will be useful, | |
15 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
16 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
17 | * GNU General Public License for more details. | |
18 | * | |
19 | * You should have received a copy of the GNU General Public License | |
20 | * along with this program; if not, write to the Free Software | |
21 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA | |
22 | */ | |
23 | ||
24 | #ifndef _ASM_PARISC_SEMAPHORE_H | |
25 | #define _ASM_PARISC_SEMAPHORE_H | |
26 | ||
27 | #include <linux/spinlock.h> | |
28 | #include <linux/wait.h> | |
29 | #include <linux/rwsem.h> | |
30 | ||
31 | #include <asm/system.h> | |
32 | ||
33 | /* | |
34 | * The `count' is initialised to the number of people who are allowed to | |
35 | * take the lock. (Normally we want a mutex, so this is `1'). if | |
36 | * `count' is positive, the lock can be taken. if it's 0, no-one is | |
37 | * waiting on it. if it's -1, at least one task is waiting. | |
38 | */ | |
39 | struct semaphore { | |
40 | spinlock_t sentry; | |
41 | int count; | |
42 | wait_queue_head_t wait; | |
43 | }; | |
44 | ||
45 | #define __SEMAPHORE_INITIALIZER(name, n) \ | |
46 | { \ | |
47 | .sentry = SPIN_LOCK_UNLOCKED, \ | |
48 | .count = n, \ | |
49 | .wait = __WAIT_QUEUE_HEAD_INITIALIZER((name).wait) \ | |
50 | } | |
51 | ||
52 | #define __MUTEX_INITIALIZER(name) \ | |
53 | __SEMAPHORE_INITIALIZER(name,1) | |
54 | ||
55 | #define __DECLARE_SEMAPHORE_GENERIC(name,count) \ | |
56 | struct semaphore name = __SEMAPHORE_INITIALIZER(name,count) | |
57 | ||
58 | #define DECLARE_MUTEX(name) __DECLARE_SEMAPHORE_GENERIC(name,1) | |
59 | #define DECLARE_MUTEX_LOCKED(name) __DECLARE_SEMAPHORE_GENERIC(name,0) | |
60 | ||
61 | extern inline void sema_init (struct semaphore *sem, int val) | |
62 | { | |
63 | *sem = (struct semaphore)__SEMAPHORE_INITIALIZER((*sem),val); | |
64 | } | |
65 | ||
66 | static inline void init_MUTEX (struct semaphore *sem) | |
67 | { | |
68 | sema_init(sem, 1); | |
69 | } | |
70 | ||
71 | static inline void init_MUTEX_LOCKED (struct semaphore *sem) | |
72 | { | |
73 | sema_init(sem, 0); | |
74 | } | |
75 | ||
76 | static inline int sem_getcount(struct semaphore *sem) | |
77 | { | |
78 | return sem->count; | |
79 | } | |
80 | ||
81 | asmlinkage void __down(struct semaphore * sem); | |
82 | asmlinkage int __down_interruptible(struct semaphore * sem); | |
83 | asmlinkage void __up(struct semaphore * sem); | |
84 | ||
85 | /* Semaphores can be `tried' from irq context. So we have to disable | |
86 | * interrupts while we're messing with the semaphore. Sorry. | |
87 | */ | |
88 | ||
89 | extern __inline__ void down(struct semaphore * sem) | |
90 | { | |
91 | might_sleep(); | |
92 | spin_lock_irq(&sem->sentry); | |
93 | if (sem->count > 0) { | |
94 | sem->count--; | |
95 | } else { | |
96 | __down(sem); | |
97 | } | |
98 | spin_unlock_irq(&sem->sentry); | |
99 | } | |
100 | ||
101 | extern __inline__ int down_interruptible(struct semaphore * sem) | |
102 | { | |
103 | int ret = 0; | |
104 | might_sleep(); | |
105 | spin_lock_irq(&sem->sentry); | |
106 | if (sem->count > 0) { | |
107 | sem->count--; | |
108 | } else { | |
109 | ret = __down_interruptible(sem); | |
110 | } | |
111 | spin_unlock_irq(&sem->sentry); | |
112 | return ret; | |
113 | } | |
114 | ||
115 | /* | |
116 | * down_trylock returns 0 on success, 1 if we failed to get the lock. | |
117 | * May not sleep, but must preserve irq state | |
118 | */ | |
119 | extern __inline__ int down_trylock(struct semaphore * sem) | |
120 | { | |
121 | int flags, count; | |
122 | ||
123 | spin_lock_irqsave(&sem->sentry, flags); | |
124 | count = sem->count - 1; | |
125 | if (count >= 0) | |
126 | sem->count = count; | |
127 | spin_unlock_irqrestore(&sem->sentry, flags); | |
128 | return (count < 0); | |
129 | } | |
130 | ||
131 | /* | |
132 | * Note! This is subtle. We jump to wake people up only if | |
133 | * the semaphore was negative (== somebody was waiting on it). | |
134 | */ | |
135 | extern __inline__ void up(struct semaphore * sem) | |
136 | { | |
137 | int flags; | |
138 | spin_lock_irqsave(&sem->sentry, flags); | |
139 | if (sem->count < 0) { | |
140 | __up(sem); | |
141 | } else { | |
142 | sem->count++; | |
143 | } | |
144 | spin_unlock_irqrestore(&sem->sentry, flags); | |
145 | } | |
146 | ||
147 | #endif /* _ASM_PARISC_SEMAPHORE_H */ |