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Diffstat (limited to 'include/asm-parisc/semaphore.h')
| -rw-r--r-- | include/asm-parisc/semaphore.h | 147 |
1 files changed, 147 insertions, 0 deletions
diff --git a/include/asm-parisc/semaphore.h b/include/asm-parisc/semaphore.h new file mode 100644 index 000000000000..f78bb2e34538 --- /dev/null +++ b/include/asm-parisc/semaphore.h @@ -0,0 +1,147 @@ +/* SMP- and interrupt-safe semaphores. + * PA-RISC version by Matthew Wilcox + * + * Linux/PA-RISC Project (http://www.parisc-linux.org/) + * Copyright (C) 1996 Linus Torvalds + * Copyright (C) 1999-2001 Matthew Wilcox < willy at debian d0T org > + * Copyright (C) 2000 Grant Grundler < grundler a debian org > + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA + */ + +#ifndef _ASM_PARISC_SEMAPHORE_H +#define _ASM_PARISC_SEMAPHORE_H + +#include <linux/spinlock.h> +#include <linux/wait.h> +#include <linux/rwsem.h> + +#include <asm/system.h> + +/* + * The `count' is initialised to the number of people who are allowed to + * take the lock. (Normally we want a mutex, so this is `1'). if + * `count' is positive, the lock can be taken. if it's 0, no-one is + * waiting on it. if it's -1, at least one task is waiting. + */ +struct semaphore { + spinlock_t sentry; + int count; + wait_queue_head_t wait; +}; + +#define __SEMAPHORE_INITIALIZER(name, n) \ +{ \ + .sentry = SPIN_LOCK_UNLOCKED, \ + .count = n, \ + .wait = __WAIT_QUEUE_HEAD_INITIALIZER((name).wait) \ +} + +#define __MUTEX_INITIALIZER(name) \ + __SEMAPHORE_INITIALIZER(name,1) + +#define __DECLARE_SEMAPHORE_GENERIC(name,count) \ + struct semaphore name = __SEMAPHORE_INITIALIZER(name,count) + +#define DECLARE_MUTEX(name) __DECLARE_SEMAPHORE_GENERIC(name,1) +#define DECLARE_MUTEX_LOCKED(name) __DECLARE_SEMAPHORE_GENERIC(name,0) + +extern inline void sema_init (struct semaphore *sem, int val) +{ + *sem = (struct semaphore)__SEMAPHORE_INITIALIZER((*sem),val); +} + +static inline void init_MUTEX (struct semaphore *sem) +{ + sema_init(sem, 1); +} + +static inline void init_MUTEX_LOCKED (struct semaphore *sem) +{ + sema_init(sem, 0); +} + +static inline int sem_getcount(struct semaphore *sem) +{ + return sem->count; +} + +asmlinkage void __down(struct semaphore * sem); +asmlinkage int __down_interruptible(struct semaphore * sem); +asmlinkage void __up(struct semaphore * sem); + +/* Semaphores can be `tried' from irq context. So we have to disable + * interrupts while we're messing with the semaphore. Sorry. + */ + +extern __inline__ void down(struct semaphore * sem) +{ + might_sleep(); + spin_lock_irq(&sem->sentry); + if (sem->count > 0) { + sem->count--; + } else { + __down(sem); + } + spin_unlock_irq(&sem->sentry); +} + +extern __inline__ int down_interruptible(struct semaphore * sem) +{ + int ret = 0; + might_sleep(); + spin_lock_irq(&sem->sentry); + if (sem->count > 0) { + sem->count--; + } else { + ret = __down_interruptible(sem); + } + spin_unlock_irq(&sem->sentry); + return ret; +} + +/* + * down_trylock returns 0 on success, 1 if we failed to get the lock. + * May not sleep, but must preserve irq state + */ +extern __inline__ int down_trylock(struct semaphore * sem) +{ + int flags, count; + + spin_lock_irqsave(&sem->sentry, flags); + count = sem->count - 1; + if (count >= 0) + sem->count = count; + spin_unlock_irqrestore(&sem->sentry, flags); + return (count < 0); +} + +/* + * Note! This is subtle. We jump to wake people up only if + * the semaphore was negative (== somebody was waiting on it). + */ +extern __inline__ void up(struct semaphore * sem) +{ + int flags; + spin_lock_irqsave(&sem->sentry, flags); + if (sem->count < 0) { + __up(sem); + } else { + sem->count++; + } + spin_unlock_irqrestore(&sem->sentry, flags); +} + +#endif /* _ASM_PARISC_SEMAPHORE_H */ |