/* 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 */