This commit was manufactured by cvs2svn to create branch 'vserver'.

[linux-2.6.git] / include / asm-avr32 / semaphore.h

diff --git a/include/asm-avr32/semaphore.h b/include/asm-avr32/semaphore.h
new file mode 100644 (file)
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+++ b/include/asm-avr32/semaphore.h
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+/*
+ * SMP- and interrupt-safe semaphores.
+ *
+ * Copyright (C) 2006 Atmel Corporation
+ *
+ * Based on include/asm-i386/semaphore.h
+ *   Copyright (C) 1996 Linus Torvalds
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#ifndef __ASM_AVR32_SEMAPHORE_H
+#define __ASM_AVR32_SEMAPHORE_H
+
+#include <linux/linkage.h>
+
+#include <asm/system.h>
+#include <asm/atomic.h>
+#include <linux/wait.h>
+#include <linux/rwsem.h>
+
+struct semaphore {
+       atomic_t count;
+       int sleepers;
+       wait_queue_head_t wait;
+};
+
+#define __SEMAPHORE_INITIALIZER(name, n)                               \
+{                                                                      \
+       .count          = ATOMIC_INIT(n),                               \
+       .wait           = __WAIT_QUEUE_HEAD_INITIALIZER((name).wait)    \
+}
+
+#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)
+
+static inline void sema_init (struct semaphore *sem, int val)
+{
+       atomic_set(&sem->count, val);
+       sem->sleepers = 0;
+       init_waitqueue_head(&sem->wait);
+}
+
+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);
+}
+
+void __down(struct semaphore * sem);
+int  __down_interruptible(struct semaphore * sem);
+void __up(struct semaphore * sem);
+
+/*
+ * This is ugly, but we want the default case to fall through.
+ * "__down_failed" is a special asm handler that calls the C
+ * routine that actually waits. See arch/i386/kernel/semaphore.c
+ */
+static inline void down(struct semaphore * sem)
+{
+       might_sleep();
+       if (unlikely(atomic_dec_return (&sem->count) < 0))
+               __down (sem);
+}
+
+/*
+ * Interruptible try to acquire a semaphore.  If we obtained
+ * it, return zero.  If we were interrupted, returns -EINTR
+ */
+static inline int down_interruptible(struct semaphore * sem)
+{
+       int ret = 0;
+
+       might_sleep();
+       if (unlikely(atomic_dec_return (&sem->count) < 0))
+               ret = __down_interruptible (sem);
+       return ret;
+}
+
+/*
+ * Non-blockingly attempt to down() a semaphore.
+ * Returns zero if we acquired it
+ */
+static inline int down_trylock(struct semaphore * sem)
+{
+       return atomic_dec_if_positive(&sem->count) < 0;
+}
+
+/*
+ * Note! This is subtle. We jump to wake people up only if
+ * the semaphore was negative (== somebody was waiting on it).
+ * The default case (no contention) will result in NO
+ * jumps for both down() and up().
+ */
+static inline void up(struct semaphore * sem)
+{
+       if (unlikely(atomic_inc_return (&sem->count) <= 0))
+               __up (sem);
+}
+
+#endif /*__ASM_AVR32_SEMAPHORE_H */