1 files changed, 109 insertions, 0 deletions

diff --git a/include/asm-avr32/semaphore.h b/include/asm-avr32/semaphore.h
new file mode 100644
index 000000000000..ef99ddccc10c
--- /dev/null
+++ b/include/asm-avr32/semaphore.h
@@ -0,0 +1,109 @@
+/*
+ * 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 */