1 files changed, 153 insertions, 0 deletions
diff --git a/include/asm-alpha/semaphore.h b/include/asm-alpha/semaphore.h
new file mode 100644
index 00000000000..eb2cbd97d40
--- /dev/null
+++ b/include/asm-alpha/semaphore.h
@@ -0,0 +1,153 @@
+#ifndef _ALPHA_SEMAPHORE_H
+#define _ALPHA_SEMAPHORE_H
+
+/*
+ * SMP- and interrupt-safe semaphores..
+ *
+ * (C) Copyright 1996 Linus Torvalds
+ * (C) Copyright 1996, 2000 Richard Henderson
+ */
+
+#include <asm/current.h>
+#include <asm/system.h>
+#include <asm/atomic.h>
+#include <linux/compiler.h>
+#include <linux/wait.h>
+#include <linux/rwsem.h>
+
+struct semaphore {
+	atomic_t count;
+	wait_queue_head_t wait;
+};
+
+#define __SEMAPHORE_INITIALIZER(name, n)			\
+{								\
+	.count	= ATOMIC_INIT(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)
+
+static inline void sema_init(struct semaphore *sem, int val)
+{
+	/*
+	 * Logically, 
+	 *   *sem = (struct semaphore)__SEMAPHORE_INITIALIZER((*sem),val);
+	 * except that gcc produces better initializing by parts yet.
+	 */
+
+	atomic_set(&sem->count, val);
+	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);
+}
+
+extern void down(struct semaphore *);
+extern void __down_failed(struct semaphore *);
+extern int  down_interruptible(struct semaphore *);
+extern int  __down_failed_interruptible(struct semaphore *);
+extern int  down_trylock(struct semaphore *);
+extern void up(struct semaphore *);
+extern void __up_wakeup(struct semaphore *);
+
+/*
+ * Hidden out of line code is fun, but extremely messy.  Rely on newer
+ * compilers to do a respectable job with this.  The contention cases
+ * are handled out of line in arch/alpha/kernel/semaphore.c.
+ */
+
+static inline void __down(struct semaphore *sem)
+{
+	long count;
+	might_sleep();
+	count = atomic_dec_return(&sem->count);
+	if (unlikely(count < 0))
+		__down_failed(sem);
+}
+
+static inline int __down_interruptible(struct semaphore *sem)
+{
+	long count;
+	might_sleep();
+	count = atomic_dec_return(&sem->count);
+	if (unlikely(count < 0))
+		return __down_failed_interruptible(sem);
+	return 0;
+}
+
+/*
+ * down_trylock returns 0 on success, 1 if we failed to get the lock.
+ */
+
+static inline int __down_trylock(struct semaphore *sem)
+{
+	long ret;
+
+	/* "Equivalent" C:
+
+	   do {
+		ret = ldl_l;
+		--ret;
+		if (ret < 0)
+			break;
+		ret = stl_c = ret;
+	   } while (ret == 0);
+	*/
+	__asm__ __volatile__(
+		"1:	ldl_l	%0,%1\n"
+		"	subl	%0,1,%0\n"
+		"	blt	%0,2f\n"
+		"	stl_c	%0,%1\n"
+		"	beq	%0,3f\n"
+		"	mb\n"
+		"2:\n"
+		".subsection 2\n"
+		"3:	br	1b\n"
+		".previous"
+		: "=&r" (ret), "=m" (sem->count)
+		: "m" (sem->count));
+
+	return ret < 0;
+}
+
+static inline void __up(struct semaphore *sem)
+{
+	if (unlikely(atomic_inc_return(&sem->count) <= 0))
+		__up_wakeup(sem);
+}
+
+#if !defined(CONFIG_DEBUG_SEMAPHORE)
+extern inline void down(struct semaphore *sem)
+{
+	__down(sem);
+}
+extern inline int down_interruptible(struct semaphore *sem)
+{
+	return __down_interruptible(sem);
+}
+extern inline int down_trylock(struct semaphore *sem)
+{
+	return __down_trylock(sem);
+}
+extern inline void up(struct semaphore *sem)
+{
+	__up(sem);
+}
+#endif
+
+#endif