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 000000000000..eb2cbd97d404
--- /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