From 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 Mon Sep 17 00:00:00 2001
From: Linus Torvalds <torvalds@ppc970.osdl.org>
Date: Sat, 16 Apr 2005 15:20:36 -0700
Subject: Linux-2.6.12-rc2

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!
---
 include/asm-s390/semaphore.h | 110 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 110 insertions(+)
 create mode 100644 include/asm-s390/semaphore.h

(limited to 'include/asm-s390/semaphore.h')

diff --git a/include/asm-s390/semaphore.h b/include/asm-s390/semaphore.h
new file mode 100644
index 000000000000..873def6f363a
--- /dev/null
+++ b/include/asm-s390/semaphore.h
@@ -0,0 +1,110 @@
+/*
+ *  include/asm-s390/semaphore.h
+ *
+ *  S390 version
+ *    Copyright (C) 1999 IBM Deutschland Entwicklung GmbH, IBM Corporation
+ *
+ *  Derived from "include/asm-i386/semaphore.h"
+ *    (C) Copyright 1996 Linus Torvalds
+ */
+
+#ifndef _S390_SEMAPHORE_H
+#define _S390_SEMAPHORE_H
+
+#include <asm/system.h>
+#include <asm/atomic.h>
+#include <linux/wait.h>
+#include <linux/rwsem.h>
+
+struct semaphore {
+	/*
+	 * Note that any negative value of count is equivalent to 0,
+	 * but additionally indicates that some process(es) might be
+	 * sleeping on `wait'.
+	 */
+	atomic_t count;
+	wait_queue_head_t wait;
+};
+
+#define __SEMAPHORE_INITIALIZER(name,count) \
+	{ ATOMIC_INIT(count), __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)
+{
+	*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);
+}
+
+asmlinkage void __down(struct semaphore * sem);
+asmlinkage int  __down_interruptible(struct semaphore * sem);
+asmlinkage int  __down_trylock(struct semaphore * sem);
+asmlinkage void __up(struct semaphore * sem);
+
+static inline void down(struct semaphore * sem)
+{
+	might_sleep();
+	if (atomic_dec_return(&sem->count) < 0)
+		__down(sem);
+}
+
+static inline int down_interruptible(struct semaphore * sem)
+{
+	int ret = 0;
+
+	might_sleep();
+	if (atomic_dec_return(&sem->count) < 0)
+		ret = __down_interruptible(sem);
+	return ret;
+}
+
+static inline int down_trylock(struct semaphore * sem)
+{
+	int old_val, new_val;
+
+	/*
+	 * This inline assembly atomically implements the equivalent
+	 * to the following C code:
+	 *   old_val = sem->count.counter;
+	 *   if ((new_val = old_val) > 0)
+	 *       sem->count.counter = --new_val;
+	 * In the ppc code this is called atomic_dec_if_positive.
+	 */
+	__asm__ __volatile__ (
+		"   l    %0,0(%3)\n"
+		"0: ltr  %1,%0\n"
+		"   jle  1f\n"
+		"   ahi  %1,-1\n"
+		"   cs   %0,%1,0(%3)\n"
+		"   jl   0b\n"
+		"1:"
+		: "=&d" (old_val), "=&d" (new_val), "=m" (sem->count.counter)
+		: "a" (&sem->count.counter), "m" (sem->count.counter)
+		: "cc", "memory" );
+	return old_val <= 0;
+}
+
+static inline void up(struct semaphore * sem)
+{
+	if (atomic_inc_return(&sem->count) <= 0)
+		__up(sem);
+}
+
+#endif
-- 
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