1 files changed, 43 insertions, 0 deletions
diff --git a/include/asm-alpha/semaphore.h b/include/asm-alpha/semaphore.h
new file mode 100644
index 000000000..210c2a5b3
--- /dev/null
+++ b/include/asm-alpha/semaphore.h
@@ -0,0 +1,43 @@
+#ifndef _ALPHA_SEMAPHORE_H
+#define _ALPHA_SEMAPHORE_H
+
+/*
+ * SMP- and interrupt-safe semaphores..
+ *
+ * (C) Copyright 1996 Linus Torvalds
+ */
+
+#include <asm/atomic.h>
+
+struct semaphore {
+	atomic_t count;
+	atomic_t waiting;
+	struct wait_queue * wait;
+};
+
+#define MUTEX ((struct semaphore) { 1, 0, NULL })
+#define MUTEX_LOCKED ((struct semaphore) { 0, 0, NULL })
+
+extern void __down(struct semaphore * sem);
+extern void __up(struct semaphore * sem);
+
+/*
+ * This isn't quite as clever as the x86 side, but the gp register
+ * makes things a bit more complicated on the alpha..
+ */
+extern inline void down(struct semaphore * sem)
+{
+	for (;;) {
+		if (atomic_dec_return(&sem->count) >= 0)
+			break;
+		__down(sem);
+	}
+}
+
+extern inline void up(struct semaphore * sem)
+{
+	if (atomic_inc_return(&sem->count) <= 0)
+		__up(sem);
+}	
+
+#endif