diff --git a/drivers/char/snsc.h b/drivers/char/snsc.h
new file mode 100644
index 0000000..c22c6c5
--- /dev/null
+++ b/drivers/char/snsc.h
@@ -0,0 +1,50 @@
+/*
+ * SN Platform system controller communication support
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Copyright (C) 2004 Silicon Graphics, Inc. All rights reserved.
+ */
+
+/*
+ * This file contains macros and data types for communication with the
+ * system controllers in SGI SN systems.
+ */
+
+#ifndef _SN_SYSCTL_H_
+#define _SN_SYSCTL_H_
+
+#include <linux/types.h>
+#include <linux/spinlock.h>
+#include <linux/wait.h>
+#include <linux/kobject.h>
+#include <linux/fs.h>
+#include <linux/cdev.h>
+#include <asm/sn/types.h>
+#include <asm/semaphore.h>
+
+#define CHUNKSIZE 127
+
+/* This structure is used to track an open subchannel. */
+struct subch_data_s {
+	nasid_t sd_nasid;	/* node on which the subchannel was opened */
+	int sd_subch;		/* subchannel number */
+	spinlock_t sd_rlock;	/* monitor lock for rsv */
+	spinlock_t sd_wlock;	/* monitor lock for wsv */
+	wait_queue_head_t sd_rq;	/* wait queue for readers */
+	wait_queue_head_t sd_wq;	/* wait queue for writers */
+	struct semaphore sd_rbs;	/* semaphore for read buffer */
+	struct semaphore sd_wbs;	/* semaphore for write buffer */
+
+	char sd_rb[CHUNKSIZE];	/* read buffer */
+	char sd_wb[CHUNKSIZE];	/* write buffer */
+};
+
+struct sysctl_data_s {
+	struct cdev scd_cdev;	/* Character device info */
+	nasid_t scd_nasid;	/* Node on which subchannels are opened. */
+};
+
+#endif /* _SN_SYSCTL_H_ */