X25: Add if_x25.h and x25 to device identifiers

V2 Feedback from John Hughes.
- Add header for userspace implementations such as xot/xoe to use
- Use explicit values for interface stability
- No changes to driver patches

V1
- Use identifiers instead of magic numbers for X25 layer 3 to device interface.
- Also fixed checkpatch notes on updated code.

[ Add new user header to include/linux/Kbuild  -DaveM ]

Signed-off-by: Andrew Hendry <andrew.hendry@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/Kbuild

@@ -94,6 +94,7 @@ header-y += if_ppp.h
 header-y += if_slip.h
 header-y += if_strip.h
 header-y += if_tun.h
+header-y += if_x25.h
 header-y += in_route.h
 header-y += ioctl.h
 header-y += ip6_tunnel.h

include/linux/if_x25.h

@@ -0,0 +1,26 @@
+/*
+ *  Linux X.25 packet to device interface
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ *  GNU General Public License for more details.
+ */
+
+#ifndef _IF_X25_H
+#define _IF_X25_H
+
+#include <linux/types.h>
+
+/* Documentation/networking/x25-iface.txt */
+#define X25_IFACE_DATA		0x00
+#define X25_IFACE_CONNECT	0x01
+#define X25_IFACE_DISCONNECT	0x02
+#define X25_IFACE_PARAMS	0x03
+
+#endif /* _IF_X25_H */