diff --git a/include/linux/synclink.h b/include/linux/synclink.h
index 45f6bc8..c844a22 100644
--- a/include/linux/synclink.h
+++ b/include/linux/synclink.h
@@ -136,6 +136,7 @@
 #define MGSL_INTERFACE_RTS_EN   0x10
 #define MGSL_INTERFACE_LL       0x20
 #define MGSL_INTERFACE_RL       0x40
+#define MGSL_INTERFACE_MSB_FIRST 0x80
 
 typedef struct _MGSL_PARAMS
 {