-#define GIGASET_REDIR _IOWR (GIGASET_IOCTL, 0, int)
-#define GIGASET_CONFIG _IOWR (GIGASET_IOCTL, 1, int)
-#define GIGASET_BRKCHARS _IOW (GIGASET_IOCTL, 2, unsigned char[6]) //FIXME [6] okay?
-#define GIGASET_VERSION _IOWR (GIGASET_IOCTL, 3, unsigned[4])
+/* enable adapter configuration mode (M10x only) */
+#define GIGASET_CONFIG _IOWR(GIGASET_IOCTL, 1, int)
+
+/* set break characters (M105 only) */
+#define GIGASET_BRKCHARS _IOW(GIGASET_IOCTL, 2, unsigned char[6])
+
+/* get version information selected by arg[0] */
+#define GIGASET_VERSION _IOWR(GIGASET_IOCTL, 3, unsigned[4])
+/* values for GIGASET_VERSION arg[0] */
+#define GIGVER_DRIVER 0 /* get driver version */
+#define GIGVER_COMPAT 1 /* get interface compatibility version */
+#define GIGVER_FWBASE 2 /* get base station firmware version */