N_TTY		0
N_SLIP		1
N_MOUSE		2
N_PPP		3
N_STRIP		4
N_AX25		5
N_X25		6	/* X.25 async */
N_6PACK		7
N_MASC		8	/* Reserved for Mobitex module <kaz@cafe.net> */
N_R3964		9	/* Reserved for Simatic R3964 module */
N_PROFIBUS_FDL	10	/* Reserved for Profibus */
N_IRDA		11	/* Linux IrDa - http://irda.sourceforge.net/ */
N_SMSBLOCK	12	/* SMS block mode - for talking to GSM data cards about SMS messages */
N_HDLC		13	/* synchronous HDLC */
N_SYNC_PPP	14	/* synchronous PPP */
N_HCI		15	/* Bluetooth HCI UART */
N_GIGASET_M101	16	/* Siemens Gigaset M101 serial DECT adapter */
N_SLCAN		17	/* Serial / USB serial CAN Adaptors */
N_PPS		18	/* Pulse per Second */
N_V253		19	/* Codec control over voice modem */
N_CAIF		20      /* CAIF protocol for talking to modems */
N_GSM0710	21	/* GSM 0710 Mux */
N_TI_WL		22	/* for TI's WL BT, FM, GPS combo chips */
N_TRACESINK	23	/* Trace data routing for MIPI P1149.7 */
N_TRACEROUTER	24	/* Trace data routing for MIPI P1149.7 */
N_NCI		25	/* NFC NCI UART */
N_SPEAKUP	26	/* Speakup communication with synths */
N_NULL		27	/* Null ldisc used for error handling */