diff --git a/drivers/accessibility/speakup/spk_ttyio.c b/drivers/accessibility/speakup/spk_ttyio.c
index b7fd094700d96f..8faa27bae6bfc2 100644
--- a/drivers/accessibility/speakup/spk_ttyio.c
+++ b/drivers/accessibility/speakup/spk_ttyio.c
@@ -105,6 +105,7 @@ static int spk_ttyio_receive_buf2(struct tty_struct *tty,
 
 static struct tty_ldisc_ops spk_ttyio_ldisc_ops = {
 	.owner          = THIS_MODULE,
+	.num		= N_SPEAKUP,
 	.name           = "speakup_ldisc",
 	.open           = spk_ttyio_ldisc_open,
 	.close          = spk_ttyio_ldisc_close,
@@ -212,7 +213,7 @@ static int spk_ttyio_initialise_ldisc(struct spk_synth *synth)
 
 void spk_ttyio_register_ldisc(void)
 {
-	if (tty_register_ldisc(N_SPEAKUP, &spk_ttyio_ldisc_ops))
+	if (tty_register_ldisc(&spk_ttyio_ldisc_ops))
 		pr_warn("speakup: Error registering line discipline. Most synths won't work.\n");
 }
 
diff --git a/drivers/bluetooth/hci_ldisc.c b/drivers/bluetooth/hci_ldisc.c
index e785851a92c142..ee32006e8fc957 100644
--- a/drivers/bluetooth/hci_ldisc.c
+++ b/drivers/bluetooth/hci_ldisc.c
@@ -821,6 +821,7 @@ static __poll_t hci_uart_tty_poll(struct tty_struct *tty,
 
 static struct tty_ldisc_ops hci_uart_ldisc = {
 	.owner		= THIS_MODULE,
+	.num		= N_HCI,
 	.name		= "n_hci",
 	.open		= hci_uart_tty_open,
 	.close		= hci_uart_tty_close,
@@ -840,7 +841,7 @@ static int __init hci_uart_init(void)
 	BT_INFO("HCI UART driver ver %s", VERSION);
 
 	/* Register the tty discipline */
-	err = tty_register_ldisc(N_HCI, &hci_uart_ldisc);
+	err = tty_register_ldisc(&hci_uart_ldisc);
 	if (err) {
 		BT_ERR("HCI line discipline registration failed. (%d)", err);
 		return err;
diff --git a/drivers/input/serio/serport.c b/drivers/input/serio/serport.c
index ff37153155929a..870b1d2606fcd9 100644
--- a/drivers/input/serio/serport.c
+++ b/drivers/input/serio/serport.c
@@ -274,6 +274,7 @@ static void serport_ldisc_write_wakeup(struct tty_struct * tty)
 
 static struct tty_ldisc_ops serport_ldisc = {
 	.owner =	THIS_MODULE,
+	.num =		N_MOUSE,
 	.name =		"input",
 	.open =		serport_ldisc_open,
 	.close =	serport_ldisc_close,
@@ -294,7 +295,7 @@ static struct tty_ldisc_ops serport_ldisc = {
 static int __init serport_init(void)
 {
 	int retval;
-	retval = tty_register_ldisc(N_MOUSE, &serport_ldisc);
+	retval = tty_register_ldisc(&serport_ldisc);
 	if (retval)
 		printk(KERN_ERR "serport.c: Error registering line discipline.\n");
 
diff --git a/drivers/misc/ti-st/st_core.c b/drivers/misc/ti-st/st_core.c
index 239a75502cd621..a4f5d02940c7c4 100644
--- a/drivers/misc/ti-st/st_core.c
+++ b/drivers/misc/ti-st/st_core.c
@@ -845,6 +845,7 @@ static void st_tty_flush_buffer(struct tty_struct *tty)
 }
 
 static struct tty_ldisc_ops st_ldisc_ops = {
+	.num = N_TI_WL,
 	.name = "n_st",
 	.open = st_tty_open,
 	.close = st_tty_close,
@@ -860,7 +861,7 @@ int st_core_init(struct st_data_s **core_data)
 	struct st_data_s *st_gdata;
 	long err;
 
-	err = tty_register_ldisc(N_TI_WL, &st_ldisc_ops);
+	err = tty_register_ldisc(&st_ldisc_ops);
 	if (err) {
 		pr_err("error registering %d line discipline %ld",
 			   N_TI_WL, err);
diff --git a/drivers/net/caif/caif_serial.c b/drivers/net/caif/caif_serial.c
index b0566588ce3326..2407a0f6656d3a 100644
--- a/drivers/net/caif/caif_serial.c
+++ b/drivers/net/caif/caif_serial.c
@@ -382,6 +382,7 @@ static void ldisc_close(struct tty_struct *tty)
 /* The line discipline structure. */
 static struct tty_ldisc_ops caif_ldisc = {
 	.owner =	THIS_MODULE,
+	.num =		N_CAIF,
 	.name =		"n_caif",
 	.open =		ldisc_open,
 	.close =	ldisc_close,
@@ -431,7 +432,7 @@ static int __init caif_ser_init(void)
 {
 	int ret;
 
-	ret = tty_register_ldisc(N_CAIF, &caif_ldisc);
+	ret = tty_register_ldisc(&caif_ldisc);
 	if (ret < 0)
 		pr_err("cannot register CAIF ldisc=%d err=%d\n", N_CAIF, ret);
 
diff --git a/drivers/net/can/slcan.c b/drivers/net/can/slcan.c
index 7dc3e79cb5c40d..e3f528c8224253 100644
--- a/drivers/net/can/slcan.c
+++ b/drivers/net/can/slcan.c
@@ -698,6 +698,7 @@ static int slcan_ioctl(struct tty_struct *tty, struct file *file,
 
 static struct tty_ldisc_ops slc_ldisc = {
 	.owner		= THIS_MODULE,
+	.num		= N_SLCAN,
 	.name		= "slcan",
 	.open		= slcan_open,
 	.close		= slcan_close,
@@ -722,7 +723,7 @@ static int __init slcan_init(void)
 		return -ENOMEM;
 
 	/* Fill in our line protocol discipline, and register it */
-	status = tty_register_ldisc(N_SLCAN, &slc_ldisc);
+	status = tty_register_ldisc(&slc_ldisc);
 	if (status)  {
 		printk(KERN_ERR "slcan: can't register line discipline\n");
 		kfree(slcan_devs);
diff --git a/drivers/net/hamradio/6pack.c b/drivers/net/hamradio/6pack.c
index c0a80f04dd8ee0..4db1d3c4d771bb 100644
--- a/drivers/net/hamradio/6pack.c
+++ b/drivers/net/hamradio/6pack.c
@@ -744,6 +744,7 @@ static int sixpack_ioctl(struct tty_struct *tty, struct file *file,
 
 static struct tty_ldisc_ops sp_ldisc = {
 	.owner		= THIS_MODULE,
+	.num		= N_6PACK,
 	.name		= "6pack",
 	.open		= sixpack_open,
 	.close		= sixpack_close,
@@ -766,7 +767,8 @@ static int __init sixpack_init_driver(void)
 	printk(msg_banner);
 
 	/* Register the provided line protocol discipline */
-	if ((status = tty_register_ldisc(N_6PACK, &sp_ldisc)) != 0)
+	status = tty_register_ldisc(&sp_ldisc);
+	if (status)
 		printk(msg_regfail, status);
 
 	return status;
diff --git a/drivers/net/hamradio/mkiss.c b/drivers/net/hamradio/mkiss.c
index fc05ded481785e..1eb87a5a93948a 100644
--- a/drivers/net/hamradio/mkiss.c
+++ b/drivers/net/hamradio/mkiss.c
@@ -933,6 +933,7 @@ static void mkiss_write_wakeup(struct tty_struct *tty)
 
 static struct tty_ldisc_ops ax_ldisc = {
 	.owner		= THIS_MODULE,
+	.num		= N_AX25,
 	.name		= "mkiss",
 	.open		= mkiss_open,
 	.close		= mkiss_close,
@@ -952,7 +953,7 @@ static int __init mkiss_init_driver(void)
 
 	printk(banner);
 
-	status = tty_register_ldisc(N_AX25, &ax_ldisc);
+	status = tty_register_ldisc(&ax_ldisc);
 	if (status != 0)
 		printk(msg_regfail, status);
 
diff --git a/drivers/net/ppp/ppp_async.c b/drivers/net/ppp/ppp_async.c
index 9f08bd19551f7a..4bfb66c40c86df 100644
--- a/drivers/net/ppp/ppp_async.c
+++ b/drivers/net/ppp/ppp_async.c
@@ -372,6 +372,7 @@ ppp_asynctty_wakeup(struct tty_struct *tty)
 
 static struct tty_ldisc_ops ppp_ldisc = {
 	.owner  = THIS_MODULE,
+	.num	= N_PPP,
 	.name	= "ppp",
 	.open	= ppp_asynctty_open,
 	.close	= ppp_asynctty_close,
@@ -389,7 +390,7 @@ ppp_async_init(void)
 {
 	int err;
 
-	err = tty_register_ldisc(N_PPP, &ppp_ldisc);
+	err = tty_register_ldisc(&ppp_ldisc);
 	if (err != 0)
 		printk(KERN_ERR "PPP_async: error %d registering line disc.\n",
 		       err);
diff --git a/drivers/net/ppp/ppp_synctty.c b/drivers/net/ppp/ppp_synctty.c
index c82c4e6df4cbc4..0942d3ee48e08c 100644
--- a/drivers/net/ppp/ppp_synctty.c
+++ b/drivers/net/ppp/ppp_synctty.c
@@ -365,6 +365,7 @@ ppp_sync_wakeup(struct tty_struct *tty)
 
 static struct tty_ldisc_ops ppp_sync_ldisc = {
 	.owner	= THIS_MODULE,
+	.num	= N_SYNC_PPP,
 	.name	= "pppsync",
 	.open	= ppp_sync_open,
 	.close	= ppp_sync_close,
@@ -382,7 +383,7 @@ ppp_sync_init(void)
 {
 	int err;
 
-	err = tty_register_ldisc(N_SYNC_PPP, &ppp_sync_ldisc);
+	err = tty_register_ldisc(&ppp_sync_ldisc);
 	if (err != 0)
 		printk(KERN_ERR "PPP_sync: error %d registering line disc.\n",
 		       err);
diff --git a/drivers/net/slip/slip.c b/drivers/net/slip/slip.c
index 4dda49e617456c..938ac0ec030566 100644
--- a/drivers/net/slip/slip.c
+++ b/drivers/net/slip/slip.c
@@ -1263,6 +1263,7 @@ static int sl_ioctl(struct net_device *dev, struct ifreq *rq, int cmd)
 
 static struct tty_ldisc_ops sl_ldisc = {
 	.owner 		= THIS_MODULE,
+	.num		= N_SLIP,
 	.name 		= "slip",
 	.open 		= slip_open,
 	.close	 	= slip_close,
@@ -1298,7 +1299,7 @@ static int __init slip_init(void)
 		return -ENOMEM;
 
 	/* Fill in our line protocol discipline, and register it */
-	status = tty_register_ldisc(N_SLIP, &sl_ldisc);
+	status = tty_register_ldisc(&sl_ldisc);
 	if (status != 0) {
 		printk(KERN_ERR "SLIP: can't register line discipline (err = %d)\n", status);
 		kfree(slip_devs);
diff --git a/drivers/pps/clients/pps-ldisc.c b/drivers/pps/clients/pps-ldisc.c
index bf26cc56b863a4..2a88e678d0b8d1 100644
--- a/drivers/pps/clients/pps-ldisc.c
+++ b/drivers/pps/clients/pps-ldisc.c
@@ -112,12 +112,13 @@ static int __init pps_tty_init(void)
 
 	/* Init PPS_TTY data */
 	pps_ldisc_ops.owner = THIS_MODULE;
+	pps_ldisc_ops.num = N_PPS;
 	pps_ldisc_ops.name = "pps_tty";
 	pps_ldisc_ops.dcd_change = pps_tty_dcd_change;
 	pps_ldisc_ops.open = pps_tty_open;
 	pps_ldisc_ops.close = pps_tty_close;
 
-	err = tty_register_ldisc(N_PPS, &pps_ldisc_ops);
+	err = tty_register_ldisc(&pps_ldisc_ops);
 	if (err)
 		pr_err("can't register PPS line discipline\n");
 	else
diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c
index 477403ecc44561..654e439ff6c815 100644
--- a/drivers/tty/n_gsm.c
+++ b/drivers/tty/n_gsm.c
@@ -2857,6 +2857,7 @@ static int gsm_create_network(struct gsm_dlci *dlci, struct gsm_netconfig *nc)
 /* Line discipline for real tty */
 static struct tty_ldisc_ops tty_ldisc_packet = {
 	.owner		 = THIS_MODULE,
+	.num		 = N_GSM0710,
 	.name            = "n_gsm",
 	.open            = gsmld_open,
 	.close           = gsmld_close,
@@ -3242,7 +3243,7 @@ static const struct tty_operations gsmtty_ops = {
 static int __init gsm_init(void)
 {
 	/* Fill in our line protocol discipline, and register it */
-	int status = tty_register_ldisc(N_GSM0710, &tty_ldisc_packet);
+	int status = tty_register_ldisc(&tty_ldisc_packet);
 	if (status != 0) {
 		pr_err("n_gsm: can't register line discipline (err = %d)\n",
 								status);
diff --git a/drivers/tty/n_hdlc.c b/drivers/tty/n_hdlc.c
index 62b1d1a6e0f1ca..2256039911f575 100644
--- a/drivers/tty/n_hdlc.c
+++ b/drivers/tty/n_hdlc.c
@@ -788,6 +788,7 @@ static struct n_hdlc_buf *n_hdlc_buf_get(struct n_hdlc_buf_list *buf_list)
 
 static struct tty_ldisc_ops n_hdlc_ldisc = {
 	.owner		= THIS_MODULE,
+	.num		= N_HDLC,
 	.name		= "hdlc",
 	.open		= n_hdlc_tty_open,
 	.close		= n_hdlc_tty_close,
@@ -807,7 +808,7 @@ static int __init n_hdlc_init(void)
 	/* range check maxframe arg */
 	maxframe = clamp(maxframe, 4096, MAX_HDLC_FRAME_SIZE);
 
-	status = tty_register_ldisc(N_HDLC, &n_hdlc_ldisc);
+	status = tty_register_ldisc(&n_hdlc_ldisc);
 	if (!status)
 		pr_info("N_HDLC line discipline registered with maxframe=%d\n",
 				maxframe);
diff --git a/drivers/tty/n_null.c b/drivers/tty/n_null.c
index 2ff373d2f98d27..ee229c812dce58 100644
--- a/drivers/tty/n_null.c
+++ b/drivers/tty/n_null.c
@@ -40,6 +40,7 @@ static void n_null_receivebuf(struct tty_struct *tty,
 
 static struct tty_ldisc_ops null_ldisc = {
 	.owner		=	THIS_MODULE,
+	.num		=	N_NULL,
 	.name		=	"n_null",
 	.open		=	n_null_open,
 	.close		=	n_null_close,
@@ -50,7 +51,7 @@ static struct tty_ldisc_ops null_ldisc = {
 
 static int __init n_null_init(void)
 {
-	BUG_ON(tty_register_ldisc(N_NULL, &null_ldisc));
+	BUG_ON(tty_register_ldisc(&null_ldisc));
 	return 0;
 }
 
diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c
index 8ce712eec02641..2fe27905c39838 100644
--- a/drivers/tty/n_tty.c
+++ b/drivers/tty/n_tty.c
@@ -2424,6 +2424,7 @@ static int n_tty_ioctl(struct tty_struct *tty, struct file *file,
 
 static struct tty_ldisc_ops n_tty_ops = {
 	.owner		 = THIS_MODULE,
+	.num		 = N_TTY,
 	.name            = "n_tty",
 	.open            = n_tty_open,
 	.close           = n_tty_close,
@@ -2455,5 +2456,5 @@ EXPORT_SYMBOL_GPL(n_tty_inherit_ops);
 
 void __init n_tty_init(void)
 {
-	tty_register_ldisc(N_TTY, &n_tty_ops);
+	tty_register_ldisc(&n_tty_ops);
 }
diff --git a/drivers/tty/tty_ldisc.c b/drivers/tty/tty_ldisc.c
index 03f414172f34d8..9aff04bee4cdad 100644
--- a/drivers/tty/tty_ldisc.c
+++ b/drivers/tty/tty_ldisc.c
@@ -59,17 +59,16 @@ static struct tty_ldisc_ops *tty_ldiscs[NR_LDISCS];
  *		takes tty_ldiscs_lock to guard against ldisc races
  */
 
-int tty_register_ldisc(int disc, struct tty_ldisc_ops *new_ldisc)
+int tty_register_ldisc(struct tty_ldisc_ops *new_ldisc)
 {
 	unsigned long flags;
 	int ret = 0;
 
-	if (disc < N_TTY || disc >= NR_LDISCS)
+	if (new_ldisc->num < N_TTY || new_ldisc->num >= NR_LDISCS)
 		return -EINVAL;
 
 	raw_spin_lock_irqsave(&tty_ldiscs_lock, flags);
-	tty_ldiscs[disc] = new_ldisc;
-	new_ldisc->num = disc;
+	tty_ldiscs[new_ldisc->num] = new_ldisc;
 	new_ldisc->refcount = 0;
 	raw_spin_unlock_irqrestore(&tty_ldiscs_lock, flags);
 
diff --git a/include/linux/tty.h b/include/linux/tty.h
index 283ac5f29052a1..95c632299fb46b 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -636,7 +636,7 @@ static inline int tty_port_users(struct tty_port *port)
 	return port->count + port->blocked_open;
 }
 
-extern int tty_register_ldisc(int disc, struct tty_ldisc_ops *new_ldisc);
+extern int tty_register_ldisc(struct tty_ldisc_ops *new_ldisc);
 extern int tty_unregister_ldisc(int disc);
 extern int tty_set_ldisc(struct tty_struct *tty, int disc);
 extern int tty_ldisc_receive_buf(struct tty_ldisc *ld, const unsigned char *p,
diff --git a/net/nfc/nci/uart.c b/net/nfc/nci/uart.c
index 98102ef64004c0..648c26b4bad808 100644
--- a/net/nfc/nci/uart.c
+++ b/net/nfc/nci/uart.c
@@ -442,6 +442,7 @@ EXPORT_SYMBOL_GPL(nci_uart_set_config);
 
 static struct tty_ldisc_ops nci_uart_ldisc = {
 	.owner		= THIS_MODULE,
+	.num		= N_NCI,
 	.name		= "n_nci",
 	.open		= nci_uart_tty_open,
 	.close		= nci_uart_tty_close,
@@ -456,7 +457,7 @@ static struct tty_ldisc_ops nci_uart_ldisc = {
 
 static int __init nci_uart_init(void)
 {
-	return tty_register_ldisc(N_NCI, &nci_uart_ldisc);
+	return tty_register_ldisc(&nci_uart_ldisc);
 }
 
 static void __exit nci_uart_exit(void)
diff --git a/sound/soc/ti/ams-delta.c b/sound/soc/ti/ams-delta.c
index 55a6736a378e51..fcbb791bf27a51 100644
--- a/sound/soc/ti/ams-delta.c
+++ b/sound/soc/ti/ams-delta.c
@@ -396,6 +396,7 @@ static void cx81801_wakeup(struct tty_struct *tty)
 
 static struct tty_ldisc_ops cx81801_ops = {
 	.name = "cx81801",
+	.num = N_V253,
 	.owner = THIS_MODULE,
 	.open = cx81801_open,
 	.close = cx81801_close,
@@ -503,7 +504,7 @@ static int ams_delta_cx20442_init(struct snd_soc_pcm_runtime *rtd)
 	}
 
 	/* Register optional line discipline for over the modem control */
-	ret = tty_register_ldisc(N_V253, &cx81801_ops);
+	ret = tty_register_ldisc(&cx81801_ops);
 	if (ret) {
 		dev_warn(card->dev,
 				"Failed to register line discipline, "