diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c
index e050d76385ba..f8a8c4059907 100644
--- a/drivers/tty/n_gsm.c
+++ b/drivers/tty/n_gsm.c
@@ -63,6 +63,13 @@
 static int debug;
 module_param(debug, int, 0600);
 
+/* Module debug bits */
+#define DBG_DUMP	BIT(0) /* Data transmission dump. */
+#define DBG_CD_ON	BIT(1) /* Always assume CD line on. */
+#define DBG_DATA	BIT(2) /* Data transmission details. */
+#define DBG_ERRORS	BIT(3) /* Details for fail conditions. */
+#define DBG_TTY		BIT(4) /* Transmission statistics for DLCI TTYs. */
+
 /* Defaults: these are from the specification */
 
 #define T1	10		/* 100mS */
@@ -535,7 +542,7 @@ static int gsm_register_devices(struct tty_driver *driver, unsigned int index)
 		 */
 		dev = tty_register_device(gsm_tty_driver, base + i, NULL);
 		if (IS_ERR(dev)) {
-			if (debug & 8)
+			if (debug & DBG_ERRORS)
 				pr_info("%s failed to register device minor %u",
 					__func__, base + i);
 			for (i--; i >= 1; i--)
@@ -589,7 +596,7 @@ static void gsm_unregister_devices(struct tty_driver *driver,
 static void gsm_print_packet(const char *hdr, int addr, int cr,
 					u8 control, const u8 *data, int dlen)
 {
-	if (!(debug & 1))
+	if (!(debug & DBG_DUMP))
 		return;
 
 	pr_info("%s %d) %c: ", hdr, addr, "RC"[cr]);
@@ -833,7 +840,7 @@ static int gsm_send_packet(struct gsm_mux *gsm, struct gsm_msg *msg)
 		len += 2;
 	}
 
-	if (debug & 4)
+	if (debug & DBG_DATA)
 		gsm_hex_dump_bytes(__func__, gsm->txframe, len);
 	gsm_print_packet("-->", msg->addr, gsm->initiator, msg->ctrl, msg->data,
 			 msg->len);
@@ -1766,7 +1773,7 @@ static int gsm_control_wait(struct gsm_mux *gsm, struct gsm_control *control)
 static void gsm_dlci_close(struct gsm_dlci *dlci)
 {
 	del_timer(&dlci->t1);
-	if (debug & 8)
+	if (debug & DBG_ERRORS)
 		pr_debug("DLCI %d goes closed.\n", dlci->addr);
 	dlci->state = DLCI_CLOSED;
 	/* Prevent us from sending data before the link is up again */
@@ -1800,7 +1807,7 @@ static void gsm_dlci_open(struct gsm_dlci *dlci)
 	/* This will let a tty open continue */
 	dlci->state = DLCI_OPEN;
 	dlci->constipated = false;
-	if (debug & 8)
+	if (debug & DBG_ERRORS)
 		pr_debug("DLCI %d goes open.\n", dlci->addr);
 	/* Send current modem state */
 	if (dlci->addr)
@@ -1836,7 +1843,7 @@ static void gsm_dlci_t1(struct timer_list *t)
 			gsm_command(dlci->gsm, dlci->addr, SABM|PF);
 			mod_timer(&dlci->t1, jiffies + gsm->t1 * HZ / 100);
 		} else if (!dlci->addr && gsm->control == (DM | PF)) {
-			if (debug & 8)
+			if (debug & DBG_ERRORS)
 				pr_info("DLCI %d opening in ADM mode.\n",
 					dlci->addr);
 			dlci->mode = DLCI_MODE_ADM;
@@ -1941,7 +1948,7 @@ static void gsm_dlci_data(struct gsm_dlci *dlci, const u8 *data, int clen)
 	unsigned int modem = 0;
 	int len;
 
-	if (debug & 16)
+	if (debug & DBG_TTY)
 		pr_debug("%d bytes for tty\n", clen);
 	switch (dlci->adaption)  {
 	/* Unsupported types */
@@ -2029,7 +2036,7 @@ static void gsm_kick_timer(struct timer_list *t)
 		sent = gsm_dlci_data_sweep(gsm);
 	spin_unlock_irqrestore(&gsm->tx_lock, flags);
 
-	if (sent && debug & 4)
+	if (sent && debug & DBG_DATA)
 		pr_info("%s TX queue stalled\n", __func__);
 }
 
@@ -2163,7 +2170,7 @@ static void gsm_queue(struct gsm_mux *gsm)
 
 	if (gsm->fcs != GOOD_FCS) {
 		gsm->bad_fcs++;
-		if (debug & 4)
+		if (debug & DBG_DATA)
 			pr_debug("BAD FCS %02x\n", gsm->fcs);
 		return;
 	}
@@ -2789,7 +2796,7 @@ static int gsmld_output(struct gsm_mux *gsm, u8 *data, int len)
 		set_bit(TTY_DO_WRITE_WAKEUP, &gsm->tty->flags);
 		return -ENOSPC;
 	}
-	if (debug & 4)
+	if (debug & DBG_DATA)
 		gsm_hex_dump_bytes(__func__, data, len);
 	return gsm->tty->ops->write(gsm->tty, data, len);
 }
@@ -2876,7 +2883,7 @@ static void gsmld_receive_buf(struct tty_struct *tty, const unsigned char *cp,
 	struct gsm_mux *gsm = tty->disc_data;
 	char flags = TTY_NORMAL;
 
-	if (debug & 4)
+	if (debug & DBG_DATA)
 		gsm_hex_dump_bytes(__func__, cp, count);
 
 	for (; count; count--, cp++) {
@@ -3416,7 +3423,7 @@ static int gsm_carrier_raised(struct tty_port *port)
 	/* Not yet open so no carrier info */
 	if (dlci->state != DLCI_OPEN)
 		return 0;
-	if (debug & 2)
+	if (debug & DBG_CD_ON)
 		return 1;
 
 	/*
