Merge tag 'tty-5.18-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty

Pull tty/serial fixes from Greg KH:
 "Here are some small serial driver fixes, and a larger number of GSM
  line discipline fixes for 5.18-rc5.

  These include:

   - lots of tiny n_gsm fixes for issues to resolve a number of reported
     problems. Seems that people are starting to actually use this code
     again.

   - 8250 driver fixes for some devices

   - imx serial driver fix

   - amba-pl011 driver fix

  All of these have been in linux-next for a while with no reported
  issues"

* tag 'tty-5.18-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty: (27 commits)
  tty: n_gsm: fix sometimes uninitialized warning in gsm_dlci_modem_output()
  serial: 8250: Correct the clock for EndRun PTP/1588 PCIe device
  serial: 8250: Also set sticky MCR bits in console restoration
  tty: n_gsm: fix software flow control handling
  tty: n_gsm: fix invalid use of MSC in advanced option
  tty: n_gsm: fix broken virtual tty handling
  Revert "serial: sc16is7xx: Clear RS485 bits in the shutdown"
  tty: n_gsm: fix missing update of modem controls after DLCI open
  serial: 8250: Fix runtime PM for start_tx() for empty buffer
  serial: imx: fix overrun interrupts in DMA mode
  serial: amba-pl011: do not time out prematurely when draining tx fifo
  tty: n_gsm: fix incorrect UA handling
  tty: n_gsm: fix reset fifo race condition
  tty: n_gsm: fix missing tty wakeup in convergence layer type 2
  tty: n_gsm: fix wrong signal octets encoding in MSC
  tty: n_gsm: fix wrong command frame length field encoding
  tty: n_gsm: fix wrong command retry handling
  tty: n_gsm: fix missing explicit ldisc flush
  tty: n_gsm: fix wrong DLCI release order
  tty: n_gsm: fix insufficient txframe size
  ...

6 files changed, 293 insertions, 215 deletions

diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c
index fa92f727fdf8..a38b922bcbc1 100644
--- a/drivers/tty/n_gsm.c
+++ b/drivers/tty/n_gsm.c
@@ -73,6 +73,8 @@ module_param(debug, int, 0600);
  */
 #define MAX_MRU 1500
 #define MAX_MTU 1500
+/* SOF, ADDR, CTRL, LEN1, LEN2, ..., FCS, EOF */
+#define PROT_OVERHEAD 7
 #define	GSM_NET_TX_TIMEOUT (HZ*10)
 
 /*
@@ -219,7 +221,6 @@ struct gsm_mux {
 	int encoding;
 	u8 control;
 	u8 fcs;
-	u8 received_fcs;
 	u8 *txframe;			/* TX framing buffer */
 
 	/* Method for the receiver side */
@@ -231,6 +232,7 @@ struct gsm_mux {
 	int initiator;			/* Did we initiate connection */
 	bool dead;			/* Has the mux been shut down */
 	struct gsm_dlci *dlci[NUM_DLCI];
+	int old_c_iflag;		/* termios c_iflag value before attach */
 	bool constipated;		/* Asked by remote to shut up */
 
 	spinlock_t tx_lock;
@@ -271,10 +273,6 @@ static DEFINE_SPINLOCK(gsm_mux_lock);
 
 static struct tty_driver *gsm_tty_driver;
 
-/* Save dlci open address */
-static int addr_open[256] = { 0 };
-/* Save dlci open count */
-static int addr_cnt;
 /*
  *	This section of the driver logic implements the GSM encodings
  *	both the basic and the 'advanced'. Reliable transport is not
@@ -369,6 +367,7 @@ static const u8 gsm_fcs8[256] = {
 #define GOOD_FCS	0xCF
 
 static int gsmld_output(struct gsm_mux *gsm, u8 *data, int len);
+static int gsm_modem_update(struct gsm_dlci *dlci, u8 brk);
 
 /**
  *	gsm_fcs_add	-	update FCS
@@ -832,7 +831,7 @@ static int gsm_dlci_data_output(struct gsm_mux *gsm, struct gsm_dlci *dlci)
 			break;
 		case 2:	/* Unstructed with modem bits.
 		Always one byte as we never send inline break data */
-			*dp++ = gsm_encode_modem(dlci);
+			*dp++ = (gsm_encode_modem(dlci) << 1) | EA;
 			break;
 		}
 		WARN_ON(kfifo_out_locked(&dlci->fifo, dp , len, &dlci->lock) != len);
@@ -917,6 +916,66 @@ static int gsm_dlci_data_output_framed(struct gsm_mux *gsm,
 }
 
 /**
+ *	gsm_dlci_modem_output	-	try and push modem status out of a DLCI
+ *	@gsm: mux
+ *	@dlci: the DLCI to pull modem status from
+ *	@brk: break signal
+ *
+ *	Push an empty frame in to the transmit queue to update the modem status
+ *	bits and to transmit an optional break.
+ *
+ *	Caller must hold the tx_lock of the mux.
+ */
+
+static int gsm_dlci_modem_output(struct gsm_mux *gsm, struct gsm_dlci *dlci,
+				 u8 brk)
+{
+	u8 *dp = NULL;
+	struct gsm_msg *msg;
+	int size = 0;
+
+	/* for modem bits without break data */
+	switch (dlci->adaption) {
+	case 1: /* Unstructured */
+		break;
+	case 2: /* Unstructured with modem bits. */
+		size++;
+		if (brk > 0)
+			size++;
+		break;
+	default:
+		pr_err("%s: unsupported adaption %d\n", __func__,
+		       dlci->adaption);
+		return -EINVAL;
+	}
+
+	msg = gsm_data_alloc(gsm, dlci->addr, size, gsm->ftype);
+	if (!msg) {
+		pr_err("%s: gsm_data_alloc error", __func__);
+		return -ENOMEM;
+	}
+	dp = msg->data;
+	switch (dlci->adaption) {
+	case 1: /* Unstructured */
+		break;
+	case 2: /* Unstructured with modem bits. */
+		if (brk == 0) {
+			*dp++ = (gsm_encode_modem(dlci) << 1) | EA;
+		} else {
+			*dp++ = gsm_encode_modem(dlci) << 1;
+			*dp++ = (brk << 4) | 2 | EA; /* Length, Break, EA */
+		}
+		break;
+	default:
+		/* Handled above */
+		break;
+	}
+
+	__gsm_data_queue(dlci, msg);
+	return size;
+}
+
+/**
  *	gsm_dlci_data_sweep		-	look for data to send
  *	@gsm: the GSM mux
  *
@@ -1093,7 +1152,6 @@ static void gsm_control_modem(struct gsm_mux *gsm, const u8 *data, int clen)
 {
 	unsigned int addr = 0;
 	unsigned int modem = 0;
-	unsigned int brk = 0;
 	struct gsm_dlci *dlci;
 	int len = clen;
 	int slen;
@@ -1123,17 +1181,8 @@ static void gsm_control_modem(struct gsm_mux *gsm, const u8 *data, int clen)
 			return;
 	}
 	len--;
-	if (len > 0) {
-		while (gsm_read_ea(&brk, *dp++) == 0) {
-			len--;
-			if (len == 0)
-				return;
-		}
-		modem <<= 7;
-		modem |= (brk & 0x7f);
-	}
 	tty = tty_port_tty_get(&dlci->port);
-	gsm_process_modem(tty, dlci, modem, slen);
+	gsm_process_modem(tty, dlci, modem, slen - len);
 	if (tty) {
 		tty_wakeup(tty);
 		tty_kref_put(tty);
@@ -1193,7 +1242,6 @@ static void gsm_control_rls(struct gsm_mux *gsm, const u8 *data, int clen)
 }
 
 static void gsm_dlci_begin_close(struct gsm_dlci *dlci);
-static void gsm_dlci_close(struct gsm_dlci *dlci);
 
 /**
  *	gsm_control_message	-	DLCI 0 control processing
@@ -1212,28 +1260,15 @@ static void gsm_control_message(struct gsm_mux *gsm, unsigned int command,
 {
 	u8 buf[1];
 	unsigned long flags;
-	struct gsm_dlci *dlci;
-	int i;
-	int address;
 
 	switch (command) {
 	case CMD_CLD: {
-		if (addr_cnt > 0) {
-			for (i = 0; i < addr_cnt; i++) {
-				address = addr_open[i];
-				dlci = gsm->dlci[address];
-				gsm_dlci_close(dlci);
-				addr_open[i] = 0;
-			}
-		}
+		struct gsm_dlci *dlci = gsm->dlci[0];
 		/* Modem wishes to close down */
-		dlci = gsm->dlci[0];
 		if (dlci) {
 			dlci->dead = true;
 			gsm->dead = true;
-			gsm_dlci_close(dlci);
-			addr_cnt = 0;
-			gsm_response(gsm, 0, UA|PF);
+			gsm_dlci_begin_close(dlci);
 		}
 		}
 		break;
@@ -1326,11 +1361,12 @@ static void gsm_control_response(struct gsm_mux *gsm, unsigned int command,
 
 static void gsm_control_transmit(struct gsm_mux *gsm, struct gsm_control *ctrl)
 {
-	struct gsm_msg *msg = gsm_data_alloc(gsm, 0, ctrl->len + 1, gsm->ftype);
+	struct gsm_msg *msg = gsm_data_alloc(gsm, 0, ctrl->len + 2, gsm->ftype);
 	if (msg == NULL)
 		return;
-	msg->data[0] = (ctrl->cmd << 1) | 2 | EA;	/* command */
-	memcpy(msg->data + 1, ctrl->data, ctrl->len);
+	msg->data[0] = (ctrl->cmd << 1) | CR | EA;	/* command */
+	msg->data[1] = (ctrl->len << 1) | EA;
+	memcpy(msg->data + 2, ctrl->data, ctrl->len);
 	gsm_data_queue(gsm->dlci[0], msg);
 }
 
@@ -1353,7 +1389,6 @@ static void gsm_control_retransmit(struct timer_list *t)
 	spin_lock_irqsave(&gsm->control_lock, flags);
 	ctrl = gsm->pending_cmd;
 	if (ctrl) {
-		gsm->cretries--;
 		if (gsm->cretries == 0) {
 			gsm->pending_cmd = NULL;
 			ctrl->error = -ETIMEDOUT;
@@ -1362,6 +1397,7 @@ static void gsm_control_retransmit(struct timer_list *t)
 			wake_up(&gsm->event);
 			return;
 		}
+		gsm->cretries--;
 		gsm_control_transmit(gsm, ctrl);
 		mod_timer(&gsm->t2_timer, jiffies + gsm->t2 * HZ / 100);
 	}
@@ -1402,7 +1438,7 @@ retry:
 
 	/* If DLCI0 is in ADM mode skip retries, it won't respond */
 	if (gsm->dlci[0]->mode == DLCI_MODE_ADM)
-		gsm->cretries = 1;
+		gsm->cretries = 0;
 	else
 		gsm->cretries = gsm->n2;
 
@@ -1450,20 +1486,22 @@ static int gsm_control_wait(struct gsm_mux *gsm, struct gsm_control *control)
 
 static void gsm_dlci_close(struct gsm_dlci *dlci)
 {
+	unsigned long flags;
+
 	del_timer(&dlci->t1);
 	if (debug & 8)
 		pr_debug("DLCI %d goes closed.\n", dlci->addr);
 	dlci->state = DLCI_CLOSED;
 	if (dlci->addr != 0) {
 		tty_port_tty_hangup(&dlci->port, false);
+		spin_lock_irqsave(&dlci->lock, flags);
 		kfifo_reset(&dlci->fifo);
+		spin_unlock_irqrestore(&dlci->lock, flags);
 		/* Ensure that gsmtty_open() can return. */
 		tty_port_set_initialized(&dlci->port, 0);
 		wake_up_interruptible(&dlci->port.open_wait);
 	} else
 		dlci->gsm->dead = true;
-	/* Unregister gsmtty driver,report gsmtty dev remove uevent for user */
-	tty_unregister_device(gsm_tty_driver, dlci->addr);
 	wake_up(&dlci->gsm->event);
 	/* A DLCI 0 close is a MUX termination so we need to kick that
 	   back to userspace somehow */
@@ -1485,8 +1523,9 @@ static void gsm_dlci_open(struct gsm_dlci *dlci)
 	dlci->state = DLCI_OPEN;
 	if (debug & 8)
 		pr_debug("DLCI %d goes open.\n", dlci->addr);
-	/* Register gsmtty driver,report gsmtty dev add uevent for user */
-	tty_register_device(gsm_tty_driver, dlci->addr, NULL);
+	/* Send current modem state */
+	if (dlci->addr)
+		gsm_modem_update(dlci, 0);
 	wake_up(&dlci->gsm->event);
 }
 
@@ -1623,6 +1662,7 @@ static void gsm_dlci_data(struct gsm_dlci *dlci, const u8 *data, int clen)
 		tty = tty_port_tty_get(port);
 		if (tty) {
 			gsm_process_modem(tty, dlci, modem, slen);
+			tty_wakeup(tty);
 			tty_kref_put(tty);
 		}
 		fallthrough;
@@ -1793,19 +1833,7 @@ static void gsm_queue(struct gsm_mux *gsm)
 	struct gsm_dlci *dlci;
 	u8 cr;
 	int address;
-	int i, j, k, address_tmp;
-	/* We have to sneak a look at the packet body to do the FCS.
-	   A somewhat layering violation in the spec */
 
-	if ((gsm->control & ~PF) == UI)
-		gsm->fcs = gsm_fcs_add_block(gsm->fcs, gsm->buf, gsm->len);
-	if (gsm->encoding == 0) {
-		/* WARNING: gsm->received_fcs is used for
-		gsm->encoding = 0 only.
-		In this case it contain the last piece of data
-		required to generate final CRC */
-		gsm->fcs = gsm_fcs_add(gsm->fcs, gsm->received_fcs);
-	}
 	if (gsm->fcs != GOOD_FCS) {
 		gsm->bad_fcs++;
 		if (debug & 4)
@@ -1836,11 +1864,6 @@ static void gsm_queue(struct gsm_mux *gsm)
 		else {
 			gsm_response(gsm, address, UA|PF);
 			gsm_dlci_open(dlci);
-			/* Save dlci open address */
-			if (address) {
-				addr_open[addr_cnt] = address;
-				addr_cnt++;
-			}
 		}
 		break;
 	case DISC|PF:
@@ -1851,35 +1874,9 @@ static void gsm_queue(struct gsm_mux *gsm)
 			return;
 		}
 		/* Real close complete */
-		if (!address) {
-			if (addr_cnt > 0) {
-				for (i = 0; i < addr_cnt; i++) {
-					address = addr_open[i];
-					dlci = gsm->dlci[address];
-					gsm_dlci_close(dlci);
-					addr_open[i] = 0;
-				}
-			}
-			dlci = gsm->dlci[0];
-			gsm_dlci_close(dlci);
-			addr_cnt = 0;
-			gsm_response(gsm, 0, UA|PF);
-		} else {
-			gsm_response(gsm, address, UA|PF);
-			gsm_dlci_close(dlci);
-			/* clear dlci address */
-			for (j = 0; j < addr_cnt; j++) {
-				address_tmp = addr_open[j];
-				if (address_tmp == address) {
-					for (k = j; k < addr_cnt; k++)
-						addr_open[k] = addr_open[k+1];
-					addr_cnt--;
-					break;
-				}
-			}
-		}
+		gsm_response(gsm, address, UA|PF);
+		gsm_dlci_close(dlci);
 		break;
-	case UA:
 	case UA|PF:
 		if (cr == 0 || dlci == NULL)
 			break;
@@ -1993,19 +1990,25 @@ static void gsm0_receive(struct gsm_mux *gsm, unsigned char c)
 		break;
 	case GSM_DATA:		/* Data */
 		gsm->buf[gsm->count++] = c;
-		if (gsm->count == gsm->len)
+		if (gsm->count == gsm->len) {
+			/* Calculate final FCS for UI frames over all data */
+			if ((gsm->control & ~PF) != UIH) {
+				gsm->fcs = gsm_fcs_add_block(gsm->fcs, gsm->buf,
+							     gsm->count);
+			}
 			gsm->state = GSM_FCS;
+		}
 		break;
 	case GSM_FCS:		/* FCS follows the packet */
-		gsm->received_fcs = c;
-		gsm_queue(gsm);
+		gsm->fcs = gsm_fcs_add(gsm->fcs, c);
 		gsm->state = GSM_SSOF;
 		break;
 	case GSM_SSOF:
-		if (c == GSM0_SOF) {
-			gsm->state = GSM_SEARCH;
-			break;
-		}
+		gsm->state = GSM_SEARCH;
+		if (c == GSM0_SOF)
+			gsm_queue(gsm);
+		else
+			gsm->bad_size++;
 		break;
 	default:
 		pr_debug("%s: unhandled state: %d\n", __func__, gsm->state);
@@ -2023,12 +2026,35 @@ static void gsm0_receive(struct gsm_mux *gsm, unsigned char c)
 
 static void gsm1_receive(struct gsm_mux *gsm, unsigned char c)
 {
+	/* handle XON/XOFF */
+	if ((c & ISO_IEC_646_MASK) == XON) {
+		gsm->constipated = true;
+		return;
+	} else if ((c & ISO_IEC_646_MASK) == XOFF) {
+		gsm->constipated = false;
+		/* Kick the link in case it is idling */
+		gsm_data_kick(gsm, NULL);
+		return;
+	}
 	if (c == GSM1_SOF) {
-		/* EOF is only valid in frame if we have got to the data state
-		   and received at least one byte (the FCS) */
-		if (gsm->state == GSM_DATA && gsm->count) {
-			/* Extract the FCS */
+		/* EOF is only valid in frame if we have got to the data state */
+		if (gsm->state == GSM_DATA) {
+			if (gsm->count < 1) {
+				/* Missing FSC */
+				gsm->malformed++;
+				gsm->state = GSM_START;
+				return;
+			}
+			/* Remove the FCS from data */
 			gsm->count--;
+			if ((gsm->control & ~PF) != UIH) {
+				/* Calculate final FCS for UI frames over all
+				 * data but FCS
+				 */
+				gsm->fcs = gsm_fcs_add_block(gsm->fcs, gsm->buf,
+							     gsm->count);
+			}
+			/* Add the FCS itself to test against GOOD_FCS */
 			gsm->fcs = gsm_fcs_add(gsm->fcs, gsm->buf[gsm->count]);
 			gsm->len = gsm->count;
 			gsm_queue(gsm);
@@ -2037,7 +2063,8 @@ static void gsm1_receive(struct gsm_mux *gsm, unsigned char c)
 		}
 		/* Any partial frame was a runt so go back to start */
 		if (gsm->state != GSM_START) {
-			gsm->malformed++;
+			if (gsm->state != GSM_SEARCH)
+				gsm->malformed++;
 			gsm->state = GSM_START;
 		}
 		/* A SOF in GSM_START means we are still reading idling or
@@ -2106,74 +2133,43 @@ static void gsm_error(struct gsm_mux *gsm)
 	gsm->io_error++;
 }
 
-static int gsm_disconnect(struct gsm_mux *gsm)
-{
-	struct gsm_dlci *dlci = gsm->dlci[0];
-	struct gsm_control *gc;
-
-	if (!dlci)
-		return 0;
-
-	/* In theory disconnecting DLCI 0 is sufficient but for some
-	   modems this is apparently not the case. */
-	gc = gsm_control_send(gsm, CMD_CLD, NULL, 0);
-	if (gc)
-		gsm_control_wait(gsm, gc);
-
-	del_timer_sync(&gsm->t2_timer);
-	/* Now we are sure T2 has stopped */
-
-	gsm_dlci_begin_close(dlci);
-	wait_event_interruptible(gsm->event,
-				dlci->state == DLCI_CLOSED);
-
-	if (signal_pending(current))
-		return -EINTR;
-
-	return 0;
-}
-
 /**
  *	gsm_cleanup_mux		-	generic GSM protocol cleanup
  *	@gsm: our mux
+ *	@disc: disconnect link?
  *
  *	Clean up the bits of the mux which are the same for all framing
  *	protocols. Remove the mux from the mux table, stop all the timers
  *	and then shut down each device hanging up the channels as we go.
  */
 
-static void gsm_cleanup_mux(struct gsm_mux *gsm)
+static void gsm_cleanup_mux(struct gsm_mux *gsm, bool disc)
 {
 	int i;
 	struct gsm_dlci *dlci = gsm->dlci[0];
 	struct gsm_msg *txq, *ntxq;
 
 	gsm->dead = true;
+	mutex_lock(&gsm->mutex);
 
-	spin_lock(&gsm_mux_lock);
-	for (i = 0; i < MAX_MUX; i++) {
-		if (gsm_mux[i] == gsm) {
-			gsm_mux[i] = NULL;
-			break;
+	if (dlci) {
+		if (disc && dlci->state != DLCI_CLOSED) {
+			gsm_dlci_begin_close(dlci);
+			wait_event(gsm->event, dlci->state == DLCI_CLOSED);
 		}
+		dlci->dead = true;
 	}
-	spin_unlock(&gsm_mux_lock);
-	/* open failed before registering => nothing to do */
-	if (i == MAX_MUX)
-		return;
 
+	/* Finish outstanding timers, making sure they are done */
 	del_timer_sync(&gsm->t2_timer);
-	/* Now we are sure T2 has stopped */
-	if (dlci)
-		dlci->dead = true;
 
-	/* Free up any link layer users */
-	mutex_lock(&gsm->mutex);
-	for (i = 0; i < NUM_DLCI; i++)
+	/* Free up any link layer users and finally the control channel */
+	for (i = NUM_DLCI - 1; i >= 0; i--)
 		if (gsm->dlci[i])
 			gsm_dlci_release(gsm->dlci[i]);
 	mutex_unlock(&gsm->mutex);
 	/* Now wipe the queues */
+	tty_ldisc_flush(gsm->tty);
 	list_for_each_entry_safe(txq, ntxq, &gsm->tx_list, list)
 		kfree(txq);
 	INIT_LIST_HEAD(&gsm->tx_list);
@@ -2191,7 +2187,6 @@ static void gsm_cleanup_mux(struct gsm_mux *gsm)
 static int gsm_activate_mux(struct gsm_mux *gsm)
 {
 	struct gsm_dlci *dlci;
-	int i = 0;
 
 	timer_setup(&gsm->t2_timer, gsm_control_retransmit, 0);
 	init_waitqueue_head(&gsm->event);
@@ -2203,18 +2198,6 @@ static int gsm_activate_mux(struct gsm_mux *gsm)
 	else
 		gsm->receive = gsm1_receive;
 
-	spin_lock(&gsm_mux_lock);
-	for (i = 0; i < MAX_MUX; i++) {
-		if (gsm_mux[i] == NULL) {
-			gsm->num = i;
-			gsm_mux[i] = gsm;
-			break;
-		}
-	}
-	spin_unlock(&gsm_mux_lock);
-	if (i == MAX_MUX)
-		return -EBUSY;
-
 	dlci = gsm_dlci_alloc(gsm, 0);
 	if (dlci == NULL)
 		return -ENOMEM;
@@ -2230,6 +2213,15 @@ static int gsm_activate_mux(struct gsm_mux *gsm)
  */
 static void gsm_free_mux(struct gsm_mux *gsm)
 {
+	int i;
+
+	for (i = 0; i < MAX_MUX; i++) {
+		if (gsm == gsm_mux[i]) {
+			gsm_mux[i] = NULL;
+			break;
+		}
+	}
+	mutex_destroy(&gsm->mutex);
 	kfree(gsm->txframe);
 	kfree(gsm->buf);
 	kfree(gsm);
@@ -2249,12 +2241,20 @@ static void gsm_free_muxr(struct kref *ref)
 
 static inline void mux_get(struct gsm_mux *gsm)
 {
+	unsigned long flags;
+
+	spin_lock_irqsave(&gsm_mux_lock, flags);
 	kref_get(&gsm->ref);
+	spin_unlock_irqrestore(&gsm_mux_lock, flags);
 }
 
 static inline void mux_put(struct gsm_mux *gsm)
 {
+	unsigned long flags;
+
+	spin_lock_irqsave(&gsm_mux_lock, flags);
 	kref_put(&gsm->ref, gsm_free_muxr);
+	spin_unlock_irqrestore(&gsm_mux_lock, flags);
 }
 
 static inline unsigned int mux_num_to_base(struct gsm_mux *gsm)
@@ -2275,6 +2275,7 @@ static inline unsigned int mux_line_to_num(unsigned int line)
 
 static struct gsm_mux *gsm_alloc_mux(void)
 {
+	int i;
 	struct gsm_mux *gsm = kzalloc(sizeof(struct gsm_mux), GFP_KERNEL);
 	if (gsm == NULL)
 		return NULL;
@@ -2283,7 +2284,7 @@ static struct gsm_mux *gsm_alloc_mux(void)
 		kfree(gsm);
 		return NULL;
 	}
-	gsm->txframe = kmalloc(2 * MAX_MRU + 2, GFP_KERNEL);
+	gsm->txframe = kmalloc(2 * (MAX_MTU + PROT_OVERHEAD - 1), GFP_KERNEL);
 	if (gsm->txframe == NULL) {
 		kfree(gsm->buf);
 		kfree(gsm);
@@ -2304,6 +2305,26 @@ static struct gsm_mux *gsm_alloc_mux(void)
 	gsm->mtu = 64;
 	gsm->dead = true;	/* Avoid early tty opens */
 
+	/* Store the instance to the mux array or abort if no space is
+	 * available.
+	 */
+	spin_lock(&gsm_mux_lock);
+	for (i = 0; i < MAX_MUX; i++) {
+		if (!gsm_mux[i]) {
+			gsm_mux[i] = gsm;
+			gsm->num = i;
+			break;
+		}
+	}
+	spin_unlock(&gsm_mux_lock);
+	if (i == MAX_MUX) {
+		mutex_destroy(&gsm->mutex);
+		kfree(gsm->txframe);
+		kfree(gsm->buf);
+		kfree(gsm);
+		return NULL;
+	}
+
 	return gsm;
 }
 
@@ -2339,7 +2360,7 @@ static int gsm_config(struct gsm_mux *gsm, struct gsm_config *c)
 	/* Check the MRU/MTU range looks sane */
 	if (c->mru > MAX_MRU || c->mtu > MAX_MTU || c->mru < 8 || c->mtu < 8)
 		return -EINVAL;
-	if (c->n2 < 3)
+	if (c->n2 > 255)
 		return -EINVAL;
 	if (c->encapsulation > 1)	/* Basic, advanced, no I */
 		return -EINVAL;
@@ -2370,19 +2391,11 @@ static int gsm_config(struct gsm_mux *gsm, struct gsm_config *c)
 
 	/*
 	 * Close down what is needed, restart and initiate the new
-	 * configuration
+	 * configuration. On the first time there is no DLCI[0]
+	 * and closing or cleaning up is not necessary.
 	 */
-
-	if (gsm->initiator && (need_close || need_restart)) {
-		int ret;
-
-		ret = gsm_disconnect(gsm);
-
-		if (ret)
-			return ret;
-	}
-	if (need_restart)
-		gsm_cleanup_mux(gsm);
+	if (need_close || need_restart)
+		gsm_cleanup_mux(gsm, true);
 
 	gsm->initiator = c->initiator;
 	gsm->mru = c->mru;
@@ -2450,25 +2463,26 @@ static int gsmld_attach_gsm(struct tty_struct *tty, struct gsm_mux *gsm)
 	int ret, i;
 
 	gsm->tty = tty_kref_get(tty);
+	/* Turn off tty XON/XOFF handling to handle it explicitly. */
+	gsm->old_c_iflag = tty->termios.c_iflag;
+	tty->termios.c_iflag &= (IXON | IXOFF);
 	ret =  gsm_activate_mux(gsm);
 	if (ret != 0)
 		tty_kref_put(gsm->tty);
 	else {
 		/* Don't register device 0 - this is the control channel and not
 		   a usable tty interface */
-		if (gsm->initiator) {
-			base = mux_num_to_base(gsm); /* Base for this MUX */
-			for (i = 1; i < NUM_DLCI; i++) {
-				struct device *dev;
+		base = mux_num_to_base(gsm); /* Base for this MUX */
+		for (i = 1; i < NUM_DLCI; i++) {
+			struct device *dev;
 
-				dev = tty_register_device(gsm_tty_driver,
+			dev = tty_register_device(gsm_tty_driver,
 							base + i, NULL);
-				if (IS_ERR(dev)) {
-					for (i--; i >= 1; i--)
-						tty_unregister_device(gsm_tty_driver,
-									base + i);
-					return PTR_ERR(dev);
-				}
+			if (IS_ERR(dev)) {
+				for (i--; i >= 1; i--)
+					tty_unregister_device(gsm_tty_driver,
+								base + i);
+				return PTR_ERR(dev);
 			}
 		}
 	}
@@ -2490,11 +2504,10 @@ static void gsmld_detach_gsm(struct tty_struct *tty, struct gsm_mux *gsm)
 	int i;
 
 	WARN_ON(tty != gsm->tty);
-	if (gsm->initiator) {
-		for (i = 1; i < NUM_DLCI; i++)
-			tty_unregister_device(gsm_tty_driver, base + i);
-	}
-	gsm_cleanup_mux(gsm);
+	for (i = 1; i < NUM_DLCI; i++)
+		tty_unregister_device(gsm_tty_driver, base + i);
+	/* Restore tty XON/XOFF handling. */
+	gsm->tty->termios.c_iflag = gsm->old_c_iflag;
 	tty_kref_put(gsm->tty);
 	gsm->tty = NULL;
 }
@@ -2559,6 +2572,12 @@ static void gsmld_close(struct tty_struct *tty)
 {
 	struct gsm_mux *gsm = tty->disc_data;
 
+	/* The ldisc locks and closes the port before calling our close. This
+	 * means we have no way to do a proper disconnect. We will not bother
+	 * to do one.
+	 */
+	gsm_cleanup_mux(gsm, false);
+
 	gsmld_detach_gsm(tty, gsm);
 
 	gsmld_flush_buffer(tty);
@@ -2597,7 +2616,7 @@ static int gsmld_open(struct tty_struct *tty)
 
 	ret = gsmld_attach_gsm(tty, gsm);
 	if (ret != 0) {
-		gsm_cleanup_mux(gsm);
+		gsm_cleanup_mux(gsm, false);
 		mux_put(gsm);
 	}
 	return ret;
@@ -2954,26 +2973,78 @@ static struct tty_ldisc_ops tty_ldisc_packet = {
 
 #define TX_SIZE		512
 
-static int gsmtty_modem_update(struct gsm_dlci *dlci, u8 brk)
+/**
+ *	gsm_modem_upd_via_data	-	send modem bits via convergence layer
+ *	@dlci: channel
+ *	@brk: break signal
+ *
+ *	Send an empty frame to signal mobile state changes and to transmit the
+ *	break signal for adaption 2.
+ */
+
+static void gsm_modem_upd_via_data(struct gsm_dlci *dlci, u8 brk)
 {
-	u8 modembits[5];
+	struct gsm_mux *gsm = dlci->gsm;
+	unsigned long flags;
+
+	if (dlci->state != DLCI_OPEN || dlci->adaption != 2)
+		return;
+
+	spin_lock_irqsave(&gsm->tx_lock, flags);
+	gsm_dlci_modem_output(gsm, dlci, brk);
+	spin_unlock_irqrestore(&gsm->tx_lock, flags);
+}
+
+/**
+ *	gsm_modem_upd_via_msc	-	send modem bits via control frame
+ *	@dlci: channel
+ *	@brk: break signal
+ */
+
+static int gsm_modem_upd_via_msc(struct gsm_dlci *dlci, u8 brk)
+{
+	u8 modembits[3];
 	struct gsm_control *ctrl;
 	int len = 2;
 
-	if (brk)
-		len++;
+	if (dlci->gsm->encoding != 0)
+		return 0;
 
-	modembits[0] = len << 1 | EA;		/* Data bytes */
-	modembits[1] = dlci->addr << 2 | 3;	/* DLCI, EA, 1 */
-	modembits[2] = gsm_encode_modem(dlci) << 1 | EA;
-	if (brk)
-		modembits[3] = brk << 4 | 2 | EA;	/* Valid, EA */
-	ctrl = gsm_control_send(dlci->gsm, CMD_MSC, modembits, len + 1);
+	modembits[0] = (dlci->addr << 2) | 2 | EA;  /* DLCI, Valid, EA */
+	if (!brk) {
+		modembits[1] = (gsm_encode_modem(dlci) << 1) | EA;
+	} else {
+		modembits[1] = gsm_encode_modem(dlci) << 1;
+		modembits[2] = (brk << 4) | 2 | EA; /* Length, Break, EA */
+		len++;
+	}
+	ctrl = gsm_control_send(dlci->gsm, CMD_MSC, modembits, len);
 	if (ctrl == NULL)
 		return -ENOMEM;
 	return gsm_control_wait(dlci->gsm, ctrl);
 }
 
+/**
+ *	gsm_modem_update	-	send modem status line state
+ *	@dlci: channel
+ *	@brk: break signal
+ */
+
+static int gsm_modem_update(struct gsm_dlci *dlci, u8 brk)
+{
+	if (dlci->adaption == 2) {
+		/* Send convergence layer type 2 empty data frame. */
+		gsm_modem_upd_via_data(dlci, brk);
+		return 0;
+	} else if (dlci->gsm->encoding == 0) {
+		/* Send as MSC control message. */
+		return gsm_modem_upd_via_msc(dlci, brk);
+	}
+
+	/* Modem status lines are not supported. */
+	return -EPROTONOSUPPORT;
+}
+
 static int gsm_carrier_raised(struct tty_port *port)
 {
 	struct gsm_dlci *dlci = container_of(port, struct gsm_dlci, port);
@@ -3006,7 +3077,7 @@ static void gsm_dtr_rts(struct tty_port *port, int onoff)
 		modem_tx &= ~(TIOCM_DTR | TIOCM_RTS);
 	if (modem_tx != dlci->modem_tx) {
 		dlci->modem_tx = modem_tx;
-		gsmtty_modem_update(dlci, 0);
+		gsm_modem_update(dlci, 0);
 	}
 }
 
@@ -3155,13 +3226,17 @@ static unsigned int gsmtty_chars_in_buffer(struct tty_struct *tty)
 static void gsmtty_flush_buffer(struct tty_struct *tty)
 {
 	struct gsm_dlci *dlci = tty->driver_data;
+	unsigned long flags;
+
 	if (dlci->state == DLCI_CLOSED)
 		return;
 	/* Caution needed: If we implement reliable transport classes
 	   then the data being transmitted can't simply be junked once
 	   it has first hit the stack. Until then we can just blow it
 	   away */
+	spin_lock_irqsave(&dlci->lock, flags);
 	kfifo_reset(&dlci->fifo);
+	spin_unlock_irqrestore(&dlci->lock, flags);
 	/* Need to unhook this DLCI from the transmit queue logic */
 }
 
@@ -3193,7 +3268,7 @@ static int gsmtty_tiocmset(struct tty_struct *tty,
 
 	if (modem_tx != dlci->modem_tx) {
 		dlci->modem_tx = modem_tx;
-		return gsmtty_modem_update(dlci, 0);
+		return gsm_modem_update(dlci, 0);
 	}
 	return 0;
 }
@@ -3254,7 +3329,7 @@ static void gsmtty_throttle(struct tty_struct *tty)
 		dlci->modem_tx &= ~TIOCM_RTS;
 	dlci->throttled = true;
 	/* Send an MSC with RTS cleared */
-	gsmtty_modem_update(dlci, 0);
+	gsm_modem_update(dlci, 0);
 }
 
 static void gsmtty_unthrottle(struct tty_struct *tty)
@@ -3266,7 +3341,7 @@ static void gsmtty_unthrottle(struct tty_struct *tty)
 		dlci->modem_tx |= TIOCM_RTS;
 	dlci->throttled = false;
 	/* Send an MSC with RTS set */
-	gsmtty_modem_update(dlci, 0);
+	gsm_modem_update(dlci, 0);
 }
 
 static int gsmtty_break_ctl(struct tty_struct *tty, int state)
@@ -3284,7 +3359,7 @@ static int gsmtty_break_ctl(struct tty_struct *tty, int state)
 		if (encode > 0x0F)
 			encode = 0x0F;	/* Best effort */
 	}
-	return gsmtty_modem_update(dlci, encode);
+	return gsm_modem_update(dlci, encode);
 }
 
 static void gsmtty_cleanup(struct tty_struct *tty)
diff --git a/drivers/tty/serial/8250/8250_pci.c b/drivers/tty/serial/8250/8250_pci.c
index e17e97ea86fa..a293e9f107d0 100644
--- a/drivers/tty/serial/8250/8250_pci.c
+++ b/drivers/tty/serial/8250/8250_pci.c
@@ -2667,7 +2667,7 @@ enum pci_board_num_t {
 	pbn_panacom2,
 	pbn_panacom4,
 	pbn_plx_romulus,
-	pbn_endrun_2_4000000,
+	pbn_endrun_2_3906250,
 	pbn_oxsemi,
 	pbn_oxsemi_1_3906250,
 	pbn_oxsemi_2_3906250,
@@ -3195,10 +3195,10 @@ static struct pciserial_board pci_boards[] = {
 	* signal now many ports are available
 	* 2 port 952 Uart support
 	*/
-	[pbn_endrun_2_4000000] = {
+	[pbn_endrun_2_3906250] = {
 		.flags		= FL_BASE0,
 		.num_ports	= 2,
-		.base_baud	= 4000000,
+		.base_baud	= 3906250,
 		.uart_offset	= 0x200,
 		.first_offset	= 0x1000,
 	},
@@ -4115,7 +4115,7 @@ static const struct pci_device_id serial_pci_tbl[] = {
 	*/
 	{	PCI_VENDOR_ID_ENDRUN, PCI_DEVICE_ID_ENDRUN_1588,
 		PCI_ANY_ID, PCI_ANY_ID, 0, 0,
-		pbn_endrun_2_4000000 },
+		pbn_endrun_2_3906250 },
 	/*
 	 * Quatech cards. These actually have configurable clocks but for
 	 * now we just use the default.
diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
index 318af6f13605..1fbd5bf264be 100644
--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c
@@ -1675,11 +1675,11 @@ static void serial8250_start_tx(struct uart_port *port)
 	struct uart_8250_port *up = up_to_u8250p(port);
 	struct uart_8250_em485 *em485 = up->em485;
 
-	serial8250_rpm_get_tx(up);
-
 	if (!port->x_char && uart_circ_empty(&port->state->xmit))
 		return;
 
+	serial8250_rpm_get_tx(up);
+
 	if (em485 &&
 	    em485->active_timer == &em485->start_tx_timer)
 		return;
@@ -3329,7 +3329,7 @@ static void serial8250_console_restore(struct uart_8250_port *up)
 
 	serial8250_set_divisor(port, baud, quot, frac);
 	serial_port_out(port, UART_LCR, up->lcr);
-	serial8250_out_MCR(up, UART_MCR_DTR | UART_MCR_RTS);
+	serial8250_out_MCR(up, up->mcr | UART_MCR_DTR | UART_MCR_RTS);
 }
 
 /*
diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
index 51ecb050ae40..4d11a3e547f9 100644
--- a/drivers/tty/serial/amba-pl011.c
+++ b/drivers/tty/serial/amba-pl011.c
@@ -1255,13 +1255,18 @@ static inline bool pl011_dma_rx_running(struct uart_amba_port *uap)
 
 static void pl011_rs485_tx_stop(struct uart_amba_port *uap)
 {
+	/*
+	 * To be on the safe side only time out after twice as many iterations
+	 * as fifo size.
+	 */
+	const int MAX_TX_DRAIN_ITERS = uap->port.fifosize * 2;
 	struct uart_port *port = &uap->port;
 	int i = 0;
 	u32 cr;
 
 	/* Wait until hardware tx queue is empty */
 	while (!pl011_tx_empty(port)) {
-		if (i == port->fifosize) {
+		if (i > MAX_TX_DRAIN_ITERS) {
 			dev_warn(port->dev,
 				 "timeout while draining hardware tx queue\n");
 			break;
@@ -2052,7 +2057,7 @@ pl011_set_termios(struct uart_port *port, struct ktermios *termios,
 	 * with the given baud rate. We use this as the poll interval when we
 	 * wait for the tx queue to empty.
 	 */
-	uap->rs485_tx_drain_interval = (bits * 1000 * 1000) / baud;
+	uap->rs485_tx_drain_interval = DIV_ROUND_UP(bits * 1000 * 1000, baud);
 
 	pl011_setup_status_masks(port, termios);
 
diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index fd38e6ed4fda..a2100be8d554 100644
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -1448,7 +1448,7 @@ static int imx_uart_startup(struct uart_port *port)
 	imx_uart_writel(sport, ucr1, UCR1);
 
 	ucr4 = imx_uart_readl(sport, UCR4) & ~(UCR4_OREN | UCR4_INVR);
-	if (!sport->dma_is_enabled)
+	if (!dma_is_inited)
 		ucr4 |= UCR4_OREN;
 	if (sport->inverted_rx)
 		ucr4 |= UCR4_INVR;
diff --git a/drivers/tty/serial/sc16is7xx.c b/drivers/tty/serial/sc16is7xx.c
index e857fb61efbf..5fb201c1b563 100644
--- a/drivers/tty/serial/sc16is7xx.c
+++ b/drivers/tty/serial/sc16is7xx.c
@@ -1238,12 +1238,10 @@ static void sc16is7xx_shutdown(struct uart_port *port)
 
 	/* Disable all interrupts */
 	sc16is7xx_port_write(port, SC16IS7XX_IER_REG, 0);
-	/* Disable TX/RX, clear auto RS485 and RTS invert */
+	/* Disable TX/RX */
 	sc16is7xx_port_update(port, SC16IS7XX_EFCR_REG,
 			      SC16IS7XX_EFCR_RXDISABLE_BIT |
-			      SC16IS7XX_EFCR_TXDISABLE_BIT |
-			      SC16IS7XX_EFCR_AUTO_RS485_BIT |
-			      SC16IS7XX_EFCR_RTS_INVERT_BIT,
+			      SC16IS7XX_EFCR_TXDISABLE_BIT,
 			      SC16IS7XX_EFCR_RXDISABLE_BIT |
 			      SC16IS7XX_EFCR_TXDISABLE_BIT);