Merge tag 'tty-6.4-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty

Pull tty / serial updates from Greg KH:
 "Here is the big set of tty/serial driver updates for 6.4-rc1.

  Nothing major, just lots of tiny, constant, forward development. This
  includes:

   - obligatory n_gsm updates and feature additions

   - 8250_em driver updates

   - sh-sci driver updates

   - dts cleanups and updates

   - general cleanups and improvements by Ilpo and Jiri

   - other small serial driver core fixes and driver updates

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

* tag 'tty-6.4-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty: (87 commits)
  n_gsm: Use array_index_nospec() with index that comes from userspace
  tty: vt: drop checks for undefined VT_SINGLE_DRIVER
  tty: vt: distribute EXPORT_SYMBOL()
  tty: vt: simplify some cases in tioclinux()
  tty: vt: reformat tioclinux()
  tty: serial: sh-sci: Fix end of transmission on SCI
  tty: serial: sh-sci: Add support for tx end interrupt handling
  tty: serial: sh-sci: Fix TE setting on SCI IP
  tty: serial: sh-sci: Add RZ/G2L SCIFA DMA rx support
  tty: serial: sh-sci: Add RZ/G2L SCIFA DMA tx support
  serial: max310x: fix IO data corruption in batched operations
  serial: core: Disable uart_start() on uart_remove_one_port()
  serial: 8250: Reinit port->pm on port specific driver unbind
  serial: 8250: Add missing wakeup event reporting
  tty: serial: fsl_lpuart: use UARTMODIR register bits for lpuart32 platform
  tty: serial: fsl_lpuart: adjust buffer length to the intended size
  serial: fix TIOCSRS485 locking
  serial: make SiFive serial drivers depend on ARCH_ symbols
  tty: synclink_gt: don't allocate and pass dummy flags
  tty: serial: simplify qcom_geni_serial_send_chunk_fifo()
  ...

34 files changed, 771 insertions, 401 deletions

diff --git a/drivers/tty/Kconfig b/drivers/tty/Kconfig
index d35fc068da74..84caac32f0fd 100644
--- a/drivers/tty/Kconfig
+++ b/drivers/tty/Kconfig
@@ -160,7 +160,7 @@ config LEGACY_TIOCSTI
 	  a dangerous legacy operation, and can be disabled on most
 	  systems.
 
-	  Say 'Y here only if you have confirmed that your system's
+	  Say Y here only if you have confirmed that your system's
 	  userspace depends on this functionality to continue operating
 	  normally.
 
diff --git a/drivers/tty/amiserial.c b/drivers/tty/amiserial.c
index d7515d61659e..c06ad0a0744b 100644
--- a/drivers/tty/amiserial.c
+++ b/drivers/tty/amiserial.c
@@ -347,7 +347,7 @@ static void check_modem_status(struct serial_state *info)
 #if (defined(SERIAL_DEBUG_INTR) || defined(SERIAL_DEBUG_FLOW))
 				printk("CTS tx start...");
 #endif
-				port->tty->hw_stopped = 0;
+				port->tty->hw_stopped = false;
 				info->IER |= UART_IER_THRI;
 				amiga_custom.intena = IF_SETCLR | IF_TBE;
 				mb();
@@ -362,7 +362,7 @@ static void check_modem_status(struct serial_state *info)
 #if (defined(SERIAL_DEBUG_INTR) || defined(SERIAL_DEBUG_FLOW))
 				printk("CTS tx stop...");
 #endif
-				port->tty->hw_stopped = 1;
+				port->tty->hw_stopped = true;
 				info->IER &= ~UART_IER_THRI;
 				/* disable Tx interrupt and remove any pending interrupts */
 				amiga_custom.intena = IF_TBE;
@@ -1197,7 +1197,7 @@ static void rs_set_termios(struct tty_struct *tty, const struct ktermios *old_te
 
 	/* Handle turning off CRTSCTS */
 	if ((old_termios->c_cflag & CRTSCTS) && !C_CRTSCTS(tty)) {
-		tty->hw_stopped = 0;
+		tty->hw_stopped = false;
 		rs_start(tty);
 	}
 
diff --git a/drivers/tty/mxser.c b/drivers/tty/mxser.c
index ef3116e87975..10855e66fda1 100644
--- a/drivers/tty/mxser.c
+++ b/drivers/tty/mxser.c
@@ -553,7 +553,7 @@ static void mxser_handle_cts(struct tty_struct *tty, struct mxser_port *info,
 
 	if (tty->hw_stopped) {
 		if (cts) {
-			tty->hw_stopped = 0;
+			tty->hw_stopped = false;
 
 			if (!mxser_16550A_or_MUST(info))
 				__mxser_start_tx(info);
@@ -563,7 +563,7 @@ static void mxser_handle_cts(struct tty_struct *tty, struct mxser_port *info,
 	} else if (cts)
 		return;
 
-	tty->hw_stopped = 1;
+	tty->hw_stopped = true;
 	if (!mxser_16550A_or_MUST(info))
 		__mxser_stop_tx(info);
 }
@@ -1361,7 +1361,7 @@ static void mxser_set_termios(struct tty_struct *tty,
 	spin_unlock_irqrestore(&info->slock, flags);
 
 	if ((old_termios->c_cflag & CRTSCTS) && !C_CRTSCTS(tty)) {
-		tty->hw_stopped = 0;
+		tty->hw_stopped = false;
 		mxser_start(tty);
 	}
 
diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c
index 7aa05ebed8e1..b411a26cc092 100644
--- a/drivers/tty/n_gsm.c
+++ b/drivers/tty/n_gsm.c
@@ -42,6 +42,7 @@
 #include <linux/ctype.h>
 #include <linux/mm.h>
 #include <linux/math.h>
+#include <linux/nospec.h>
 #include <linux/string.h>
 #include <linux/slab.h>
 #include <linux/poll.h>
@@ -128,6 +129,7 @@ struct gsm_msg {
 
 enum gsm_dlci_state {
 	DLCI_CLOSED,
+	DLCI_WAITING_CONFIG,	/* Waiting for DLCI configuration from user */
 	DLCI_CONFIGURE,		/* Sending PN (for adaption > 1) */
 	DLCI_OPENING,		/* Sending SABM not seen UA */
 	DLCI_OPEN,		/* SABM/UA complete */
@@ -330,6 +332,7 @@ struct gsm_mux {
 	unsigned int t3;	/* Power wake-up timer in seconds. */
 	int n2;			/* Retry count */
 	u8 k;			/* Window size */
+	bool wait_config;	/* Wait for configuration by ioctl before DLCI open */
 	u32 keep_alive;		/* Control channel keep-alive in 10ms */
 
 	/* Statistics (not currently exposed) */
@@ -451,6 +454,7 @@ static int gsm_modem_update(struct gsm_dlci *dlci, u8 brk);
 static struct gsm_msg *gsm_data_alloc(struct gsm_mux *gsm, u8 addr, int len,
 								u8 ctrl);
 static int gsm_send_packet(struct gsm_mux *gsm, struct gsm_msg *msg);
+static struct gsm_dlci *gsm_dlci_alloc(struct gsm_mux *gsm, int addr);
 static void gsmld_write_trigger(struct gsm_mux *gsm);
 static void gsmld_write_task(struct work_struct *work);
 
@@ -2280,6 +2284,7 @@ static void gsm_dlci_begin_open(struct gsm_dlci *dlci)
 
 	switch (dlci->state) {
 	case DLCI_CLOSED:
+	case DLCI_WAITING_CONFIG:
 	case DLCI_CLOSING:
 		dlci->retries = gsm->n2;
 		if (!need_pn) {
@@ -2311,6 +2316,7 @@ static void gsm_dlci_set_opening(struct gsm_dlci *dlci)
 {
 	switch (dlci->state) {
 	case DLCI_CLOSED:
+	case DLCI_WAITING_CONFIG:
 	case DLCI_CLOSING:
 		dlci->state = DLCI_OPENING;
 		break;
@@ -2320,6 +2326,24 @@ static void gsm_dlci_set_opening(struct gsm_dlci *dlci)
 }
 
 /**
+ * gsm_dlci_set_wait_config	-	wait for channel configuration
+ * @dlci: DLCI to configure
+ *
+ * Wait for a DLCI configuration from the application.
+ */
+static void gsm_dlci_set_wait_config(struct gsm_dlci *dlci)
+{
+	switch (dlci->state) {
+	case DLCI_CLOSED:
+	case DLCI_CLOSING:
+		dlci->state = DLCI_WAITING_CONFIG;
+		break;
+	default:
+		break;
+	}
+}
+
+/**
  *	gsm_dlci_begin_close	-	start channel open procedure
  *	@dlci: DLCI to open
  *
@@ -2453,6 +2477,128 @@ static void gsm_kick_timer(struct timer_list *t)
 		pr_info("%s TX queue stalled\n", __func__);
 }
 
+/**
+ * gsm_dlci_copy_config_values	-	copy DLCI configuration
+ * @dlci: source DLCI
+ * @dc: configuration structure to fill
+ */
+static void gsm_dlci_copy_config_values(struct gsm_dlci *dlci, struct gsm_dlci_config *dc)
+{
+	memset(dc, 0, sizeof(*dc));
+	dc->channel = (u32)dlci->addr;
+	dc->adaption = (u32)dlci->adaption;
+	dc->mtu = (u32)dlci->mtu;
+	dc->priority = (u32)dlci->prio;
+	if (dlci->ftype == UIH)
+		dc->i = 1;
+	else
+		dc->i = 2;
+	dc->k = (u32)dlci->k;
+}
+
+/**
+ * gsm_dlci_config	-	configure DLCI from configuration
+ * @dlci: DLCI to configure
+ * @dc: DLCI configuration
+ * @open: open DLCI after configuration?
+ */
+static int gsm_dlci_config(struct gsm_dlci *dlci, struct gsm_dlci_config *dc, int open)
+{
+	struct gsm_mux *gsm;
+	bool need_restart = false;
+	bool need_open = false;
+	unsigned int i;
+
+	/*
+	 * Check that userspace doesn't put stuff in here to prevent breakages
+	 * in the future.
+	 */
+	for (i = 0; i < ARRAY_SIZE(dc->reserved); i++)
+		if (dc->reserved[i])
+			return -EINVAL;
+
+	if (!dlci)
+		return -EINVAL;
+	gsm = dlci->gsm;
+
+	/* Stuff we don't support yet - I frame transport */
+	if (dc->adaption != 1 && dc->adaption != 2)
+		return -EOPNOTSUPP;
+	if (dc->mtu > MAX_MTU || dc->mtu < MIN_MTU || dc->mtu > gsm->mru)
+		return -EINVAL;
+	if (dc->priority >= 64)
+		return -EINVAL;
+	if (dc->i == 0 || dc->i > 2)  /* UIH and UI only */
+		return -EINVAL;
+	if (dc->k > 7)
+		return -EINVAL;
+
+	/*
+	 * See what is needed for reconfiguration
+	 */
+	/* Framing fields */
+	if (dc->adaption != dlci->adaption)
+		need_restart = true;
+	if (dc->mtu != dlci->mtu)
+		need_restart = true;
+	if (dc->i != dlci->ftype)
+		need_restart = true;
+	/* Requires care */
+	if (dc->priority != dlci->prio)
+		need_restart = true;
+
+	if ((open && gsm->wait_config) || need_restart)
+		need_open = true;
+	if (dlci->state == DLCI_WAITING_CONFIG) {
+		need_restart = false;
+		need_open = true;
+	}
+
+	/*
+	 * Close down what is needed, restart and initiate the new
+	 * configuration.
+	 */
+	if (need_restart) {
+		gsm_dlci_begin_close(dlci);
+		wait_event_interruptible(gsm->event, dlci->state == DLCI_CLOSED);
+		if (signal_pending(current))
+			return -EINTR;
+	}
+	/*
+	 * Setup the new configuration values
+	 */
+	dlci->adaption = (int)dc->adaption;
+
+	if (dc->mtu)
+		dlci->mtu = (unsigned int)dc->mtu;
+	else
+		dlci->mtu = gsm->mtu;
+
+	if (dc->priority)
+		dlci->prio = (u8)dc->priority;
+	else
+		dlci->prio = roundup(dlci->addr + 1, 8) - 1;
+
+	if (dc->i == 1)
+		dlci->ftype = UIH;
+	else if (dc->i == 2)
+		dlci->ftype = UI;
+
+	if (dc->k)
+		dlci->k = (u8)dc->k;
+	else
+		dlci->k = gsm->k;
+
+	if (need_open) {
+		if (gsm->initiator)
+			gsm_dlci_begin_open(dlci);
+		else
+			gsm_dlci_set_opening(dlci);
+	}
+
+	return 0;
+}
+
 /*
  *	Allocate/Free DLCI channels
  */
@@ -3078,6 +3224,7 @@ static struct gsm_mux *gsm_alloc_mux(void)
 	gsm->mru = 64;	/* Default to encoding 1 so these should be 64 */
 	gsm->mtu = 64;
 	gsm->dead = true;	/* Avoid early tty opens */
+	gsm->wait_config = false; /* Disabled */
 	gsm->keep_alive = 0;	/* Disabled */
 
 	/* Store the instance to the mux array or abort if no space is
@@ -3130,8 +3277,8 @@ static int gsm_config(struct gsm_mux *gsm, struct gsm_config *c)
 	int need_close = 0;
 	int need_restart = 0;
 
-	/* Stuff we don't support yet - UI or I frame transport, windowing */
-	if ((c->adaption != 1 && c->adaption != 2) || c->k)
+	/* Stuff we don't support yet - UI or I frame transport */
+	if (c->adaption != 1 && c->adaption != 2)
 		return -EOPNOTSUPP;
 	/* Check the MRU/MTU range looks sane */
 	if (c->mru < MIN_MTU || c->mtu < MIN_MTU)
@@ -3218,6 +3365,7 @@ static void gsm_copy_config_ext_values(struct gsm_mux *gsm,
 				       struct gsm_config_ext *ce)
 {
 	memset(ce, 0, sizeof(*ce));
+	ce->wait_config = gsm->wait_config ? 1 : 0;
 	ce->keep_alive = gsm->keep_alive;
 }
 
@@ -3233,7 +3381,12 @@ static int gsm_config_ext(struct gsm_mux *gsm, struct gsm_config_ext *ce)
 		if (ce->reserved[i])
 			return -EINVAL;
 
+	/*
+	 * Setup the new configuration values
+	 */
+	gsm->wait_config = ce->wait_config ? true : false;
 	gsm->keep_alive = ce->keep_alive;
+
 	return 0;
 }
 
@@ -3433,9 +3586,16 @@ static int gsmld_open(struct tty_struct *tty)
 	tty->receive_room = 65536;
 
 	/* Attach the initial passive connection */
-	gsm->encoding = GSM_ADV_OPT;
 	gsmld_attach_gsm(tty, gsm);
 
+	/* The mux will not be activated yet, we wait for correct
+	 * configuration first.
+	 */
+	if (gsm->encoding == GSM_BASIC_OPT)
+		gsm->receive = gsm0_receive;
+	else
+		gsm->receive = gsm1_receive;
+
 	return 0;
 }
 
@@ -3556,8 +3716,10 @@ static int gsmld_ioctl(struct tty_struct *tty, unsigned int cmd,
 {
 	struct gsm_config c;
 	struct gsm_config_ext ce;
+	struct gsm_dlci_config dc;
 	struct gsm_mux *gsm = tty->disc_data;
-	unsigned int base;
+	unsigned int base, addr;
+	struct gsm_dlci *dlci;
 
 	switch (cmd) {
 	case GSMIOC_GETCONF:
@@ -3581,6 +3743,35 @@ static int gsmld_ioctl(struct tty_struct *tty, unsigned int cmd,
 		if (copy_from_user(&ce, (void __user *)arg, sizeof(ce)))
 			return -EFAULT;
 		return gsm_config_ext(gsm, &ce);
+	case GSMIOC_GETCONF_DLCI:
+		if (copy_from_user(&dc, (void __user *)arg, sizeof(dc)))
+			return -EFAULT;
+		if (dc.channel == 0 || dc.channel >= NUM_DLCI)
+			return -EINVAL;
+		addr = array_index_nospec(dc.channel, NUM_DLCI);
+		dlci = gsm->dlci[addr];
+		if (!dlci) {
+			dlci = gsm_dlci_alloc(gsm, addr);
+			if (!dlci)
+				return -ENOMEM;
+		}
+		gsm_dlci_copy_config_values(dlci, &dc);
+		if (copy_to_user((void __user *)arg, &dc, sizeof(dc)))
+			return -EFAULT;
+		return 0;
+	case GSMIOC_SETCONF_DLCI:
+		if (copy_from_user(&dc, (void __user *)arg, sizeof(dc)))
+			return -EFAULT;
+		if (dc.channel == 0 || dc.channel >= NUM_DLCI)
+			return -EINVAL;
+		addr = array_index_nospec(dc.channel, NUM_DLCI);
+		dlci = gsm->dlci[addr];
+		if (!dlci) {
+			dlci = gsm_dlci_alloc(gsm, addr);
+			if (!dlci)
+				return -ENOMEM;
+		}
+		return gsm_dlci_config(dlci, &dc, 0);
 	default:
 		return n_tty_ioctl_helper(tty, cmd, arg);
 	}
@@ -4008,7 +4199,6 @@ static int gsmtty_open(struct tty_struct *tty, struct file *filp)
 {
 	struct gsm_dlci *dlci = tty->driver_data;
 	struct tty_port *port = &dlci->port;
-	struct gsm_mux *gsm = dlci->gsm;
 
 	port->count++;
 	tty_port_tty_set(port, tty);
@@ -4018,10 +4208,15 @@ static int gsmtty_open(struct tty_struct *tty, struct file *filp)
 	   a DM straight back. This is ok as that will have caused a hangup */
 	tty_port_set_initialized(port, true);
 	/* Start sending off SABM messages */
-	if (gsm->initiator)
-		gsm_dlci_begin_open(dlci);
-	else
-		gsm_dlci_set_opening(dlci);
+	if (!dlci->gsm->wait_config) {
+		/* Start sending off SABM messages */
+		if (dlci->gsm->initiator)
+			gsm_dlci_begin_open(dlci);
+		else
+			gsm_dlci_set_opening(dlci);
+	} else {
+		gsm_dlci_set_wait_config(dlci);
+	}
 	/* And wait for virtual carrier */
 	return tty_port_block_til_ready(port, tty, filp);
 }
@@ -4142,6 +4337,7 @@ static int gsmtty_ioctl(struct tty_struct *tty,
 {
 	struct gsm_dlci *dlci = tty->driver_data;
 	struct gsm_netconfig nc;
+	struct gsm_dlci_config dc;
 	int index;
 
 	if (dlci->state == DLCI_CLOSED)
@@ -4165,6 +4361,23 @@ static int gsmtty_ioctl(struct tty_struct *tty,
 		gsm_destroy_network(dlci);
 		mutex_unlock(&dlci->mutex);
 		return 0;
+	case GSMIOC_GETCONF_DLCI:
+		if (copy_from_user(&dc, (void __user *)arg, sizeof(dc)))
+			return -EFAULT;
+		if (dc.channel != dlci->addr)
+			return -EPERM;
+		gsm_dlci_copy_config_values(dlci, &dc);
+		if (copy_to_user((void __user *)arg, &dc, sizeof(dc)))
+			return -EFAULT;
+		return 0;
+	case GSMIOC_SETCONF_DLCI:
+		if (copy_from_user(&dc, (void __user *)arg, sizeof(dc)))
+			return -EFAULT;
+		if (dc.channel >= NUM_DLCI)
+			return -EINVAL;
+		if (dc.channel != 0 && dc.channel != dlci->addr)
+			return -EPERM;
+		return gsm_dlci_config(dlci, &dc, 1);
 	case TIOCMIWAIT:
 		return gsm_wait_modem_change(dlci, (u32)arg);
 	default:
diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c
index c8f56c9b1a1c..1c9e5d2ea7de 100644
--- a/drivers/tty/n_tty.c
+++ b/drivers/tty/n_tty.c
@@ -28,27 +28,26 @@
  *		EAGAIN
  */
 
-#include <linux/types.h>
-#include <linux/major.h>
+#include <linux/bitmap.h>
+#include <linux/bitops.h>
+#include <linux/ctype.h>
 #include <linux/errno.h>
-#include <linux/signal.h>
+#include <linux/export.h>
 #include <linux/fcntl.h>
+#include <linux/file.h>
+#include <linux/jiffies.h>
+#include <linux/math.h>
+#include <linux/poll.h>
+#include <linux/ratelimit.h>
 #include <linux/sched.h>
-#include <linux/interrupt.h>
-#include <linux/tty.h>
-#include <linux/timer.h>
-#include <linux/ctype.h>
-#include <linux/mm.h>
-#include <linux/string.h>
+#include <linux/signal.h>
 #include <linux/slab.h>
-#include <linux/poll.h>
-#include <linux/bitops.h>
-#include <linux/audit.h>
-#include <linux/file.h>
+#include <linux/string.h>
+#include <linux/tty.h>
+#include <linux/types.h>
 #include <linux/uaccess.h>
-#include <linux/module.h>
-#include <linux/ratelimit.h>
 #include <linux/vmalloc.h>
+
 #include "tty.h"
 
 /*
@@ -625,7 +624,7 @@ static size_t __process_echoes(struct tty_struct *tty)
 		c = echo_buf(ldata, tail);
 		if (c == ECHO_OP_START) {
 			unsigned char op;
-			int no_space_left = 0;
+			bool space_left = true;
 
 			/*
 			 * Since add_echo_byte() is called without holding
@@ -664,7 +663,7 @@ static size_t __process_echoes(struct tty_struct *tty)
 				num_bs = 8 - (num_chars & 7);
 
 				if (num_bs > space) {
-					no_space_left = 1;
+					space_left = false;
 					break;
 				}
 				space -= num_bs;
@@ -690,7 +689,7 @@ static size_t __process_echoes(struct tty_struct *tty)
 			case ECHO_OP_START:
 				/* This is an escaped echo op start code */
 				if (!space) {
-					no_space_left = 1;
+					space_left = false;
 					break;
 				}
 				tty_put_char(tty, ECHO_OP_START);
@@ -710,7 +709,7 @@ static size_t __process_echoes(struct tty_struct *tty)
 				 *
 				 */
 				if (space < 2) {
-					no_space_left = 1;
+					space_left = false;
 					break;
 				}
 				tty_put_char(tty, '^');
@@ -720,7 +719,7 @@ static size_t __process_echoes(struct tty_struct *tty)
 				tail += 2;
 			}
 
-			if (no_space_left)
+			if (!space_left)
 				break;
 		} else {
 			if (O_OPOST(tty)) {
@@ -1177,7 +1176,7 @@ static void n_tty_receive_overrun(struct tty_struct *tty)
 
 	ldata->num_overrun++;
 	if (time_after(jiffies, ldata->overrun_time + HZ) ||
-			time_after(ldata->overrun_time, jiffies)) {
+	    time_after(ldata->overrun_time, jiffies)) {
 		tty_warn(tty, "%d input overrun(s)\n", ldata->num_overrun);
 		ldata->overrun_time = jiffies;
 		ldata->num_overrun = 0;
@@ -1691,7 +1690,7 @@ n_tty_receive_buf_common(struct tty_struct *tty, const unsigned char *cp,
 
 		room = N_TTY_BUF_SIZE - (ldata->read_head - tail);
 		if (I_PARMRK(tty))
-			room = (room + 2) / 3;
+			room = DIV_ROUND_UP(room, 3);
 		room--;
 		if (room <= 0) {
 			overflow = ldata->icanon && ldata->canon_head == tail;
diff --git a/drivers/tty/serial/8250/8250.h b/drivers/tty/serial/8250/8250.h
index 287153d32536..1e8fe44a7099 100644
--- a/drivers/tty/serial/8250/8250.h
+++ b/drivers/tty/serial/8250/8250.h
@@ -365,6 +365,13 @@ static inline void serial8250_do_prepare_rx_dma(struct uart_8250_port *p)
 	if (dma->prepare_rx_dma)
 		dma->prepare_rx_dma(p);
 }
+
+static inline bool serial8250_tx_dma_running(struct uart_8250_port *p)
+{
+	struct uart_8250_dma *dma = p->dma;
+
+	return dma && dma->tx_running;
+}
 #else
 static inline int serial8250_tx_dma(struct uart_8250_port *p)
 {
@@ -380,6 +387,11 @@ static inline int serial8250_request_dma(struct uart_8250_port *p)
 	return -1;
 }
 static inline void serial8250_release_dma(struct uart_8250_port *p) { }
+
+static inline bool serial8250_tx_dma_running(struct uart_8250_port *p)
+{
+	return false;
+}
 #endif
 
 static inline int ns16550a_goto_highspeed(struct uart_8250_port *up)
diff --git a/drivers/tty/serial/8250/8250_bcm7271.c b/drivers/tty/serial/8250/8250_bcm7271.c
index ed5a94747692..f801b1f5b46c 100644
--- a/drivers/tty/serial/8250/8250_bcm7271.c
+++ b/drivers/tty/serial/8250/8250_bcm7271.c
@@ -1014,14 +1014,16 @@ static int brcmuart_probe(struct platform_device *pdev)
 	/* See if a Baud clock has been specified */
 	baud_mux_clk = of_clk_get_by_name(np, "sw_baud");
 	if (IS_ERR(baud_mux_clk)) {
-		if (PTR_ERR(baud_mux_clk) == -EPROBE_DEFER)
-			return -EPROBE_DEFER;
+		if (PTR_ERR(baud_mux_clk) == -EPROBE_DEFER) {
+			ret = -EPROBE_DEFER;
+			goto release_dma;
+		}
 		dev_dbg(dev, "BAUD MUX clock not specified\n");
 	} else {
 		dev_dbg(dev, "BAUD MUX clock found\n");
 		ret = clk_prepare_enable(baud_mux_clk);
 		if (ret)
-			return ret;
+			goto release_dma;
 		priv->baud_mux_clk = baud_mux_clk;
 		init_real_clk_rates(dev, priv);
 		clk_rate = priv->default_mux_rate;
@@ -1029,7 +1031,8 @@ static int brcmuart_probe(struct platform_device *pdev)
 
 	if (clk_rate == 0) {
 		dev_err(dev, "clock-frequency or clk not defined\n");
-		return -EINVAL;
+		ret = -EINVAL;
+		goto release_dma;
 	}
 
 	dev_dbg(dev, "DMA is %senabled\n", priv->dma_enabled ? "" : "not ");
@@ -1116,7 +1119,9 @@ err1:
 	serial8250_unregister_port(priv->line);
 err:
 	brcmuart_free_bufs(dev, priv);
-	brcmuart_arbitration(priv, 0);
+release_dma:
+	if (priv->dma_enabled)
+		brcmuart_arbitration(priv, 0);
 	return ret;
 }
 
@@ -1128,7 +1133,8 @@ static int brcmuart_remove(struct platform_device *pdev)
 	hrtimer_cancel(&priv->hrt);
 	serial8250_unregister_port(priv->line);
 	brcmuart_free_bufs(&pdev->dev, priv);
-	brcmuart_arbitration(priv, 0);
+	if (priv->dma_enabled)
+		brcmuart_arbitration(priv, 0);
 	return 0;
 }
 
diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c
index ab63c308be0a..13bf535eedcd 100644
--- a/drivers/tty/serial/8250/8250_core.c
+++ b/drivers/tty/serial/8250/8250_core.c
@@ -1158,6 +1158,7 @@ void serial8250_unregister_port(int line)
 		uart->port.type = PORT_UNKNOWN;
 		uart->port.dev = &serial8250_isa_devs->dev;
 		uart->capabilities = 0;
+		serial8250_init_port(uart);
 		serial8250_apply_quirks(uart);
 		uart_add_one_port(&serial8250_reg, &uart->port);
 	} else {
diff --git a/drivers/tty/serial/8250/8250_em.c b/drivers/tty/serial/8250/8250_em.c
index d94c3811a8f7..25a9ecf26be6 100644
--- a/drivers/tty/serial/8250/8250_em.c
+++ b/drivers/tty/serial/8250/8250_em.c
@@ -13,36 +13,49 @@
 #include <linux/serial_reg.h>
 #include <linux/platform_device.h>
 #include <linux/clk.h>
-#include <linux/slab.h>
 
 #include "8250.h"
 
 #define UART_DLL_EM 9
 #define UART_DLM_EM 10
+#define UART_HCR0_EM 11
+
+/*
+ * A high value for UART_FCR_EM avoids overlapping with existing UART_*
+ * register defines. UART_FCR_EM_HW is the real HW register offset.
+ */
+#define UART_FCR_EM 0x10003
+#define UART_FCR_EM_HW 3
+
+#define UART_HCR0_EM_SW_RESET	BIT(7) /* SW Reset */
 
 struct serial8250_em_priv {
-	struct clk *sclk;
 	int line;
 };
 
-static void serial8250_em_serial_out(struct uart_port *p, int offset, int value)
+static void serial8250_em_serial_out_helper(struct uart_port *p, int offset,
+					    int value)
 {
 	switch (offset) {
 	case UART_TX: /* TX @ 0x00 */
 		writeb(value, p->membase);
 		break;
-	case UART_FCR: /* FCR @ 0x0c (+1) */
 	case UART_LCR: /* LCR @ 0x10 (+1) */
 	case UART_MCR: /* MCR @ 0x14 (+1) */
 	case UART_SCR: /* SCR @ 0x20 (+1) */
 		writel(value, p->membase + ((offset + 1) << 2));
 		break;
+	case UART_FCR_EM:
+		writel(value, p->membase + (UART_FCR_EM_HW << 2));
+		break;
 	case UART_IER: /* IER @ 0x04 */
 		value &= 0x0f; /* only 4 valid bits - not Xscale */
 		fallthrough;
 	case UART_DLL_EM: /* DLL @ 0x24 (+9) */
 	case UART_DLM_EM: /* DLM @ 0x28 (+9) */
+	case UART_HCR0_EM: /* HCR0 @ 0x2c */
 		writel(value, p->membase + (offset << 2));
+		break;
 	}
 }
 
@@ -51,20 +64,81 @@ static unsigned int serial8250_em_serial_in(struct uart_port *p, int offset)
 	switch (offset) {
 	case UART_RX: /* RX @ 0x00 */
 		return readb(p->membase);
+	case UART_LCR: /* LCR @ 0x10 (+1) */
 	case UART_MCR: /* MCR @ 0x14 (+1) */
 	case UART_LSR: /* LSR @ 0x18 (+1) */
 	case UART_MSR: /* MSR @ 0x1c (+1) */
 	case UART_SCR: /* SCR @ 0x20 (+1) */
 		return readl(p->membase + ((offset + 1) << 2));
+	case UART_FCR_EM:
+		return readl(p->membase + (UART_FCR_EM_HW << 2));
 	case UART_IER: /* IER @ 0x04 */
 	case UART_IIR: /* IIR @ 0x08 */
 	case UART_DLL_EM: /* DLL @ 0x24 (+9) */
 	case UART_DLM_EM: /* DLM @ 0x28 (+9) */
+	case UART_HCR0_EM: /* HCR0 @ 0x2c */
 		return readl(p->membase + (offset << 2));
 	}
 	return 0;