Merge tag 'usb-serial-5.12-rc1' of https://git.kernel.org/pub/scm/linux/kernel/git/johan/usb-serial into usb-next

Johan writes:

USB-serial updates for 5.12-rc1

Here are the USB-serial updates for 5.12-rc1, including:

 - a line-speed fix for newer pl2303 devices
 - a line-speed fix for FTDI FT-X devices
 - a new xr_serial driver for MaxLinear/Exar devices (non-ACM mode)
 - a cdc-acm blacklist entry for when the xr_serial driver is enabled
 - cp210x support for software flow control
 - various cp210x modem-control fixes
 - an updated ZTE P685M modem entry to stop claiming the QMI interface
 - an update to drop the port_remove() driver-callback return value

Included are also various clean ups.

All have been in linux-next with no reported issues.

* tag 'usb-serial-5.12-rc1' of https://git.kernel.org/pub/scm/linux/kernel/git/johan/usb-serial: (41 commits)
  USB: serial: drop bogus to_usb_serial_port() checks
  USB: serial: make remove callback return void
  USB: serial: drop if with an always false condition
  USB: serial: option: update interface mapping for ZTE P685M
  USB: serial: ftdi_sio: restore divisor-encoding comments
  USB: serial: ftdi_sio: fix FTX sub-integer prescaler
  USB: serial: cp210x: clean up auto-RTS handling
  USB: serial: cp210x: fix RTS handling
  USB: serial: cp210x: clean up printk zero padding
  USB: serial: cp210x: clean up flow-control debug message
  USB: serial: cp210x: drop shift macros
  USB: serial: cp210x: fix modem-control handling
  USB: serial: cp210x: suppress modem-control errors
  USB: serial: mos7720: fix error code in mos7720_write()
  USB: serial: xr: fix B0 handling
  USB: serial: xr: fix pin configuration
  USB: serial: xr: fix gpio-mode handling
  USB: serial: xr: simplify line-speed logic
  USB: serial: xr: clean up line-settings handling
  USB: serial: xr: document vendor-request recipient
  ...

44 files changed, 888 insertions, 225 deletions

diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c
index 781905745812..37f824b59daa 100644
--- a/drivers/usb/class/cdc-acm.c
+++ b/drivers/usb/class/cdc-acm.c
@@ -1901,6 +1901,12 @@ static const struct usb_device_id acm_ids[] = {
 	},
 #endif
 
+#if IS_ENABLED(CONFIG_USB_SERIAL_XR)
+	{ USB_DEVICE(0x04e2, 0x1410),   /* Ignore XR21V141X USB to Serial converter */
+	.driver_info = IGNORE_DEVICE,
+	},
+#endif
+
 	/*Samsung phone in firmware update mode */
 	{ USB_DEVICE(0x04e8, 0x685d),
 	.driver_info = IGNORE_DEVICE,
diff --git a/drivers/usb/serial/Kconfig b/drivers/usb/serial/Kconfig
index a21ff5ab6df9..de5c01257060 100644
--- a/drivers/usb/serial/Kconfig
+++ b/drivers/usb/serial/Kconfig
@@ -633,6 +633,15 @@ config USB_SERIAL_UPD78F0730
 	  To compile this driver as a module, choose M here: the
 	  module will be called upd78f0730.
 
+config USB_SERIAL_XR
+	tristate "USB MaxLinear/Exar USB to Serial driver"
+	help
+	  Say Y here if you want to use MaxLinear/Exar USB to Serial converter
+	  devices.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called xr_serial.
+
 config USB_SERIAL_DEBUG
 	tristate "USB Debugging Device"
 	help
diff --git a/drivers/usb/serial/Makefile b/drivers/usb/serial/Makefile
index 50c53aed787a..c7bb1a88173e 100644
--- a/drivers/usb/serial/Makefile
+++ b/drivers/usb/serial/Makefile
@@ -61,4 +61,5 @@ obj-$(CONFIG_USB_SERIAL_UPD78F0730)		+= upd78f0730.o
 obj-$(CONFIG_USB_SERIAL_VISOR)			+= visor.o
 obj-$(CONFIG_USB_SERIAL_WISHBONE)		+= wishbone-serial.o
 obj-$(CONFIG_USB_SERIAL_WHITEHEAT)		+= whiteheat.o
+obj-$(CONFIG_USB_SERIAL_XR)			+= xr_serial.o
 obj-$(CONFIG_USB_SERIAL_XSENS_MT)		+= xsens_mt.o
diff --git a/drivers/usb/serial/ark3116.c b/drivers/usb/serial/ark3116.c
index 71a9206ea1e2..f0ac7bb07ac1 100644
--- a/drivers/usb/serial/ark3116.c
+++ b/drivers/usb/serial/ark3116.c
@@ -178,15 +178,13 @@ static int ark3116_port_probe(struct usb_serial_port *port)
 	return 0;
 }
 
-static int ark3116_port_remove(struct usb_serial_port *port)
+static void ark3116_port_remove(struct usb_serial_port *port)
 {
 	struct ark3116_private *priv = usb_get_serial_port_data(port);
 
 	/* device is closed, so URBs and DMA should be down */
 	mutex_destroy(&priv->hw_lock);
 	kfree(priv);
-
-	return 0;
 }
 
 static void ark3116_set_termios(struct tty_struct *tty,
diff --git a/drivers/usb/serial/belkin_sa.c b/drivers/usb/serial/belkin_sa.c
index 9bb123ab9bc9..ed9193f3bb1a 100644
--- a/drivers/usb/serial/belkin_sa.c
+++ b/drivers/usb/serial/belkin_sa.c
@@ -37,7 +37,7 @@
 
 /* function prototypes for a Belkin USB Serial Adapter F5U103 */
 static int belkin_sa_port_probe(struct usb_serial_port *port);
-static int belkin_sa_port_remove(struct usb_serial_port *port);
+static void belkin_sa_port_remove(struct usb_serial_port *port);
 static int  belkin_sa_open(struct tty_struct *tty,
 			struct usb_serial_port *port);
 static void belkin_sa_close(struct usb_serial_port *port);
@@ -134,14 +134,12 @@ static int belkin_sa_port_probe(struct usb_serial_port *port)
 	return 0;
 }
 
-static int belkin_sa_port_remove(struct usb_serial_port *port)
+static void belkin_sa_port_remove(struct usb_serial_port *port)
 {
 	struct belkin_sa_private *priv;
 
 	priv = usb_get_serial_port_data(port);
 	kfree(priv);
-
-	return 0;
 }
 
 static int belkin_sa_open(struct tty_struct *tty,
diff --git a/drivers/usb/serial/bus.c b/drivers/usb/serial/bus.c
index eb0195cf37dd..7133818a58b9 100644
--- a/drivers/usb/serial/bus.c
+++ b/drivers/usb/serial/bus.c
@@ -16,19 +16,13 @@
 static int usb_serial_device_match(struct device *dev,
 						struct device_driver *drv)
 {
-	struct usb_serial_driver *driver;
-	const struct usb_serial_port *port;
+	const struct usb_serial_port *port = to_usb_serial_port(dev);
+	struct usb_serial_driver *driver = to_usb_serial_driver(drv);
 
 	/*
 	 * drivers are already assigned to ports in serial_probe so it's
 	 * a simple check here.
 	 */
-	port = to_usb_serial_port(dev);
-	if (!port)
-		return 0;
-
-	driver = to_usb_serial_driver(drv);
-
 	if (driver == port->serial->type)
 		return 1;
 
@@ -37,16 +31,12 @@ static int usb_serial_device_match(struct device *dev,
 
 static int usb_serial_device_probe(struct device *dev)
 {
+	struct usb_serial_port *port = to_usb_serial_port(dev);
 	struct usb_serial_driver *driver;
-	struct usb_serial_port *port;
 	struct device *tty_dev;
 	int retval = 0;
 	int minor;
 
-	port = to_usb_serial_port(dev);
-	if (!port)
-		return -ENODEV;
-
 	/* make sure suspend/resume doesn't race against port_probe */
 	retval = usb_autopm_get_interface(port->serial->interface);
 	if (retval)
@@ -86,16 +76,11 @@ err_autopm_put:
 
 static int usb_serial_device_remove(struct device *dev)
 {
+	struct usb_serial_port *port = to_usb_serial_port(dev);
 	struct usb_serial_driver *driver;
-	struct usb_serial_port *port;
-	int retval = 0;
 	int minor;
 	int autopm_err;
 
-	port = to_usb_serial_port(dev);
-	if (!port)
-		return -ENODEV;
-
 	/*
 	 * Make sure suspend/resume doesn't race against port_remove.
 	 *
@@ -109,7 +94,7 @@ static int usb_serial_device_remove(struct device *dev)
 
 	driver = port->serial->type;
 	if (driver->port_remove)
-		retval = driver->port_remove(port);
+		driver->port_remove(port);
 
 	dev_info(dev, "%s converter now disconnected from ttyUSB%d\n",
 		 driver->description, minor);
@@ -117,7 +102,7 @@ static int usb_serial_device_remove(struct device *dev)
 	if (!autopm_err)
 		usb_autopm_put_interface(port->serial->interface);
 
-	return retval;
+	return 0;
 }
 
 static ssize_t new_id_store(struct device_driver *driver,
diff --git a/drivers/usb/serial/ch341.c b/drivers/usb/serial/ch341.c
index 28deaaec581f..8d997b71056f 100644
--- a/drivers/usb/serial/ch341.c
+++ b/drivers/usb/serial/ch341.c
@@ -419,14 +419,12 @@ error:	kfree(priv);
 	return r;
 }
 
-static int ch341_port_remove(struct usb_serial_port *port)
+static void ch341_port_remove(struct usb_serial_port *port)
 {
 	struct ch341_private *priv;
 
 	priv = usb_get_serial_port_data(port);
 	kfree(priv);
-
-	return 0;
 }
 
 static int ch341_carrier_raised(struct usb_serial_port *port)
diff --git a/drivers/usb/serial/cp210x.c b/drivers/usb/serial/cp210x.c
index 7bec1e730b20..9e1c609792fb 100644
--- a/drivers/usb/serial/cp210x.c
+++ b/drivers/usb/serial/cp210x.c
@@ -3,6 +3,7 @@
  * Silicon Laboratories CP210x USB to RS232 serial adaptor driver
  *
  * Copyright (C) 2005 Craig Shelley (craig@microtron.org.uk)
+ * Copyright (C) 2010-2021 Johan Hovold (johan@kernel.org)
  *
  * Support to set flow control line levels using TIOCMGET and TIOCMSET
  * thanks to Karl Hiramoto karl@hiramoto.org. RTSCTS hardware flow
@@ -16,9 +17,7 @@
 #include <linux/tty.h>
 #include <linux/tty_flip.h>
 #include <linux/module.h>
-#include <linux/moduleparam.h>
 #include <linux/usb.h>
-#include <linux/uaccess.h>
 #include <linux/usb/serial.h>
 #include <linux/gpio/driver.h>
 #include <linux/bitops.h>
@@ -45,7 +44,7 @@ static int cp210x_attach(struct usb_serial *);
 static void cp210x_disconnect(struct usb_serial *);
 static void cp210x_release(struct usb_serial *);
 static int cp210x_port_probe(struct usb_serial_port *);
-static int cp210x_port_remove(struct usb_serial_port *);
+static void cp210x_port_remove(struct usb_serial_port *);
 static void cp210x_dtr_rts(struct usb_serial_port *port, int on);
 static void cp210x_process_read_urb(struct urb *urb);
 static void cp210x_enable_event_mode(struct usb_serial_port *port);
@@ -268,7 +267,12 @@ struct cp210x_port_private {
 	u8			bInterfaceNumber;
 	bool			event_mode;
 	enum cp210x_event_state event_state;
-	u8 lsr;
+	u8			lsr;
+
+	struct mutex		mutex;
+	bool			crtscts;
+	bool			dtr;
+	bool			rts;
 };
 
 static struct usb_serial_driver cp210x_device = {
@@ -379,6 +383,16 @@ static struct usb_serial_driver * const serial_drivers[] = {
 #define CONTROL_WRITE_DTR	0x0100
 #define CONTROL_WRITE_RTS	0x0200
 
+/* CP210X_(GET|SET)_CHARS */
+struct cp210x_special_chars {
+	u8	bEofChar;
+	u8	bErrorChar;
+	u8	bBreakChar;
+	u8	bEventChar;
+	u8	bXonChar;
+	u8	bXoffChar;
+};
+
 /* CP210X_VENDOR_SPECIFIC values */
 #define CP210X_READ_2NCONFIG	0x000E
 #define CP210X_READ_LATCH	0x00C2
@@ -437,17 +451,14 @@ struct cp210x_flow_ctl {
 
 /* cp210x_flow_ctl::ulControlHandshake */
 #define CP210X_SERIAL_DTR_MASK		GENMASK(1, 0)
-#define CP210X_SERIAL_DTR_SHIFT(_mode)	(_mode)
+#define CP210X_SERIAL_DTR_INACTIVE	(0 << 0)
+#define CP210X_SERIAL_DTR_ACTIVE	(1 << 0)
+#define CP210X_SERIAL_DTR_FLOW_CTL	(2 << 0)
 #define CP210X_SERIAL_CTS_HANDSHAKE	BIT(3)
 #define CP210X_SERIAL_DSR_HANDSHAKE	BIT(4)
 #define CP210X_SERIAL_DCD_HANDSHAKE	BIT(5)
 #define CP210X_SERIAL_DSR_SENSITIVITY	BIT(6)
 
-/* values for cp210x_flow_ctl::ulControlHandshake::CP210X_SERIAL_DTR_MASK */
-#define CP210X_SERIAL_DTR_INACTIVE	0
-#define CP210X_SERIAL_DTR_ACTIVE	1
-#define CP210X_SERIAL_DTR_FLOW_CTL	2
-
 /* cp210x_flow_ctl::ulFlowReplace */
 #define CP210X_SERIAL_AUTO_TRANSMIT	BIT(0)
 #define CP210X_SERIAL_AUTO_RECEIVE	BIT(1)
@@ -455,14 +466,11 @@ struct cp210x_flow_ctl {
 #define CP210X_SERIAL_NULL_STRIPPING	BIT(3)
 #define CP210X_SERIAL_BREAK_CHAR	BIT(4)
 #define CP210X_SERIAL_RTS_MASK		GENMASK(7, 6)
-#define CP210X_SERIAL_RTS_SHIFT(_mode)	(_mode << 6)
+#define CP210X_SERIAL_RTS_INACTIVE	(0 << 6)
+#define CP210X_SERIAL_RTS_ACTIVE	(1 << 6)
+#define CP210X_SERIAL_RTS_FLOW_CTL	(2 << 6)
 #define CP210X_SERIAL_XOFF_CONTINUE	BIT(31)
 
-/* values for cp210x_flow_ctl::ulFlowReplace::CP210X_SERIAL_RTS_MASK */
-#define CP210X_SERIAL_RTS_INACTIVE	0
-#define CP210X_SERIAL_RTS_ACTIVE	1
-#define CP210X_SERIAL_RTS_FLOW_CTL	2
-
 /* CP210X_VENDOR_SPECIFIC, CP210X_GET_DEVICEMODE call reads these 0x2 bytes. */
 struct cp210x_pin_mode {
 	u8	eci;
@@ -666,16 +674,13 @@ static int cp210x_write_reg_block(struct usb_serial_port *port, u8 req,
 
 	kfree(dmabuf);
 
-	if (result == bufsize) {
-		result = 0;
-	} else {
+	if (result < 0) {
 		dev_err(&port->dev, "failed set req 0x%x size %d status: %d\n",
 				req, bufsize, result);
-		if (result >= 0)
-			result = -EIO;
+		return result;
 	}
 
-	return result;
+	return 0;
 }
 
 /*
@@ -712,17 +717,14 @@ static int cp210x_write_vendor_block(struct usb_serial *serial, u8 type,
 
 	kfree(dmabuf);
 
-	if (result == bufsize) {
-		result = 0;
-	} else {
+	if (result < 0) {
 		dev_err(&serial->interface->dev,
 			"failed to set vendor val 0x%04x size %d: %d\n", val,
 			bufsize, result);
-		if (result >= 0)
-			result = -EIO;
+		return result;
 	}
 
-	return result;
+	return 0;
 }
 #endif
 
@@ -1076,30 +1078,80 @@ static void cp210x_disable_event_mode(struct usb_serial_port *port)
 	port_priv->event_mode = false;
 }
 
+static int cp210x_set_chars(struct usb_serial_port *port,
+		struct cp210x_special_chars *chars)
+{
+	struct cp210x_port_private *port_priv = usb_get_serial_port_data(port);
+	struct usb_serial *serial = port->serial;
+	void *dmabuf;
+	int result;
+
+	dmabuf = kmemdup(chars, sizeof(*chars), GFP_KERNEL);
+	if (!dmabuf)
+		return -ENOMEM;
+
+	result = usb_control_msg(serial->dev, usb_sndctrlpipe(serial->dev, 0),
+				CP210X_SET_CHARS, REQTYPE_HOST_TO_INTERFACE, 0,
+				port_priv->bInterfaceNumber,
+				dmabuf, sizeof(*chars), USB_CTRL_SET_TIMEOUT);
+
+	kfree(dmabuf);
+
+	if (result < 0) {
+		dev_err(&port->dev, "failed to set special chars: %d\n", result);
+		return result;
+	}
+
+	return 0;
+}
+
 static bool cp210x_termios_change(const struct ktermios *a, const struct ktermios *b)
 {
-	bool iflag_change;
+	bool iflag_change, cc_change;
 
-	iflag_change = ((a->c_iflag ^ b->c_iflag) & INPCK);
+	iflag_change = ((a->c_iflag ^ b->c_iflag) & (INPCK | IXON | IXOFF));
+	cc_change = a->c_cc[VSTART] != b->c_cc[VSTART] ||
+			a->c_cc[VSTOP] != b->c_cc[VSTOP];
 
-	return tty_termios_hw_change(a, b) || iflag_change;
+	return tty_termios_hw_change(a, b) || iflag_change || cc_change;
 }
 
 static void cp210x_set_flow_control(struct tty_struct *tty,
 		struct usb_serial_port *port, struct ktermios *old_termios)
 {
+	struct cp210x_port_private *port_priv = usb_get_serial_port_data(port);
+	struct cp210x_special_chars chars;
 	struct cp210x_flow_ctl flow_ctl;
 	u32 flow_repl;
 	u32 ctl_hs;
 	int ret;
 
-	if (old_termios && C_CRTSCTS(tty) == (old_termios->c_cflag & CRTSCTS))
+	if (old_termios &&
+			C_CRTSCTS(tty) == (old_termios->c_cflag & CRTSCTS) &&
+			I_IXON(tty) == (old_termios->c_iflag & IXON) &&
+			I_IXOFF(tty) == (old_termios->c_iflag & IXOFF) &&
+			START_CHAR(tty) == old_termios->c_cc[VSTART] &&
+			STOP_CHAR(tty) == old_termios->c_cc[VSTOP]) {
 		return;
+	}
+
+	if (I_IXON(tty) || I_IXOFF(tty)) {
+		memset(&chars, 0, sizeof(chars));
+
+		chars.bXonChar = START_CHAR(tty);
+		chars.bXoffChar = STOP_CHAR(tty);
+
+		ret = cp210x_set_chars(port, &chars);
+		if (ret)
+			return;
+	}
+
+	mutex_lock(&port_priv->mutex);
 
 	ret = cp210x_read_reg_block(port, CP210X_GET_FLOW, &flow_ctl,
 			sizeof(flow_ctl));
 	if (ret)
-		return;
+		goto out_unlock;
 
 	ctl_hs = le32_to_cpu(flow_ctl.ulControlHandshake);
 	flow_repl = le32_to_cpu(flow_ctl.ulFlowReplace);
@@ -1108,26 +1160,51 @@ static void cp210x_set_flow_control(struct tty_struct *tty,
 	ctl_hs &= ~CP210X_SERIAL_DCD_HANDSHAKE;
 	ctl_hs &= ~CP210X_SERIAL_DSR_SENSITIVITY;
 	ctl_hs &= ~CP210X_SERIAL_DTR_MASK;
-	ctl_hs |= CP210X_SERIAL_DTR_SHIFT(CP210X_SERIAL_DTR_ACTIVE);
+	if (port_priv->dtr)
+		ctl_hs |= CP210X_SERIAL_DTR_ACTIVE;
+	else
+		ctl_hs |= CP210X_SERIAL_DTR_INACTIVE;
 
+	flow_repl &= ~CP210X_SERIAL_RTS_MASK;
 	if (C_CRTSCTS(tty)) {
 		ctl_hs |= CP210X_SERIAL_CTS_HANDSHAKE;
-		flow_repl &= ~CP210X_SERIAL_RTS_MASK;
-		flow_repl |= CP210X_SERIAL_RTS_SHIFT(CP210X_SERIAL_RTS_FLOW_CTL);
+		if (port_priv->rts)
+			flow_repl |= CP210X_SERIAL_RTS_FLOW_CTL;
+		else
+			flow_repl |= CP210X_SERIAL_RTS_INACTIVE;
+		port_priv->crtscts = true;
 	} else {
 		ctl_hs &= ~CP210X_SERIAL_CTS_HANDSHAKE;
-		flow_repl &= ~CP210X_SERIAL_RTS_MASK;
-		flow_repl |= CP210X_SERIAL_RTS_SHIFT(CP210X_SERIAL_RTS_ACTIVE);
+		if (port_priv->rts)
+			flow_repl |= CP210X_SERIAL_RTS_ACTIVE;
+		else
+			flow_repl |= CP210X_SERIAL_RTS_INACTIVE;
+		port_priv->crtscts = false;
 	}
 
-	dev_dbg(&port->dev, "%s - ulControlHandshake=0x%08x, ulFlowReplace=0x%08x\n",
-			__func__, ctl_hs, flow_repl);
+	if (I_IXOFF(tty))
+		flow_repl |= CP210X_SERIAL_AUTO_RECEIVE;
+	else
+		flow_repl &= ~CP210X_SERIAL_AUTO_RECEIVE;
+
+	if (I_IXON(tty))
+		flow_repl |= CP210X_SERIAL_AUTO_TRANSMIT;
+	else
+		flow_repl &= ~CP210X_SERIAL_AUTO_TRANSMIT;
+
+	flow_ctl.ulXonLimit = cpu_to_le32(128);
+	flow_ctl.ulXoffLimit = cpu_to_le32(128);
+
+	dev_dbg(&port->dev, "%s - ctrl = 0x%02x, flow = 0x%02x\n", __func__,
+			ctl_hs, flow_repl);
 
 	flow_ctl.ulControlHandshake = cpu_to_le32(ctl_hs);
 	flow_ctl.ulFlowReplace = cpu_to_le32(flow_repl);
 
 	cp210x_write_reg_block(port, CP210X_SET_FLOW, &flow_ctl,
 			sizeof(flow_ctl));
+out_unlock:
+	mutex_unlock(&port_priv->mutex);
 }
 
 static void cp210x_set_termios(struct tty_struct *tty,
@@ -1212,28 +1289,77 @@ static int cp210x_tiocmset(struct tty_struct *tty,
 static int cp210x_tiocmset_port(struct usb_serial_port *port,
 		unsigned int set, unsigned int clear)
 {
+	struct cp210x_port_private *port_priv = usb_get_serial_port_data(port);
+	struct cp210x_flow_ctl flow_ctl;
+	u32 ctl_hs, flow_repl;
 	u16 control = 0;
+	int ret;
+
+	mutex_lock(&port_priv->mutex);
 
 	if (set & TIOCM_RTS) {
+		port_priv->rts = true;
 		control |= CONTROL_RTS;
 		control |= CONTROL_WRITE_RTS;
 	}
 	if (set & TIOCM_DTR) {
+		port_priv->dtr = true;
 		control |= CONTROL_DTR;
 		control |= CONTROL_WRITE_DTR;
 	}
 	if (clear & TIOCM_RTS) {
+		port_priv->rts = false;
 		control &= ~CONTROL_RTS;
 		control |= CONTROL_WRITE_RTS;
 	}
 	if (clear & TIOCM_DTR) {
+		port_priv->dtr = false;
 		control &= ~CONTROL_DTR;
 		control |= CONTROL_WRITE_DTR;
 	}
 
-	dev_dbg(&port->dev, "%s - control = 0x%.4x\n", __func__, control);
+	/*
+	 * Use SET_FLOW to set DTR and enable/disable auto-RTS when hardware
+	 * flow control is enabled.
+	 */
+	if (port_priv->crtscts && control & CONTROL_WRITE_RTS) {
+		ret = cp210x_read_reg_block(port, CP210X_GET_FLOW, &flow_ctl,
+				sizeof(flow_ctl));
+		if (ret)
+			goto out_unlock;
+
+		ctl_hs = le32_to_cpu(flow_ctl.ulControlHandshake);
+		flow_repl = le32_to_cpu(flow_ctl.ulFlowReplace);
+
+		ctl_hs &= ~CP210X_SERIAL_DTR_MASK;
+		if (port_priv->dtr)
+			ctl_hs |= CP210X_SERIAL_DTR_ACTIVE;
+		else
+			ctl_hs |= CP210X_SERIAL_DTR_INACTIVE;
 
-	return cp210x_write_u16_reg(port, CP210X_SET_MHS, control);
+		flow_repl &= ~CP210X_SERIAL_RTS_MASK;
+		if (port_priv->rts)
+			flow_repl |= CP210X_SERIAL_RTS_FLOW_CTL;
+		else
+			flow_repl |= CP210X_SERIAL_RTS_INACTIVE;
+
+		flow_ctl.ulControlHandshake = cpu_to_le32(ctl_hs);
+		flow_ctl.ulFlowReplace = cpu_to_le32(flow_repl);
+
+		dev_dbg(&port->dev, "%s - ctrl = 0x%02x, flow = 0x%02x\n",
+				__func__, ctl_hs, flow_repl);
+
+		ret = cp210x_write_reg_block(port, CP210X_SET_FLOW, &flow_ctl,
+				sizeof(flow_ctl));
+	} else {
+		dev_dbg(&port->dev, "%s - control = 0x%04x\n", __func__, control);
+
+		ret = cp210x_write_u16_reg(port, CP210X_SET_MHS, control);
+	}
+out_unlock:
+	mutex_unlock(&port_priv->mutex);
+
+	return ret;
 }
 
 static void cp210x_dtr_rts(struct usb_serial_port *port, int on)
@@ -1261,7 +1387,7 @@ static int cp210x_tiocmget(struct tty_struct *tty)
 		|((control & CONTROL_RING)? TIOCM_RI  : 0)
 		|((control & CONTROL_DCD) ? TIOCM_CD  : 0);
 
-	dev_dbg(&port->dev, "%s - control = 0x%.2x\n", __func__, control);
+	dev_dbg(&port->dev, "%s - control = 0x%02x\n", __func__, control);
 
 	return result;
 }
@@ -1710,20 +1836,19 @@ static int cp210x_port_probe(struct usb_serial_port *port)
 		return -ENOMEM;
 
 	port_priv->bInterfaceNumber = cp210x_interface_num(serial);
+	mutex_init(&port_priv->mutex);
 
 	usb_set_serial_port_data(port, port_priv);
 
 	return 0;
 }
 
-static int cp210x_port_remove(struct usb_serial_port *port)
+static void cp210x_port_remove(struct usb_serial_port *port)
 {
 	struct cp210x_port_private *port_priv;
 
 	port_priv = usb_get_serial_port_data(port);
 	kfree(port_priv);
-
-	return 0;
 }
 
 static void cp210x_init_max_speed(struct usb_serial *serial)
diff --git a/drivers/usb/serial/cyberjack.c b/drivers/usb/serial/cyberjack.c
index 2e40908963da..cf389224d528 100644
--- a/drivers/usb/serial/cyberjack.c
+++ b/drivers/usb/serial/cyberjack.c
@@ -47,7 +47,7 @@
 
 /* Function prototypes */
 static int cyberjack_port_probe(struct usb_serial_port *port);
-static int cyberjack_port_remove(struct usb_serial_port *port);
+static void cyberjack_port_remove(struct usb_serial_port *port);
 static int  cyberjack_open(struct tty_struct *tty,
 	struct usb_serial_port *port);
 static void cyberjack_close(struct usb_serial_port *port);
@@ -120,7 +120,7 @@ static int cyberjack_port_probe(struct usb_serial_port *port)
 	return 0;
 }
 
-static int cyberjack_port_remove(struct usb_serial_port *port)
+static void cyberjack_port_remove(struct usb_serial_port *port)
 {
 	struct cyberjack_private *priv;
 
@@ -128,8 +128,6 @@ static int cyberjack_port_remove(struct usb_serial_port *port)
 
 	priv = usb_get_serial_port_data(port);
 	kfree(priv);
-
-	return 0;
 }
 
 static int  cyberjack_open(struct tty_struct *tty,
diff --git a/drivers/usb/serial/cypress_m8.c b/drivers/usb/serial/cypress_m8.c
index cc028601c388..166ee2286fda 100644
--- a/drivers/usb/serial/cypress_m8.c
+++ b/drivers/usb/serial/cypress_m8.c
@@ -115,7 +115,7 @@ struct cypress_private {
 static int  cypress_earthmate_port_probe(struct usb_serial_port *port);
 static int  cypress_hidcom_port_probe(struct usb_serial_port *port);
 static int  cypress_ca42v2_port_probe(struct usb_serial_port *port);
-static int  cypress_port_remove(struct usb_serial_port *port);
+static void cypress_port_remove(struct usb_serial_port *port);
 static int  cypress_open(struct tty_struct *tty, struct usb_serial_port *port);
 static void cypress_close(struct usb_serial_port *port);
 static void cypress_dtr_rts(struct usb_serial_port *port, int on);
@@ -564,7 +564,7 @@ static int cypress_ca42v2_port_probe(struct usb_serial_port *port)
 	return 0;
 }
 
-static int cypress_port_remove(struct usb_serial_port *port)
+static void cypress_port_remove(struct usb_serial_port *port)
 {
 	struct cypress_private *priv;
 
@@ -572,8 +572,6 @@ static int cypress_port_remove(struct usb_serial_port *port)
 
 	kfifo_free(&priv->write_fifo);
 	kfree(priv);
-
-	return 0;
 }
 
 static int cypress_open(struct tty_struct *tty, struct usb_serial_port *port)
diff --git a/drivers/usb/serial/digi_acceleport.c b/drivers/usb/serial/digi_acceleport.c
index 0ecd5316d85f..8b2f06539f2c 100644
--- a/drivers/usb/serial/digi_acceleport.c
+++ b/drivers/usb/serial/digi_acceleport.c
@@ -233,7 +233,7 @@ static int digi_startup(struct usb_serial *serial);
 static void digi_disconnect(struct usb_serial *serial);
 static void digi_release(struct usb_serial *serial);
 static int digi_port_probe(struct usb_serial_port *port);
-static int digi_port_remove(struct usb_serial_port *port);
+static void digi_port_remove(struct usb_serial_port *port);
 static void digi_read_bulk_callback(struct urb *urb);
 static int digi_read_inb_callback(struct urb *urb);
 static int digi_read_oob_callback(struct urb *urb);
@@ -1281,14 +1281,12 @@ static int digi_port_probe(struct usb_serial_port *port)
 	return digi_port_init(port, port->port_number);
 }
 
-static int digi_port_remove(struct usb_serial_port *port)
+static void digi_port_remove(struct usb_serial_port *port)
 {
 	struct digi_port *priv;
 
 	priv = usb_get_serial_port_data(port);
 	kfree(priv);
-
-	return 0;
 }
 
 static void digi_read_bulk_callback(struct urb *urb)
diff --git a/drivers/usb/serial/f81232.c b/drivers/usb/serial/f81232.c
index 0c7eacc630e0..6a8f39147d8e 100644
--- a/drivers/usb/serial/f81232.c
+++ b/drivers/usb/serial/f81232.c
@@ -192,13 +192,9 @@ static int f81232_set_register(struct usb_serial_port *port, u16 reg, u8 val)
 				tmp,
 				sizeof(val),
 				USB_CTRL_SET_TIMEOUT);
-	if (status != sizeof(val)) {
+	if (status < 0) {
 		dev_err(&port->dev, "%s failed status: %d\n", __func__, status);
-
-		if (status < 0)
-			status = usb_translate_errors(status);
-		else
-			status = -EIO;
+		status = usb_translate_errors(status);
 	} else {
 		status = 0;
 	}
@@ -886,10 +882,6 @@ static int f81534a_ctrl_set_register(struct usb_interface *intf, u16 reg,
 			status = usb_translate_errors(status);
 			if (status == -EIO)
 				continue;
-		} else if (status != size) {
-			/* Retry on short transfers */
-			status = -EIO;
-			continue;
 		} else {
 			status = 0;
 		}
diff --git a/drivers/usb/serial/f81534.c b/drivers/usb/serial/f81534.c
index 5661fd03e545..a763b362f081 100644
--- a/drivers/usb/serial/f81534.c
+++ b/drivers/usb/serial/f81534.c
@@ -235,11 +235,9 @@ static int f81534_set_register(struct usb_serial *serial, u16 reg, u8 data)
 					 USB_TYPE_VENDOR | USB_DIR_OUT,
 					 reg, 0, tmp, sizeof(u8),
 					 F81534_USB_TIMEOUT);
-		if (status > 0) {
+		if (status == sizeof(u8)) {
 			status = 0;
 			break;
-		} else if (status == 0) {
-			status = -EIO;
 		}
 	}
 
@@ -1432,12 +1430,11 @@ static int f81534_port_probe(struct usb_serial_port *port)
 	return f81534_set_port_output_pin(port);
 }
 
-static int f81534_port_remove(struct usb_serial_port *port)
+static void f81534_port_remove(struct usb_serial_port *port)
 {
 	struct f81534_port_private *port_priv = usb_get_serial_port_data(port);
 
 	flush_work(&port_priv->lsr_work);
-	return 0;
 }
 
 static int f81534_tiocmget(struct tty_struct *tty)
diff --git a/drivers/usb/serial/ftdi_sio.c b/drivers/usb/serial/ftdi_sio.c
index 94398f89e600..c867592477c9 100644
--- a/drivers/usb/serial/ftdi_sio.c
+++ b/drivers/usb/serial/ftdi_sio.c
@@ -1069,7 +1069,7 @@ static const char *ftdi_chip_name[] = {
 static int  ftdi_sio_probe(struct usb_serial *serial,
 					const struct usb_device_id *id);
 static int  ftdi_sio_port_probe(struct usb_serial_port *port);
-static int  ftdi_sio_port_remove(struct usb_serial_port *port);
+static void ftdi_sio_port_remove(struct usb_serial_port *port);
 static int  ftdi_open(struct tty_struct *tty, struct usb_serial_port *port);
 static void ftdi_dtr_rts(struct usb_serial_port *port, int on);
 static void ftdi_process_read_urb(struct urb *urb);
@@ -1153,13 +1153,13 @@ static unsigned short int ftdi_232am_baud_base_to_divisor(int baud, int base)
 	divisor = divisor3 >> 3;
 	divisor3 &= 0x7;
 	if (divisor3 == 1)
-		divisor |= 0xc000;
+		divisor |= 0xc000;	/* +0.125 */
 	else if (divisor3 >= 4)
-		divisor |= 0x4000;
+		divisor |= 0x4000;	/* +0.5 */
 	else if (divisor3 != 0)
-		divisor |= 0x8000;
+		divisor |= 0x8000;	/* +0.25 */
 	else if (divisor == 1)
-		divisor = 0;	/* special case for maximum baud rate */
+		divisor = 0;		/* special case for maximum baud rate */
 	return divisor;
 }
 
@@ -1177,9 +1177,9 @@ static u32 ftdi_232bm_baud_base_to_divisor(int baud, int base)
 	divisor = divisor3 >> 3;
 	divisor |= (u32)divfrac[divisor3 & 0x7] << 14;
 	/* Deal with special cases for highest baud rates. */
-	if (divisor == 1)
+	if (divisor == 1)		/* 1.0 */
 		divisor = 0;
-	else if (divisor == 0x4001)
+	else if (divisor == 0x4001)	/* 1.5 */
 		divisor = 1;
 	return divisor;
 }
@@ -1201,9 +1201,9 @@ static u32 ftdi_2232h_baud_base_to_divisor(int baud, int base)
 	divisor = divisor3 >> 3;
 	divisor |= (u32)divfrac[divisor3 & 0x7] << 14;
 	/* Deal with special cases for highest baud rates. */
-	if (divisor == 1)
+	if (divisor == 1)		/* 1.0 */
 		divisor = 0;
-	else if (divisor == 0x4001)
+	else if (divisor == 0x4001)	/* 1.5 */
 		divisor = 1;
 	/*
 	 * Set this bit to turn off a divide by 2.5 on baud rate generator
@@ -1386,8 +1386,9 @@ static int change_speed(struct tty_struct *tty, struct usb_serial_port *port)
 	index_value = get_ftdi_divisor(tty, port);
 	value = (u16)index_value;
 	index = (u16)(index_value >> 16);
-	if ((priv->chip_type == FT2232C) || (priv->chip_type == FT2232H) ||
-		(priv->chip_type == FT4232H) || (priv->chip_type == FT232H)) {
+	if (priv->chip_type == FT2232C || priv->chip_type == FT2232H ||
+			priv->chip_type == FT4232H || priv->chip_type == FT232H ||
+			priv->chip_type == FTX) {
 		/* Probably the BM type needs the MSB of the encoded fractional
 		 * divider also moved like for the chips above. Any infos? */
 		index = (u16)((index << 8) | priv->interface);
@@ -2399,7 +2400,7 @@ static int ftdi_stmclite_probe(struct usb_serial *serial)
 	return 0;
 }
 
-static int ftdi_sio_port_remove(struct usb_serial_port *port)
+static void ftdi_sio_port_remove(struct usb_serial_port *port)
 {
 	struct ftdi_private *priv = usb_get_serial_port_data(port);
 
@@ -2408,8 +2409,6 @@ static int ftdi_sio_port_remove(struct usb_serial_port *port)
 	remove_sysfs_attrs(port);
 
 	kfree(priv);
-
-	return 0;
 }
 
 static int ftdi_open(struct tty_struct *tty, struct usb_serial_port *port)
diff --git a/drivers/usb/serial/garmin_gps.c b/drivers/usb/serial/garmin_gps.c
index c02c19bb1183..50e8bdc77e71 100644
--- a/drivers/usb/serial/garmin_gps.c
+++ b/drivers/usb/serial/garmin_gps.c
@@ -1401,7 +1401,7 @@ err_free:
 }
 
 
-static int garmin_port_remove(struct usb_serial_port *port)
+static void garmin_port_remove(struct usb_serial_port *port)
 {
 	struct garmin_data *garmin_data_p = usb_get_serial_port_data(port);
 
@@ -1409,7 +1409,6 @@ static int garmin_port_remove(struct usb_serial_port *port)
 	usb_kill_urb(port->interrupt_in_urb);
 	del_timer_sync(&garmin_data_p->timer);
 	kfree(garmin_data_p);
-	return 0;
 }
 
 
diff --git a/drivers/usb/serial/io_edgeport.c b/drivers/usb/serial/io_edgeport.c
index ba5d8df69518..a493670c06e6 100644
--- a/drivers/usb/serial/io_edgeport.c
+++ b/drivers/usb/serial/io_edgeport.c
@@ -293,7 +293,7 @@ static int  edge_startup(struct usb_serial *serial);
 static void edge_disconnect(struct usb_serial *serial);
 static void edge_release(struct usb_serial *serial);
 static int edge_port_probe(struct usb_serial_port *port);
-static int edge_port_remove(struct usb_serial_port *port);
+static void edge_port_remove(struct usb_serial_port *port);
 
 /* function prototypes for all of our local functions */
 
@@ -3078,14 +3078,12 @@ static int edge_port_probe(struct usb_serial_port *port)
 	return 0;
 }
 
-static int edge_port_remove(struct usb_serial_port *port)
+static void edge_port_remove(struct usb_serial_port *port)
 {
 	struct edgeport_port *edge_port;
 
 	edge_port = usb_get_serial_port_data(port);
 	kfree(edge_port);
-
-	return 0;
 }
 
 static struct usb_serial_driver edgeport_2port_device = {
diff --git a/drivers/usb/serial/io_ti.c b/drivers/usb/serial/io_ti.c
index c327d4cf7928..e800547be9e0 100644
--- a/drivers/usb/serial/io_ti.c
+++ b/drivers/usb/serial/io_ti.c
@@ -266,7 +266,7 @@ static int ti_vread_sync(struct usb_device *dev, __u8 request,
 	if (status < 0)
 		return status;
 	if (status != size) {
-		dev_dbg(&dev->dev, "%s - wanted to write %d, but only wrote %d\n",
+		dev_dbg(&dev->dev, "%s - wanted to read %d, but only read %d\n",
 			__func__, size, status);
 		return -ECOMM;
 	}
@@ -283,11 +283,7 @@ static int ti_vsend_sync(struct usb_device *dev, u8 request, u16 value,
 			value, index, data, size, timeout);
 	if (status < 0)
 		return status;
-	if (status != size) {
-		dev_dbg(&dev->dev, "%s - wanted to write %d, but only wrote %d\n",
-			__func__, size, status);
-		return -ECOMM;
-	}
+
 	return 0;
 }
 
@@ -2629,15 +2625,13 @@ err:
 	return ret;
 }
 
-static int edge_port_remove(struct usb_serial_port *port)
+static void edge_port_remove(struct usb_serial_port *port)
 {
 	struct edgeport_port *edge_port;
 
 	edge_port = usb_get_serial_port_data(port);
 	edge_remove_sysfs_attrs(port);
 	kfree(edge_port);
-
-	return 0;
 }
 
 /* Sysfs Attributes */
diff --git a/drivers/usb/serial/iuu_phoenix.c b/drivers/usb/serial/iuu_phoenix.c
index e8f06b41a503..093afd67a664 100644
--- a/drivers/usb/serial/iuu_phoenix.c
+++ b/drivers/usb/serial/iuu_phoenix.c
@@ -100,7 +100,7 @@ static int iuu_port_probe(struct usb_serial_port *port)
 	return 0;
 }
 
-static int iuu_port_remove(struct usb_serial_port *port)
+static void iuu_port_remove(struct usb_serial_port *port)
 {
 	struct iuu_private *priv = usb_get_serial_port_data(port);
 
@@ -108,8 +108,6 @@ static int iuu_port_remove(struct usb_serial_port *port)
 	kfree(priv->writebuf);
 	kfree(priv->buf);
 	kfree(priv);
-
-	return 0;
 }
 
 static int iuu_tiocmset(struct tty_struct *tty,
diff --git a/drivers/usb/serial/keyspan.c b/drivers/usb/serial/keyspan.c
index aa3dbce22cfb..622077dcc344 100644
--- a/drivers/usb/serial/keyspan.c
+++ b/drivers/usb/serial/keyspan.c
@@ -49,7 +49,7 @@ static int keyspan_startup(struct usb_serial *serial);
 static void keyspan_disconnect(struct usb_serial *serial);
 static void keyspan_release(struct usb_serial *serial);
 static int keyspan_port_probe(struct usb_serial_port *port);
-static int keyspan_port_remove(struct usb_serial_port *port);
+static void keyspan_port_remove(struct usb_serial_port *port);
 static int keyspan_write_room(struct tty_struct *tty);
 static int keyspan_write(struct tty_struct *tty, struct usb_serial_port *port,
 			 const unsigned char *buf, int count);
@@ -2985,7 +2985,7 @@ err_in_buffer:
 	return -ENOMEM;
 }
 
-static int keyspan_port_remove(struct usb_serial_port *port)
+static void keyspan_port_remove(struct usb_serial_port *port)
 {
 	struct keyspan_port_private *p_priv;
 	int i;
@@ -3014,8 +3014,6 @@ static int keyspan_port_remove(struct usb_serial_port *port)
 		kfree(p_priv->in_buffer[i]);
 
 	kfree(p_priv);
-
-	return 0;
 }
 
 /* Structs for the devices, pre and post renumeration. */
diff --git a/drivers/usb/serial/keyspan_pda.c b/drivers/usb/serial/keyspan_pda.c
index e6f933e8d25f..39b0f5f344c2 100644
--- a/drivers/usb/serial/keyspan_pda.c
+++ b/drivers/usb/serial/keyspan_pda.c
@@ -672,14 +672,12 @@ static int keyspan_pda_port_probe(struct usb_serial_port *port)
 	return 0;
 }
 
-static int keyspan_pda_port_remove(struct usb_serial_port *port)
+static void keyspan_pda_port_remove(struct usb_serial_port *port)
 {
 	struct keyspan_pda_private *priv;
 
 	priv = usb_get_serial_port_data(port);
 	kfree(priv);
-
-	return 0;
 }
 
 static struct usb_serial_driver keyspan_pda_fake_device = {
diff --git a/drivers/usb/serial/kl5kusb105.c b/drivers/usb/serial/kl5kusb105.c
index 5f6b82ebccc5..f1e9628a9907 100644
--- a/drivers/usb/serial/kl5kusb105.c
+++ b/drivers/usb/serial/kl5kusb105.c
@@ -52,7 +52,7 @@
  * Function prototypes
  */
 static int klsi_105_port_probe(struct usb_serial_port *port);
-static int klsi_105_port_remove(struct usb_serial_port *port);
+static void klsi_105_port_remove(struct usb_serial_port *port);
 static int  klsi_105_open(struct tty_struct *tty, struct usb_serial_port *port);
 static void klsi_105_close(struct usb_serial_port *port);
 static void klsi_105_set_termios(struct tty_struct *tty,
@@ -231,14 +231,12 @@ static int klsi_105_port_probe(struct usb_serial_port *port)
 	return 0;
 }
 
-static int klsi_105_port_remove(struct usb_serial_port *port)
+static void klsi_105_port_remove(struct usb_serial_port *port)
 {
 	struct klsi_105_private *priv;
 
 	priv = usb_get_serial_port_data(port);
 	kfree(priv);
-
-	return 0;
 }
 
 static int  klsi_105_open(struct tty_struct *tty, struct usb_serial_port *port)
diff --git a/drivers/usb/serial/kobil_sct.c b/drivers/usb/serial/kobil_sct.c
index 49aacb0a327c..a9bc546626ab 100644
--- a/drivers/usb/serial/kobil_sct.c
+++ b/drivers/usb/serial/kobil_sct.c
@@ -48,7 +48,7 @@
 
 /* Function prototypes */
 static int kobil_port_probe(struct usb_serial_port *probe);
-static int kobil_port_remove(struct usb_serial_port *probe);
+static void kobil_port_remove(struct usb_serial_port *probe);
 static int  kobil_open(struct tty_struct *tty, struct usb_serial_port *port);
 static void kobil_close(struct usb_serial_port *port);
 static int  kobil_write(struct tty_struct *tty, struct usb_serial_port *port,
@@ -143,14 +143,12 @@ static int kobil_port_probe(struct usb_serial_port *port)
 }
 
 
-static int kobil_port_remove(struct usb_serial_port *port)
+static void kobil_port_remove(struct usb_serial_port *port)
 {
 	struct kobil_private *priv;
 
 	priv = usb_get_serial_port_data(port);
 	kfree(priv);
-
-	return 0;
 }
 
 static void kobil_init_termios(struct tty_struct *tty)
diff --git a/drivers/usb/serial/mct_u232.c b/drivers/usb/serial/mct_u232.c
index 7887c312d9a9..ecd5b921e374 100644
--- a/drivers/usb/serial/mct_u232.c
+++ b/drivers/usb/serial/mct_u232.c
@@ -39,7 +39,7 @@
  * Function prototypes
  */
 static int  mct_u232_port_probe(struct usb_serial_port *port);
-static int  mct_u232_port_remove(struct usb_serial_port *remove);
+static void mct_u232_port_remove(struct usb_serial_port *remove);
 static int  mct_u232_open(struct tty_struct *tty, struct usb_serial_port *port);
 static void mct_u232_close(struct usb_serial_port *port);
 static void mct_u232_dtr_rts(struct usb_serial_port *port, int on);
@@ -400,14 +400,12 @@ static int mct_u232_port_probe(struct usb_serial_port *port)
 	return 0;
 }
 
-static int mct_u232_port_remove(struct usb_serial_port *port)
+static void mct_u232_port_remove(struct usb_serial_port *port)
 {
 	struct mct_u232_private *priv;
 
 	priv = usb_get_serial_port_data(port);
 	kfree(priv);
-
-	return 0;
 }
 
 static int  mct_u232_open(struct tty_struct *tty, struct usb_serial_port *port)
diff --git a/drivers/usb/serial/metro-usb.c b/drivers/usb/serial/metro-usb.c
index e63cea02cfd8..0bfe4459c37f 100644
--- a/drivers/usb/serial/metro-usb.c
+++ b/drivers/usb/serial/metro-usb.c
@@ -256,14 +256,12 @@ static int metrousb_port_probe(struct usb_serial_port *port)
 	return 0;
 }
 
-static int metrousb_port_remove(struct usb_serial_port *port)
+static void metrousb_port_remove(struct usb_serial_port *port)
 {
 	struct metrousb_private *metro_priv;
 
 	metro_priv = usb_get_serial_port_data(port);
 	kfree(metro_priv);
-
-	return 0;
 }
 
 static void metrousb_throttle(struct tty_struct *tty)
diff --git a/drivers/usb/serial/mos7720.c b/drivers/usb/serial/mos7720.c
index 41ee2984a0df..701dfb32b129 100644
--- a/drivers/usb/serial/mos7720.c
+++ b/drivers/usb/serial/mos7720.c
@@ -215,8 +215,10 @@ static int read_mos_reg(struct usb_serial *serial, unsigned int serial_portnum,
 	int status;
 
 	buf = kmalloc(1, GFP_KERNEL);
-	if (!buf)
+	if (!buf) {
+		*data = 0;
 		return -ENOMEM;
+	}
 
 	status = usb_control_msg(usbdev, pipe, request, requesttype, value,
 				     index, buf, 1, MOS_WDR_TIMEOUT);
@@ -1092,8 +1094,10 @@ static int mos7720_write(struct tty_struct *tty, struct usb_serial_port *port,
 	if (urb->transfer_buffer == NULL) {
 		urb->transfer_buffer = kmalloc(URB_TRANSFER_BUFFER_SIZE,
 					       GFP_ATOMIC);
-		if (!urb->transfer_buffer)
+		if (!urb->transfer_buffer) {
+			bytes_sent = -ENOMEM;
 			goto exit;
+		}
 	}
 	transfer_size = min(count, URB_TRANSFER_BUFFER_SIZE);
 
@@ -1756,14 +1760,12 @@ static int mos7720_port_probe(struct usb_serial_port *port)
 	return 0;
 }
 
-static int mos7720_port_remove(struct usb_serial_port *port)
+static void mos7720_port_remove(struct usb_serial_port *port)
 {
 	struct moschip_port *mos7720_port;
 
 	mos7720_port = usb_get_serial_port_data(port);
 	kfree(mos7720_port);
-
-	return 0;
 }
 
 static struct usb_serial_driver moschip7720_2port_driver = {
diff --git a/drivers/usb/serial/mos7840.c b/drivers/usb/serial/mos7840.c
index 23f91d658cb4..1bf0d066f55a 100644
--- a/drivers/usb/serial/mos7840.c
+++ b/drivers/usb/serial/mos7840.c
@@ -883,8 +883,10 @@ static int mos7840_write(struct tty_struct *tty, struct usb_serial_port *port,
 	if (urb->transfer_buffer == NULL) {
 		urb->transfer_buffer = kmalloc(URB_TRANSFER_BUFFER_SIZE,
 					       GFP_ATOMIC);
-		if (!urb->transfer_buffer)
+		if (!urb->transfer_buffer) {
+			bytes_sent = -ENOMEM;
 			goto exit;
+		}
 	}
 	transfer_size = min(count, URB_TRANSFER_BUFFER_SIZE);
 
@@ -1743,7 +1745,7 @@ error:
 	return status;
 }
 
-static int mos7840_port_remove(struct usb_serial_port *port)
+static void mos7840_port_remove(struct usb_serial_port *port)
 {
 	struct moschip_port *mos7840_port = usb_get_serial_port_data(port);
 
@@ -1760,8 +1762,6 @@ static int mos7840_port_remove(struct usb_serial_port *port)
 	}
 
 	kfree(mos7840_port);
-
-	return 0;
 }
 
 static struct usb_serial_driver moschip7840_4port_device = {
diff --git a/drivers/usb/serial/mxuport.c b/drivers/usb/serial/mxuport.c
index 5d38c2a0f590..eb45a9b0005c 100644
--- a/drivers/usb/serial/mxuport.c
+++ b/drivers/usb/serial/mxuport.c
@@ -261,13 +261,6 @@ static int mxuport_send_ctrl_data_urb(struct usb_serial *serial,
 		return status;
 	}
 
-	if (status != size) {
-		dev_err(&serial->interface->dev,
-			"%s - short write (%d / %zd)\n",
-			__func__, status, size);
-		return -EIO;
-	}
-
 	return 0;
 }
 
diff --git a/drivers/usb/serial/omninet.c b/drivers/usb/serial/omninet.c
index 5b6e982a9376..83c62f920c50 100644
--- a/drivers/usb/serial/omninet.c
+++ b/drivers/usb/serial/omninet.c
@@ -36,7 +36,7 @@ static int omninet_prepare_write_buffer(struct usb_serial_port *port,
 static int omninet_calc_num_ports(struct usb_serial *serial,
 				struct usb_serial_endpoints *epds);
 static int omninet_port_probe(struct usb_serial_port *port);
-static int omninet_port_remove(struct usb_serial_port *port);
+static void omninet_port_remove(struct usb_serial_port *port);
 
 static const struct usb_device_id id_table[] = {
 	{ USB_DEVICE(ZYXEL_VENDOR_ID, ZYXEL_OMNINET_ID) },
@@ -121,14 +121,12 @@ static int omninet_port_probe(struct usb_serial_port *port)
 	return 0;
 }
 
-static int omninet_port_remove(struct usb_serial_port *port)
+static void omninet_port_remove(struct usb_serial_port *port)
 {
 	struct omninet_data *od;
 
 	od = usb_get_serial_port_data(port);
 	kfree(od);
-
-	return 0;
 }
 
 #define OMNINET_HEADERLEN	4
diff --git a/drivers/usb/serial/opticon.c b/drivers/usb/serial/opticon.c
index 0af76800bd78..eecb72aef83e 100644
--- a/drivers/usb/serial/opticon.c
+++ b/drivers/usb/serial/opticon.c
@@ -385,13 +385,11 @@ static int opticon_port_probe(struct usb_serial_port *port)
 	return 0;
 }
 
-static int opticon_port_remove(struct usb_serial_port *port)
+static void opticon_port_remove(struct usb_serial_port *port)
 {
 	struct opticon_private *priv = usb_get_serial_port_data(port);
 
 	kfree(priv);
-
-	return 0;
 }
 
 static struct usb_serial_driver opticon_device = {
diff --git a/drivers/usb/serial/option.c b/drivers/usb/serial/option.c
index 2049e66f34a3..c6969ca72839 100644
--- a/drivers/usb/serial/option.c
+++ b/drivers/usb/serial/option.c
@@ -1569,7 +1569,8 @@ static const struct usb_device_id option_ids[] = {
 	{ USB_DEVICE_AND_INTERFACE_INFO(ZTE_VENDOR_ID, 0x1272, 0xff, 0xff, 0xff) },
 	{ USB_DEVICE_AND_INTERFACE_INFO(ZTE_VENDOR_ID, 0x1273, 0xff, 0xff, 0xff) },
 	{ USB_DEVICE_AND_INTERFACE_INFO(ZTE_VENDOR_ID, 0x1274, 0xff, 0xff, 0xff) },
-	{ USB_DEVICE_AND_INTERFACE_INFO(ZTE_VENDOR_ID, 0x1275, 0xff, 0xff, 0xff) },
+	{ USB_DEVICE(ZTE_VENDOR_ID, 0x1275),	/* ZTE P685M */
+	  .driver_info = RSVD(3) | RSVD(4) },
 	{ USB_DEVICE_AND_INTERFACE_INFO(ZTE_VENDOR_ID, 0x1276, 0xff, 0xff, 0xff) },
 	{ USB_DEVICE_AND_INTERFACE_INFO(ZTE_VENDOR_ID, 0x1277, 0xff, 0xff, 0xff) },
 	{ USB_DEVICE_AND_INTERFACE_INFO(ZTE_VENDOR_ID, 0x1278, 0xff, 0xff, 0xff) },
diff --git a/drivers/usb/serial/oti6858.c b/drivers/usb/serial/oti6858.c
index 8151dd7a45e8..65cd0341fa78 100644
--- a/drivers/usb/serial/oti6858.c
+++ b/drivers/usb/serial/oti6858.c
@@ -132,7 +132,7 @@ static int oti6858_tiocmget(struct tty_struct *tty);
 static int oti6858_tiocmset(struct tty_struct *tty,
 				unsigned int set, unsigned int clear);
 static int oti6858_port_probe(struct usb_serial_port *port);
-static int oti6858_port_remove(struct usb_serial_port *port);
+static void oti6858_port_remove(struct usb_serial_port *port);
 
 /* device info */
 static struct usb_serial_driver oti6858_device = {
@@ -344,14 +344,12 @@ static int oti6858_port_probe(struct usb_serial_port *port)
 	return 0;
 }
 
-static int oti6858_port_remove(struct usb_serial_port *port)
+static void oti6858_port_remove(struct usb_serial_port *port)
 {
 	struct oti6858_private *priv;
 
 	priv = usb_get_serial_port_data(port);
 	kfree(priv);
-
-	return 0;
 }
 
 static int oti6858_write(struct tty_struct *tty, struct usb_serial_port *port,
diff --git a/drivers/usb/serial/pl2303.c b/drivers/usb/serial/pl2303.c
index be8067017eaa..eed9acd1ae08 100644
--- a/drivers/usb/serial/pl2303.c
+++ b/drivers/usb/serial/pl2303.c
@@ -183,6 +183,7 @@ struct pl2303_type_data {
 	speed_t max_baud_rate;
 	unsigned long quirks;
 	unsigned int no_autoxonxoff:1;
+	unsigned int no_divisors:1;
 };
 
 struct pl2303_serial_private {
@@ -209,6 +210,7 @@ static const struct pl2303_type_data pl2303_type_data[TYPE_COUNT] = {
 	},
 	[TYPE_HXN] = {
 		.max_baud_rate		= 12000000,
+		.no_divisors		= true,
 	},
 };
 
@@ -448,13 +450,11 @@ static int pl2303_port_probe(struct usb_serial_port *port)
 	return 0;
 }
 
-static int pl2303_port_remove(struct usb_serial_port *port)
+static void pl2303_port_remove(struct usb_serial_port *port)
 {
 	struct pl2303_private *priv = usb_get_serial_port_data(port);
 
 	kfree(priv);
-
-	return 0;
 }
 
 static int pl2303_set_control_lines(struct usb_serial_port *port, u8 value)
@@ -571,8 +571,12 @@ static void pl2303_encode_baud_rate(struct tty_struct *tty,
 		baud = min_t(speed_t, baud, spriv->type->max_baud_rate);
 	/*
 	 * Use direct method for supported baud rates, otherwise use divisors.
+	 * Newer chip types do not support divisor encoding.
 	 */
-	baud_sup = pl2303_get_supported_baud_rate(baud);
+	if (spriv->type->no_divisors)
+		baud_sup = baud;
+	else
+		baud_sup = pl2303_get_supported_baud_rate(baud);
 
 	if (baud == baud_sup)
 		baud = pl2303_encode_baud_rate_direct(buf, baud);
diff --git a/drivers/usb/serial/quatech2.c b/drivers/usb/serial/quatech2.c
index 872d1bc86ab4..599dcb2e374d 100644
--- a/drivers/usb/serial/quatech2.c
+++ b/drivers/usb/serial/quatech2.c
@@ -727,7 +727,7 @@ err_buf:
 	return -ENOMEM;
 }
 
-static int qt2_port_remove(struct usb_serial_port *port)
+static void qt2_port_remove(struct usb_serial_port *port)
 {
 	struct qt2_port_private *port_priv;
 
@@ -735,8 +735,6 @@ static int qt2_port_remove(struct usb_serial_port *port)
 	usb_free_urb(port_priv->write_urb);
 	kfree(port_priv->write_buffer);
 	kfree(port_priv);
-
-	return 0;
 }
 
 static int qt2_tiocmget(struct tty_struct *tty)
diff --git a/drivers/usb/serial/sierra.c b/drivers/usb/serial/sierra.c
index 57fc3c31712e..54e16ffc30a0 100644
--- a/drivers/usb/serial/sierra.c
+++ b/drivers/usb/serial/sierra.c
@@ -901,15 +901,13 @@ static int sierra_port_probe(struct usb_serial_port *port)
 	return 0;
 }
 
-static int sierra_port_remove(struct usb_serial_port *port)
+static void sierra_port_remove(struct usb_serial_port *port)
 {
 	struct sierra_port_private *portdata;
 
 	portdata = usb_get_serial_port_data(port);
 	usb_set_serial_port_data(port, NULL);
 	kfree(portdata);
-
-	return 0;
 }
 
 #ifdef CONFIG_PM
diff --git a/drivers/usb/serial/spcp8x5.c b/drivers/usb/serial/spcp8x5.c
index 3bac55bd9bd9..7039dc918827 100644
--- a/drivers/usb/serial/spcp8x5.c
+++ b/drivers/usb/serial/spcp8x5.c
@@ -169,14 +169,12 @@ static int spcp8x5_port_probe(struct usb_serial_port *port)
 	return 0;
 }
 
-static int spcp8x5_port_remove(struct usb_serial_port *port)
+static void spcp8x5_port_remove(struct usb_serial_port *port)
 {
 	struct spcp8x5_private *priv;
 
 	priv = usb_get_serial_port_data(port);
 	kfree(priv);
-
-	return 0;
 }
 
 static int spcp8x5_set_ctrl_line(struct usb_serial_port *port, u8 mcr)
diff --git a/drivers/usb/serial/ssu100.c b/drivers/usb/serial/ssu100.c
index 7d39d35e52a1..89fdc5c19285 100644
--- a/drivers/usb/serial/ssu100.c
+++ b/drivers/usb/serial/ssu100.c
@@ -366,14 +366,12 @@ static int ssu100_port_probe(struct usb_serial_port *port)
 	return 0;
 }
 
-static int ssu100_port_remove(struct usb_serial_port *port)
+static void ssu100_port_remove(struct usb_serial_port *port)
 {
 	struct ssu100_port_private *priv;
 
 	priv = usb_get_serial_port_data(port);
 	kfree(priv);
-
-	return 0;
 }
 
 static int ssu100_tiocmget(struct tty_struct *tty)
diff --git a/drivers/usb/serial/symbolserial.c b/drivers/usb/serial/symbolserial.c
index 6ca24e86f686..d7f73ad6e778 100644
--- a/drivers/usb/serial/symbolserial.c
+++ b/drivers/usb/serial/symbolserial.c
@@ -160,13 +160,11 @@ static int symbol_port_probe(struct usb_serial_port *port)
 	return 0;
 }
 
-static int symbol_port_remove(struct usb_serial_port *port)
+static void symbol_port_remove(struct usb_serial_port *port)
 {
 	struct symbol_private *priv = usb_get_serial_port_data(port);
 
 	kfree(priv);
-
-	return 0;
 }
 
 static struct usb_serial_driver symbol_device = {
diff --git a/drivers/usb/serial/ti_usb_3410_5052.c b/drivers/usb/serial/ti_usb_3410_5052.c
index 73075b9351c5..7252b0ce75a6 100644
--- a/drivers/usb/serial/ti_usb_3410_5052.c
+++ b/drivers/usb/serial/ti_usb_3410_5052.c
@@ -303,7 +303,7 @@ struct ti_device {
 static int ti_startup(struct usb_serial *serial);
 static void ti_release(struct usb_serial *serial);
 static int ti_port_probe(struct usb_serial_port *port);
-static int ti_port_remove(struct usb_serial_port *port);
+static void ti_port_remove(struct usb_serial_port *port);
 static int ti_open(struct tty_struct *tty, struct usb_serial_port *port);
 static void ti_close(struct usb_serial_port *port);
 static int ti_write(struct tty_struct *tty, struct usb_serial_port *port,
@@ -629,14 +629,12 @@ static int ti_port_probe(struct usb_serial_port *port)
 	return 0;
 }
 
-static int ti_port_remove(struct usb_serial_port *port)
+static void ti_port_remove(struct usb_serial_port *port)
 {
 	struct ti_port *tport;
 
 	tport = usb_get_serial_port_data(port);
 	kfree(tport);
-
-	return 0;
 }
 
 static int ti_open(struct tty_struct *tty, struct usb_serial_port *port)
diff --git a/drivers/usb/serial/upd78f0730.c b/drivers/usb/serial/upd78f0730.c
index 0a2268c479af..26d7b003b7e3 100644
--- a/drivers/usb/serial/upd78f0730.c
+++ b/drivers/usb/serial/upd78f0730.c
@@ -145,14 +145,11 @@ static int upd78f0730_send_ctl(struct usb_serial_port *port,
 
 	kfree(buf);
 
-	if (res != size) {
+	if (res < 0) {
 		struct device *dev = &port->dev;
 
 		dev_err(dev, "failed to send control request %02x: %d\n",
 			*(u8 *)data, res);
-		/* The maximum expected length of a transfer is 6 bytes */
-		if (res >= 0)
-			res = -EIO;
 
 		return res;
 	}
@@ -174,15 +171,13 @@ static int upd78f0730_port_probe(struct usb_serial_port *port)
 	return 0;
 }
 
-static int upd78f0730_port_remove(struct usb_serial_port *port)
+static void upd78f0730_port_remove(struct usb_serial_port *port)
 {
 	struct upd78f0730_port_private *private;
 
 	private = usb_get_serial_port_data(port);
 	mutex_destroy(&private->lock);
 	kfree(private);
-
-	return 0;
 }
 
 static int upd78f0730_tiocmget(struct tty_struct *tty)
diff --git a/drivers/usb/serial/usb-wwan.h b/drivers/usb/serial/usb-wwan.h
index 934e9361cf6b..79dafd98e0a1 100644
--- a/drivers/usb/serial/usb-wwan.h
+++ b/drivers/usb/serial/usb-wwan.h
@@ -10,7 +10,7 @@ extern void usb_wwan_dtr_rts(struct usb_serial_port *port, int on);
 extern int usb_wwan_open(struct tty_struct *tty, struct usb_serial_port *port);
 extern void usb_wwan_close(struct usb_serial_port *port);
 extern int usb_wwan_port_probe(struct usb_serial_port *port);
-extern int usb_wwan_port_remove(struct usb_serial_port *port);
+extern void usb_wwan_port_remove(struct usb_serial_port *port);
 extern int usb_wwan_write_room(struct tty_struct *tty);
 extern int usb_wwan_tiocmget(struct tty_struct *tty);
 extern int usb_wwan_tiocmset(struct tty_struct *tty,
diff --git a/drivers/usb/serial/usb_wwan.c b/drivers/usb/serial/usb_wwan.c
index 4b9845807bee..46d46a4f99c9 100644
--- a/drivers/usb/serial/usb_wwan.c
+++ b/drivers/usb/serial/usb_wwan.c
@@ -544,7 +544,7 @@ bail_out_error:
 }
 EXPORT_SYMBOL_GPL(usb_wwan_port_probe);
 
-int usb_wwan_port_remove(struct usb_serial_port *port)
+void usb_wwan_port_remove(struct usb_serial_port *port)
 {
 	int i;
 	struct usb_wwan_port_private *portdata;
@@ -562,8 +562,6 @@ int usb_wwan_port_remove(struct usb_serial_port *port)
 	}
 
 	kfree(portdata);
-
-	return 0;
 }
 EXPORT_SYMBOL(usb_wwan_port_remove);
 
diff --git a/drivers/usb/serial/whiteheat.c b/drivers/usb/serial/whiteheat.c
index ca3bd58f2025..ccfd5ed652cd 100644
--- a/drivers/usb/serial/whiteheat.c
+++ b/drivers/usb/serial/whiteheat.c
@@ -79,7 +79,7 @@ static int  whiteheat_firmware_attach(struct usb_serial *serial);
 static int  whiteheat_attach(struct usb_serial *serial);
 static void whiteheat_release(struct usb_serial *serial);
 static int  whiteheat_port_probe(struct usb_serial_port *port);
-static int  whiteheat_port_remove(struct usb_serial_port *port);
+static void whiteheat_port_remove(struct usb_serial_port *port);
 static int  whiteheat_open(struct tty_struct *tty,
 			struct usb_serial_port *port);
 static void whiteheat_close(struct usb_serial_port *port);
@@ -345,14 +345,12 @@ static int whiteheat_port_probe(struct usb_serial_port *port)
 	return 0;
 }
 
-static int whiteheat_port_remove(struct usb_serial_port *port)
+static void whiteheat_port_remove(struct usb_serial_port *port)
 {
 	struct whiteheat_private *info;
 
 	info = usb_get_serial_port_data(port);
 	kfree(info);
-
-	return 0;
 }
 
 static int whiteheat_open(struct tty_struct *tty, struct usb_serial_port *port)
diff --git a/drivers/usb/serial/xr_serial.c b/drivers/usb/serial/xr_serial.c
new file mode 100644
index 000000000000..483d07dee19d
--- /dev/null
+++ b/drivers/usb/serial/xr_serial.c
@@ -0,0 +1,611 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * MaxLinear/Exar USB to Serial driver
+ *
+ * Copyright (c) 2020 Manivannan Sadhasivam <mani@kernel.org>
+ *
+ * Based on the initial driver written by Patong Yang:
+ *
+ *   https://lore.kernel.org/r/20180404070634.nhspvmxcjwfgjkcv@advantechmxl-desktop
+ *
+ *   Copyright (c) 2018 Patong Yang <patong.mxl@gmail.com>
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/tty.h>
+#include <linux/usb.h>
+#include <linux/usb/serial.h>
+
+struct xr_txrx_clk_mask {
+	u16 tx;
+	u16 rx0;
+	u16 rx1;
+};
+
+#define XR_INT_OSC_HZ			48000000U
+#define XR21V141X_MIN_SPEED		46U
+#define XR21V141X_MAX_SPEED		XR_INT_OSC_HZ
+
+/* USB Requests */
+#define XR21V141X_SET_REQ		0
+#define XR21V141X_GET_REQ		1
+
+#define XR21V141X_CLOCK_DIVISOR_0	0x04
+#define XR21V141X_CLOCK_DIVISOR_1	0x05
+#define XR21V141X_CLOCK_DIVISOR_2	0x06
+#define XR21V141X_TX_CLOCK_MASK_0	0x07
+#define XR21V141X_TX_CLOCK_MASK_1	0x08
+#define XR21V141X_RX_CLOCK_MASK_0	0x09
+#define XR21V141X_RX_CLOCK_MASK_1	0x0a
+
+/* XR21V141X register blocks */
+#define XR21V141X_UART_REG_BLOCK	0
+#define XR21V141X_UM_REG_BLOCK		4
+#define XR21V141X_UART_CUSTOM_BLOCK	0x66
+
+/* XR21V141X UART Manager Registers */
+#define XR21V141X_UM_FIFO_ENABLE_REG	0x10
+#define XR21V141X_UM_ENABLE_TX_FIFO	0x01
+#define XR21V141X_UM_ENABLE_RX_FIFO	0x02
+
+#define XR21V141X_UM_RX_FIFO_RESET	0x18
+#define XR21V141X_UM_TX_FIFO_RESET	0x1c
+
+#define XR21V141X_UART_ENABLE_TX	0x1
+#define XR21V141X_UART_ENABLE_RX	0x2
+
+#define XR21V141X_UART_MODE_RI		BIT(0)
+#define XR21V141X_UART_MODE_CD		BIT(1)
+#define XR21V141X_UART_MODE_DSR		BIT(2)
+#define XR21V141X_UART_MODE_DTR		BIT(3)
+#define XR21V141X_UART_MODE_CTS		BIT(4)
+#define XR21V141X_UART_MODE_RTS		BIT(5)
+
+#define XR21V141X_UART_BREAK_ON		0xff
+#define XR21V141X_UART_BREAK_OFF	0
+
+#define XR21V141X_UART_DATA_MASK	GENMASK(3, 0)
+#define XR21V141X_UART_DATA_7		0x7
+#define XR21V141X_UART_DATA_8		0x8
+
+#define XR21V141X_UART_PARITY_MASK	GENMASK(6, 4)
+#define XR21V141X_UART_PARITY_SHIFT	4
+#define XR21V141X_UART_PARITY_NONE	(0x0 << XR21V141X_UART_PARITY_SHIFT)
+#define XR21V141X_UART_PARITY_ODD	(0x1 << XR21V141X_UART_PARITY_SHIFT)
+#define XR21V141X_UART_PARITY_EVEN	(0x2 << XR21V141X_UART_PARITY_SHIFT)
+#define XR21V141X_UART_PARITY_MARK	(0x3 << XR21V141X_UART_PARITY_SHIFT)
+#define XR21V141X_UART_PARITY_SPACE	(0x4 << XR21V141X_UART_PARITY_SHIFT)
+
+#define XR21V141X_UART_STOP_MASK	BIT(7)
+#define XR21V141X_UART_STOP_SHIFT	7
+#define XR21V141X_UART_STOP_1		(0x0 << XR21V141X_UART_STOP_SHIFT)
+#define XR21V141X_UART_STOP_2		(0x1 << XR21V141X_UART_STOP_SHIFT)
+
+#define XR21V141X_UART_FLOW_MODE_NONE	0x0
+#define XR21V141X_UART_FLOW_MODE_HW	0x1
+#define XR21V141X_UART_FLOW_MODE_SW	0x2
+
+#define XR21V141X_UART_MODE_GPIO_MASK	GENMASK(2, 0)
+#define XR21V141X_UART_MODE_RTS_CTS	0x1
+#define XR21V141X_UART_MODE_DTR_DSR	0x2
+#define XR21V141X_UART_MODE_RS485	0x3
+#define XR21V141X_UART_MODE_RS485_ADDR	0x4
+
+#define XR21V141X_REG_ENABLE		0x03
+#define XR21V141X_REG_FORMAT		0x0b
+#define XR21V141X_REG_FLOW_CTRL		0x0c
+#define XR21V141X_REG_XON_CHAR		0x10
+#define XR21V141X_REG_XOFF_CHAR		0x11
+#define XR21V141X_REG_LOOPBACK		0x12
+#define XR21V141X_REG_TX_BREAK		0x14
+#define XR21V141X_REG_RS845_DELAY	0x15
+#define XR21V141X_REG_GPIO_MODE		0x1a
+#define XR21V141X_REG_GPIO_DIR		0x1b
+#define XR21V141X_REG_GPIO_INT_MASK	0x1c
+#define XR21V141X_REG_GPIO_SET		0x1d
+#define XR21V141X_REG_GPIO_CLR		0x1e
+#define XR21V141X_REG_GPIO_STATUS	0x1f
+
+static int xr_set_reg(struct usb_serial_port *port, u8 block, u8 reg, u8 val)
+{
+	struct usb_serial *serial = port->serial;
+	int ret;
+
+	ret = usb_control_msg(serial->dev,
+			      usb_sndctrlpipe(serial->dev, 0),
+			      XR21V141X_SET_REQ,
+			      USB_DIR_OUT | USB_TYPE_VENDOR | USB_RECIP_DEVICE,
+			      val, reg | (block << 8), NULL, 0,
+			      USB_CTRL_SET_TIMEOUT);
+	if (ret < 0) {
+		dev_err(&port->dev, "Failed to set reg 0x%02x: %d\n", reg, ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+static int xr_get_reg(struct usb_serial_port *port, u8 block, u8 reg, u8 *val)
+{
+	struct usb_serial *serial = port->serial;
+	u8 *dmabuf;
+	int ret;
+
+	dmabuf = kmalloc(1, GFP_KERNEL);
+	if (!dmabuf)
+		return -ENOMEM;
+
+	ret = usb_control_msg(serial->dev,
+			      usb_rcvctrlpipe(serial->dev, 0),
+			      XR21V141X_GET_REQ,
+			      USB_DIR_IN | USB_TYPE_VENDOR | USB_RECIP_DEVICE,
+			      0, reg | (block << 8), dmabuf, 1,
+			      USB_CTRL_GET_TIMEOUT);
+	if (ret == 1) {
+		*val = *dmabuf;
+		ret = 0;
+	} else {
+		dev_err(&port->dev, "Failed to get reg 0x%02x: %d\n", reg, ret);
+		if (ret >= 0)
+			ret = -EIO;
+	}
+
+	kfree(dmabuf);
+
+	return ret;
+}
+
+static int xr_set_reg_uart(struct usb_serial_port *port, u8 reg, u8 val)
+{
+	return xr_set_reg(port, XR21V141X_UART_REG_BLOCK, reg, val);
+}
+
+static int xr_get_reg_uart(struct usb_serial_port *port, u8 reg, u8 *val)
+{
+	return xr_get_reg(port, XR21V141X_UART_REG_BLOCK, reg, val);
+}
+
+static int xr_set_reg_um(struct usb_serial_port *port, u8 reg, u8 val)
+{
+	return xr_set_reg(port, XR21V141X_UM_REG_BLOCK, reg, val);
+}
+
+/*
+ * According to datasheet, below is the recommended sequence for enabling UART
+ * module in XR21V141X:
+ *
+ * Enable Tx FIFO
+ * Enable Tx and Rx
+ * Enable Rx FIFO
+ */
+static int xr_uart_enable(struct usb_serial_port *port)
+{
+	int ret;
+
+	ret = xr_set_reg_um(port, XR21V141X_UM_FIFO_ENABLE_REG,
+			    XR21V141X_UM_ENABLE_TX_FIFO);
+	if (ret)
+		return ret;
+
+	ret = xr_set_reg_uart(port, XR21V141X_REG_ENABLE,
+			      XR21V141X_UART_ENABLE_TX | XR21V141X_UART_ENABLE_RX);
+	if (ret)
+		return ret;
+
+	ret = xr_set_reg_um(port, XR21V141X_UM_FIFO_ENABLE_REG,
+			    XR21V141X_UM_ENABLE_TX_FIFO | XR21V141X_UM_ENABLE_RX_FIFO);
+
+	if (ret)
+		xr_set_reg_uart(port, XR21V141X_REG_ENABLE, 0);
+
+	return ret;
+}
+
+static int xr_uart_disable(struct usb_serial_port *port)
+{
+	int ret;
+
+	ret = xr_set_reg_uart(port, XR21V141X_REG_ENABLE, 0);
+	if (ret)
+		return ret;
+
+	ret = xr_set_reg_um(port, XR21V141X_UM_FIFO_ENABLE_REG, 0);
+
+	return ret;
+}
+
+static int xr_tiocmget(struct tty_struct *tty)
+{
+	struct usb_serial_port *port = tty->driver_data;
+	u8 status;
+	int ret;
+
+	ret = xr_get_reg_uart(port, XR21V141X_REG_GPIO_STATUS, &status);
+	if (ret)
+		return ret;
+
+	/*
+	 * Modem control pins are active low, so reading '0' means it is active
+	 * and '1' means not active.
+	 */
+	ret = ((status & XR21V141X_UART_MODE_DTR) ? 0 : TIOCM_DTR) |
+	      ((status & XR21V141X_UART_MODE_RTS) ? 0 : TIOCM_RTS) |
+	      ((status & XR21V141X_UART_MODE_CTS) ? 0 : TIOCM_CTS) |
+	      ((status & XR21V141X_UART_MODE_DSR) ? 0 : TIOCM_DSR) |
+	      ((status & XR21V141X_UART_MODE_RI) ? 0 : TIOCM_RI) |
+	      ((status & XR21V141X_UART_MODE_CD) ? 0 : TIOCM_CD);
+
+	return ret;
+}
+
+static int xr_tiocmset_port(struct usb_serial_port *port,
+			    unsigned int set, unsigned int clear)
+{
+	u8 gpio_set = 0;
+	u8 gpio_clr = 0;
+	int ret = 0;
+
+	/* Modem control pins are active low, so set & clr are swapped */
+	if (set & TIOCM_RTS)
+		gpio_clr |= XR21V141X_UART_MODE_RTS;
+	if (set & TIOCM_DTR)
+		gpio_clr |= XR21V141X_UART_MODE_DTR;
+	if (clear & TIOCM_RTS)
+		gpio_set |= XR21V141X_UART_MODE_RTS;
+	if (clear & TIOCM_DTR)
+		gpio_set |= XR21V141X_UART_MODE_DTR;
+
+	/* Writing '0' to gpio_{set/clr} bits has no effect, so no need to do */
+	if (gpio_clr)
+		ret = xr_set_reg_uart(port, XR21V141X_REG_GPIO_CLR, gpio_clr);
+
+	if (gpio_set)
+		ret = xr_set_reg_uart(port, XR21V141X_REG_GPIO_SET, gpio_set);
+
+	return ret;
+}
+
+static int xr_tiocmset(struct tty_struct *tty,
+		       unsigned int set, unsigned int clear)
+{
+	struct usb_serial_port *port = tty->driver_data;
+
+	return xr_tiocmset_port(port, set, clear);
+}
+
+static void xr_dtr_rts(struct usb_serial_port *port, int on)
+{
+	if (on)
+		xr_tiocmset_port(port, TIOCM_DTR | TIOCM_RTS, 0);
+	else
+		xr_tiocmset_port(port, 0, TIOCM_DTR | TIOCM_RTS);
+}
+
+static void xr_break_ctl(struct tty_struct *tty, int break_state)
+{
+	struct usb_serial_port *port = tty->driver_data;
+	u8 state;
+
+	if (break_state == 0)
+		state = XR21V141X_UART_BREAK_OFF;
+	else
+		state = XR21V141X_UART_BREAK_ON;
+
+	dev_dbg(&port->dev, "Turning break %s\n",
+		state == XR21V141X_UART_BREAK_OFF ? "off" : "on");
+	xr_set_reg_uart(port, XR21V141X_REG_TX_BREAK, state);
+}
+
+/* Tx and Rx clock mask values obtained from section 3.3.4 of datasheet */
+static const struct xr_txrx_clk_mask xr21v141x_txrx_clk_masks[] = {
+	{ 0x000, 0x000, 0x000 },
+	{ 0x000, 0x000, 0x000 },
+	{ 0x100, 0x000, 0x100 },
+	{ 0x020, 0x400, 0x020 },
+	{ 0x010, 0x100, 0x010 },
+	{ 0x208, 0x040, 0x208 },
+	{ 0x104, 0x820, 0x108 },
+	{ 0x844, 0x210, 0x884 },
+	{ 0x444, 0x110, 0x444 },
+	{ 0x122, 0x888, 0x224 },
+	{ 0x912, 0x448, 0x924 },
+	{ 0x492, 0x248, 0x492 },
+	{ 0x252, 0x928, 0x292 },
+	{ 0x94a, 0x4a4, 0xa52 },
+	{ 0x52a, 0xaa4, 0x54a },
+	{ 0xaaa, 0x954, 0x4aa },
+	{ 0xaaa, 0x554, 0xaaa },
+	{ 0x555, 0xad4, 0x5aa },
+	{ 0xb55, 0xab4, 0x55a },
+	{ 0x6b5, 0x5ac, 0xb56 },
+	{ 0x5b5, 0xd6c, 0x6d6 },
+	{ 0xb6d, 0xb6a, 0xdb6 },
+	{ 0x76d, 0x6da, 0xbb6 },
+	{ 0xedd, 0xdda, 0x76e },
+	{ 0xddd, 0xbba, 0xeee },
+	{ 0x7bb, 0xf7a, 0xdde },
+	{ 0xf7b, 0xef6, 0x7de },
+	{ 0xdf7, 0xbf6, 0xf7e },
+	{ 0x7f7, 0xfee, 0xefe },
+	{ 0xfdf, 0xfbe, 0x7fe },
+	{ 0xf7f, 0xefe, 0xffe },
+	{ 0xfff, 0xffe, 0xffd },
+};
+
+static int xr_set_baudrate(struct tty_struct *tty,
+			   struct usb_serial_port *port)
+{
+	u32 divisor, baud, idx;
+	u16 tx_mask, rx_mask;
+	int ret;
+
+	baud = tty->termios.c_ospeed;
+	if (!baud)
+		return 0;
+
+	baud = clamp(baud, XR21V141X_MIN_SPEED, XR21V141X_MAX_SPEED);
+	divisor = XR_INT_OSC_HZ / baud;
+	idx = ((32 * XR_INT_OSC_HZ) / baud) & 0x1f;
+	tx_mask = xr21v141x_txrx_clk_masks[idx].tx;
+
+	if (divisor & 0x01)
+		rx_mask = xr21v141x_txrx_clk_masks[idx].rx1;
+	else
+		rx_mask = xr21v141x_txrx_clk_masks[idx].rx0;
+
+	dev_dbg(&port->dev, "Setting baud rate: %u\n", baud);
+	/*
+	 * XR21V141X uses fractional baud rate generator with 48MHz internal
+	 * oscillator and 19-bit programmable divisor. So theoretically it can
+	 * generate most commonly used baud rates with high accuracy.
+	 */
+	ret = xr_set_reg_uart(port, XR21V141X_CLOCK_DIVISOR_0,
+			      divisor & 0xff);
+	if (ret)
+		return ret;
+
+	ret = xr_set_reg_uart(port, XR21V141X_CLOCK_DIVISOR_1,
+			      (divisor >>  8) & 0xff);
+	if (ret)
+		return ret;
+
+	ret = xr_set_reg_uart(port, XR21V141X_CLOCK_DIVISOR_2,
+			      (divisor >> 16) & 0xff);
+	if (ret)
+		return ret;
+
+	ret = xr_set_reg_uart(port, XR21V141X_TX_CLOCK_MASK_0,
+			      tx_mask & 0xff);
+	if (ret)
+		return ret;
+
+	ret = xr_set_reg_uart(port, XR21V141X_TX_CLOCK_MASK_1,
+			      (tx_mask >>  8) & 0xff);
+	if (ret)
+		return ret;
+
+	ret = xr_set_reg_uart(port, XR21V141X_RX_CLOCK_MASK_0,
+			      rx_mask & 0xff);
+	if (ret)
+		return ret;
+
+	ret = xr_set_reg_uart(port, XR21V141X_RX_CLOCK_MASK_1,
+			      (rx_mask >>  8) & 0xff);
+	if (ret)
+		return ret;
+
+	tty_encode_baud_rate(tty, baud, baud);
+
+	return 0;
+}
+
+static void xr_set_flow_mode(struct tty_struct *tty,
+			     struct usb_serial_port *port,
+			     struct ktermios *old_termios)
+{
+	u8 flow, gpio_mode;
+	int ret;
+
+	ret = xr_get_reg_uart(port, XR21V141X_REG_GPIO_MODE, &gpio_mode);
+	if (ret)
+		return;
+
+	/* Set GPIO mode for controlling the pins manually by default. */
+	gpio_mode &= ~XR21V141X_UART_MODE_GPIO_MASK;
+
+	if (C_CRTSCTS(tty) && C_BAUD(tty) != B0) {
+		dev_dbg(&port->dev, "Enabling hardware flow ctrl\n");
+		gpio_mode |= XR21V141X_UART_MODE_RTS_CTS;
+		flow = XR21V141X_UART_FLOW_MODE_HW;
+	} else if (I_IXON(tty)) {
+		u8 start_char = START_CHAR(tty);
+		u8 stop_char = STOP_CHAR(tty);
+
+		dev_dbg(&port->dev, "Enabling sw flow ctrl\n");
+		flow = XR21V141X_UART_FLOW_MODE_SW;
+
+		xr_set_reg_uart(port, XR21V141X_REG_XON_CHAR, start_char);
+		xr_set_reg_uart(port, XR21V141X_REG_XOFF_CHAR, stop_char);
+	} else {
+		dev_dbg(&port->dev, "Disabling flow ctrl\n");
+		flow = XR21V141X_UART_FLOW_MODE_NONE;
+	}
+
+	/*
+	 * As per the datasheet, UART needs to be disabled while writing to
+	 * FLOW_CONTROL register.
+	 */
+	xr_uart_disable(port);
+	xr_set_reg_uart(port, XR21V141X_REG_FLOW_CTRL, flow);
+	xr_uart_enable(port);
+
+	xr_set_reg_uart(port, XR21V141X_REG_GPIO_MODE, gpio_mode);
+
+	if (C_BAUD(tty) == B0)
+		xr_dtr_rts(port, 0);
+	else if (old_termios && (old_termios->c_cflag & CBAUD) == B0)
+		xr_dtr_rts(port, 1);
+}
+
+static void xr_set_termios(struct tty_struct *tty,
+			   struct usb_serial_port *port,
+			   struct ktermios *old_termios)
+{
+	struct ktermios *termios = &tty->termios;
+	u8 bits = 0;
+	int ret;
+
+	if (!old_termios || (tty->termios.c_ospeed != old_termios->c_ospeed))
+		xr_set_baudrate(tty, port);
+
+	switch (C_CSIZE(tty)) {
+	case CS5:
+	case CS6:
+		/* CS5 and CS6 are not supported, so just restore old setting */
+		termios->c_cflag &= ~CSIZE;
+		if (old_termios)
+			termios->c_cflag |= old_termios->c_cflag & CSIZE;
+		else
+			bits |= XR21V141X_UART_DATA_8;
+		break;
+	case CS7:
+		bits |= XR21V141X_UART_DATA_7;
+		break;
+	case CS8:
+	default:
+		bits |= XR21V141X_UART_DATA_8;
+		break;
+	}
+
+	if (C_PARENB(tty)) {
+		if (C_CMSPAR(tty)) {
+			if (C_PARODD(tty))
+				bits |= XR21V141X_UART_PARITY_MARK;
+			else
+				bits |= XR21V141X_UART_PARITY_SPACE;
+		} else {
+			if (C_PARODD(tty))
+				bits |= XR21V141X_UART_PARITY_ODD;
+			else
+				bits |= XR21V141X_UART_PARITY_EVEN;
+		}
+	}
+
+	if (C_CSTOPB(tty))
+		bits |= XR21V141X_UART_STOP_2;
+	else
+		bits |= XR21V141X_UART_STOP_1;
+
+	ret = xr_set_reg_uart(port, XR21V141X_REG_FORMAT, bits);
+	if (ret)
+		return;
+
+	xr_set_flow_mode(tty, port, old_termios);
+}
+
+static int xr_open(struct tty_struct *tty, struct usb_serial_port *port)
+{
+	u8 gpio_dir;
+	int ret;
+
+	ret = xr_uart_enable(port);
+	if (ret) {
+		dev_err(&port->dev, "Failed to enable UART\n");
+		return ret;
+	}
+
+	/*
+	 * Configure DTR and RTS as outputs and RI, CD, DSR and CTS as
+	 * inputs.
+	 */
+	gpio_dir = XR21V141X_UART_MODE_DTR | XR21V141X_UART_MODE_RTS;
+	xr_set_reg_uart(port, XR21V141X_REG_GPIO_DIR, gpio_dir);
+
+	/* Setup termios */
+	if (tty)
+		xr_set_termios(tty, port, NULL);
+
+	ret = usb_serial_generic_open(tty, port);
+	if (ret) {
+		xr_uart_disable(port);
+		return ret;
+	}
+
+	return 0;
+}
+
+static void xr_close(struct usb_serial_port *port)
+{
+	usb_serial_generic_close(port);
+
+	xr_uart_disable(port);
+}
+
+static int xr_probe(struct usb_serial *serial, const struct usb_device_id *id)
+{
+	struct usb_driver *driver = serial->type->usb_driver;
+	struct usb_interface *control_interface;
+	int ret;
+
+	/* Don't bind to control interface */
+	if (serial->interface->cur_altsetting->desc.bInterfaceNumber == 0)
+		return -ENODEV;
+
+	/* But claim the control interface during data interface probe */
+	control_interface = usb_ifnum_to_if(serial->dev, 0);
+	if (!control_interface)
+		return -ENODEV;
+
+	ret = usb_driver_claim_interface(driver, control_interface, NULL);
+	if (ret) {
+		dev_err(&serial->interface->dev, "Failed to claim control interface\n");
+		return ret;
+	}
+
+	return 0;
+}
+
+static void xr_disconnect(struct usb_serial *serial)
+{
+	struct usb_driver *driver = serial->type->usb_driver;
+	struct usb_interface *control_interface;
+
+	control_interface = usb_ifnum_to_if(serial->dev, 0);
+	usb_driver_release_interface(driver, control_interface);
+}
+
+static const struct usb_device_id id_table[] = {
+	{ USB_DEVICE(0x04e2, 0x1410) }, /* XR21V141X */
+	{ }
+};
+MODULE_DEVICE_TABLE(usb, id_table);
+
+static struct usb_serial_driver xr_device = {
+	.driver = {
+		.owner = THIS_MODULE,
+		.name =	"xr_serial",
+	},
+	.id_table		= id_table,
+	.num_ports		= 1,
+	.probe			= xr_probe,
+	.disconnect		= xr_disconnect,
+	.open			= xr_open,
+	.close			= xr_close,
+	.break_ctl		= xr_break_ctl,
+	.set_termios		= xr_set_termios,
+	.tiocmget		= xr_tiocmget,
+	.tiocmset		= xr_tiocmset,
+	.dtr_rts		= xr_dtr_rts
+};
+
+static struct usb_serial_driver * const serial_drivers[] = {
+	&xr_device, NULL
+};
+
+module_usb_serial_driver(serial_drivers, id_table);
+
+MODULE_AUTHOR("Manivannan Sadhasivam <mani@kernel.org>");
+MODULE_DESCRIPTION("MaxLinear/Exar USB to Serial driver");
+MODULE_LICENSE("GPL");
diff --git a/include/linux/usb/serial.h b/include/linux/usb/serial.h
index 1c09b922f8b0..952272002e48 100644
--- a/include/linux/usb/serial.h
+++ b/include/linux/usb/serial.h
@@ -260,7 +260,7 @@ struct usb_serial_driver {
 	void (*release)(struct usb_serial *serial);
 
 	int (*port_probe)(struct usb_serial_port *port);
-	int (*port_remove)(struct usb_serial_port *port);
+	void (*port_remove)(struct usb_serial_port *port);
 
 	int (*suspend)(struct usb_serial *serial, pm_message_t message);
 	int (*resume)(struct usb_serial *serial);