Merge tag 'usb-5.12-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb

Pull USB and Thunderbolt updates from Greg KH:
 "Here is the big set of USB and Thunderbolt driver changes for
  5.12-rc1.

  It's been an active set of development in these subsystems for the
  past few months:

   - loads of typec features added for new hardware

   - xhci features and bugfixes

   - dwc3 features added for more hardware support

   - dwc2 fixes and new hardware support

   - cdns3 driver updates for more hardware support

   - gadget driver cleanups and minor fixes

   - usb-serial fixes, new driver, and more devices supported

   - thunderbolt feature additions for new hardware

   - lots of other tiny fixups and additions

  The chrome driver changes are in here as well, as they depended on
  some of the typec changes, and the maintainer acked them.

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

* tag 'usb-5.12-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb: (300 commits)
  dt-bindings: usb: mediatek: musb: add mt8516 compatbile
  dt-bindings: usb: mtk-xhci: add compatible for mt2701 and mt7623
  dt-bindings: usb: mtk-xhci: add optional assigned clock properties
  Documentation: connector: Update the description of sink-vdos
  usb: misc: usb3503: Fix logic in usb3503_init()
  dt-bindings: usb: usb-device: fix typo in required properties
  usb: Replace lkml.org links with lore
  dt-bindings: usb: dwc3: add description for rk3328
  dt-bindings: usb: convert rockchip,dwc3.txt to yaml
  usb: quirks: add quirk to start video capture on ELMO L-12F document camera reliable
  USB: quirks: sort quirk entries
  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: gadget: Assign boolean values to a bool variable
  usb: typec: tcpm: Get Sink VDO from fwnode
  dt-bindings: connector: Add SVDM VDO properties
  usb: typec: displayport: Fill the negotiated SVDM Version in the header
  usb: typec: ucsi: Determine common SVDM Version
  usb: typec: tcpm: Determine common SVDM Version
  ...

42 files changed, 885 insertions, 227 deletions

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..b9bedfe9bd09 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,
@@ -719,9 +717,10 @@ MODULE_DESCRIPTION(DRIVER_DESC);
  * hardware bug or something.
  *
  * According to a patch provided here
- * (http://lkml.org/lkml/2009/7/26/56), the ARK3116 can also be used
- * as an IrDA dongle. Since I do not have such a thing, I could not
- * investigate that aspect. However, I can speculate ;-).
+ * https://lore.kernel.org/lkml/200907261419.50702.linux@rainbow-software.org
+ * the ARK3116 can also be used as an IrDA dongle. Since I do not have
+ * such a thing, I could not investigate that aspect. However, I can
+ * speculate ;-).
  *
  * - IrDA encodes data differently than RS232. Most likely, one of
  *   the bits in registers 9..E enables the IR ENDEC (encoder/decoder).
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");