Merge tag 'usb-serial-5.9-rc1' of https://git.kernel.org/pub/scm/linux/kernel/git/johan/usb-serial into usb-next

Johan writes:

USB-serial updates for 5.9-rc1

Here are the USB-serial updates for 5.9-rc1, including:

 - console flow-control support
 - simulated line-breaks on some ch341
 - hardware flow-control fixes for cp210x
 - break-detection and sysrq fixes for ftdi_sio
 - sysrq optimisations
 - input parity checking for cp210x

Included are also some new device ids and various clean ups.

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

* tag 'usb-serial-5.9-rc1' of https://git.kernel.org/pub/scm/linux/kernel/git/johan/usb-serial: (31 commits)
  USB: serial: qcserial: add EM7305 QDL product ID
  USB: serial: iuu_phoenix: fix led-activity helpers
  USB: serial: sierra: clean up special-interface handling
  USB: serial: cp210x: use in-kernel types in port data
  USB: serial: cp210x: drop unnecessary packed attributes
  USB: serial: cp210x: add support for TIOCGICOUNT
  USB: serial: cp210x: add support for line-status events
  USB: serial: cp210x: disable interface on errors in open
  USB: serial: drop redundant transfer-buffer casts
  USB: serial: drop extern keyword from function declarations
  USB: serial: drop unnecessary sysrq include
  USB: serial: add sysrq break-handler dummy
  USB: serial: inline sysrq dummy function
  USB: serial: only process sysrq when enabled
  USB: serial: only set sysrq timestamp for consoles
  USB: serial: ftdi_sio: fix break and sysrq handling
  USB: serial: ftdi_sio: clean up receive processing
  USB: serial: ftdi_sio: make process-packet buffer unsigned
  USB: serial: use fallthrough pseudo-keyword
  USB: serial: ch341: fix missing simulated-break margin
  ...

22 files changed, 459 insertions, 146 deletions

diff --git a/drivers/usb/serial/aircable.c b/drivers/usb/serial/aircable.c
index 84d52953dd0a..a1df686c3066 100644
--- a/drivers/usb/serial/aircable.c
+++ b/drivers/usb/serial/aircable.c
@@ -117,7 +117,7 @@ static int aircable_process_packet(struct usb_serial_port *port,
 static void aircable_process_read_urb(struct urb *urb)
 {
 	struct usb_serial_port *port = urb->context;
-	char *data = (char *)urb->transfer_buffer;
+	char *data = urb->transfer_buffer;
 	int has_headers;
 	int count;
 	int len;
diff --git a/drivers/usb/serial/ch341.c b/drivers/usb/serial/ch341.c
index 8fbaef5c9d69..a2e2f56c88cd 100644
--- a/drivers/usb/serial/ch341.c
+++ b/drivers/usb/serial/ch341.c
@@ -59,7 +59,11 @@
 #define CH341_REQ_MODEM_CTRL   0xA4
 
 #define CH341_REG_BREAK        0x05
+#define CH341_REG_PRESCALER    0x12
+#define CH341_REG_DIVISOR      0x13
 #define CH341_REG_LCR          0x18
+#define CH341_REG_LCR2         0x25
+
 #define CH341_NBREAK_BITS      0x01
 
 #define CH341_LCR_ENABLE_RX    0x80
@@ -74,6 +78,7 @@
 #define CH341_LCR_CS5          0x00
 
 #define CH341_QUIRK_LIMITED_PRESCALER	BIT(0)
+#define CH341_QUIRK_SIMULATE_BREAK	BIT(1)
 
 static const struct usb_device_id id_table[] = {
 	{ USB_DEVICE(0x4348, 0x5523) },
@@ -91,6 +96,7 @@ struct ch341_private {
 	u8 msr;
 	u8 lcr;
 	unsigned long quirks;
+	unsigned long break_end;
 };
 
 static void ch341_set_termios(struct tty_struct *tty,
@@ -153,6 +159,10 @@ static const speed_t ch341_min_rates[] = {
 	CH341_MIN_RATE(3),
 };
 
+/* Supported range is 46 to 3000000 bps. */
+#define CH341_MIN_BPS	DIV_ROUND_UP(CH341_CLKRATE, CH341_CLK_DIV(0, 0) * 256)
+#define CH341_MAX_BPS	(CH341_CLKRATE / (CH341_CLK_DIV(3, 0) * 2))
+
 /*
  * The device line speed is given by the following equation:
  *
@@ -163,10 +173,9 @@ static const speed_t ch341_min_rates[] = {
  *		2 <= div <= 256 if fact = 0, or
  *		9 <= div <= 256 if fact = 1
  */
-static int ch341_get_divisor(struct ch341_private *priv)
+static int ch341_get_divisor(struct ch341_private *priv, speed_t speed)
 {
 	unsigned int fact, div, clk_div;
-	speed_t speed = priv->baud_rate;
 	bool force_fact0 = false;
 	int ps;
 
@@ -174,7 +183,7 @@ static int ch341_get_divisor(struct ch341_private *priv)
 	 * Clamp to supported range, this makes the (ps < 0) and (div < 2)
 	 * sanity checks below redundant.
 	 */
-	speed = clamp(speed, 46U, 3000000U);
+	speed = clamp_val(speed, CH341_MIN_BPS, CH341_MAX_BPS);
 
 	/*
 	 * Start with highest possible base clock (fact = 1) that will give a
@@ -229,15 +238,16 @@ static int ch341_get_divisor(struct ch341_private *priv)
 }
 
 static int ch341_set_baudrate_lcr(struct usb_device *dev,
-				  struct ch341_private *priv, u8 lcr)
+				  struct ch341_private *priv,
+				  speed_t baud_rate, u8 lcr)
 {
 	int val;
 	int r;
 
-	if (!priv->baud_rate)
+	if (!baud_rate)
 		return -EINVAL;
 
-	val = ch341_get_divisor(priv);
+	val = ch341_get_divisor(priv, baud_rate);
 	if (val < 0)
 		return -EINVAL;
 
@@ -247,11 +257,20 @@ static int ch341_set_baudrate_lcr(struct usb_device *dev,
 	 */
 	val |= BIT(7);
 
-	r = ch341_control_out(dev, CH341_REQ_WRITE_REG, 0x1312, val);
+	r = ch341_control_out(dev, CH341_REQ_WRITE_REG,
+			      CH341_REG_DIVISOR << 8 | CH341_REG_PRESCALER,
+			      val);
 	if (r)
 		return r;
 
-	r = ch341_control_out(dev, CH341_REQ_WRITE_REG, 0x2518, lcr);
+	/*
+	 * Chip versions before version 0x30 as read using
+	 * CH341_REQ_READ_VERSION used separate registers for line control
+	 * (stop bits, parity and word length). Version 0x30 and above use
+	 * CH341_REG_LCR only and CH341_REG_LCR2 is always set to zero.
+	 */
+	r = ch341_control_out(dev, CH341_REQ_WRITE_REG,
+			      CH341_REG_LCR2 << 8 | CH341_REG_LCR, lcr);
 	if (r)
 		return r;
 
@@ -308,7 +327,7 @@ static int ch341_configure(struct usb_device *dev, struct ch341_private *priv)
 	if (r < 0)
 		goto out;
 
-	r = ch341_set_baudrate_lcr(dev, priv, priv->lcr);
+	r = ch341_set_baudrate_lcr(dev, priv, priv->baud_rate, priv->lcr);
 	if (r < 0)
 		goto out;
 
@@ -341,8 +360,8 @@ static int ch341_detect_quirks(struct usb_serial_port *port)
 			    USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_IN,
 			    CH341_REG_BREAK, 0, buffer, size, DEFAULT_TIMEOUT);
 	if (r == -EPIPE) {
-		dev_dbg(&port->dev, "break control not supported\n");
-		quirks = CH341_QUIRK_LIMITED_PRESCALER;
+		dev_info(&port->dev, "break control not supported, using simulated break\n");
+		quirks = CH341_QUIRK_LIMITED_PRESCALER | CH341_QUIRK_SIMULATE_BREAK;
 		r = 0;
 		goto out;
 	}
@@ -523,7 +542,8 @@ static void ch341_set_termios(struct tty_struct *tty,
 	if (baud_rate) {
 		priv->baud_rate = baud_rate;
 
-		r = ch341_set_baudrate_lcr(port->serial->dev, priv, lcr);
+		r = ch341_set_baudrate_lcr(port->serial->dev, priv,
+					   priv->baud_rate, lcr);
 		if (r < 0 && old_termios) {
 			priv->baud_rate = tty_termios_baud_rate(old_termios);
 			tty_termios_copy_hw(&tty->termios, old_termios);
@@ -542,15 +562,98 @@ static void ch341_set_termios(struct tty_struct *tty,
 	ch341_set_handshake(port->serial->dev, priv->mcr);
 }
 
+/*
+ * A subset of all CH34x devices don't support a real break condition and
+ * reading CH341_REG_BREAK fails (see also ch341_detect_quirks). This function
+ * simulates a break condition by lowering the baud rate to the minimum
+ * supported by the hardware upon enabling the break condition and sending
+ * a NUL byte.
+ *
+ * Incoming data is corrupted while the break condition is being simulated.
+ *
+ * Normally the duration of the break condition can be controlled individually
+ * by userspace using TIOCSBRK and TIOCCBRK or by passing an argument to
+ * TCSBRKP. Due to how the simulation is implemented the duration can't be
+ * controlled. The duration is always about (1s / 46bd * 9bit) = 196ms.
+ */
+static void ch341_simulate_break(struct tty_struct *tty, int break_state)
+{
+	struct usb_serial_port *port = tty->driver_data;
+	struct ch341_private *priv = usb_get_serial_port_data(port);
+	unsigned long now, delay;
+	int r;
+
+	if (break_state != 0) {
+		dev_dbg(&port->dev, "enter break state requested\n");
+
+		r = ch341_set_baudrate_lcr(port->serial->dev, priv,
+				CH341_MIN_BPS,
+				CH341_LCR_ENABLE_RX | CH341_LCR_ENABLE_TX | CH341_LCR_CS8);
+		if (r < 0) {
+			dev_err(&port->dev,
+				"failed to change baud rate to %u: %d\n",
+				CH341_MIN_BPS, r);
+			goto restore;
+		}
+
+		r = tty_put_char(tty, '\0');
+		if (r < 0) {
+			dev_err(&port->dev,
+				"failed to write NUL byte for simulated break condition: %d\n",
+				r);
+			goto restore;
+		}
+
+		/*
+		 * Compute expected transmission duration including safety
+		 * margin. The original baud rate is only restored after the
+		 * computed point in time.
+		 *
+		 * 11 bits = 1 start, 8 data, 1 stop, 1 margin
+		 */
+		priv->break_end = jiffies + (11 * HZ / CH341_MIN_BPS);
+
+		return;
+	}
+
+	dev_dbg(&port->dev, "leave break state requested\n");
+
+	now = jiffies;
+
+	if (time_before(now, priv->break_end)) {
+		/* Wait until NUL byte is written */
+		delay = priv->break_end - now;
+		dev_dbg(&port->dev,
+			"wait %d ms while transmitting NUL byte at %u baud\n",
+			jiffies_to_msecs(delay), CH341_MIN_BPS);
+		schedule_timeout_interruptible(delay);
+	}
+
+restore:
+	/* Restore original baud rate */
+	r = ch341_set_baudrate_lcr(port->serial->dev, priv, priv->baud_rate,
+				   priv->lcr);
+	if (r < 0)
+		dev_err(&port->dev,
+			"restoring original baud rate of %u failed: %d\n",
+			priv->baud_rate, r);
+}
+
 static void ch341_break_ctl(struct tty_struct *tty, int break_state)
 {
 	const uint16_t ch341_break_reg =
 			((uint16_t) CH341_REG_LCR << 8) | CH341_REG_BREAK;
 	struct usb_serial_port *port = tty->driver_data;
+	struct ch341_private *priv = usb_get_serial_port_data(port);
 	int r;
 	uint16_t reg_contents;
 	uint8_t *break_reg;
 
+	if (priv->quirks & CH341_QUIRK_SIMULATE_BREAK) {
+		ch341_simulate_break(tty, break_state);
+		return;
+	}
+
 	break_reg = kmalloc(2, GFP_KERNEL);
 	if (!break_reg)
 		return;
diff --git a/drivers/usb/serial/console.c b/drivers/usb/serial/console.c
index 7d289302ff6c..b97aa40ca4d1 100644
--- a/drivers/usb/serial/console.c
+++ b/drivers/usb/serial/console.c
@@ -79,7 +79,7 @@ static int usb_console_setup(struct console *co, char *options)
 		if (*s)
 			doflow = (*s++ == 'r');
 	}
-	
+
 	/* Sane default */
 	if (baud == 0)
 		baud = 9600;
@@ -102,6 +102,9 @@ static int usb_console_setup(struct console *co, char *options)
 		break;
 	}
 
+	if (doflow)
+		cflag |= CRTSCTS;
+
 	/*
 	 * no need to check the index here: if the index is wrong, console
 	 * code won't call us
diff --git a/drivers/usb/serial/cp210x.c b/drivers/usb/serial/cp210x.c
index f5143eedbc48..d0c05aa8a0d6 100644
--- a/drivers/usb/serial/cp210x.c
+++ b/drivers/usb/serial/cp210x.c
@@ -50,6 +50,9 @@ 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_dtr_rts(struct usb_serial_port *p, int on);
+static void cp210x_process_read_urb(struct urb *urb);
+static void cp210x_enable_event_mode(struct usb_serial_port *port);
+static void cp210x_disable_event_mode(struct usb_serial_port *port);
 
 static const struct usb_device_id id_table[] = {
 	{ USB_DEVICE(0x045B, 0x0053) }, /* Renesas RX610 RX-Stick */
@@ -253,9 +256,21 @@ struct cp210x_serial_private {
 	bool			use_actual_rate;
 };
 
+enum cp210x_event_state {
+	ES_DATA,
+	ES_ESCAPE,
+	ES_LSR,
+	ES_LSR_DATA_0,
+	ES_LSR_DATA_1,
+	ES_MSR
+};
+
 struct cp210x_port_private {
-	__u8			bInterfaceNumber;
+	u8			bInterfaceNumber;
 	bool			has_swapped_line_ctl;
+	bool			event_mode;
+	enum cp210x_event_state event_state;
+	u8 lsr;
 };
 
 static struct usb_serial_driver cp210x_device = {
@@ -272,14 +287,18 @@ static struct usb_serial_driver cp210x_device = {
 	.break_ctl		= cp210x_break_ctl,
 	.set_termios		= cp210x_set_termios,
 	.tx_empty		= cp210x_tx_empty,
+	.throttle		= usb_serial_generic_throttle,
+	.unthrottle		= usb_serial_generic_unthrottle,
 	.tiocmget		= cp210x_tiocmget,
 	.tiocmset		= cp210x_tiocmset,
+	.get_icount		= usb_serial_generic_get_icount,
 	.attach			= cp210x_attach,
 	.disconnect		= cp210x_disconnect,
 	.release		= cp210x_release,
 	.port_probe		= cp210x_port_probe,
 	.port_remove		= cp210x_port_remove,
-	.dtr_rts		= cp210x_dtr_rts
+	.dtr_rts		= cp210x_dtr_rts,
+	.process_read_urb	= cp210x_process_read_urb,
 };
 
 static struct usb_serial_driver * const serial_drivers[] = {
@@ -401,13 +420,22 @@ struct cp210x_comm_status {
  */
 #define PURGE_ALL		0x000f
 
+/* CP210X_EMBED_EVENTS */
+#define CP210X_ESCCHAR		0xec
+
+#define CP210X_LSR_OVERRUN	BIT(1)
+#define CP210X_LSR_PARITY	BIT(2)
+#define CP210X_LSR_FRAME	BIT(3)
+#define CP210X_LSR_BREAK	BIT(4)
+
+
 /* CP210X_GET_FLOW/CP210X_SET_FLOW read/write these 0x10 bytes */
 struct cp210x_flow_ctl {
 	__le32	ulControlHandshake;
 	__le32	ulFlowReplace;
 	__le32	ulXonLimit;
 	__le32	ulXoffLimit;
-} __packed;
+};
 
 /* cp210x_flow_ctl::ulControlHandshake */
 #define CP210X_SERIAL_DTR_MASK		GENMASK(1, 0)
@@ -441,7 +469,7 @@ struct cp210x_flow_ctl {
 struct cp210x_pin_mode {
 	u8	eci;
 	u8	sci;
-} __packed;
+};
 
 #define CP210X_PIN_MODE_MODEM		0
 #define CP210X_PIN_MODE_GPIO		BIT(0)
@@ -504,7 +532,7 @@ struct cp210x_single_port_config {
 struct cp210x_gpio_write {
 	u8	mask;
 	u8	state;
-} __packed;
+};
 
 /*
  * Helper to get interface number when we only have struct usb_serial.
@@ -807,6 +835,7 @@ static int cp210x_get_line_ctl(struct usb_serial_port *port, u16 *ctl)
 
 static int cp210x_open(struct tty_struct *tty, struct usb_serial_port *port)
 {
+	struct cp210x_port_private *port_priv = usb_get_serial_port_data(port);
 	int result;
 
 	result = cp210x_write_u16_reg(port, CP210X_IFC_ENABLE, UART_ENABLE);
@@ -818,21 +847,144 @@ static int cp210x_open(struct tty_struct *tty, struct usb_serial_port *port)
 	/* Configure the termios structure */
 	cp210x_get_termios(tty, port);
 
-	/* The baud rate must be initialised on cp2104 */
-	if (tty)
+	if (tty) {
+		/* The baud rate must be initialised on cp2104 */
 		cp210x_change_speed(tty, port, NULL);
 
-	return usb_serial_generic_open(tty, port);
+		if (I_INPCK(tty))
+			cp210x_enable_event_mode(port);
+	}
+
+	result = usb_serial_generic_open(tty, port);
+	if (result)
+		goto err_disable;
+
+	return 0;
+
+err_disable:
+	cp210x_write_u16_reg(port, CP210X_IFC_ENABLE, UART_DISABLE);
+	port_priv->event_mode = false;
+
+	return result;
 }
 
 static void cp210x_close(struct usb_serial_port *port)
 {
+	struct cp210x_port_private *port_priv = usb_get_serial_port_data(port);
+
 	usb_serial_generic_close(port);
 
 	/* Clear both queues; cp2108 needs this to avoid an occasional hang */
 	cp210x_write_u16_reg(port, CP210X_PURGE, PURGE_ALL);
 
 	cp210x_write_u16_reg(port, CP210X_IFC_ENABLE, UART_DISABLE);
+
+	/* Disabling the interface disables event-insertion mode. */
+	port_priv->event_mode = false;
+}
+
+static void cp210x_process_lsr(struct usb_serial_port *port, unsigned char lsr, char *flag)
+{
+	if (lsr & CP210X_LSR_BREAK) {
+		port->icount.brk++;
+		*flag = TTY_BREAK;
+	} else if (lsr & CP210X_LSR_PARITY) {
+		port->icount.parity++;
+		*flag = TTY_PARITY;
+	} else if (lsr & CP210X_LSR_FRAME) {
+		port->icount.frame++;
+		*flag = TTY_FRAME;
+	}
+
+	if (lsr & CP210X_LSR_OVERRUN) {
+		port->icount.overrun++;
+		tty_insert_flip_char(&port->port, 0, TTY_OVERRUN);
+	}
+}
+
+static bool cp210x_process_char(struct usb_serial_port *port, unsigned char *ch, char *flag)
+{
+	struct cp210x_port_private *port_priv = usb_get_serial_port_data(port);
+
+	switch (port_priv->event_state) {
+	case ES_DATA:
+		if (*ch == CP210X_ESCCHAR) {
+			port_priv->event_state = ES_ESCAPE;
+			break;
+		}
+		return false;
+	case ES_ESCAPE:
+		switch (*ch) {
+		case 0:
+			dev_dbg(&port->dev, "%s - escape char\n", __func__);
+			*ch = CP210X_ESCCHAR;
+			port_priv->event_state = ES_DATA;
+			return false;
+		case 1:
+			port_priv->event_state = ES_LSR_DATA_0;
+			break;
+		case 2:
+			port_priv->event_state = ES_LSR;
+			break;
+		case 3:
+			port_priv->event_state = ES_MSR;
+			break;
+		default:
+			dev_err(&port->dev, "malformed event 0x%02x\n", *ch);
+			port_priv->event_state = ES_DATA;
+			break;
+		}
+		break;
+	case ES_LSR_DATA_0:
+		port_priv->lsr = *ch;
+		port_priv->event_state = ES_LSR_DATA_1;
+		break;
+	case ES_LSR_DATA_1:
+		dev_dbg(&port->dev, "%s - lsr = 0x%02x, data = 0x%02x\n",
+				__func__, port_priv->lsr, *ch);
+		cp210x_process_lsr(port, port_priv->lsr, flag);
+		port_priv->event_state = ES_DATA;
+		return false;
+	case ES_LSR:
+		dev_dbg(&port->dev, "%s - lsr = 0x%02x\n", __func__, *ch);
+		port_priv->lsr = *ch;
+		cp210x_process_lsr(port, port_priv->lsr, flag);
+		port_priv->event_state = ES_DATA;
+		break;
+	case ES_MSR:
+		dev_dbg(&port->dev, "%s - msr = 0x%02x\n", __func__, *ch);
+		/* unimplemented */
+		port_priv->event_state = ES_DATA;
+		break;
+	}
+
+	return true;
+}
+
+static void cp210x_process_read_urb(struct urb *urb)
+{
+	struct usb_serial_port *port = urb->context;
+	struct cp210x_port_private *port_priv = usb_get_serial_port_data(port);
+	unsigned char *ch = urb->transfer_buffer;
+	char flag;
+	int i;
+
+	if (!urb->actual_length)
+		return;
+
+	if (port_priv->event_mode) {
+		for (i = 0; i < urb->actual_length; i++, ch++) {
+			flag = TTY_NORMAL;
+
+			if (cp210x_process_char(port, ch, &flag))
+				continue;
+
+			tty_insert_flip_char(&port->port, *ch, flag);
+		}
+	} else {
+		tty_insert_flip_string(&port->port, ch, urb->actual_length);
+	}
+	tty_flip_buffer_push(&port->port);
 }
 
 /*
@@ -915,6 +1067,7 @@ static void cp210x_get_termios_port(struct usb_serial_port *port,
 	u32 baud;
 	u16 bits;
 	u32 ctl_hs;
+	u32 flow_repl;
 
 	cp210x_read_u32_reg(port, CP210X_GET_BAUDRATE, &baud);
 
@@ -1015,6 +1168,22 @@ static void cp210x_get_termios_port(struct usb_serial_port *port,
 	ctl_hs = le32_to_cpu(flow_ctl.ulControlHandshake);
 	if (ctl_hs & CP210X_SERIAL_CTS_HANDSHAKE) {
 		dev_dbg(dev, "%s - flow control = CRTSCTS\n", __func__);
+		/*
+		 * When the port is closed, the CP210x hardware disables
+		 * auto-RTS and RTS is deasserted but it leaves auto-CTS when
+		 * in hardware flow control mode. When re-opening the port, if
+		 * auto-CTS is enabled on the cp210x, then auto-RTS must be
+		 * re-enabled in the driver.
+		 */
+		flow_repl = le32_to_cpu(flow_ctl.ulFlowReplace);
+		flow_repl &= ~CP210X_SERIAL_RTS_MASK;
+		flow_repl |= CP210X_SERIAL_RTS_SHIFT(CP210X_SERIAL_RTS_FLOW_CTL);
+		flow_ctl.ulFlowReplace = cpu_to_le32(flow_repl);
+		cp210x_write_reg_block(port,
+				CP210X_SET_FLOW,
+				&flow_ctl,
+				sizeof(flow_ctl));
+
 		cflag |= CRTSCTS;
 	} else {
 		dev_dbg(dev, "%s - flow control = NONE\n", __func__);
@@ -1148,6 +1317,41 @@ static void cp210x_change_speed(struct tty_struct *tty,
 	tty_encode_baud_rate(tty, baud, baud);
 }
 
+static void cp210x_enable_event_mode(struct usb_serial_port *port)
+{
+	struct cp210x_port_private *port_priv = usb_get_serial_port_data(port);
+	int ret;
+
+	if (port_priv->event_mode)
+		return;
+
+	port_priv->event_state = ES_DATA;
+	port_priv->event_mode = true;
+
+	ret = cp210x_write_u16_reg(port, CP210X_EMBED_EVENTS, CP210X_ESCCHAR);
+	if (ret) {
+		dev_err(&port->dev, "failed to enable events: %d\n", ret);
+		port_priv->event_mode = false;
+	}
+}
+
+static void cp210x_disable_event_mode(struct usb_serial_port *port)
+{
+	struct cp210x_port_private *port_priv = usb_get_serial_port_data(port);
+	int ret;
+
+	if (!port_priv->event_mode)
+		return;
+
+	ret = cp210x_write_u16_reg(port, CP210X_EMBED_EVENTS, 0);
+	if (ret) {
+		dev_err(&port->dev, "failed to disable events: %d\n", ret);
+		return;
+	}
+
+	port_priv->event_mode = false;
+}
+
 static void cp210x_set_termios(struct tty_struct *tty,
 		struct usb_serial_port *port, struct ktermios *old_termios)
 {
@@ -1270,6 +1474,14 @@ static void cp210x_set_termios(struct tty_struct *tty,
 				sizeof(flow_ctl));
 	}
 
+	/*
+	 * Enable event-insertion mode only if input parity checking is
+	 * enabled for now.
+	 */
+	if (I_INPCK(tty))
+		cp210x_enable_event_mode(port);
+	else
+		cp210x_disable_event_mode(port);
 }
 
 static int cp210x_tiocmset(struct tty_struct *tty,
diff --git a/drivers/usb/serial/cypress_m8.c b/drivers/usb/serial/cypress_m8.c
index ecda82198798..cc028601c388 100644
--- a/drivers/usb/serial/cypress_m8.c
+++ b/drivers/usb/serial/cypress_m8.c
@@ -1048,7 +1048,7 @@ static void cypress_read_int_callback(struct urb *urb)
 		return;
 	case -EPIPE:
 		/* Can't call usb_clear_halt while in_interrupt */
-		/* FALLS THROUGH */
+		fallthrough;
 	default:
 		/* something ugly is going on... */
 		dev_err(dev, "%s - unexpected nonzero read status received: %d\n",
@@ -1197,7 +1197,7 @@ static void cypress_write_int_callback(struct urb *urb)
 		return;
 	case -EPIPE:
 		/* Cannot call usb_clear_halt while in_interrupt */
-		/* FALLTHROUGH */
+		fallthrough;
 	default:
 		dev_err(dev, "%s - unexpected nonzero write status received: %d\n",
 			__func__, status);
diff --git a/drivers/usb/serial/f81232.c b/drivers/usb/serial/f81232.c
index dcda7fb164b4..0c7eacc630e0 100644
--- a/drivers/usb/serial/f81232.c
+++ b/drivers/usb/serial/f81232.c
@@ -424,7 +424,7 @@ static void f81232_process_read_urb(struct urb *urb)
 		lsr = data[i];
 		tty_flag = f81232_handle_lsr(port, lsr);
 
-		if (port->port.console && port->sysrq) {
+		if (port->sysrq) {
 			if (usb_serial_handle_sysrq_char(port, data[i + 1]))
 				continue;
 		}
@@ -461,7 +461,7 @@ static void f81534a_process_read_urb(struct urb *urb)
 	lsr = data[len - 1];
 	tty_flag = f81232_handle_lsr(port, lsr);
 
-	if (port->port.console && port->sysrq) {
+	if (port->sysrq) {
 		for (i = 1; i < len - 1; ++i) {
 			if (!usb_serial_handle_sysrq_char(port, data[i])) {
 				tty_insert_flip_char(&port->port, data[i],
diff --git a/drivers/usb/serial/f81534.c b/drivers/usb/serial/f81534.c
index 2b39bda035c7..5661fd03e545 100644
--- a/drivers/usb/serial/f81534.c
+++ b/drivers/usb/serial/f81534.c
@@ -1238,7 +1238,7 @@ static void f81534_process_per_serial_block(struct usb_serial_port *port,
 			schedule_work(&port_priv->lsr_work);
 		}
 
-		if (port->port.console && port->sysrq) {
+		if (port->sysrq) {
 			if (usb_serial_handle_sysrq_char(port, data[i]))
 				continue;
 		}
diff --git a/drivers/usb/serial/ftdi_sio.c b/drivers/usb/serial/ftdi_sio.c
index 9ad44a96dfe3..871cdccf3a5f 100644
--- a/drivers/usb/serial/ftdi_sio.c
+++ b/drivers/usb/serial/ftdi_sio.c
@@ -2480,12 +2480,12 @@ static int ftdi_prepare_write_buffer(struct usb_serial_port *port,
 #define FTDI_RS_ERR_MASK (FTDI_RS_BI | FTDI_RS_PE | FTDI_RS_FE | FTDI_RS_OE)
 
 static int ftdi_process_packet(struct usb_serial_port *port,
-		struct ftdi_private *priv, char *packet, int len)
+		struct ftdi_private *priv, unsigned char *buf, int len)
 {
+	unsigned char status;
+	bool brkint = false;
 	int i;
-	char status;
 	char flag;
-	char *ch;
 
 	if (len < 2) {
 		dev_dbg(&port->dev, "malformed packet\n");
@@ -2495,7 +2495,7 @@ static int ftdi_process_packet(struct usb_serial_port *port,
 	/* Compare new line status to the old one, signal if different/
 	   N.B. packet may be processed more than once, but differences
 	   are only processed once.  */
-	status = packet[0] & FTDI_STATUS_B0_MASK;
+	status = buf[0] & FTDI_STATUS_B0_MASK;
 	if (status != priv->prev_status) {
 		char diff_status = status ^ priv->prev_status;
 
@@ -2521,13 +2521,12 @@ static int ftdi_process_packet(struct usb_serial_port *port,
 	}
 
 	/* save if the transmitter is empty or not */
-	if (packet[1] & FTDI_RS_TEMT)
+	if (buf[1] & FTDI_RS_TEMT)
 		priv->transmit_empty = 1;
 	else
 		priv->transmit_empty = 0;
 
-	len -= 2;
-	if (!len)
+	if (len == 2)
 		return 0;	/* status only */
 
 	/*
@@ -2535,47 +2534,57 @@ static int ftdi_process_packet(struct usb_serial_port *port,
 	 * data payload to avoid over-reporting.
 	 */
 	flag = TTY_NORMAL;
-	if (packet[1] & FTDI_RS_ERR_MASK) {
-		/* Break takes precedence over parity, which takes precedence
-		 * over framing errors */
-		if (packet[1] & FTDI_RS_BI) {
-			flag = TTY_BREAK;
+	if (buf[1] & FTDI_RS_ERR_MASK) {
+		/*
+		 * Break takes precedence over parity, which takes precedence
+		 * over framing errors. Note that break is only associated
+		 * with the last character in the buffer and only when it's a
+		 * NUL.
+		 */
+		if (buf[1] & FTDI_RS_BI && buf[len - 1] == '\0') {
 			port->icount.brk++;
-			usb_serial_handle_break(port);
-		} else if (packet[1] & FTDI_RS_PE) {
+			brkint = true;
+		}
+		if (buf[1] & FTDI_RS_PE) {
 			flag = TTY_PARITY;
 			port->icount.parity++;
-		} else if (packet[1] & FTDI_RS_FE) {
+		} else if (buf[1] & FTDI_RS_FE) {
 			flag = TTY_FRAME;
 			port->icount.frame++;
 		}
 		/* Overrun is special, not associated with a char */
-		if (packet[1] & FTDI_RS_OE) {
+		if (buf[1] & FTDI_RS_OE) {
 			port->icount.overrun++;
 			tty_insert_flip_char(&port->port, 0, TTY_OVERRUN);
 		}
 	}
 
-	port->icount.rx += len;
-	ch = packet + 2;
+	port->icount.rx += len - 2;
 
-	if (port->port.console && port->sysrq) {
-		for (i = 0; i < len; i++, ch++) {
-			if (!usb_serial_handle_sysrq_char(port, *ch))
-				tty_insert_flip_char(&port->port, *ch, flag);
+	if (brkint || port->sysrq) {
+		for (i = 2; i < len; i++) {
+			if (brkint && i == len - 1) {
+				if (usb_serial_handle_break(port))
+					return len - 3;
+				flag = TTY_BREAK;
+			}
+			if (usb_serial_handle_sysrq_char(port, buf[i]))
+				continue;
+			tty_insert_flip_char(&port->port, buf[i], flag);
 		}
 	} else {
-		tty_insert_flip_string_fixed_flag(&port->port, ch, flag, len);
+		tty_insert_flip_string_fixed_flag(&port->port, buf + 2, flag,
+				len - 2);
 	}
 
-	return len;
+	return len - 2;
 }
 
 static void ftdi_process_read_urb(struct urb *urb)
 {
 	struct usb_serial_port *port = urb->context;
 	struct ftdi_private *priv = usb_get_serial_port_data(port);
-	char *data = (char *)urb->transfer_buffer;
+	char *data = urb->transfer_buffer;
 	int i;
 	int len;
 	int count = 0;
diff --git a/drivers/usb/serial/garmin_gps.c b/drivers/usb/serial/garmin_gps.c
index d63072fee099..c02c19bb1183 100644
--- a/drivers/usb/serial/garmin_gps.c
+++ b/drivers/usb/serial/garmin_gps.c
@@ -179,19 +179,22 @@ static unsigned char const GARMIN_START_SESSION_REPLY[]
 	= { 0, 0, 0, 0,  6, 0, 0, 0, 4, 0, 0, 0 };
 static unsigned char const GARMIN_BULK_IN_AVAIL_REPLY[]
 	= { 0, 0, 0, 0,  2, 0, 0, 0, 0, 0, 0, 0 };
+static unsigned char const GARMIN_STOP_TRANSFER_REQ[]
+	= { 20, 0, 0, 0,  10, 0, 0, 0, 2, 0, 0, 0, 0, 0 };
+static unsigned char const GARMIN_STOP_TRANSFER_REQ_V2[]
+	= { 20, 0, 0, 0,  10, 0, 0, 0, 1, 0, 0, 0, 0 };
+
+/* packets currently unused, left as documentation */
+#if 0
 static unsigned char const GARMIN_APP_LAYER_REPLY[]
 	= { 0x14, 0, 0, 0 };
 static unsigned char const GARMIN_START_PVT_REQ[]
 	= { 20, 0, 0, 0,  10, 0, 0, 0, 2, 0, 0, 0, 49, 0 };
 static unsigned char const GARMIN_STOP_PVT_REQ[]
 	= { 20, 0, 0, 0,  10, 0, 0, 0, 2, 0, 0, 0, 50, 0 };
-static unsigned char const GARMIN_STOP_TRANSFER_REQ[]
-	= { 20, 0, 0, 0,  10, 0, 0, 0, 2, 0, 0, 0, 0, 0 };
-static unsigned char const GARMIN_STOP_TRANSFER_REQ_V2[]
-	= { 20, 0, 0, 0,  10, 0, 0, 0, 1, 0, 0, 0, 0 };
 static unsigned char const PRIVATE_REQ[]
 	=    { 0x4B, 0x6E, 0x10, 0x01,  0xFF, 0, 0, 0, 0xFF, 0, 0, 0 };
-
+#endif
 
 
 static const struct usb_device_id id_table[] = {
diff --git a/drivers/usb/serial/generic.c b/drivers/usb/serial/generic.c
index 5cdf180cda23..d10aa3d2ee49 100644
--- a/drivers/usb/serial/generic.c
+++ b/drivers/usb/serial/generic.c
@@ -345,7 +345,7 @@ EXPORT_SYMBOL_GPL(usb_serial_generic_submit_read_urbs);
 void usb_serial_generic_process_read_urb(struct urb *urb)
 {
 	struct usb_serial_port *port = urb->context;
-	char *ch = (char *)urb->transfer_buffer;
+	char *ch = urb->transfer_buffer;
 	int i;
 
 	if (!urb->actual_length)
@@ -355,13 +355,13 @@ void usb_serial_generic_process_read_urb(struct urb *urb)
 	 * stuff like 3G modems, so shortcircuit it in the 99.9999999% of
 	 * cases where the USB serial is not a console anyway.
 	 */
-	if (!port->port.console || !port->sysrq) {
-		tty_insert_flip_string(&port->port, ch, urb->actual_length);
-	} else {
+	if (port->sysrq) {
 		for (i = 0; i < urb->actual_length; i++, ch++) {