Commit 8c4dd350 authored by Johan Hovold's avatar Johan Hovold Committed by Phil Elwell
Browse files

USB: serial: ch341: change initial line-control settings 



commit 7c61b0d5 upstream.

Some CH340 devices appear unable to change the initial LCR settings, so
set a sane 8N1 default during probe to enable basic support for such
devices.

Also drop a redundant LCR read during device initialisation.

Signed-off-by: default avatarJohan Hovold <johan@kernel.org>
parent 3c1164cc

drivers/usb/serial/ch341.c

+103 −84
Original line number Diff line number Diff line
@@ -61,13 +61,26 @@ 
 * the Net/FreeBSD uchcom.c driver by Takanori Watanabe.  Domo arigato.

 */



#define CH341_REQ_READ_VERSION 0x5F

#define CH341_REQ_WRITE_REG    0x9A

#define CH341_REQ_READ_REG     0x95

#define CH341_REG_BREAK1       0x05

#define CH341_REG_BREAK2       0x18

#define CH341_NBREAK_BITS_REG1 0x01

#define CH341_NBREAK_BITS_REG2 0x40



#define CH341_REQ_SERIAL_INIT  0xA1

#define CH341_REQ_MODEM_CTRL   0xA4



#define CH341_REG_BREAK        0x05

#define CH341_REG_LCR          0x18

#define CH341_NBREAK_BITS      0x01



#define CH341_LCR_ENABLE_RX    0x80

#define CH341_LCR_ENABLE_TX    0x40

#define CH341_LCR_MARK_SPACE   0x20

#define CH341_LCR_PAR_EVEN     0x10

#define CH341_LCR_ENABLE_PAR   0x08

#define CH341_LCR_STOP_BITS_2  0x04

#define CH341_LCR_CS8          0x03

#define CH341_LCR_CS7          0x02

#define CH341_LCR_CS6          0x01

#define CH341_LCR_CS5          0x00



static const struct usb_device_id id_table[] = {

	{ USB_DEVICE(0x4348, 0x5523) },
@@ -82,6 +95,7 @@ struct ch341_private { 
	unsigned baud_rate; /* set baud rate */

	u8 line_control; /* set line control value RTS/DTR */

	u8 line_status; /* active status of modem control inputs */

	u8 lcr;

};



static void ch341_set_termios(struct tty_struct *tty,
@@ -134,10 +148,10 @@ static int ch341_control_in(struct usb_device *dev, 
	return 0;

}



static int ch341_set_baudrate(struct usb_device *dev,

			      struct ch341_private *priv)

static int ch341_set_baudrate_lcr(struct usb_device *dev,

				  struct ch341_private *priv, u8 lcr)

{

	short a, b;

	short a;

	int r;

	unsigned long factor;

	short divisor;
@@ -157,18 +171,27 @@ static int ch341_set_baudrate(struct usb_device *dev, 


	factor = 0x10000 - factor;

	a = (factor & 0xff00) | divisor;

	b = factor & 0xff;



	r = ch341_control_out(dev, 0x9a, 0x1312, a);

	if (!r)

		r = ch341_control_out(dev, 0x9a, 0x0f2c, b);

	/*

	 * CH341A buffers data until a full endpoint-size packet (32 bytes)

	 * has been received unless bit 7 is set.

	 */

	a |= BIT(7);



	r = ch341_control_out(dev, CH341_REQ_WRITE_REG, 0x1312, a);

	if (r)

		return r;



	r = ch341_control_out(dev, CH341_REQ_WRITE_REG, 0x2518, lcr);

	if (r)

		return r;



	return r;

}



static int ch341_set_handshake(struct usb_device *dev, u8 control)

{

	return ch341_control_out(dev, 0xa4, ~control, 0);

	return ch341_control_out(dev, CH341_REQ_MODEM_CTRL, ~control, 0);

}



static int ch341_get_status(struct usb_device *dev, struct ch341_private *priv)
@@ -182,7 +205,7 @@ static int ch341_get_status(struct usb_device *dev, struct ch341_private *priv) 
	if (!buffer)

		return -ENOMEM;



	r = ch341_control_in(dev, 0x95, 0x0706, 0, buffer, size);

	r = ch341_control_in(dev, CH341_REQ_READ_REG, 0x0706, 0, buffer, size);

	if (r < 0)

		goto out;
@@ -207,46 +230,20 @@ static int ch341_configure(struct usb_device *dev, struct ch341_private *priv) 
		return -ENOMEM;



	/* expect two bytes 0x27 0x00 */

	r = ch341_control_in(dev, 0x5f, 0, 0, buffer, size);

	if (r < 0)

		goto out;



	r = ch341_control_out(dev, 0xa1, 0, 0);

	r = ch341_control_in(dev, CH341_REQ_READ_VERSION, 0, 0, buffer, size);

	if (r < 0)

		goto out;

	dev_dbg(&dev->dev, "Chip version: 0x%02x\n", buffer[0]);



	r = ch341_set_baudrate(dev, priv);

	r = ch341_control_out(dev, CH341_REQ_SERIAL_INIT, 0, 0);

	if (r < 0)

		goto out;



	/* expect two bytes 0x56 0x00 */

	r = ch341_control_in(dev, 0x95, 0x2518, 0, buffer, size);

	if (r < 0)

		goto out;



	r = ch341_control_out(dev, 0x9a, 0x2518, 0x0050);

	if (r < 0)

		goto out;



	/* expect 0xff 0xee */

	r = ch341_get_status(dev, priv);

	if (r < 0)

		goto out;



	r = ch341_control_out(dev, 0xa1, 0x501f, 0xd90a);

	if (r < 0)

		goto out;



	r = ch341_set_baudrate(dev, priv);

	r = ch341_set_baudrate_lcr(dev, priv, priv->lcr);

	if (r < 0)

		goto out;



	r = ch341_set_handshake(dev, priv->line_control);

	if (r < 0)

		goto out;



	/* expect 0x9f 0xee */

	r = ch341_get_status(dev, priv);



out:	kfree(buffer);

	return r;
@@ -263,6 +260,11 @@ static int ch341_port_probe(struct usb_serial_port *port) 


	spin_lock_init(&priv->lock);

	priv->baud_rate = DEFAULT_BAUD_RATE;

	/*

	 * Some CH340 devices appear unable to change the initial LCR

	 * settings, so set a sane 8N1 default.

	 */

	priv->lcr = CH341_LCR_ENABLE_RX | CH341_LCR_ENABLE_TX | CH341_LCR_CS8;



	r = ch341_configure(port->serial->dev, priv);

	if (r < 0)
@@ -318,14 +320,9 @@ static void ch341_close(struct usb_serial_port *port) 
/* open this device, set default parameters */

static int ch341_open(struct tty_struct *tty, struct usb_serial_port *port)

{

	struct usb_serial *serial = port->serial;

	struct ch341_private *priv = usb_get_serial_port_data(port);

	int r;



	r = ch341_configure(serial->dev, priv);

	if (r)

		return r;



	if (tty)

		ch341_set_termios(tty, port, NULL);
@@ -337,6 +334,12 @@ static int ch341_open(struct tty_struct *tty, struct usb_serial_port *port) 
		return r;

	}



	r = ch341_get_status(port->serial->dev, priv);

	if (r < 0) {

		dev_err(&port->dev, "failed to read modem status: %d\n", r);

		goto err_kill_interrupt_urb;

	}



	r = usb_serial_generic_open(tty, port);

	if (r)

		goto err_kill_interrupt_urb;
@@ -358,44 +361,54 @@ static void ch341_set_termios(struct tty_struct *tty, 
	struct ch341_private *priv = usb_get_serial_port_data(port);

	unsigned baud_rate;

	unsigned long flags;

	unsigned int par_flags;

	unsigned char ctrl;

	int r;



	/* redundant changes may cause the chip to lose bytes */

	if (old_termios && !tty_termios_hw_change(&tty->termios, old_termios))

		return;



	baud_rate = tty_get_baud_rate(tty);



	if (baud_rate) {

		priv->baud_rate = baud_rate;

		ch341_set_baudrate(port->serial->dev, priv);

	}

	ctrl = CH341_LCR_ENABLE_RX | CH341_LCR_ENABLE_TX;



	/* Unimplemented:

	 * (cflag & CSIZE) : data bits [5, 8]

	 * (cflag & CSTOPB) : stop bits [1, 2]

	 */

	switch (C_CSIZE(tty)) {

	case CS5:

		ctrl |= CH341_LCR_CS5;

		break;

	case CS6:

		ctrl |= CH341_LCR_CS6;

		break;

	case CS7:

		ctrl |= CH341_LCR_CS7;

		break;

	case CS8:

		ctrl |= CH341_LCR_CS8;

		break;

	}



	/* CH340 doesn't appear to support variable stop bits or data bits */

	if (C_PARENB(tty)) {

		if (C_PARODD(tty)) {

			if (tty->termios.c_cflag & CMSPAR) {

				dev_dbg(&port->dev, "parity = mark\n");

				par_flags = 0xeb;

			} else {

				dev_dbg(&port->dev, "parity = odd\n");

				par_flags = 0xcb;

			}

		} else {

			if (tty->termios.c_cflag & CMSPAR) {

				dev_dbg(&port->dev, "parity = space\n");

				par_flags = 0xfb;

			} else {

				dev_dbg(&port->dev, "parity = even\n");

				par_flags = 0xdb;

		ctrl |= CH341_LCR_ENABLE_PAR;

		if (C_PARODD(tty) == 0)

			ctrl |= CH341_LCR_PAR_EVEN;

		if (C_CMSPAR(tty))

			ctrl |= CH341_LCR_MARK_SPACE;

	}



	if (C_CSTOPB(tty))

		ctrl |= CH341_LCR_STOP_BITS_2;



	if (baud_rate) {

		priv->baud_rate = baud_rate;



		r = ch341_set_baudrate_lcr(port->serial->dev, priv, ctrl);

		if (r < 0 && old_termios) {

			priv->baud_rate = tty_termios_baud_rate(old_termios);

			tty_termios_copy_hw(&tty->termios, old_termios);

		} else if (r == 0) {

			priv->lcr = ctrl;

		}

	} else {

		dev_dbg(&port->dev, "parity = none\n");

		par_flags = 0xc3;

	}

	ch341_control_out(port->serial->dev, 0x9a, 0x2518, par_flags);



	spin_lock_irqsave(&priv->lock, flags);

	if (C_BAUD(tty) == B0)
@@ -410,7 +423,7 @@ static void ch341_set_termios(struct tty_struct *tty, 
static void ch341_break_ctl(struct tty_struct *tty, int break_state)

{

	const uint16_t ch341_break_reg =

			((uint16_t) CH341_REG_BREAK2 << 8) | CH341_REG_BREAK1;

			((uint16_t) CH341_REG_LCR << 8) | CH341_REG_BREAK;

	struct usb_serial_port *port = tty->driver_data;

	int r;

	uint16_t reg_contents;
@@ -431,12 +444,12 @@ static void ch341_break_ctl(struct tty_struct *tty, int break_state) 
		__func__, break_reg[0], break_reg[1]);

	if (break_state != 0) {

		dev_dbg(&port->dev, "%s - Enter break state requested\n", __func__);

		break_reg[0] &= ~CH341_NBREAK_BITS_REG1;

		break_reg[1] &= ~CH341_NBREAK_BITS_REG2;

		break_reg[0] &= ~CH341_NBREAK_BITS;

		break_reg[1] &= ~CH341_LCR_ENABLE_TX;

	} else {

		dev_dbg(&port->dev, "%s - Leave break state requested\n", __func__);

		break_reg[0] |= CH341_NBREAK_BITS_REG1;

		break_reg[1] |= CH341_NBREAK_BITS_REG2;

		break_reg[0] |= CH341_NBREAK_BITS;

		break_reg[1] |= CH341_LCR_ENABLE_TX;

	}

	dev_dbg(&port->dev, "%s - New ch341 break register contents - reg1: %x, reg2: %x\n",

		__func__, break_reg[0], break_reg[1]);
@@ -593,6 +606,12 @@ static int ch341_reset_resume(struct usb_serial *serial) 
				ret);

			return ret;

		}



		ret = ch341_get_status(port->serial->dev, priv);

		if (ret < 0) {

			dev_err(&port->dev, "failed to read modem status: %d\n",

				ret);

		}

	}



	return usb_serial_generic_resume(serial);