Commit df1cd63d authored by Johan Hovold's avatar Johan Hovold
Browse files

USB: serial: ftdi_sio: clean up flow control management 



Clean up the somewhat convoluted hardware-assisted flow control
handling.

Reviewed-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: default avatarJohan Hovold <johan@kernel.org>
parent 16410115

drivers/usb/serial/ftdi_sio.c

+23 −58
Original line number Diff line number Diff line
@@ -2191,12 +2191,8 @@ static void ftdi_set_termios(struct tty_struct *tty, 
	struct ftdi_private *priv = usb_get_serial_port_data(port);

	struct ktermios *termios = &tty->termios;

	unsigned int cflag = termios->c_cflag;

	u16 value;



	/* Added for xon/xoff support */

	unsigned int iflag = termios->c_iflag;

	unsigned char vstop;

	unsigned char vstart;

	u16 value, index;

	int ret;



	/* Force baud rate if this device requires it, unless it is set to

	   B0. */
@@ -2325,61 +2321,30 @@ static void ftdi_set_termios(struct tty_struct *tty, 
			set_mctrl(port, TIOCM_DTR | TIOCM_RTS);

	}



	/* Set flow control */

	/* Note device also supports DTR/CD (ugh) and Xon/Xoff in hardware */

no_c_cflag_changes:

	if (cflag & CRTSCTS) {

		dev_dbg(ddev, "%s Setting to CRTSCTS flow control\n", __func__);

		if (usb_control_msg(dev,

				    usb_sndctrlpipe(dev, 0),

				    FTDI_SIO_SET_FLOW_CTRL_REQUEST,

				    FTDI_SIO_SET_FLOW_CTRL_REQUEST_TYPE,

				    0 , (FTDI_SIO_RTS_CTS_HS | priv->interface),

				    NULL, 0, WDR_TIMEOUT) < 0) {

			dev_err(ddev, "urb failed to set to rts/cts flow control\n");

		}

	} else {

		/*

		 * Xon/Xoff code

		 */

		if (iflag & IXON) {

			dev_dbg(ddev, "%s  request to enable xonxoff iflag=%04x\n",

				__func__, iflag);

			/* Try to enable the XON/XOFF on the ftdi_sio

			 * Set the vstart and vstop -- could have been done up

			 * above where a lot of other dereferencing is done but

			 * that would be very inefficient as vstart and vstop

			 * are not always needed.

			 */

			vstart = termios->c_cc[VSTART];

			vstop = termios->c_cc[VSTOP];

			value = (vstop << 8) | (vstart);

	/* Set hardware-assisted flow control */

	value = 0;



			if (usb_control_msg(dev,

					    usb_sndctrlpipe(dev, 0),

					    FTDI_SIO_SET_FLOW_CTRL_REQUEST,

					    FTDI_SIO_SET_FLOW_CTRL_REQUEST_TYPE,

					    value , (FTDI_SIO_XON_XOFF_HS

							 | priv->interface),

					    NULL, 0, WDR_TIMEOUT) < 0) {

				dev_err(&port->dev, "urb failed to set to "

					"xon/xoff flow control\n");

			}

	if (C_CRTSCTS(tty)) {

		dev_dbg(&port->dev, "enabling rts/cts flow control\n");

		index = FTDI_SIO_RTS_CTS_HS;

	} else if (I_IXON(tty)) {

		dev_dbg(&port->dev, "enabling xon/xoff flow control\n");

		index = FTDI_SIO_XON_XOFF_HS;

		value = STOP_CHAR(tty) << 8 | START_CHAR(tty);

	} else {

			/* else clause to only run if cflag ! CRTSCTS and iflag

			 * ! XON. CHECKME Assuming XON/XOFF handled by tty

			 * stack - not by device */

			dev_dbg(ddev, "%s Turning off hardware flow control\n", __func__);

			if (usb_control_msg(dev,

					    usb_sndctrlpipe(dev, 0),

		dev_dbg(&port->dev, "disabling flow control\n");

		index = FTDI_SIO_DISABLE_FLOW_CTRL;

	}



	index |= priv->interface;



	ret = usb_control_msg(dev, usb_sndctrlpipe(dev, 0),

			FTDI_SIO_SET_FLOW_CTRL_REQUEST,

			FTDI_SIO_SET_FLOW_CTRL_REQUEST_TYPE,

					    0, priv->interface,

					    NULL, 0, WDR_TIMEOUT) < 0) {

				dev_err(ddev, "urb failed to clear flow control\n");

			}

		}

	}

			value, index, NULL, 0, WDR_TIMEOUT);

	if (ret < 0)

		dev_err(&port->dev, "failed to set flow control: %d\n", ret);

}



/*