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Commit e5990874 authored by Johan Hovold's avatar Johan Hovold Committed by Greg Kroah-Hartman
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USB: cp210x: clean up, refactor and document speed handling 



Clean up and refactor speed handling.
Document baud rate handling for CP210{1,2,4,5,10}.

Signed-off-by: default avatarJohan Hovold <jhovold@gmail.com>
Cc: Preston Fick <preston.fick@silabs.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent be125d9c

drivers/usb/serial/cp210x.c

+57 −14
Original line number Diff line number Diff line
@@ -39,6 +39,8 @@ static void cp210x_get_termios(struct tty_struct *, 
	struct usb_serial_port *port);

static void cp210x_get_termios_port(struct usb_serial_port *port,

	unsigned int *cflagp, unsigned int *baudp);

static void cp210x_change_speed(struct tty_struct *, struct usb_serial_port *,

							struct ktermios *);

static void cp210x_set_termios(struct tty_struct *, struct usb_serial_port *,

							struct ktermios*);

static int cp210x_tiocmget(struct tty_struct *);
@@ -576,11 +578,62 @@ static void cp210x_get_termios_port(struct usb_serial_port *port, 
	*cflagp = cflag;

}



/*

 * CP2101 supports the following baud rates:

 *

 *	300, 600, 1200, 1800, 2400, 4800, 7200, 9600, 14400, 19200, 28800,

 *	38400, 56000, 57600, 115200, 128000, 230400, 460800, 921600

 *

 * CP2102 and CP2103 support the following additional rates:

 *

 *	4000, 16000, 51200, 64000, 76800, 153600, 250000, 256000, 500000,

 *	576000

 *

 * The device will map a requested rate to a supported one, but the result

 * of requests for rates greater than 1053257 is undefined (see AN205).

 *

 * CP2104, CP2105 and CP2110 support most rates up to 2M, 921k and 1M baud,

 * respectively, with an error less than 1%. The actual rates are determined

 * by

 *

 *	div = round(freq / (2 x prescale x request))

 *	actual = freq / (2 x prescale x div)

 *

 * For CP2104 and CP2105 freq is 48Mhz and prescale is 4 for request <= 365bps

 * or 1 otherwise.

 * For CP2110 freq is 24Mhz and prescale is 4 for request <= 300bps or 1

 * otherwise.

 */

static void cp210x_change_speed(struct tty_struct *tty,

		struct usb_serial_port *port, struct ktermios *old_termios)

{

	u32 baud;



	baud = tty->termios->c_ospeed;



	/* This maps the requested rate to a rate valid on cp2102 or cp2103.

	 *

	 * NOTE: B0 is not implemented.

	 */

	baud = cp210x_quantise_baudrate(baud);



	dbg("%s - setting baud rate to %u", __func__, baud);

	if (cp210x_set_config(port, CP210X_SET_BAUDRATE, &baud,

							sizeof(baud))) {

		dev_warn(&port->dev, "failed to set baud rate to %u\n", baud);

		if (old_termios)

			baud = old_termios->c_ospeed;

		else

			baud = 9600;

	}



	tty_encode_baud_rate(tty, baud, baud);

}



static void cp210x_set_termios(struct tty_struct *tty,

		struct usb_serial_port *port, struct ktermios *old_termios)

{

	unsigned int cflag, old_cflag;

	u32 baud;

	unsigned int bits;

	unsigned int modem_ctl[4];
@@ -591,19 +644,9 @@ static void cp210x_set_termios(struct tty_struct *tty, 


	cflag = tty->termios->c_cflag;

	old_cflag = old_termios->c_cflag;

	baud = cp210x_quantise_baudrate(tty_get_baud_rate(tty));



	/* If the baud rate is to be updated*/

	if (baud != tty_termios_baud_rate(old_termios) && baud != 0) {

		dbg("%s - Setting baud rate to %d baud", __func__,

				baud);

		if (cp210x_set_config(port, CP210X_SET_BAUDRATE, &baud, sizeof(baud))) {

			dbg("Baud rate requested not supported by device");

			baud = tty_termios_baud_rate(old_termios);

		}

	}

	/* Report back the resulting baud rate */

	tty_encode_baud_rate(tty, baud, baud);

	if (tty->termios->c_ospeed != old_termios->c_ospeed)

		cp210x_change_speed(tty, port, old_termios);



	/* If the number of data bits is to be updated */

	if ((cflag & CSIZE) != (old_cflag & CSIZE)) {