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Commit ef8b6bcb authored by Craig Shelley's avatar Craig Shelley Committed by Greg Kroah-Hartman
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USB: CP2101 Support AN205 baud rates 



This patch adds support for the extended range of baud rates supported
by CP2102 and CP2103 devices described in SiLabs AN205.  An additional
function cp2101_quantise_baudrate rounds the baud rate as per AN205
Table 1.  A modification to the baud rate calculation removes a rounding
error, allowing the full range of baud rates to be used.

Signed-off-by: default avatarCraig Shelley <craig@microtron.org.uk>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent 31dbb803

drivers/usb/serial/cp2101.c

+52 −40
Original line number Diff line number Diff line
@@ -31,7 +31,7 @@ 
/*

 * Version Information

 */

#define DRIVER_VERSION "v0.07"

#define DRIVER_VERSION "v0.08"

#define DRIVER_DESC "Silicon Labs CP2101/CP2102 RS232 serial adaptor driver"



/*
@@ -301,6 +301,47 @@ static inline int cp2101_set_config_single(struct usb_serial_port *port, 
	return cp2101_set_config(port, request, &data, 2);

}



/*

 * cp2101_quantise_baudrate

 * Quantises the baud rate as per AN205 Table 1

 */

static unsigned int cp2101_quantise_baudrate(unsigned int baud) {

	if      (baud <= 56)       baud = 0;

	else if (baud <= 300)      baud = 300;

	else if (baud <= 600)      baud = 600;

	else if (baud <= 1200)     baud = 1200;

	else if (baud <= 1800)     baud = 1800;

	else if (baud <= 2400)     baud = 2400;

	else if (baud <= 4000)     baud = 4000;

	else if (baud <= 4803)     baud = 4800;

	else if (baud <= 7207)     baud = 7200;

	else if (baud <= 9612)     baud = 9600;

	else if (baud <= 14428)    baud = 14400;

	else if (baud <= 16062)    baud = 16000;

	else if (baud <= 19250)    baud = 19200;

	else if (baud <= 28912)    baud = 28800;

	else if (baud <= 38601)    baud = 38400;

	else if (baud <= 51558)    baud = 51200;

	else if (baud <= 56280)    baud = 56000;

	else if (baud <= 58053)    baud = 57600;

	else if (baud <= 64111)    baud = 64000;

	else if (baud <= 77608)    baud = 76800;

	else if (baud <= 117028)   baud = 115200;

	else if (baud <= 129347)   baud = 128000;

	else if (baud <= 156868)   baud = 153600;

	else if (baud <= 237832)   baud = 230400;

	else if (baud <= 254234)   baud = 250000;

	else if (baud <= 273066)   baud = 256000;

	else if (baud <= 491520)   baud = 460800;

	else if (baud <= 567138)   baud = 500000;

	else if (baud <= 670254)   baud = 576000;

	else if (baud <= 1053257)  baud = 921600;

	else if (baud <= 1474560)  baud = 1228800;

	else if (baud <= 2457600)  baud = 1843200;

	else                       baud = 3686400;

	return baud;

}



static int cp2101_open(struct tty_struct *tty, struct usb_serial_port *port,

				struct file *filp)

{
@@ -388,7 +429,7 @@ static void cp2101_get_termios (struct tty_struct *tty) 
	cp2101_get_config(port, CP2101_BAUDRATE, &baud, 2);

	/* Convert to baudrate */

	if (baud)

		baud = BAUD_RATE_GEN_FREQ / baud;

		baud = cp2101_quantise_baudrate((BAUD_RATE_GEN_FREQ + baud/2)/ baud);



	dbg("%s - baud rate = %d", __func__, baud);
@@ -517,48 +558,19 @@ static void cp2101_set_termios(struct tty_struct *tty, 
	tty->termios->c_cflag &= ~CMSPAR;

	cflag = tty->termios->c_cflag;

	old_cflag = old_termios->c_cflag;

	baud = tty_get_baud_rate(tty);

	baud = cp2101_quantise_baudrate(tty_get_baud_rate(tty));



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

	if (baud != tty_termios_baud_rate(old_termios)) {

		switch (baud) {

		case 0:

		case 600:

		case 1200:

		case 1800:

		case 2400:

		case 4800:

		case 7200:

		case 9600:

		case 14400:

		case 19200:

		case 28800:

		case 38400:

		case 55854:

		case 57600:

		case 115200:

		case 127117:

		case 230400:

		case 460800:

		case 921600:

		case 3686400:

			break;

		default:

			baud = 9600;

			break;

		}



		if (baud) {

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

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

				baud);

		if (cp2101_set_config_single(port, CP2101_BAUDRATE,

						(BAUD_RATE_GEN_FREQ / baud))) {

					((BAUD_RATE_GEN_FREQ + baud/2) / baud))) {

			dev_err(&port->dev, "Baud rate requested not "

					"supported by device\n");

			baud = tty_termios_baud_rate(old_termios);

		}

	}

	}

	/* Report back the resulting baud rate */

	tty_encode_baud_rate(tty, baud, baud);