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USB: CP2101 Support AN205 baud rates

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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: Craig Shelley <craig@microtron.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Craig Shelley 2009-02-26 22:19:22 +00:00 committed by Greg Kroah-Hartman
parent 31dbb80346
commit ef8b6bcb39
1 changed files with 52 additions and 40 deletions
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92
drivers/usb/serial/cp2101.c
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@ -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);
@ -517,46 +558,17 @@ 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) {
dbg("%s - Setting baud rate to %d baud", __func__,
baud);
if (cp2101_set_config_single(port, CP2101_BAUDRATE,
(BAUD_RATE_GEN_FREQ / baud))) {
dev_err(&port->dev, "Baud rate requested not "
"supported by device\n");
baud = tty_termios_baud_rate(old_termios);
}
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/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 */