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USB: cp210x: clean up, refactor and document speed handling

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

Signed-off-by: Johan Hovold <jhovold@gmail.com>
Cc: Preston Fick <preston.fick@silabs.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Johan Hovold 2012-01-16 00:36:51 +01:00 committed by Greg Kroah-Hartman
parent be125d9c8d
commit e5990874e5
1 changed files with 56 additions and 13 deletions
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69
drivers/usb/serial/cp210x.c
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@ -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)) {