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tty: make tty_get_{char,frame}_size available

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Many tty drivers contain code to compute bits count depending on termios
cflags. So extract this code from serial core to two separate tty helper
functions:
* tty_get_char_size -- only size of a character, without flags,
* tty_get_frame_size -- complete size of a frame including flags.

In the next patch, calls to these new functions replace many copies of
this code.

Note that we accept only cflag as a parameter. That's because some
callers like pch_uart_startup or sunsab_console_setup don't have at hand
termios which we could pass around.

Cc: Joe Perches <joe@perches.com>
Cc: Johan Hovold <johan@kernel.org>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20210610090247.2593-1-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Jiri Slaby 2021-06-10 11:02:44 +02:00 committed by Greg Kroah-Hartman
parent fb524360f5
commit 654ee49b7e
3 changed files with 51 additions and 27 deletions
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30
drivers/tty/serial/serial_core.c
View File

@ -334,39 +334,15 @@ void
uart_update_timeout(struct uart_port *port, unsigned int cflag,
unsigned int baud)
{
unsigned int bits;
unsigned int size;
/* byte size and parity */
switch (cflag & CSIZE) {
case CS5:
bits = 7;
break;
case CS6:
bits = 8;
break;
case CS7:
bits = 9;
break;
default:
bits = 10;
break; /* CS8 */
}
if (cflag & CSTOPB)
bits++;
if (cflag & PARENB)
bits++;
/*
* The total number of bits to be transmitted in the fifo.
*/
bits = bits * port->fifosize;
size = tty_get_frame_size(cflag) * port->fifosize;
/*
* Figure the timeout to send the above number of bits.
* Add .02 seconds of slop
*/
port->timeout = (HZ * bits) / baud + HZ/50;
port->timeout = (HZ * size) / baud + HZ/50;
}
EXPORT_SYMBOL(uart_update_timeout);

45
drivers/tty/tty_ioctl.c
View File

@ -279,6 +279,51 @@ int tty_termios_hw_change(const struct ktermios *a, const struct ktermios *b)
}
EXPORT_SYMBOL(tty_termios_hw_change);
/**
* tty_get_char_size - get size of a character
* @cflag: termios cflag value
*
* Get the size (in bits) of a character depending on @cflag's %CSIZE
* setting.
*/
unsigned char tty_get_char_size(unsigned int cflag)
{
switch (cflag & CSIZE) {
case CS5:
return 5;
case CS6:
return 6;
case CS7:
return 7;
case CS8:
default:
return 8;
}
}
EXPORT_SYMBOL_GPL(tty_get_char_size);
/**
* tty_get_frame_size - get size of a frame
* @cflag: termios cflag value
*
* Get the size (in bits) of a frame depending on @cflag's %CSIZE, %CSTOPB,
* and %PARENB setting. The result is a sum of character size, start and
* stop bits -- one bit each -- second stop bit (if set), and parity bit
* (if set).
*/
unsigned char tty_get_frame_size(unsigned int cflag)
{
unsigned char bits = 2 + tty_get_char_size(cflag);
if (cflag & CSTOPB)
bits++;
if (cflag & PARENB)
bits++;
return bits;
}
EXPORT_SYMBOL_GPL(tty_get_frame_size);
/**
* tty_set_termios - update termios values
* @tty: tty to update

3
include/linux/tty.h
View File

@ -495,6 +495,9 @@ static inline speed_t tty_get_baud_rate(struct tty_struct *tty)
return tty_termios_baud_rate(&tty->termios);
}
unsigned char tty_get_char_size(unsigned int cflag);
unsigned char tty_get_frame_size(unsigned int cflag);
extern void tty_termios_copy_hw(struct ktermios *new, struct ktermios *old);
extern int tty_termios_hw_change(const struct ktermios *a, const struct ktermios *b);
extern int tty_set_termios(struct tty_struct *tty, struct ktermios *kt);