diff options
| author |   Ilpo Järvinen <ilpo.jarvinen@linux.intel.com> | 2022-06-24 23:42:09 +0300 |
|---|---|---|
| committer |   Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-06-27 14:44:20 +0200 |
| commit | 4f768e94774c58c9f7f54ebd38dadf172970046a (patch) | |
| tree | f237520975e9f0839fd2dbbd911d2681288f949e /drivers/tty/tty_ioctl.c | |
| parent | serial: take termios_rwsem for ->rs485_config() & pass termios as param (diff) | |
| download | linux-dev-4f768e94774c58c9f7f54ebd38dadf172970046a.tar.xz linux-dev-4f768e94774c58c9f7f54ebd38dadf172970046a.zip | |
serial: Support for RS-485 multipoint addresses
Add support for RS-485 multipoint addressing using 9th bit [*]. The
addressing mode is configured through ->rs485_config().
ADDRB in termios indicates 9th bit addressing mode is enabled. In this
mode, 9th bit is used to indicate an address (byte) within the
communication line. ADDRB can only be enabled/disabled through
->rs485_config() that is also responsible for setting the destination and
receiver (filter) addresses.
Add traps to detect unwanted changes to struct serial_rs485 layout using
static_assert().
[*] Technically, RS485 is just an electronic spec and does not itself
specify the 9th bit addressing mode but 9th bit seems at least
"semi-standard" way to do addressing with RS485.
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20220624204210.11112-6-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty/tty_ioctl.c')
| -rw-r--r-- | drivers/tty/tty_ioctl.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/drivers/tty/tty_ioctl.c b/drivers/tty/tty_ioctl.c index adae687f654b..2a76b330e108 100644 --- a/drivers/tty/tty_ioctl.c +++ b/drivers/tty/tty_ioctl.c @@ -319,6 +319,8 @@ unsigned char tty_get_frame_size(unsigned int cflag) bits++; if (cflag & PARENB) bits++; + if (cflag & ADDRB) + bits++; return bits; } @@ -353,6 +355,8 @@ int tty_set_termios(struct tty_struct *tty, struct ktermios *new_termios) old_termios = tty->termios; tty->termios = *new_termios; unset_locked_termios(tty, &old_termios); + /* Reset any ADDRB changes, ADDRB is changed through ->rs485_config() */ + tty->termios.c_cflag ^= (tty->termios.c_cflag ^ old_termios.c_cflag) & ADDRB; if (tty->ops->set_termios) tty->ops->set_termios(tty, &old_termios); |