From: Daniel Starke <daniel.starke@xxxxxxxxxxx> The status lines ring and carrier detect are used by the modem to signal incoming calls (RING) or an established connection (CD). This is implemented as physical lines on a standard RS232 connection. However, the muxer protocol encodes these status lines as modem bits IC and DV. These incoming lines are masked by tty driver (see tty_io.c) and cannot be set by a user application. Allow setting RING via TIOCM_OUT1 and CD via TIOCM_OUT2 to allow implementation of a modem or modem emulator. Signed-off-by: Daniel Starke <daniel.starke@xxxxxxxxxxx> --- drivers/tty/n_gsm.c | 5 +++++ 1 file changed, 5 insertions(+) v3 -> v4: No changes. Link: https://lore.kernel.org/all/20230203145023.6012-3-daniel.starke@xxxxxxxxxxx/ diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c index c94df9cd282f..79efbfd27171 100644 --- a/drivers/tty/n_gsm.c +++ b/drivers/tty/n_gsm.c @@ -546,6 +546,11 @@ static u8 gsm_encode_modem(const struct gsm_dlci *dlci) modembits |= MDM_IC; if (dlci->modem_tx & TIOCM_CD || dlci->gsm->initiator) modembits |= MDM_DV; + /* special mappings for passive side to operate as UE */ + if (dlci->modem_tx & TIOCM_OUT1) + modembits |= MDM_IC; + if (dlci->modem_tx & TIOCM_OUT2) + modembits |= MDM_DV; return modembits; } -- 2.34.1
