Line Discipline or Termios lacks ?

Cedric Aubert cedric_aubert at
Thu Sep 18 15:06:04 UTC 2003

--- Thomas Doerfler <Thomas.Doerfler at>
> Hello Cedric,
> rtems termios has a feature to control the hardware
> handshake 
> lines (or, actually, only the RTS line) to signal to
> the 
> oposite side, that the receive buffer is almost
> full, or that 
> there is more space available. This features is
> available in 
> some console drivers, it depends on the
> implementation of the 
> "stopRemoteTx" and "startRemoteTx" hooks. 
> If the hardware driver in use supports these calls
> and the 
> device has the CRTSCTS flag set, then termios will
> control the 
> hardware handshake output line RTS for you.

Yes, I see this features ! It's ok transfert RTS/CTS
control. But I need to manualy control RTS/CTS or DSR
or DTR or CD on some device, I don't found this
on termios.

> This has nothing to do with "line discipline". The
> "line 
> discipline" feature allows redirecting the character
> stream to 
> certain additional, external functions, that can do
> wierd 
> things like decoding the incoming character stream
> as PPP 
> packets and so on. 
> If the functionality in termios for hardware
> handshake line 
> control is not sufficent for you, you might add
> "private" 
> functions to the "ioctl" function of your device
> driver, which 
> might in turn do whatever you want with the hardware
> handshake 
> lines of your devices.

Ok, I want to do this !! :-) But I don't found how
termios_ioctl will call my private driver ioctl

Termios_icotl have a switch(command) :
case KnwonCommand1 :
case KnwonCommand2 :
case KnwonCommand3 :
default : Call line discipline ioctl function

So How can I do, that's what I don't understand and
found a solution to do this and use termios ?

> wkr,
> 	Thomas.

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