Hi everyone,
The problem.
------------
I'd like to write an applciation that monitors a serial port and shows
what leds on the mode would be on. In fact the application is done,
but it kind of disturbs the normal operation of the serial port. This
is neccesary on Linux boxen, as you can have lots of serial ports,
more than you can monitor by putting the modem on your desk.
I can open the port, which raises DTR. I can then do the TIOCMGET
ioctl to get the current state of the modem control signals. Then
if the port gets closed, DTR doesn't drop, as I still have the
port open.
I can't open the port when it's in ppp mode. It seems I can keep the
port open while in ppp mode.
The ioctl doesn't tell me of the activity on RX and TX. (Gnome users
will jump up-and-down saying that they have an applett that does show
TX and RX. Well, kind of: This only works when it's in "ppp" mode.)
Design goals.
-------------
- Don't influence the normal operation of the port.
- unlimited "portwatchers".
- has a way of monitoring the TX and RX activity.
Current implementation.
-----------------------
On User Space Serial Ports (*) and Specialix SX (#) and RIO (#) ports
I can make an ioctl on the "control/firmware" device that couples the
file descriptor virtually with the requested port, so that the
tiocmget returns the stats for the port. Also the usage count of the
port won't be influenced. So DTR behaves normally.
I also keep a count of total RX and TX chars. Whenever those change,
the application can turn on the RX and TX leds.
However, this is not easily adapted to other serial ports. (e.g. the
standard 16550 ports).
Suggestions?
Roger.
(*) Implemented
(#) Not yet implemented.
-- ** R.E.Wolff@BitWizard.nl ** http://www.BitWizard.nl/ ** +31-15-2137555 ** *-- BitWizard writes Linux device drivers for any device you may have! --* * Common sense is the collection of * ****** prejudices acquired by age eighteen. -- Albert Einstein ********- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.rutgers.edu Please read the FAQ at http://www.tux.org/lkml/
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