How to probe a modem exposing virtual ports (GSM 07.10 muxed ports)

Garfield Watkins garfield.watkins at
Wed Mar 6 12:24:10 UTC 2024


I have a situation where I have a ublox modem, the LISA u200, wired up 
using its SPI bus as the communication channel. On the DTE side is a 
raspberry pi SBC with a custom spi platform driver that exposes a tty 
device for modem. This driver is not capable of multiplexing and 
exposing multiple virtual channels.

To overcome this I have a user mode daemon that performs this function 
by connection to the single tty port exposed by the spi driver and in 
turn creating 5 pseudo tty's (/dev/ptty1 -> /dev/ptty5) to interact 
with. These are actually links to /dev/pts/1 to /dev/pts/5.

I want the ublox plugin to manage this device but there seems to be no 
way to filter/grab those ports.

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