How to implement TIOCOUTQ for USB modem on Linux Ubuntu
 

Hi,

I need to override ioctl operation for a few USB drivers (sierra, option, cdc-acm) on Linux Ubuntu 2.6.34sb2 to support TIOCOUTQ command.

Unfortunately, none of the drivers I mentioned above support TIOCOUTQ because it seems unclear to know amount of data inside a modem.

Does Linux provide a way to control amount of data not sent by a modem?