Can a driver call another driver directly?

[Doug Toppin]

Is it possible for a device driver to call another device driver directly?
I have the following problem:

I need to send a command to a serial device in less than 100 milliseconds
of receiving data from a custom device.
I would like to have my custom driver call the serial driver directly
and pass it the data to send.
Is it possible to call an entry point of the serial driver directly
from another driver?
If so, how do you pass data directly?
In the past I have done something similar on a different operating system
by putting data into the clist and calling the line discipline entry
point of the serial driver.
I would like a more direct (and documented) means of doing this.

Here are the specifics:
    * I am using Motorola Unix R3V5 on the MVME-147A (68030)
    * serial card is the MVME-332XT device, 19.2K rate
    * I cannot afford overhead of bubbling up to an application and back down

Please respond by mail or post.
thanks
Doug Toppin
uunet!melpar!toppin