On Fri, 3 Mar 2000 14:39:00 +0000 
 Julian Coleman <J.D.Coleman@newcastle.ac.uk> wrote:

 > Background: the Tadpole Sparcbook has power on/off control for the serial
 > ports driven by a separate device (aux2 register).  In order to be able to
 > power on the ports when a serial port is opened (and power them off when the
 > serial ports are closed), I'd like to add some MD hooks to the zsopen() and
 > zsclose() functions in dev/ic/z8530tty.c (see diffs).

Take a look at dev/ic/com.c for the enable/disable hooks present in that
driver (for power management on PCMCIA cards).

        -- Jason R. Thorpe <thorpej@nas.nasa.gov>