Reading Sun 3 timer register within Kernel device driver

[Andrew Harker]

I have a problem relating to SUN OS3.5 kernel device drivers. I want to
measure the performance of the driver by calling a routine at certain
points in the driver which records a timer value in a buffer somewhere.
Outside the kernel, the obvious answer is to use gettimeofday(), but this
is no good inside the device driver.

Is there a way of accessing the SUN's timer register from within the
kernel? Is there an easier way?