The ESS chip on the Shark has a MIDI port (located in the
game port, I presume).  It's an MPU401 compatible port so
I thought I'd set up the driver for it.

But now I need to understand the OpenFirmware mystique to
do it "The Right Way"(tm).  Looking at dmesg I see

...
game@i201 at ofisa0 not configured
midi@i330 at ofisa0 not configured
ess0 at ofisa0 (sound@i220): ESST,es1887-codec
...

These three are really handled by the same chip, the ESS1887.
Has OFW already programmed the ESS1887 to have the midi port at
330 at this point?  (You need to set a config register for
it to appear there.)  If it has done that and the MIDI port
is not sharing an interrupt with the sound I could make the
mpu401 driver attach to ofisa.
If I want to write an mpu401_ofisa driver, how do I find out 
what strings I should match for in the probe routine?

        -- Lennart