Linux 2.4.2 and later have support for the Maestro 3 chipset. This driver seems to work very well. Linux 2.4.3 incorporates a patch from Zach Brown that fixes the problem with PCM output on machines with more than 256 MB of RAM. This driver handles suspend correctly.

One problem with the Linux driver is that the mixer settings are always reset to particular values when the machine is powered on. These aren't particularly useful settings, so this means it's necessary to adjust them every time the machine is booted. To simplify this, I've written a program to save the settings when the machine is shut down, and to restore them when it is booted. There's a for the program. (There is also source code for non-Debian systems.)

ALSA 0.5.10 supports the Maestro 3 chipset. The driver doesn't handle suspend right, so it's necessary to unload and reload ALSA around the suspend. There's also a bug: the PCM driver doesn't work right if you have more than 256 MB of RAM installed. (I assume Zach Brown's patch will soon be integrated into the ALSA driver to fix this.)

One remaining detail is that the volume-control buttons don't work. Neither the rocker switch on the right side of the case, nor the Fn-shifted up and down arrow keys, have any effect on the volume.

The Open Sound System driver, version 3.9.3r, also works, but now that there is good free support for this chipset there's little reason to spend $30 on a non-free driver. However, if you want to use OSS, here is a Debian-style to turn it on at boot and off at shutdown.