Linux ALSA driver
This sound chip is supported by the snd-ad1848 kernel module. Use the following options line when loading this module:
options snd-ad1848 snd_index=0 snd_port=0x4e30 snd_irq=10 snd_dma1=0 snd_thinkpad=1
If you're running Debian Woody: Its ALSA 0.9 hasn't this Thinkpad support yet. Hence, you need to recompile the kernel (2.4.18) including the soundcore module and adding ALSA 1.0.