Opal SSC (encrypted) hard drives unsupported, despite TPM support?

The http://www.coreboot.org/Benefits page says under "possible
advantages":

*  TPMs...

with no detail.  (note that the three dots are literally on the
webpage, not my paraphrasing).

Support for TPMs /could/ mean support for self-encrypted (Opal) hard
drives, but there are other kinds of TPMs (e.g. fingerprint reading)
so it's unclear what actually works on coreboot.

Someone in #coreboot hinted (without confidence) that only software
encryption is possible under coreboot.  Is that true?