In 2006 Sun Microsystems released their Open Firmware implementation OpenBoot under a BSL like license. Their code supports the sun4v architecture running on a hypervisor.
The code can be browsed online with the ViewVC facility.
The repository is available through Subversion:
You can check it out as follows:
$ svn co svn://openbios.org/openboot/
if you want a specific revision:
$ svn co svn://openbios.org/openboot -r 1
If your company installed a firewall that blocks the svn port (3690) you can also check out using the webdav frontend:
$ svn co https://www.openbios.org/openboot-svn/ openboot