Its new home is: https://github.com/chipsalliance/aib-phy-hardware

AIB is now a CHIPS Alliance Specification and a CHIPS Alliance project! Find out more about the CHIPS Alliance at https://chipsalliance.org/.

The mission of the CHIPS Alliance is to develop high-quality, open source hardware designs relevant to silicon devices and FPGAs.

By creating an open and collaborative environment, CHIPS Alliance shares resources to lower the cost of development.

Source: chipsalliance.org

See also Intel Joins the CHIPS Alliance