Changes after first round of tests.
Support FreeBSD 12.x and other fixes
Most files lack required license and copyright headers. The few that do have them indicate this is GPL licensed which is generally unacceptable for new drivers. Ideally this driver should be licensed under the 2-line BSD or dual licensed under it and the GPL if that is necessary. The complete list of commonly acceptable licenses can be found at https://www.freebsd.org/internal/software-license.html
Is there something amd64 specific about this driver?