I got in touch with Zhu Yi from Intel who works on the Linux drivers for the Intel wifi cards. He helpfully pointed me towards some code in the Linux kernel tree which documents both 2200 and 3945+ cards in more detail than the FreeBSD code. To avoid any confusion: no Intel did not provide any internal documentation etc. because according to Yi it doesn’t exist. We did get pointed to places where we can find the information, and where we weren’t looking earlier. So now we have quite a bit of more docs to look at while coding. Development should be faster now.