Freebsd wifi setup on raspberry pi

Get TP-Link USB wifi module to load.
 Edit /boot/loader.conf
 Add

if_rtwn_load="YES"
legal.realtek.license_ack=1
if_rtwn_usb_load="YES"
wlan_wep_load="YES"
wlan_ccmp_load="YES"
wlan_tkip_load="YES"

Then reboot.

Run ifconfig -a to check if wlan0 is up.

Manual test
ifconfig wlan create wlandev rtwn0 inet 192.168.0.20 netmask 0xffffff00

 wlan0 is now up.