Con debian Jessie:
https://wiki.debian.org/brcm80211#Debian_7_.22Wheezy.22

deb http://http.debian.net/debian/ wheezy main contrib non-free
apt-get install firmware-brcm80211
modprobe -r brcmsmac ; modprobe brcmsmac

Si no funciona, probad este: https://wiki.debian.org/wl#Debian_7_.22Wheezy.22