Here’s a link to the official open source driver from Broadcom.
Broadcom.com - 802.11 Linux STA driver
official - yes
Broadcom - yes
open source - no
Make sure that you download the appropriate tar because the hybrid binary file must be of the appropriate architecture type. The hybrid binary file is agnostic to the specific version of the Linux kernel because it is designed to perform all interactions with the operating system through operating-system-specific files and an operating system abstraction layer file. All Linux operating-system-specific code is provided in source form, making it possible to retarget to different kernel versions and fix operating system related issues.
NOTE: You must read the LICENSE.TXT file in the lib directory before using this software
Ok, partially open source.
" All Linux operating-system-specific code is provided in source form, making it possible to retarget to different kernel versions and fix operating system related issues."