Qualcomm Atheros has open-sourced the firmware for the AR9271 and AR7010 802.11n WiFi chipsets. The source-code to the firmware as well as the build tools have been opened up. The new Atheros code is under a combination of the GPLv2 and MIT.
The Qualcomm Atheros AR7010 and AR9271 802.11n wireless chips are already supported under Linux using the ath9k 802.11n driver. The wireless adapters are also supported under BSD using the athn driver. The AR9271 is a single-chip SoC solution while the AR7010 is commonly paired with the AR9280 or AR9277 chip for external wireless.
The opened up firmware for these Qualcomm Atheros USB WiFi adapters can be found hosted on GitHub. It was Atheros developers who previously called for killing all proprietary drivers for good. Back in 2008 the company also open-sourced their HAL.