The open-source HostAP driver supports the IEEE 802.11b Prism 2/2.5/3 family of chips.
Wireless adaptors which use the Prism chipset are known for compatibility, and are preferred for specialist applications such as packet capture.
Intersil initially provided a Linux driver for the first Prism54 chips which implemented a large part of the 802.11 stack in the firmware.
In the meantime, the PRISM business was sold to Conexant, which never published information about the newer firmware API that would enable a Linux driver to be written.
However, a reverse engineering effort eventually made it possible to use the new Prism54 chipsets under the Linux and BSD operating systems.