So I decided to use the OpenBSD website manual pages and
Wikipedia to try to answer this question- Wikipedia is not authoritative per se, but likely they are correct on their information in this regard.
The Broadcom chipsets listed on the Wikipedia page are 4700 series and higher. The
bwi(4) man page only lists hardware in the 4300 series of chipsets.
The Atheros chipsets listed on the Wikipedia page are the AR2317 and AR5100AP chipsets. The
ath(4) man page only lists hardware in the 5200 series of chipsets.
The WRT54GC uses the Marvell Libertas chipset, listed as AR914. The
malo(4) man page lists the 88W8335/88W8310/88W8385 based cards. Perhaps the AR914 is one of these in another name. Perhaps not.
Perhaps the information contained on Wikipedia is inaccurate, I cannot vouch for it.