I'm searching a OpenSource software stack to run Wifi module with STM32 with SDIO connection up to 48Mhz, I found this Company in US offering a nice solution with a GPL code :
there is a module from RS advertised as WiFi Application Module EDP-AM-WFSD
''... Through hosting a WiFi SD cad, such as Spectec 802.11b card, the module allows communication rates of 11Mbit/s over distances of up to 150m...'' It doesn't say anything about software, but as it is for EDP systems http://rswww.com/edp it must run for example on STR9 (???) Jan