This is common code for isl38xx/stlc45xx based modules. This module does nothing by itself - the USB/PCI/SPI front-ends also need to be enabled in order to support any devices. These devices require softmac firmware which can be found at <http://wireless.kernel.org/en/users/Drivers/p54> If you choose to build a module, it'll be called p54common.
This driver is for USB isl38xx based wireless cards. These devices require softmac firmware which can be found at <http://wireless.kernel.org/en/users/Drivers/p54> If you choose to build a module, it'll be called p54usb.
This driver is for PCI isl38xx based wireless cards. This driver supports most devices that are supported by the fullmac prism54 driver plus many devices which are not supported by the fullmac driver/firmware. This driver requires softmac firmware which can be found at <http://wireless.kernel.org/en/users/Drivers/p54> If you choose to build a module, it'll be called p54pci.
This driver is for stlc4550 or stlc4560 based wireless chips such as Nokia's N800/N810 Portable Internet Tablet. If you choose to build a module, it'll be called p54spi.
Unlike the PCI or USB devices, the SPI variants don't have a dedicated EEPROM chip to store all device specific values for calibration, country and interface settings. The driver will try to load the image "3826.eeprom", if the file is put at the right place. (usually /lib/firmware.) Only if this request fails, this option will provide a backup set of generic values to get the device working. Enabling this option adds about 4k to p54spi.