p54 is the mac80211 stack dependent wireless driver, it supports softMAC Intersil/Conexant Prism GT, fullMAC Intersil Prism GT, as well as Intersil/Conexant Prism GT USB dongle based chipsets. This driver has been incorporated into kernel since 2.6.26.
Not to be confused with prism54 driver which is dependent on the legacy ieee80211 stack, has injection support but only supports Intersil Prism GT fullMAC cards.
Injection patches are available but you will need to patch it against the mac80211 stack and recompile the driver. It is recommended that you have at least kernel 2.6.28 or above as p54 may have issues recognising firmware properly.
More information on how to get the driver working can be found at http://wireless.kernel.org/en/users/Drivers/p54. If you have difficulty understanding what filename should the firmware be named as for it to work, once you plug the device in, check the last few lines of dmesg or /var/log/messages for information.