It is possible to have a platform specific firmware files released by Broadcom to support specific partner modules or added features.
In order to accommodate specific firmware files for WLAN and BT/BLE, the common firmware files could be replaced in ./resources/firmware/<WLAN_CHIP>/ for WLAN and ./libraries/drivers/bluetooth/firmware/<BT_CHIP><BT_CHIP_REVISION>/ for BT/BLE. Replacing these firmware files will effect all other platforms because they share the same firmware files.
Instead of replacing the WLAN firmware file in common ./resources/firmware/<WLAN_CHIP>/ directory, the platform specific WLAN firmware could be placed in the platform directory. Such as, ./platforms/<platform>/firmware/ directory could be created and the platform specific WLAN firmware could be placed in there.
In order for makefiles to pick up the correct firmware, below lines need to be added in the platform makefile, ./platforms/<platform>/<platform>.mk:
The ./libraries/drivers/bluetooth/firmware/43341B0_PlatformSpecificHCD specific directory is created based on above changes. The platform specific BT/BLE firmware file bt_firmware_image.c file is placed in this new directory.
If needed, a platform specific firmware for 40MHz operations could be placed in the ./libraries/drivers/bluetooth/firmware/43341B0_PlatformSpecificHCD/40MHz directory as well.