There is a mapping based on the device number, for e.g if the user tries to use the below sysfs file for loading
/sys/devices/virtual/misc/intel_ifs_<N>/current_batch
The driver will look for the below test image for loading
/lib/firmware/intel/ifs_<N>/ff-mm-ss-02x.<test_type>
The number<N> is same in both the above path.