Here the PolarSSL maintainer
Sounds like the assembly code selects some code that seems appropriate but is not on a Elan 520..
The only assembly code selected is in bn_mult.h and timing.c. It is selected based on compiler defines (mostly based on platform and CPU).
Are you able to dig up for me which 'branch' of the assembly is used for both files?
If so, I might be able to tighten down the defines to not be selected on these chips..
You can also contact me directly if that makes it easier: paul at polarssl dot org
Regards,
Paul