Subversion Repositories openrisc_2011-10-31

This is a Wishbone wrapper for the Actel user flash ROM (UFR) found on its

FPGAs. This flash ROM cannot be inferred and must be explicitly instantiated.

The instantiated module devboard_flashrom should be in the

backend/actel/rtl/verilog path, and was generated with Actel's smartgen.

See the user flashrom handbook from Actel for further information on the UFR:

http://www.actel.com/documents/LPD_FlashROM_HBs.pdf

This document from Actel says that "the access time is 10 ns for a device

supporting commercial specifications", and the Wishbone interface asserts

wb_ack after 2 cycles, allowing even a 200MHz wishbone bus to access the module

in time, however after PAR, timing reports a maximum access frequency of 14MHz,

so do more testing before relying on this module.