CHERIoT hardware revocation engine

This block is integrated from the CHERIoT Safe repository. It controls the hardware revoker inside CHERIoT Ibex which is the thing that does the revocation, it is looking for capabilities to freed memory. When a piece of memory is freed its revocation bits are set. The hardware revoker sweeps from the start until the end address for capabilities that point to any revoked region. For more information on how this works please refer to Section 3.3.3 (background pipelined revoker) of this paper.

These are the register offsets:

OffsetRegister
0x0000Start address to begin sweeping.
0x0004End address to stop sweeping.
0x0008Most significant byte is set to constant 0x55. least significant bit is asserted for one cycle when sweeping starts.
0x000CEpoch, where the last bit means a sweep is currently happening.
0x0010Read interrupt status, but is only high for one cycle.
0x0014Enable bit for raising an interrupt when sweeping is done.
0x0040Debug: FIFO empty and read data values.
0x0044Debug FIFO full, empty and depth values.