BFE_IMASK
CSR_WRITE_4(sc, BFE_IMASK, BFE_IMASK_DEF);
CSR_WRITE_4(sc, BFE_IMASK, 0);
CSR_READ_4(sc, BFE_IMASK);
CSR_WRITE_4(sc, BFE_IMASK, 0);
CSR_READ_4(sc, BFE_IMASK);
CSR_WRITE_4(sc, BFE_IMASK, BFE_IMASK_DEF);
CSR_READ_4(sc, BFE_IMASK);