ZY7_SLCR_FPGA_THR_CNT
WR4(sc, ZY7_SLCR_FPGA_THR_CNT(unit), 0);
WR4(sc, ZY7_SLCR_FPGA_THR_CNT(unit), 1);
reg = RD4(sc, ZY7_SLCR_FPGA_THR_CNT(unit));