TWS_I2O0_HIBDB
reg = tws_read_reg(sc, TWS_I2O0_HIBDB, 4);
TWS_TRACE_DEBUG(sc, "in bound door bell read ", reg, TWS_I2O0_HIBDB);
tws_write_reg(sc, TWS_I2O0_HIBDB, reg | TWS_BIT8, 4);