RK_SPI_TXFTLR
RK_SPI_WRITE_4(sc, RK_SPI_TXFTLR, txftlr);
reg = RK_SPI_READ_4(sc, RK_SPI_TXFTLR);
RK_SPI_WRITE_4(sc, RK_SPI_TXFTLR, 0);
RK_SPI_WRITE_4(sc, RK_SPI_TXFTLR, sc->fifo_size/2 - 1);