SPI_SR
while((READ4(sc, SPI_SR) & SR_EOQF) == 0)
reg = READ4(sc, SPI_SR);
WRITE4(sc, SPI_SR, reg);
while((READ4(sc, SPI_SR) & SR_RFDF) == 0)
while(!(READ4(sc, SPI_SR) & SR_TX_EMPTY))