APPLE_SPI_IE_XFER
reg_write(spi, APPLE_SPI_IE_XFER, 0);
u32 xfer = reg_read(spi, APPLE_SPI_IF_XFER) & reg_read(spi, APPLE_SPI_IE_XFER);
reg_write(spi, APPLE_SPI_IE_XFER, 0);
reg_write(spi, APPLE_SPI_IE_XFER, xfer_bit);
reg_write(spi, APPLE_SPI_IE_XFER, 0);