Summary
We just dealt with SPI drivers and can now take advantage of this faster serial (and full-duplex) bus. We walked through data transfer over SPI, which was the most important section. You may need more abstraction in order not to bother with SPI or I2C APIs. This is where the next chapter comes in, dealing with the regmap API, which offers a higher and unified level of abstraction, so that SPI (or I2C) commands will become transparent to you.