Those are just drivers to stuff that runs its own cpu and interfaces over some kind of serial port. Printers are a well known example of this. Also intel wireless nics with their firmware blobs.

Not are drivers are like that. For instance, drivers/input/serio/ps2-gpio.c is all about timing the right signals.

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charcircuit 3 days ago | parent [-]

You are missing the point. The kernel is still abstracting over those GPIO timings so programs don't need to know the timings themselves. This is the benefit of using a platform. These low level things get abstracted away from what you have to do.

	▲	tosti 3 days ago \| parent [-]
		Oh, I see. You're piecing together the layers much like a cake. The way I see it, everything is tied together as some kind of flow chart where different elements have different jobs. Linux is quite a small part of the system when compared to Google Chrome. Even if you were to invert the cake, as a whole it still wouldn't make sense to me to see it that way. Hardware tends to have more distinct layering than the lalala-land of software where pretty much anything goes.