Eric Anholt [off-list ref] writes:

The BCM2835-ARM-Peripherals.pdf documentation specifies what the
function selects do for the pins, and there are a bunch of obvious
groupings to be made.  With these created, we'll be able to replace
bcm2835-rpi.dtsi's main "set all of these pins to alt0" with
references to specific groups we want enabled.

Sigh.  The host I've been using for relaying SMTP apparently decided
this week that it doesn't like half my mail.

I'll be off fixing this, so for now if anyone wants to look at the
series it's just in my repo:

https://github.com/anholt/linux/tree/bcm2835-dt-gpio