> If you can solve a problem in userspace, why bother force-fitting it into the kernel? Chumby probably could have figured out a way to make the STM32 show up as an actual /dev/rtc0 device…but what would the advantage have been over the scripts they wrote? None.

For something like the Chumby, where userland is basically fixed and doesn't have a half dozen distros building on top of it, I agree. But if this were commodity hardware that Debian, Ubuntu, Arch, Mint, etc wanted to pull in support for, the extra time spent making /dev/rtc0 would mean the distros don't have to implement their own non-standard implementation of setting the clock.