Oliver O'Halloran [off-list ref] writes:

Rather than checking the compatible string in serial_driver_init()
we call into the driver's init function and wait for a driver to
inidicate it bound to the device by returning zero.

The pointers to each driver probe functions are stored in the
".serialdrv" section of the zImage, similar to how initcalls and
whatnot are handled inside Linux. This structure allows us to
conditionally compile specific driver files based on the KConfig
settings. This is needed because we don't have access to the
KConfig #defines in the zImage source files (it's a giant #include
headache) so conditional compilation is the only way to eliminate
unnecessary code.

Did you actually get the config.h include working? Or was it such a big
headache that it doesn't even work?

I'm pretty happy with this patch regardless, but it would be simpler and
less bug prone if the CONFIG_ symbols were usable in the boot code.

cheers