[coreboot] [PATCH] Proposal for dealing with superio *.c includes

[Alex G.]

Hi guys!

I present a proposal for dealing with the annoying:
#include "superio/vendor/model/early_serial.c"
present in virtually all romstage.c files.

The steps are as follows:
1) Declare a generic prototype: superio_enable_early_serial();
2) Remove #include */early_serial.c from romstage
3) add a romstage-$(CONFIG_THIS_SUPERIO) += early_serial.c to the
superio's Makefile.inc
4) Include the generic "superio/early_serial.h" definition in romstage.c
5) Include the superio specific header in romstage.c
6) Done

I'm demonstrating this with the fintek/f81865f superio, and the
amd/persimmon board. Besides discussion, this patch is also intended for
inclusion.

See patch for more details.