This adds support for line-buffered console output to System76 EC firmware.
Once the print command is received, the EC firmware multiplexes the output
to any enabled console on the EC. This can be a memory ringbuffer, a
parallel port (using the keyboard connector), or i2c (using the battery
connector). Once the entire buffer is sent, it sets the command register
to 0, indicating completion. For more information, please see:
https://github.com/system76/ec/blob/master/doc/debugging.md
Tested on system76/lemp9 with CONSOLE_SYSTEM76_EC enabled.
Signed-off-by: Jeremy Soller <jeremy@system76.com>
Change-Id: I861bf3e22f40dd6c3ec7ba1d73711b399358e332
Reviewed-on: https://review.coreboot.org/c/coreboot/+/43718
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Michael Niewöhner
52785ab327