[L] Change in flashrom[master]: programmer: Add bitbanging programmer driver for Linux libgpiod

[Steve Markgraf (Code Review)]

Attention is currently required from: Thomas Heijligen, Angel Pons, Steve Markgraf.

Hello build bot (Jenkins), Thomas Heijligen, Angel Pons,

I'd like you to reexamine a change. Please visit

https://review.coreboot.org/c/flashrom/+/71801

to look at the new patch set (#2).

Change subject: programmer: Add bitbanging programmer driver for Linux libgpiod
......................................................................

programmer: Add bitbanging programmer driver for Linux libgpiod

With this driver, any single board computer, old smartphone, etc. with
a few spare GPIOs can be used for flashrom.

An example invocation looks like this:

flashrom -p linux_gpiod:gpiochip=0,cs=18,sck=19,mosi=13,miso=56

This uses /dev/gpiochip0 with the specified GPIO numbers for the SPI
lines. All arguments are required.

Reading of a 2048 kB flash chip on a Qualcomm MSM8916 SoC @800 MHz:

Found GigaDevice flash chip "GD25LQ16" (2048 kB, SPI) on linux_gpiod.
real    1m 33.96s

Change-Id: Icad3eb7764f28feaea51bda3a7893da724c86d06
Signed-off-by: Steve Markgraf 
---
M MAINTAINERS
M Makefile
M flashrom.8.tmpl
M include/programmer.h
A linux_gpiod.c
M programmer_table.c
6 files changed, 254 insertions(+), 1 deletion(-)

git pull ssh://review.coreboot.org:29418/flashrom refs/changes/01/71801/2