This patch allows user to simply select which GPIOs he wants to use
and access them via /dev/gpio_a0 or similar device with standard
gpio driver.
By default gpio names match pin names printed on the board. So when
enabling A3 pin, it will show as /dev/gpio_a3 in runtime. This name
can be changed in kconfig.
User can also select pin function (input, output, interrupt) as well
as standard pin settings like, pull up/down, output type
pushpull/open drain etc.
All pins that are exposed via boards goldpins are listed in Kconfig.
Extra pins that are supported by chiip but are not exposed for easy
usage are not listed.
To have this nice Kconfig configuration and for things to be easily
debugable/understandable it requires code to have big Kconfig and
header file with all possible definitions
Because of file sizes I decided to split gpio related kconfig and
header into separate files. Otherwise it would really make original
files hard to read and find anything.
Signed-off-by: Michał Łyszczek <michal.lyszczek@bofc.pl>
