ec/kontron/kempld: Add minimal GPIO driver

The patch adds an interface for configuring GPIOs inside the Kontron
CPLD/EC. This allows to statically define the mode for each GPIO pin
in devicetree.cb of the motherboard or carrier board. For example:

chip ec/kontron/kempld
	device gpio 0 on
		register "gpio[0]"  = "KEMPLD_GPIO_INPUT"
		register "gpio[4]"  = "KEMPLD_GPIO_OUTPUT_LOW"
		register "gpio[5]"  = "KEMPLD_GPIO_OUTPUT_HIGH"
		register "gpio[11]" = "KEMPLD_GPIO_DEFAULT"
	end
end

In this case, <device gpio 0>, like all other devices, is not a real
device inside the EC. These definitions are used to understand the EC
resources and systematize configuration options, but if mark this as
<off>, the initialization step will be skipped in the driver code.

Use KEMPLD_GPIO_DEFAULT or skip it in devicetree.cb to not configure
the GPIO and keep the default mode after CPLD reset.

This work is based on code from the drivers/gpio/gpio-kempld.c linux
driver. Tested on Kontron mAL-10 COMe module [1].

[1] CB:54380 , Change-Id: I7d354aa32ac8c64f54b2bcbdb4f1b8915f55264e

Change-Id: Id767aa451fbf2ca1c0dccfc9aa2c024c6f37c1bb
Signed-off-by: Maxim Polyakov <max.senia.poliak@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/47595
Reviewed-by: Nico Huber <nico.h@gmx.de>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

0 files changed, 0 insertions, 0 deletions