GPIO use

Pierre PAK · July 2017

I have some difficulties to reach GPIO pin through Panasonic 100-Pin connectors with an Linux OS.
The main problem concern is that the mapping provided does not contain the port numbers GPIO side OS (Ubilinux). After some tests, it turns out that the GPIO ports on the Linux side start at 318 and then dispatch "randomly" (it's over 500). It is therefore difficult to connect the pin 46 (GPIO25 / PWM0) with the corresponding port on the Linux side. It is necessary for us to interface with a driver.

Could you help us to use GPIO port with linux?

Aling · August 2017

Hi ,

UP Core is still not in officially released yet. We will come back to support once we finish all the verification and start mass production.

stez_mind · May 2018

Hi @Aling , any news on this?

UpCore has been long released but still, I can't find any documentation regarding GPIO mapping on Linux.

It would be very helpful to have a page for UpCore similar to this one for UpBoard.

Thanks,
Stefano

stez_mind · May 2018

FYI,
it's possible to retrieve the information from the relevant Intel pinctrl driver that handles the mapping:

https://github.com/emutex/ubilinux-kernel/blob/upboard-4.9/drivers/pinctrl/intel/pinctrl-cherryview.c

GPIOs are divided into 4 groups, and you can find the base number for each group with:

cat /sys/kernel/debug/gpio

which on my setup gives:

gpiochip3: GPIOs 318-372, parent: platform/INT33FF:03, INT33FF:03:

gpiochip2: GPIOs 373-396, parent: platform/INT33FF:02, INT33FF:02:

gpiochip1: GPIOs 397-455, parent: platform/INT33FF:01, INT33FF:01:
 gpio-404 (                    |ACPI:OpRegion       ) out hi

gpiochip0: GPIOs 456-511, parent: platform/INT33FF:00, INT33FF:00:

Then, you need to lookup the index of the GPIO you need (in my case Pin32 of the 100-pin connector, ISH_GPIO0 on the UpCore datasheet, which correspondes to "MF_ISH_GPIO_0" in the driver) and sum it to the relevant base GPIO number (in my case 373, so the Linux GPIO for that pin is 373+18=391).

It still would be nice if someone has time to prepare a ready available table as there is one for the UpBoard.