GPIO support

[gabrielandrade2]

Hello,

I would like to know if the GPIO command inside u-boot is supported for the Edison.
I need to set some of the pins as early as possible during the boot process and since the intel IFWI is not open, u-boot should be the way.

I was able to compile the source code from the v2015.10 branch with the #define CONFIG_CMD_GPIO enable on the edison.h file and the gpio command is now available inside u-boot,b ut I cannot set or clean any of the GPIO pins. I keep getting "Command 'gpio' failed: Error -22" at every command I try.
Testing "gpio status -a" doesn't return anything.

This behavior made me believe that there is some code that make u-boot compilable with that define enable but it is not the correct code for the Edison GPIO. Am I correct?

Thanks in advance.

[andy-shev]

Handling GPIO requires a driver for GPIO and an underlying pin control support. I'm pretty sure that is absent in U-Boot for Merrifield and quite likely will be staying this way. Of course you might port it from recent Linux kernels (though in this case I would recommend to use my version of U-Boot).

[andy-shev]

@akiyama-san

There is also native Linux way how to do that, I posted an example here.

P.S. This will require to use at least v4.8 Linux kernel (better to use it from my eds branch).