Using SCU_GPIO0_01 as a GPIO from A35 on i.MX 8QuadXPlus

[wmr-veranex]

Is it possible to change the output of SCU_GPIO0_01 from the A35 in Yocto Linux 6.6.y without changing either the SCU or the M40 firmware?

I am working with a hardware design that is already mature and has SCU_GPIO0_01 wired out to other logic circuits that I need to control.

Or, is it possible to change the pinmux function of that pin from Linux userspace?  I have found that switching between the functions SCU_GPIO0_IO01 and M40_UART0_TX by changing device trees and rebooting gives the low and high outputs on that pin that I am seeking, so changing the pinmux from userspace would be another way that I could control that line if changing the drive directly is not an option.

[JorgeCas · Accepted solution]

Hello,

Is needed to modify SCFW to modify IOMUX registers as you can check in:

https://community.nxp.com/t5/i-MX-Processors-Knowledge-Base/System-Controller-Firmware-101-Pad-confi... 

I suggest you take a look in the next post:

https://community.nxp.com/t5/i-MX-Processors/How-to-access-SCU-GPIO0-00-from-core-A35-u-boot-or-Linu... 

Best regards.