How can I set up GPIO in I.MX8QuadXPlus

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Dear NXP

I’m developing with Digi connectCore 8X SBC Pro(NXP i.MX8QuadXPlus).

I’d like to set the mode and direction of GPIO0_IO05, but I failed.

Would you please tell me how to set up GPIO.

The following is how I set up GPIO in device tree.

1) Find the i.MX 8x pad name for GPIO0_IO05

I could find the pad name through the manual web site.

https://www.digi.com/resources/documentation/digidocs/PDFs/90002295.pdf

I found that ESAI0_TX1, the pad name what I found, is related to Ethernet.

Also, I found these macros related to ESAI0_TX1.

SC_P_ENET0_RGMII_RXD3_CONN_ENET0_RGMII_RXD3

SC_P_ESAI0_TX1_CONN_ENET1_RGMII_RXD3

2) Device tree Settings for GPIO pads

I did device tree setting for GPIO pads by referring below website.

https://github.com/FrankBau/meta-marsboard-bsp/wiki/iMX6-Pad-Mux-and-Pad-Control

The following is device tree setting by referring to the website.

/* IOMUX */

&iomuxc {

        pinctrl-names = "default", "default";

        pinctrl-0 = <&pinctrl_expansion>;

        pinctrl-1 = <&pinctrl_hog>;

           /* Expansion Connector */

        pinctrl_expansion: expansiongrp {

                fsl,pins = <

                                 . . .

pinctrl_hog: hoggrp {

                fsl,pins = <

                                 /* (1<<3): output drive strength of 150 Ohm at 3.3V */

                        SC_P_ENET0_RGMII_RXD3_CONN_ENET0_RGMII_RXD3     8

                        SC_P_ESAI0_TX1_CONN_ENET1_RGMII_RXD3    8

                >;

        };

};

3) Check the GPIO status on sysfs

The following is an output of GPIO status from sysfs after kernel boot.

But, GPIO0_IO05 which kernel number is 485 was not found in the GPIO status list for sysfs.

The Linux GPIO number of GPIO0_IO05 is 485.

The Linux GPIO number can be calculated through the formular.

https://www.digi.com/resources/documentation/digidocs/embedded/android/pie/cc8x/bsp_r_gpio_8x

N = 480 – (32 * <port_index>) + pin

1. ex) GPIO0_IO05(port 0, pin 5) is: 480 + 5 = 485

ccimx8xsbcpro:/ # cat /sys/kernel/debug/gpio                                  

gpiochip9: GPIOs 204-223, parent: platform/mca-cc8x-gpio, mca-gpio, can sleep:

 gpio-210 (                    |ADC                 ) in  lo   

 gpio-211 (                    |ADC                 ) in  lo   

gpiochip8: GPIOs 224-255, parent: platform/58222000.gpio, 58222000.gpio:

gpiochip7: GPIOs 256-287, parent: platform/5d0f0000.gpio, 5d0f0000.gpio:

gpiochip6: GPIOs 288-319, parent: platform/5d0e0000.gpio, 5d0e0000.gpio:

gpiochip5: GPIOs 320-351, parent: platform/5d0d0000.gpio, 5d0d0000.gpio:

gpiochip4: GPIOs 352-383, parent: platform/5d0c0000.gpio, 5d0c0000.gpio:

 gpio-352 (                    |PCIe reset          ) out hi   

 gpio-353 (                    |PCIe CLKREQ         ) out lo   

 gpio-357 (                    |3v3_usb_sw          ) out hi   

 gpio-374 (                    |cd                  ) in  hi IRQ

gpiochip3: GPIOs 384-415, parent: platform/5d0b0000.gpio, 5d0b0000.gpio:

 gpio-393 (                    |mca-fw-update       ) out lo   

 gpio-394 (                    |BT power enable     ) out hi   

 gpio-395 (                    |PCIe DIS            ) out hi   

 gpio-396 (                    |epdev_on            ) out hi   

 gpio-397 (                    |3v3_eth0            ) out lo   

gpiochip2: GPIOs 416-447, parent: platform/5d0a0000.gpio, 5d0a0000.gpio:

gpiochip1: GPIOs 448-479, parent: platform/5d090000.gpio, 5d090000.gpio:

gpiochip0: GPIOs 480-511, parent: platform/5d080000.gpio, 5d080000.gpio:

 gpio-493 (                    |5v_display          ) out lo   

 gpio-494 (                    |3v3_audio           ) out lo   

 gpio-495 (                    |3v3_usb_hub         ) out hi   

 gpio-511 (                    |vcc                 ) out hi