Hi Sun,
Yes, it can be configured as GPIO, below is from reference manual.
It has been defined in "arch/arm/boot/dts/imx6ul-pinctrl.h",
#define MX6UL_PAD_NAND_DQS__GPIO4_IO16 0x01b8 0x0444 0x0000 5 0
You should add it to device tree .like imx6ull-14x14-evk.dts. see below, please!
&iomuxc {
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_hog_1>;
pinctrl_hog_1: hoggrp-1 {
fsl,pins = <
MX6UL_PAD_UART1_RTS_B__GPIO1_IO19 0x17059 /* SD1 CD */
MX6UL_PAD_GPIO1_IO05__USDHC1_VSELECT 0x17059 /* SD1 VSELECT */
MX6UL_PAD_GPIO1_IO09__GPIO1_IO09 0x17059 /* SD1 RESET */
MX6UL_PAD_NAND_DQS__GPIO4_IO16 0x17059
>;
};
Then on application level , you can operate it , detailed information can be obtained from internet. see the link, please!
https://blog.csdn.net/tiger99111/article/details/80940953
Have an nice day!
BR,
Weidong