Additionaly to the info provided by JerryChang you can set a GPIO to high through a device tree definition. You can take the following code as reference, this uses the gpio-controller node (see https://www.kernel.org/doc/Documentation/devicetree/bindings/gpio/gpio.txt). GPIOs for the TX2 are defined in hardware/nvidia/soc/tegra/kernel-include/dt-bindings/gpio/tegra186-gpio.h.
gpios = <TEGRA_MAIN_GPIO(X, 6) 0>;
label = "camera-enable-output";
status = "okay";
To map a GPIO from schematics to the corresponding device tree definition you’ll need the pinmux spreadsheet https://developer.nvidia.com/embedded/dlc/jetson-tx2-series-module-pinmux. For example, in the definition above the gpio478 (GPIO3_PX.06) is being set to high.
Hope this info helps.