Mapping TEGRA234_MAIN_GPIO to 40-pin GPIO on Nvidia Jetson Orin Nano

Issue Overview

Users of the Nvidia Jetson Orin Nano development board are seeking guidance on how to correctly map the TEGRA234_MAIN_GPIO to the 40-pin GPIO header. This mapping is crucial for proper GPIO control in device tree source (dtsi) files and kernel drivers. The specific challenge involves adding the correct GPIO configuration in the device tree and using the of_get_named_gpio function in the kernel driver to retrieve and control the GPIO pins.

Possible Causes

1. Lack of documentation: Users may not have access to or be aware of the specific pinout and mapping information for the Jetson Orin Nano.

2. Complexity of GPIO mapping: The relationship between the TEGRA234_MAIN_GPIO nomenclature and the physical 40-pin header may not be immediately obvious.

3. Differences between devkit and custom boards: The GPIO mapping might vary depending on whether a user is using the official developer kit or a custom board.

Troubleshooting Steps, Solutions & Fixes

To properly map TEGRA234_MAIN_GPIO to the 40-pin GPIO header on the Nvidia Jetson Orin Nano, follow these steps:

1. Identify your board type:
   Determine whether you are using the official Jetson Orin Nano Developer Kit or a custom board, as this may affect the GPIO mapping.

2. Consult documentation:
   Refer to the Jetson Orin Nano Developer Kit Carrier Board document and the pinmux spreadsheet for accurate pin mapping information.

3. Locate the desired GPIO pin:
   Find the specific pin you want to use on the 40-pin header in the carrier board document. For example, PIN32 corresponds to GPIO07.

4. Cross-reference with pinmux spreadsheet:
   Look up the chosen pin in the pinmux spreadsheet to find its corresponding TEGRA234_MAIN_GPIO designation. For PIN32 (GPIO07), it is identified as PG.06 when used as a GPIO.

5. Configure the device tree:
   Use the information obtained to properly configure the TEGRA234_MAIN_GPIO in your device tree. For the PIN32 example, the configuration would be:

   gpio = <&tegra_main_gpio TEGRA234_MAIN_GPIO(G, 6) GPIO_ACTIVE_LOW>;
   

   Replace (G, 6) with the appropriate values for your chosen pin.

6. Implement kernel driver:
   In your kernel driver, use the of_get_named_gpio function to retrieve and control the GPIO pin as intended.

7. Verify configuration:
   Test your GPIO configuration to ensure it’s working as expected. You may need to use additional tools or write test code to confirm proper functionality.

8. Repeat for other pins:
   If you need to configure multiple GPIO pins, repeat steps 3-7 for each pin, ensuring you use the correct TEGRA234_MAIN_GPIO mapping for each.

By following these steps and using the provided documentation, you should be able to successfully map TEGRA234_MAIN_GPIO to the 40-pin GPIO header on your Nvidia Jetson Orin Nano board. If you encounter any issues or need further clarification, consult the official Nvidia Jetson documentation or seek support from the Nvidia developer community.