Enable SPI0 On Ubuntu 24 (Orange Pi 5 Plus)

Oct 22, 2025 by SLV Team 44 views

Enabling SPI0 on Ubuntu 24 (Orange Pi 5 Plus) via Device Tree Overlays

Hey everyone! Today, we're diving into the process of enabling SPI0 on Ubuntu 24 running on an Orange Pi 5 Plus. We'll walk through the steps to get your SPI interface up and running using device tree overlays. This guide is perfect for those looking to integrate hardware modules like TPM2.0 or other SPI-based devices.

Introduction to SPI and Device Tree Overlays

Before we get our hands dirty, let's briefly touch on what SPI and device tree overlays are. SPI (Serial Peripheral Interface) is a synchronous serial communication interface used for short-distance communication, primarily in embedded systems. It's a common way for microcontrollers to talk to peripherals like sensors, memory, and other integrated circuits.

Now, device tree overlays are a way to dynamically modify the device tree at boot time. The device tree describes the hardware components of a system, and overlays allow you to add or modify nodes in the tree without recompiling the entire device tree. This is incredibly useful for enabling or configuring hardware features like SPI without having to rebuild the kernel every time.

Use Case: Integrating a TPM2.0 Module

In our specific scenario, we're integrating a TPM2.0 (Trusted Platform Module) for enhanced security. TPM2.0 modules often communicate via SPI, so enabling SPI0 is a crucial step. The user successfully integrated the TPM2.0 module using the official Ubuntu 22.04 image by compiling a new kernel and adding a custom overlay. However, they want to leverage the newer TPM2.0 APIs available in Ubuntu 24.04. So, the goal is to activate a precompiled SPI0 overlay on Ubuntu 24 to test its functionality.

Prerequisites

Before we begin, ensure you have the following:

An Orange Pi 5 Plus.
Ubuntu 24.04 installed on your Orange Pi 5 Plus.
Basic familiarity with Linux command line.
Root access to your Orange Pi 5 Plus.
A text editor like nano or vim.

Step-by-Step Guide to Activating SPI0

1. Kernel Configuration

First, ensure that your kernel is compiled with the necessary configurations. This involves enabling the TCG_TPM and TCG_SPI_TIS options. If you've already compiled a kernel with these options, you can skip this step. If not, you'll need to recompile your kernel.

Here’s a quick overview of how to compile the kernel (assuming you have the kernel source code):

make ARCH=arm64 defconfig
make ARCH=arm64 menuconfig

In the menuconfig, navigate to:

Device Drivers  --->
    <*> TCG Core Options  --->
        <*>   TPM Hardware Support  --->
            <*>   TPM Interface Specification (TIS) using SPI

Ensure that these options are selected. Then, compile and install the kernel:

make ARCH=arm64 -j$(nproc)
sudo make ARCH=arm64 modules_install
sudo make ARCH=arm64 install

Note: Compiling a kernel can take a significant amount of time, depending on your hardware.

2. Identifying the Correct Device Tree Overlay

Navigate to the device tree overlay directory:

cd /lib/firmware/6.1.0-xxxx-rockchip/device-tree/rockchip/overlay/
ls

Here, you'll find a list of precompiled overlays. Look for an overlay that corresponds to SPI0. It might be named something like spi0-overlay.dtbo or similar. The exact name may vary depending on your specific kernel and overlay package.

3. Modifying U-Boot Configuration

The key to enabling the overlay is to modify the U-Boot configuration. This involves editing the uEnv.txt file.

sudo nano /boot/firmware/uEnv.txt

Locate the U_BOOT_FDT_OVERLAYS variable. If it doesn't exist, you can add it. If it does, append the path to your SPI0 overlay to the variable. For example:

U_BOOT_FDT_OVERLAYS=/lib/firmware/6.1.0-xxxx-rockchip/device-tree/rockchip/overlay/spi0-overlay.dtbo

If you have multiple overlays, separate them with a space:

U_BOOT_FDT_OVERLAYS=/lib/firmware/6.1.0-xxxx-rockchip/device-tree/rockchip/overlay/spi0-overlay.dtbo /lib/firmware/6.1.0-xxxx-rockchip/device-tree/rockchip/overlay/another-overlay.dtbo

Important: Ensure the path is correct. A typo here can prevent the overlay from loading.

4. Updating U-Boot and Rebooting

After modifying the uEnv.txt file, update U-Boot and reboot your Orange Pi 5 Plus:

sudo u-boot-update
sudo reboot

The u-boot-update command updates the U-Boot environment with the changes you made in uEnv.txt. The reboot ensures that the new configuration is loaded.

5. Verifying SPI0 Activation

After the reboot, check if SPI0 is active by looking for it under the /dev/ directory:

ls /dev/spi*

If SPI0 is correctly enabled, you should see something like /dev/spidev0.0 and /dev/spidev0.1 (the numbers may vary).

Troubleshooting

If SPI0 does not appear under /dev/, here are some troubleshooting steps:

Check the Overlay Path: Double-check the path in U_BOOT_FDT_OVERLAYS to ensure it's correct.
Verify the Overlay File: Make sure the overlay file (spi0-overlay.dtbo) exists in the specified directory.
Kernel Configuration: Ensure that the necessary kernel configurations (TCG_TPM, TCG_SPI_TIS, etc.) are enabled and that the kernel has been correctly compiled and installed.
U-Boot Update: Sometimes, the u-boot-update command may fail. Check its output for any errors.
Device Tree Syntax: The overlay file may contain syntax errors. You can use the dtc command to check the syntax:
```
dtc -I dtbo -O dts /lib/firmware/6.1.0-xxxx-rockchip/device-tree/rockchip/overlay/spi0-overlay.dtbo
```
This command will convert the .dtbo file to a .dts file (device tree source), which is human-readable. Review the output for any syntax errors.
Check for Conflicts: Ensure that there are no conflicting overlays or device tree settings that might be preventing SPI0 from being enabled.

Example SPI0 Overlay (DTS Source)

Here’s an example of what an SPI0 overlay might look like in device tree source (DTS) format:

/dts-v1/;
/plugin/;

/ {
    compatible = "rockchip,rk3588";

    fragment@0 {
        target = <&spi0>;
        __overlay__ {
            status = "okay";

            spidev0: spidev@0 {
                compatible = "spidev";
                reg = <0>;
                spi-max-frequency = <1000000>;
            };
        };
    };

    fragment@1 {
        target = <&gpio0>;
        __overlay__ {
            spi0_pins: spi0_pins {
                rockchip,pins = <
                    RK_PB4 RK_FUNC_1 &pinctrl0
                    RK_PB5 RK_FUNC_1 &pinctrl0
                    RK_PB6 RK_FUNC_1 &pinctrl0
                    RK_PB7 RK_FUNC_1 &pinctrl0
                >;
            };
        };
    };
};

This overlay does the following:

Enables SPI0: Sets the status of the spi0 node to "okay".
Creates a spidev Node: Creates a spidev0 node, which allows you to access SPI0 as a character device (e.g., /dev/spidev0.0).
Configures GPIO Pins: Configures the GPIO pins for SPI0 (MOSI, MISO, SCLK, and CS).

Note: The exact pin configuration may vary depending on your specific hardware setup.

Compiling the Overlay

If you need to compile the overlay from a .dts file, you can use the dtc command:

dtc -I dts -O dtbo -@ spi0-overlay.dts -o spi0-overlay.dtbo

This command compiles spi0-overlay.dts into spi0-overlay.dtbo.

Conclusion

Enabling SPI0 on Ubuntu 24 for the Orange Pi 5 Plus involves configuring the kernel, modifying the U-Boot environment, and verifying the SPI device. By following these steps, you should be able to successfully activate SPI0 and integrate your SPI-based modules, such as TPM2.0. Remember to double-check your configurations and troubleshoot any issues that arise. Happy hacking, and have a great time integrating the TPM2.0 module into your Orange Pi 5 Plus!