Adding device tree info and GPIO boot-up states to EEPROM

[mehrdadfeller]

Currently I am using the eeptools for Pi utilities to read, write, and update the eeprom content. I have a python wrapper for the CLI and that part works well (needs some code clean though)

https://github.com/raspberrypi/utils/tree/master/eeptools

Right now I am not adding any DTB (Device Tree Blobs) and GPIO Info to EEPROM and only custom data (which is the factory test result).

Here we can share ideas for different blobs to add and what config to load into the EEPROM.

[mehrdadfeller]

Here's an example of DTB:

/dts-v1/;
/plugin/;

/ {
    compatible = "raspberrypi,my-hat";

    fragment@0 {
        target = <&i2c1>;
        __overlay__ {
            #address-cells = <1>;
            #size-cells = <0>;

            my_sensor: sensor@76 {
                compatible = "vendor,sensor-model";
                reg = <0x76>; // I2C address
                status = "okay";
                
                interrupt-parent = <&gpio>;
                interrupts = <17 2>; // GPIO 17, falling edge interrupt
                interrupt-names = "data-ready";
            };
        };
    };

    fragment@1 {
        target = <&gpio>;
        __overlay__ {
            my_gpio: gpio {
                brcm,pins = <17>; // GPIO pin number
                brcm,function = <0>; // 0:input, 1:output
                brcm,pull = <2>; // 2:pull-up, 1:pull-down, 0:no pull
            };
        };
    };
};

[mehrdadfeller]

@sassanh looks like uncle jeff has a good write up on this:

https://www.jeffgeerling.com/blog/2023/how-customize-dtb-device-tree-binary-on-raspberry-pi