Trying to add CAN-BUS arduino shield(MCP2515) to the IOT2050

Hello!

I am trying to add a CAN-BUS arduino shield(MCP2515) to the IOT2050. I would like to have the drivers booted and device recognized at boot with the kernel. For that i know i need to compile the kernel with CONFIG_CAN_MCP251X=m so i get the driver. Than i would need to edit the device tree. And this is where i get a bit lost.

Would like some help with configuring the device tree so i can add a CAN device? Or could you at least tell me witch register addresses correspond to witch SPI ports on the arduino(arduino pins SCK - 13, MISO - 12, MOSI - 11, CS_CAN - 10,  INT - 3)?

Also is there an easier way to edit the .config file and .dts files in kas then file editor?

Thank you for your help.

Update: i was able to configure the device tree so the MCP2515 is recognized by the kernel. It loads it under spi0.0 which is connected to the arduino shield pins 10,11,12,13. In my configuration the interrupt pin is set on the arduino pin 3. The only edited file was k3-am65-iot2050-common.dtsi

Under the &mcu_spi0 i replaced the premade spidev@0 with my can device

can@0 {
        status = "okay";
        reg = <0>;
        compatible = "microchip,mcp2515";
        pinctrl-names = "default";
        pinctrl-0 = <&mcp2515_int>;
        spi-max-frequency = <10000000>;
        interrupt-parent = <&wkup_gpio0>;
        interrupts = <33 2>;
        clocks = <&mcp2515_clock>;

        mcp251x,oscillator-frequency = <16000000>;
        mcp251x,irq-gpios = <&wkup_gpio0 33 0>;
        mcp251x,stay-awake = <1>;
        mcp251x,enable-clkout = <1>;
        gpio-controller;
        #gpio-cells = <2>;
};

 The clock and int pin were added to the &wkup_pmx0

    mcp2515_int: mcp2515_int {
        pinctrl-single,pins = <
            AM65X_WKUP_IOPAD(0x0054, PIN_INPUT, 7)
        >;
    };

    mcp2515_clock: mcp2515_clock {
        compatible = "fixed-clock";
        #clock-cells = <0>;
        clock-frequency = <16000000>;
    };

Hey there,

We will try to help you as much as possible. Unfortunately, we do not currently have access to a sample of your shield, so the following names may differ slightly. :)

To add support for the MCP2515 CAN controller on your Shield, you will need to perform the following steps:

1. Enable the MCP251X driver in the kernel configuration by setting the CONFIG_CAN_MCP251X option to m (for modules).

2. Modify the device tree to describe the MCP2515 device and let it start at boot.

Regarding the second step, you can add the following device tree overlay to describe the MCP2515 device on your Arduino shield as you already did:

{

   fragment@0 {

      target = <&spi0>;

      __overlay__ {

      #address-cells = <1>;

      #size-cells = <0>;

      mcp2515@0 {

         compatible = "microchip,mcp2515";

         reg = <0>;

         spi-max-frequency = <10000000>;

         interrupt-parent = <&gpio1>;

         interrupts = <15 0x2>;

         status = "okay";

                };

             };

       };

};

 This device tree overlay describes the MCP2515 device connected to your device. It specifies the device's compatible string, the SPI bus frequency, and the interrupt line connected to the INT pin on the extension shield.

To apply this overlay, you can add the following line to the local.conf file in the Project build directory:

DEVICE_TREE_OVERLAYS_append ="mcp2515"

This will include the MCP's device tree overlay in the resulting Linux image, if you want to build your own.

BR

Almost, but DEVICE_TREE_OVERLAYS is Yocto, this is Isar.

In Isar, you can add overlays to u-boot-script (when not using UEFI boot) by defining a custom /etc/default/u-boot-script config file (https://github.com/ilbers/isar/blob/master/meta/recipes-bsp/u-boot-script/files/u-boot-script). How to build an overlay can be derived from https://github.com/siemens/jailhouse-images/tree/master/recipes-bsp/rpi-firmware. For installing on the target, the overlay dtbo has to be added to IMAGE_BOOT_FILES, similar to https://github.com/siemens/jailhouse-images/blob/master/conf/machine/rpi4.conf#L26.

All that is not very convenient I have to admit, likely because that case was not stressed frequently enough yet. Much simpler would be writing a patch for the kernel that modifies the effective dtb and adding that in a bbappend to the iot2050 kernel recipe so that no extra deployment is needed. That would also be compatible with UEFI and secure boot out of the box.

Hello

I am also in need of connecting MCP2515 to IOT2050 (in matter of fact 8 of them, or at least 4)

Can you please elaborate how to add custom devicetree patch to kas/isar build framework? Simplified  step-by step tutorial would be nice, or an example. 

I am still linux newbie and I find Isar/kas confusing.

So far I have been able to compile new example image with added kernel modules (for old intel minipcie wlan) and some additional debian packages.

Thank you