Interfacing with MCP2518FD on RockPi 4B

Austin Dubes · June 14

Hello,

I have been trying to interface with a MCP2518FD CAN controller using a RockPi 4b and have been encountering some issues.

The specifications in which I want the CANbus to operate are as such:

Baud: 250kb/s

FD: OFF

Other details:

Oscillator: 40MHz

SPI Bus: SPI1 (see below)

The RockPi pins that are being used are the following (based on the standard pinout of the RockPi 4B https://wiki.radxa.com/Rock4/hardware/gpio)

Pin #19 SPI1_TXD -> MOSI

Pin #21 SPI1_RXD -> MISO

Pin #23 SPI1_CLK -> SCK

Pin #22 GPIO4_D5 -> INT

Pin #24 SPI1_CSn -> CS

I have tried various DT overlay files and most files don't even provide an output for the commands "dmesg | grep spi" or "dmesg | grep mcp" except for this overlay that gives me a response that chip select 0 is already in use:

/dts-v1/;
/plugin/;

/ {
	compatible = "rockchip,rockpi","rockchip,rk3399";

	fragment@0 {
		target = <&pinctrl>;

		__overlay__ {
			mcp2518_int_pin: mcp2518_int_pin {
				rockchip,pins = <4 29 0 &pcfg_pull_none>;
			};
		};		
	};

	fragment@1 {
		target-path = "/";

		__overlay__ {
			can_mcp2518_osc: can-mcp2518-osc {
				compatible = "fixed-clock";
				clock-frequency = <40000000>; // Change to 40 MHz
				#clock-cells = <0>;
			};
		};
	};

	fragment@2 {
		target = <&spi1>;

		__overlay__ {
			status = "okay";
			max-frequency = <10000000>; // Keep it at 10 MHz
			#address-cells = <1>;
			#size-cells = <0>;

			can_mcp2518: can-mcp2518@0 {
				status = "okay";
				compatible = "microchip,mcp2518";
				reg = <0>;
				interrupt-parent = <&gpio4>;
				interrupts = <29 2>;
				spi-max-frequency = <10000000>; // Keep it at 10 MHz
				clocks = <&can_mcp2518_osc>; // Change to the new clock node
				vdd-supply = <&vcc3v3_sys>;
				xceiver-supply = <&vcc3v3_sys>;
				pinctrl-names = "default";
				#pinctrl-0 = <&mcp2518_int_pin>; // Change to the new pin name
			};
		};
	};
};

And this is the specific message I get when I compile this DTS (via command "armbian-add-overlay") and reboot:

root@rockpi-4b:~# dmesg | grep spi

[ 1.522099] rockchip-spi ff1d0000.spi: chipselect 0 already in use

[ 1.522115] spi_master spi1: spi_device register error /spi@ff1d0000/spidev@0

[ 1.522141] spi_master spi1: Failed to create SPI device for /spi@ff1d0000/spidev@0

And there is no response on dmesg | grep mcp or any can0 interface created on ifconfig....

The operating system in which I am running is 5.15.74-rockchip64

I have previously used this board to successfully interface with a MCP2515 @250Kb/s, but I am looking to upgrade to the 2518. I removed the previous DTBO and user-overlay from armbianEnv.txt.

If anyone has any idea on what the issue may be or can walk me through step by step on how to set this up, I would greatly appreciate it. I am not great with linux, so please bear with me. if a solution involves installing a driver or rebuilding the kernel, I am not entirely sure on how to perform that, so any resource or information on this would be extremely helpful for me. Even if I have to start from a scratch image, this is okay.