MCP2515 on SPI0 UEXT

[lilianEver]

Hello,

I want to add CAN functionality on my Olimex card and i am a little stuck.

Olimex: A64-OLinuXino-2Ge8G-IND
Réference:
Can module
Overlay exemple

I want to use the module on the SPI0 on UEXT connector:

| Olimex A64 | Nb Conn |   Function   | Output | Module  |
| ---------- | ------- | ------------ | ------ | ------- |
| +3.3       | 1       |              | VCC    | 7       |
| GND        | 2       |              | GND    | 6       |
| PH4        | 3       | UART3TX      |        |         |
| PH5        | 4       | UART3RX      |        |         |
| PH2        | 5       | TWI1-SCK     | INT    | 1       |
| PH3        | 6       | TWI1-SDA     |        |         |
| PC1        | 7       | SPI_MISO     | SO     | 4       |
| PC0        | 8       | SPI_MOSI     | SI     | 3       |
| PC2        | 9       | SPI_CLK      | SCK    | 2       |
| PC3        | 10      | SPI_CS       | CS     | 5       |

I have added some module to load for the kernel in "/etc/modules"
can-dev
mcp251x

Here the overlay i have tryed to add on the system:

Code Select Expand

/dts-v1/;
/plugin/;

/ {
        model = "Olimex A64-olinuxino-2Ge8G";
        compatible = "olimex,a64-olinuxino-2Ge8G\0allwinner,sun50i-a64";

        fragment@0 {
                target-path = "/clocks";
                __overlay__ {
                        can0_osc_fixed: can0_osc_fixed {
                                compatible = "fixed-clock";
                                #clock-cells = <0>;
                                clock-frequency  = <8000000>;
                        };
                };
        };

        fragment@1 {
                target = <&r_pio>;
                __overlay__ {
                        can0_pin_irq: can0_pin_irq {
                                pins = "PH2";
                                function = "irq";
                                bias-pull-up;
                        };
                };
        };

        fragment@2 {
                target = <&spi0>;
                __overlay__ {
                        status = "okay";
                        #address-cells = <1>;
                        #size-cells = <0>;
                        can0:mcp2515@0 {
                                reg = <0>;
                                compatible = "microchip,mcp2515";
                                pinctrl-names = "default";
                                pinctrl-0 = <&can0_pin_irq>;
                                spi-max-frequency = <10000000>;
                                interrupt-parent = <&r_pio>;
                                interrupts = <0 8 2>; /* FIXME PH2 IRQ_TYPE_EDGE_FALLING */
                                clocks = <&can0_osc_fixed>;
                                status = "okay";
                        };
                };
        };
};
Then i do:

Code Select Expand

armbian-add-overlay spi-a64-mcp2515.dts
But after a reboot, i see nothing  on dmesg

Code Select Expand

dmesg | grep mcp
I forget something to enable the spi or the can bus ?

Thank for your help.

[lilianEver]

Update:

I was on ARMBIAN. (official image from armbian focal)
I have seen this topic: Enable SPI0 on UEXT.

So i have download this image : A64-OLinuXino-focal-minimal-20210318-122357.img

- Enable modules on "/etc/modules"

- Donloaded the script for overlay : here

then:

Code Select Expand

dtc -O dtb -o sun50i-a64-mcp251x.dtbo -b 0 -@ sun50i-a64-mcp251x.dts
cp ../sun50i-a64/sun50i-a64-mcp251x.dtbo /usr/lib/olinuxino-overlays/sun50i-a64/
./olinuxino-overlays/scripts/olinuxino-overlay

- Enable spi0 and my custom mcp251x. I don't see any changes.

[LubOlimex]

The unmodified image has the script inside. Download the image, boot and just type:

olinuxino-overlay

[lilianEver]

Hello,

The overlay was bugged, i changed few things and the can0 appear (with both image Olinuxino and Armbian)

i have change "/clocks" to "/" and change "r_pio" by "pio".

The complete changes:

Code Select Expand

/dts-v1/;
/plugin/;

/ {
        compatible = "allwinner,sun50i-a64",
                "olimex,a64-olinuxino";
        description = "Enable mcp2515 on SPI0";

        fragment@0 {
                target-path = "/";
                __overlay__ {
                        can0_osc_fixed: can0_osc_fixed {
                                compatible = "fixed-clock";
                                #clock-cells = <0>;
                                clock-frequency  = <8000000>;
                        };
                };
        };

        fragment@1 {
                target = <&pio>;
                __overlay__ {
                        can0_pin_irq: can0_pin_irq {
                                pins = "PH2";
                                function = "irq";
                                bias-pull-up;
                        };
                };
        };

        fragment@2 {
                target = <&spi0>;
                __overlay__ {
                        status = "okay";
                        #address-cells = <1>;
                        #size-cells = <0>;
                        can0:mcp2515@0 {
                                reg = <0>;
                                compatible = "microchip,mcp2515";
                                pinctrl-names = "default";
                                pinctrl-0 = <&can0_pin_irq>;
                                spi-max-frequency = <10000000>;
                                interrupt-parent = <&pio>;
                                interrupts = <0 194 2>; /* PH2 IRQ_TYPE_EDGE_FALLING */
                                clocks = <&can0_osc_fixed>;
                                status = "okay";
                        };
                };
        };
};

when i use the command "dmesg", i got:

Code Select Expand

mcp251x spi0.0 can0: MCP2515 successfully initialized.
In my first attempt, it was impossible to up the can0 interface with the command :

Code Select Expand

ip link set can0 up type can bitrate 500000
After some changes on this line:

Code Select Expand

  interrupts = <0 194 2>; /* PH2 IRQ_TYPE_EDGE_FALLING */ It is was possible to up the interface without problem.
But i think my settings are wrongs. I don't see interrupt when i do

Code Select Expand

cat /proc/interrupts
Someone know how to configure this line ?

[JohnS]

You might try asking on linux-sunxi.

John

[lilianEver]

Hello, after some search i found more overlays here.

i have deduce how set interrupts:

Code Select Expand

- Interrupts = <7 9 2>; /* PH9 IRQ_TYPE_EDGE_FALLING */
- Interrupts = <0 10 2>; /* PA10 IRQ_TYPE_EDGE_FALLING */

I use PB0 pin so i set this one:

Code Select Expand

interrupts = <1 0 2>; /* PB0 */

I tested it on Armbian (kernel 5.10). The new problem was the impossibility to up the CAN bus. IT was freezing when you do "ip link set can0 up"
The last problem was interrupt type:

Code Select Expand

1 = low-to-high edge triggered.
2 = high-to-low edge triggered.
4 = active high level-sensitive.
8 = active low level-sensitive.
We need set to "8" the interrupt type:

Code Select Expand

interrupts = <1 0 8>; /* PB0 */

That it. the can0 bus seem to work now.

[JohnS]

Good find! And excellent

John