mcp2515 CAN controller via SPI

[simeon]

I've enabled SPI via UART4 with the help of this post

There is a dst file for NVIDEA Tegra boards here

However I have difficulties to enable the MPC2515 CAN controller via SPI, since I don't know how to bring up the correct DST config.

Here is my config from arch/arm64/boot/dts/rockchip/rk3399-nanopi4-common.dtsi so far:

Code: Select all

...
        clocks {
                /* 8MHz external crystal oscillator */
                clk8m: mcp251x_osc {
                        #clock-cells = <0>;
                        compatible = "fixed-clock";
                        clock-frequency = <8000000>;
                };
        };

...
spi1 {
        status = "okay";
        pinctrl-names = "default", "sleep";
        pinctrl-1 = <&spi1_gpio>;

        spidev0: spidev@0 {
                compatible = "rockchip,spidev";
                reg = <0>;
                spi-max-frequency = <10000000>;
                status = "okay";
        };

        can@0 {
                #address-cells = <0x1>;
                #size-cells = <0x0>;
                compatible = "microchip,mcp2515";
                reg = <0x0>;

                clocks = <&clk8m>;
                interrupt-parent = <&tegra_aon_gpio>;
                interrupts = <DAXC03_INT IRQ_TYPE_EDGE_FALLING>;
                spi-max-frequency = <2000000>;

                vdd-supply = <&spmic_ldo5>;
                xceiver-supply = <&spmic_ldo5>;
        };
};

I have wired GPIO4_C5 (GPIO 149) for the interrupt line. The rest (MISO, MOSI, CS and CLK) should be the default ones from the 260 pin spec.
I have no clue what interrupt-parent should look like, how to reference GPIO4_C5 in interrupts, what vdd-supply and xceiver-supply are.
How would the correct dst config look like?

[simeon]

I think more info is needed. Hardware used: SOM-RK3399 with SOM-RK339 Dev-Kit. Wiring infos:

Code: Select all

|MCP2515   | SOM-RK3399 pin         | dev_kit Connector  | Signal name                |
|----------|------------------------|--------------------|----------------------------|
|SCK       | SPI1_CLK (62)          | CON8 pin 7         | GPIO1_B1                   |
|SI        | SPI1_TXD/UART4_TX (58) | UART4 TX           | GPIO1_B0/SPI1_TXD/UART4_TX |
|SO        | SPI1_RXD/UART4_RX (60) | UART4 RX           | GPIO1_A7/SPI1_RXD/UART4_RX |
|CS        | SPI1_CSn0 (56)         | CON8 pin 9         | GPIO1_B2                   |
|INT       | GPIO4_C5/SPDIF_TX (50) | CON8 pin 10        | GPIO4_C5/SPDIF_TX          |

We are using linux 4.4.y and enabled SPI as described in the wiki

We added a DTS description for the MCP2515 like by extending the &spi1 section from arch/arm64/boot/dts/rockchip/rk3399-nanopi4-common.dtsi like the following:

Code: Select all

/ {
        model = "FriendlyElec boards based on Rockchip RK3399";
        compatible = "friendlyelec,nanopi4",
                   "rockchip,rk3399";
        clocks {
                /* 8MHz external crystal oscillator */
                clk8m: mcp251x_osc {
                        #clock-cells = <0>;
                        compatible = "fixed-clock";
                        clock-frequency = <8000000>;
                };
        };

...

&spi1 {
        status = "okay";
        pinctrl-names = "default", "sleep";
        pinctrl-1 = <&spi1_gpio>;

        can@0 {
                #address-cells = <0x1>;
                #size-cells = <0x0>;
                compatible = "microchip,mcp2515";
                reg = <0x0>;

                clocks = <&clk8m>;
                interrupt-parent = <&gpio4>;
                interrupts = <149 IRQ_TYPE_EDGE_FALLING>;
                spi-max-frequency = <1000000>;

                //vdd-supply = <&spmic_ldo5>;
                //xceiver-supply = <&spmic_ldo5>;
        };
};

On boot, dmesg tells us:

Code: Select all

[    1.203206] rockchip-spi ff1d0000.spi: no high_speed pinctrl state
[    1.205447] rk_gmac-dwmac fe300000.ethernet: clock input or output? (input).
[    1.206074] rk_gmac-dwmac fe300000.ethernet: TX delay(0x28).
[    1.206592] rk_gmac-dwmac fe300000.ethernet: RX delay(0x11).
[    1.207112] rk_gmac-dwmac fe300000.ethernet: integrated PHY? (no).
[    1.207839] rk_gmac-dwmac fe300000.ethernet: cannot get clock clk_mac_speed
[    1.208469] rk_gmac-dwmac fe300000.ethernet: clock input from PHY
[    1.214014] rk_gmac-dwmac fe300000.ethernet: init for RGMII
...

[    3.905627] CAN device driver interface
[    3.910709] error: hwirq 0x95 is too large for gpio4
[    3.910742] ------------[ cut here ]------------
[    3.910748] WARNING: at kernel/irq/irqdomain.c:347
[    3.910754] Modules linked in: mcp251x(+) can_dev bcmdhd binfmt_misc uio_pdrv_genirq uio sch_fq_codel bnep ip_tables x_tables

[    3.910809] CPU: 2 PID: 327 Comm: systemd-udevd Not tainted 4.4.179 #4
[    3.910815] Hardware name: FriendlyElec SOM-RK3399 (DT)
[    3.910822] task: ffffffc07a2f0000 task.stack: ffffffc07a15c000
[    3.910837] PC is at irq_domain_associate+0x14c/0x1e8
[    3.910844] LR is at irq_domain_associate+0x14c/0x1e8

...

Questions:

Is SPDIF_TX used otherwise or can it be used as interrupt for the MCP2515 CAN module? If yes, what do you recommend as alternative?
How do I correctly reference the interrupt from GPIO4_C5?

How would the correct MCP configuration look like?

[simeon]

So this is the correct dtsi config in arch/arm64/boot/dts/rockchip/rk3399-nanopi4-common.dtsi

Code: Select all

/ {
        model = "FriendlyElec boards based on Rockchip RK3399";
        compatible = "friendlyelec,nanopi4",
                   "rockchip,rk3399";
        clocks {
                /* 8MHz external crystal oscillator */
                clk8m: mcp251x_osc {
                        #clock-cells = <0>;
                        compatible = "fixed-clock";
                        clock-frequency = <8000000>;
                };
        };
....
&spi1 {
        status = "okay";
        pinctrl-names = "default", "sleep";
        pinctrl-1 = <&spi1_gpio>;

        can@0 {
                #address-cells = <0x1>;
                #size-cells = <0x0>;
                compatible = "microchip,mcp2515";
                reg = <0x0>;

                clocks = <&clk8m>;
                interrupt-parent = <&gpio4>;
                interrupts = <21 IRQ_TYPE_EDGE_FALLING>;
                spi-max-frequency = <1000000>;

                //vdd-supply = <&spmic_ldo5>;
                //xceiver-supply = <&spmic_ldo5>;
        };
};

The biggest knowledge gap was how to calculate the interrupt number for GPIO4_C5. There is the formula for calculating pin numbers on linux:

Bank * 32 + Port*8 + Pin

Port: A=0; B=1; C=2...

Example GPIO4_C5:

4*32 + 2*8 + 5 = 149

Now for the interrupt config in the dtsi, there is the bank already referenced with the interrupt-parent gpio4. It looks like only the latter part are relevant for the interrupt number:

2*8 + 5 = 21

[mangokid]

Thanks for posting the update. Did you get the MCP2515 part working?

I was able to build everything okay and in some cases was able to probe the device but setup failed after that. Was there anything else you modified in the device trees or the kernel config? Thanks!

[simeon]

Yes with the above mentioned dtsi

[simeon]

Thanks for posting the update. Did you get the MCP2515 part working?

I was able to build everything okay and in some cases was able to probe the device but setup failed after that. Was there anything else you modified in the device trees or the kernel config? Thanks!

Yes, I've enabled SPI via UART4 with the help of this post (see my initial question).