STM32G0B1RE dual can configuration

[adri1mart1]

Hello,

I am currently creating a dts file for a custom board based on an STM32G0B1RE chip that has a dual FDCAN controller (See: https://www.st.com/en/microcontrollers-microprocessors/stm32g0b1re.html ).

However, digging into different STM32G0B1RE dts related file to find nodes, I could only find a single fdcan1 node here --> https://github.com/zephyrproject-rtos/zephyr/blob/23b3e5741ea39543f29efaadaa53c21c072ad514/dts/arm/st/g0/stm32g0b1.dtsi#L33C5-L33C5

Is there any reason why fdcan2 is not there ?

(Searching everywhere...)

zephyr/dts/arm/st/g0$ grep -nre "fdcan"
stm32g0b1.dtsi:33:              fdcan1: can@40006400 {
stm32g0b1.dtsi:34:                      compatible = "st,stm32-fdcan";

[ndrs-pst]

@adri1mart1, After reviewing the reference manual, it appears that FDCAN1 and FDCAN2 indeed share the same IRQ. The distinction between the interrupt sources requires SYSCFG_ITLINE21 and SYSCFG_ITLINE22. Therefore, my current understanding is that effectively supporting multiple CANFDs that share the same IRQ presents a significant challenge, one that hasn't been implemented yet since it's involved with IRQ handling in architecture level (isr_wrapper.S).

By the way, if you want to test fdcan2 while disabled fdcan1 then you may add this to .overlay file.

fdcan2: can@40006800 {
    compatible = "st,stm32-fdcan";
    reg = <0x40006800 0x400>, <0x4000b800 0x350>;
    reg-names = "m_can", "message_ram";
    interrupts = <21 0>, <22 0>;
    interrupt-names = "LINE_0", "LINE_1";
    clocks = <&rcc STM32_CLOCK_BUS_APB1 0x00001000>;
    bosch,mram-cfg = <0x0 28 8 3 3 0 3 3>;
    sample-point = <875>;
    sample-point-data = <875>;
    status = "okay";
};

[henrikbrixandersen]

Actually, Zephyr supports shared interrupts on the architecture level now, so it should be possible to implement support for both FDCAN instances.

[ndrs-pst]

@henrikbrixandersen, Thanks for the informations.

@adri1mart1 You may have to take a look at these issues
#67087
#49379

[adri1mart1]

Thank you for your fast answers.

As far as I've read issues / PRs, the only remaining step would be to modify the can_stm32_fdcan.c driver to support shared irq that has been recently merged.

There is this PR #34963 that seems very linked with what I need, however, it was opened in May 2021 and left as is.

I'm not sure I'll be able to modify the driver myself, do you suggest me to opened a new issue to highlight exactly what I would ideally like ?

[ndrs-pst]

@adri1mart1, I've taken a look at PR #34963, and it aligns closely with the requirements for supporting shared IRQ in the can_stm32_fdcan.c driver. Since it has been inactive for a while, I encourage you to reference this PR and try to implement the necessary features 🚀.

There seems to be no need to open a new issue. Instead, you could return with a new PR that builds on the original one, giving credit to the initial work. ✌️

[adri1mart1]

Alright, thanks, I'll have a look and give any feedback if needed. I'll mark your comment as an answer.
Regards,
Adrien M.