Best way to add new USB endpoints

[gaborcsapo]

Hey, we want to add 2 more CDC endpoints to our beefed up STM32H743 HIC HAL project and want to ask you opinion about it.

We want to be able to talk to 2 devices under test at the same time over UART and also talk to DAPLink through a shell console. The cleanest solution from a user perspective is if we add separate CDC endpoints for the additional use cases.

From a code perspective I see two ways forward:

• Just add the function definitions and macros for the new CDC_B and CDC_C endpoints to the existing files. Of course we'd conditionalize any extra code with build flags. The functions similar to usbd_cdc_b_acm.c would be implemented by the HIC HAL for its specific use case. Pros: fairly straightforward change. Cons: a lot of extra code in shared usb files, which you might not prefer since only our project would use it.
• Create hooks to define any board specific USB endpoints. This is more complex and the hooks in the case of header files and macros need to be implemented on a case-by-case basis. Different files require different types of hooks to make it work. I scoped this effort and while there seems to be a workaround for most files, I have a feeling the end product might end up becoming a spaghetti...

Which path do you prefer? I'm asking you this, because committing back our HIC HAL is still in scope. We don't want to change shared code in unacceptable ways to avoid any merge issues. In the worst case, we can just maintain our HIC HAL in our own repo, instead of committing it back, which would be unfortunate.