How to integrate with Zephyr when in a module

[nylnx]

Hi, My question is rather simple: How can I integrate more deeply into Zephyr from within a module?

I have, for example, a custom UART driver in my module and for it to use Zephyr toolchain intelligence I need to define CONFIG_SERIAL, but this causes a CMake warning, because no driver sources got added to the drivers__serial CMake library and I also have to configure my Kconfig variables under modules->my_module->my_uart or something, rather than the correct location under Device Drivers->Serial->my_uart like all the other official UART drivers.

Is there any way I can integrate more deeply with Zephyr and its build and configuration system from the outside?
Or are there ideas from other people that most likely had the same problem as I do?

Thanks, any help is appreciated :)

[yashi]

I haven't tested but can you add your drive to drivers__serial by using zephyr_library_get_current_dir_lib_name and zephyr_library_named? These are how zephyr_library() use built.

[nylnx]

By researching these functions I actually found zephyr_library_amend() (which is used instead of zephyr_library()) and actually lets you add out-of-tree CMake sources as long as the module has the same directory structure as the Zephyr tree. So if I put my UART driver into my_module/drivers/serial/my_uart.c and have a CMakeLists.txt use zephyr_library_amend() and zephyr_library_sources(my_uart.c) it just works and eliminates the CMake warning :)

For Kconfig there seems to be no way (as far as I can tell) to enable this behavior. But I found that it probably would be possible to add a custom preprocessor command, which expands to potential module Kconfigs... You just would have to expand the current Zephyr tree Kconfigs with some kind of "hook" at the end... But this is probably not something I could design with all the side effects this could have and potential opposition :D Maybe somebody has insight as to how Linux does this kind of thing, since I cannot imagine there is no solution to this...