logging: uart: get device from dedicated zephyr,log-uart node

[ycsin]

Changes the UART log backend to use a new dedicated zephyr,log-uart node instead of the chosen zephyr,console node, just like the zephyr,shell-uart.

This helps with the development of cleaner multi-instance UART log backend implementation, see #64917.

Devicetree modified using the following command, with a few exceptions:

grep -rl 'zephyr,console = ' ./ | xargs sed -i 's/\(.*\)zephyr,console = \&\(.*\)\;/\1zephyr,console = \&\2\;\n\1zephyr,log-uart = \&\2\;/'

The compilation of the log_backend_uart now depends on having an enabled serial driver & chosen zephyr,log-uart node in the devicetree instead of UART_CONSOLE

• migration notes for out-of-tree boards

[henrikbrixandersen]

This change will break pretty much all board configurations.

Please state the nature of the problem this is solving.

[ycsin]

Please state the nature of the problem this is solving.

Updated OP, this is required to have cleaner implementation in #64917

[cfriedt]

Changes the UART log backend to use a new dedicated zephyr,log-uart node instead of the chosen zephyr,console node, just like the zephyr,shell-uart.

I don't think it should be necessary for all boards to switch.

Many boards are fine simply using the existing zephyr,console, a singleton.

For those who want multiple instances, the previous approach that I used was probably the least invasive; adding a child node with the Zephyr,log-uart compatible; the backing UART device is implicitly the parent of that node.

It could also be added to any existing configuration without requiring a lot of change.

[dcpleung]

Maybe use zephyr,log-uart if it's defined, else use zephyr,console? Shell requires interactivity so it may want to use another UART dedicated to it. However, logging simply requires output, which can be on console.

[cfriedt]

Maybe use zephyr,log-uart if it's defined, else use zephyr,console? Shell requires interactivity so it may want to use another UART dedicated to it. However, logging simply requires output, which can be on console.

Exactly.

The associated pr has changed a bit since I wrote it originally. I don't think we need a tree-wide change, but probably what is above (which I believe was @ycsin's original submission) would be fine.