Is your enhancement proposal related to a problem? Please describe.
I would like to during run time de-initialize (de-configure) the uart, and later re-initilise (re-configure) the uart. Initilisation of uart seems to be done on startup and there does not seem to be any api to allow de-configuring and re-configuring the uart after boot.

My reason for this is that I am implementing SDI-12 and which mostly resembles standard serial however has specific periods where the line must be held in a specific state (eg logic low for 12ms). These special periods I'm hoping to deconfigure the uart, reconfigure as GPIO, manually set state, wait for a period of time, and then deconfigure GPIO and return to uart mode.

Though I am working on an nrf52840, I know from previous use of STM32 devices that some devices effectively disconnect the physical pin from the GPIO and attach to an "alternate" peripheral (the uart) and as such, the reconfiguring between the uart and gpio is required (as opposed to setting up as a uart and then trying to write gpio out while in uart mode).

Describe the solution you'd like
Functions to de-initialize (de-configure) the uart, and later re-initilise (re-configure) the uart. Also these should cope with changing out of other modes if in those (specifically the GPIO mode).

Describe alternatives you've considered
Bit banging... I've considered bit banging the SDI-12 interface (it's 1200 baud so quite slow), but it would be cleaner to do in hardware (specially if can use DMA).

Additional context
For SDI-12 specification, please see http://www.sdi-12.org/current_specification/SDI-12_version-1_4-Jan-10-2019.pdf. Section 4.0 has the details on the protocol including the "break" (the 12ms logic low). Section 4.1 has the uart specifics. I'm planning on implementing the start bit as the first bit of an 8 bit uart frame.