Christian Tacke c55ec70f49 STM32: USART: Fix baudrate calculation for LPUART1
LPUART1 needs BRR to be 256 times the normal value.

Doing this with 64 bit math would work, but that pulls in quite a lot of
code for every platform, even if they don't have LPUART.

A little bit of maths, thanks to zyp on irc, lets us keep it in 32bit,
provided people don't try and use > 16MBaud on LPUARTs

Originally tracked via https://github.com/libopencm3/libopencm3/pull/888
2018-08-17 00:15:01 +00:00
..
2015-11-10 14:27:57 +01:00