GD32V bare metal
using LLVM 11.0.1
sudo cp 11-ftdi.rules /etc/udev/rules.d/
sudo udevadm control --reload-rules && udevadm trigger
https://habr.com/ru/post/556498/
https://www.appelsiini.net/2020/programming-gd32v-longan-nano/
https://github.com/riscv-rust/seedstudio-gd32v
https://www.rvmcu.com/uploadfile/pdf/0/0/239.pdf
riscv-collab/riscv-openocd#518
http://microsin.net/programming/arm/configuring-openocd-for-the-at91sam7se.html
https://dzone.com/articles/jtag-debugging-the-esp32-with-ft2232-and-openocd
https://mcuoneclipse.com/2019/10/20/jtag-debugging-the-esp32-with-ft2232-and-openocd/
https://balau82.wordpress.com/2013/08/04/jtag-connection-with-openocd-and-ftdi-cable/
https://gist.github.com/elfmimi/1deb9c94b0f0900ae8a9df740b62bcd6
https://controllerstech.com/stm32-i2c-configuration-using-registers/