artiq/artiq/firmware/libboard_misoc/uart.rs

use csr;

pub fn set_speed(rate: u32) {
    unsafe {
        let tuning_word = (rate as u64) * (1 << 32) / (csr::CONFIG_CLOCK_FREQUENCY as u64);
        csr::uart_phy::tuning_word_write(tuning_word as u32);
    }
}