use core::marker::PhantomData;
use embassy_hal_internal::{into_ref, Peripheral};
use stm32_metapac::iwdg::vals::{Key, Pr};
use crate::rcc::LSI_FREQ;
pub struct IndependentWatchdog<'d, T: Instance> {
wdg: PhantomData<&'d mut T>,
}
const MAX_RL: u16 = 0xFFF;
const fn get_timeout_us(prescaler: u16, reload_value: u16) -> u32 {
1_000_000 * (reload_value + 1) as u32 / (LSI_FREQ.0 / prescaler as u32)
}
const fn reload_value(prescaler: u16, timeout_us: u32) -> u16 {
(timeout_us / prescaler as u32 * LSI_FREQ.0 / 1_000_000) as u16 - 1
}
impl<'d, T: Instance> IndependentWatchdog<'d, T> {
pub fn new(_instance: impl Peripheral<P = T> + 'd, timeout_us: u32) -> Self {
into_ref!(_instance);
let psc_power = unwrap!((2..=8).find(|psc_power| {
let psc = 2u16.pow(*psc_power);
timeout_us <= get_timeout_us(psc, MAX_RL)
}));
let psc = 2u16.pow(psc_power);
let pr = psc_power as u8 - 2;
assert!(pr <= 0b110);
let rl = reload_value(psc, timeout_us);
let wdg = T::regs();
wdg.kr().write(|w| w.set_key(Key::ENABLE));
wdg.pr().write(|w| w.set_pr(Pr::from_bits(pr)));
wdg.rlr().write(|w| w.set_rl(rl));
trace!(
"Watchdog configured with {}us timeout, desired was {}us (PR={}, RL={})",
get_timeout_us(psc, rl),
timeout_us,
pr,
rl
);
IndependentWatchdog { wdg: PhantomData }
}
pub fn unleash(&mut self) {
T::regs().kr().write(|w| w.set_key(Key::START));
}
pub fn pet(&mut self) {
T::regs().kr().write(|w| w.set_key(Key::RESET));
}
}
mod sealed {
pub trait Instance {
fn regs() -> crate::pac::iwdg::Iwdg;
}
}
pub trait Instance: sealed::Instance {}
foreach_peripheral!(
(iwdg, $inst:ident) => {
impl sealed::Instance for crate::peripherals::$inst {
fn regs() -> crate::pac::iwdg::Iwdg {
crate::pac::$inst
}
}
impl Instance for crate::peripherals::$inst {}
};
);
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn can_compute_timeout_us() {
assert_eq!(125, get_timeout_us(4, 0));
assert_eq!(512_000, get_timeout_us(4, MAX_RL));
assert_eq!(8_000, get_timeout_us(256, 0));
assert_eq!(32_768_000, get_timeout_us(256, MAX_RL));
assert_eq!(8_000_000, get_timeout_us(64, 3999));
}
#[test]
fn can_compute_reload_value() {
assert_eq!(0xFFF, reload_value(4, 512_000));
assert_eq!(0xFFF, reload_value(256, 32_768_000));
assert_eq!(3999, reload_value(64, 8_000_000));
}
}