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stm32/rcc: reset backup domain before enabling LSE.

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This commit is contained in:
Dario Nieuwenhuis 2023-10-02 22:03:18 +02:00
parent eff61648fe
commit b856d760f4
1 changed files with 47 additions and 46 deletions
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93
embassy-stm32/src/rcc/bd.rs
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@ -88,6 +88,12 @@ impl BackupDomain {
))]
#[allow(dead_code, unused_variables)]
pub fn configure_ls(clock_source: RtcClockSource, lsi: bool, lse: Option<LseDrive>) {
match clock_source {
RtcClockSource::LSI => assert!(lsi),
RtcClockSource::LSE => assert!(&lse.is_some()),
_ => {}
};
if lsi {
#[cfg(rtc_v3u5)]
let csr = crate::pac::RCC.bdcr();
@ -111,6 +117,40 @@ impl BackupDomain {
while !csr.read().lsi1rdy() {}
}
// backup domain configuration (LSEON, RTCEN, RTCSEL) is kept across resets.
// once set, changing it requires a backup domain reset.
// first check if the configuration matches what we want.
// check if it's already enabled and in the source we want.
let reg = Self::read();
let mut ok = true;
ok &= reg.rtcsel() == clock_source;
#[cfg(not(rcc_wba))]
{
ok &= reg.rtcen() == (clock_source != RtcClockSource::NOCLOCK);
}
ok &= reg.lseon() == lse.is_some();
#[cfg(any(rtc_v2f7, rtc_v2h7, rtc_v2l0, rtc_v2l4))]
if let Some(lse_drive) = lse {
ok &= reg.lsedrv() == lse_drive.into();
}
// if configuration is OK, we're done.
if ok {
// RTC code assumes backup domain is unlocked
Self::modify(|w| {});
trace!("BDCR ok: {:08x}", Self::read().0);
return;
}
// If not OK, reset backup domain and configure it.
#[cfg(not(any(rcc_l0, rcc_l1)))]
{
Self::modify(|w| w.set_bdrst(true));
Self::modify(|w| w.set_bdrst(false));
}
if let Some(lse_drive) = lse {
Self::modify(|w| {
#[cfg(any(rtc_v2f7, rtc_v2h7, rtc_v2l0, rtc_v2l4))]
@ -121,56 +161,17 @@ impl BackupDomain {
while !Self::read().lserdy() {}
}
match clock_source {
RtcClockSource::LSI => assert!(lsi),
RtcClockSource::LSE => assert!(&lse.is_some()),
_ => {}
};
if clock_source == RtcClockSource::NOCLOCK {
// disable it
if clock_source != RtcClockSource::NOCLOCK {
Self::modify(|w| {
#[cfg(any(rtc_v2h7, rtc_v2l4, rtc_v2wb, rtc_v3, rtc_v3u5))]
assert!(!w.lsecsson(), "RTC is not compatible with LSE CSS, yet.");
#[cfg(not(rcc_wba))]
w.set_rtcen(false);
w.set_rtcen(true);
w.set_rtcsel(clock_source);
});
} else {
// check if it's already enabled and in the source we want.
let reg = Self::read();
let ok = reg.rtcsel() == clock_source;
#[cfg(not(rcc_wba))]
let ok = ok & reg.rtcen();
// if not, configure it.
if !ok {
#[cfg(any(rtc_v2h7, rtc_v2l4, rtc_v2wb, rtc_v3, rtc_v3u5))]
assert!(!reg.lsecsson(), "RTC is not compatible with LSE CSS, yet.");
#[cfg(not(any(rcc_l0, rcc_l1)))]
Self::modify(|w| w.set_bdrst(true));
Self::modify(|w| {
// Reset
#[cfg(not(any(rcc_l0, rcc_l1)))]
w.set_bdrst(false);
#[cfg(not(rcc_wba))]
w.set_rtcen(true);
w.set_rtcsel(clock_source);
// Restore bcdr
#[cfg(any(rtc_v2l4, rtc_v2wb, rtc_v3, rtc_v3u5))]
w.set_lscosel(reg.lscosel());
#[cfg(any(rtc_v2l4, rtc_v2wb, rtc_v3, rtc_v3u5))]
w.set_lscoen(reg.lscoen());
w.set_lseon(reg.lseon());
#[cfg(any(rtc_v2f0, rtc_v2f7, rtc_v2h7, rtc_v2l4, rtc_v2wb, rtc_v3, rtc_v3u5))]
w.set_lsedrv(reg.lsedrv());
w.set_lsebyp(reg.lsebyp());
});
}
}
trace!("BDCR configured: {:08x}", Self::read().0);
}
}