embassy/embassy-stm32/src/rcc/bd.rs

#[derive(Copy, Clone, Debug, PartialEq)]
#[repr(u8)]
#[allow(dead_code)]
pub enum RtcClockSource {
    /// 00: No clock
    NoClock = 0b00,
    /// 01: LSE oscillator clock used as RTC clock
    LSE = 0b01,
    /// 10: LSI oscillator clock used as RTC clock
    LSI = 0b10,
    /// 11: HSE oscillator clock divided by 32 used as RTC clock
    HSE = 0b11,
}

#[cfg(not(any(rtc_v2l0, rtc_v2l1, stm32c0)))]
#[allow(dead_code)]
type Bdcr = crate::pac::rcc::regs::Bdcr;

#[cfg(any(rtc_v2l0, rtc_v2l1))]
#[allow(dead_code)]
type Bdcr = crate::pac::rcc::regs::Csr;

#[allow(dead_code)]
pub struct BackupDomain {}

impl BackupDomain {
    #[cfg(any(
        rtc_v2f0, rtc_v2f2, rtc_v2f3, rtc_v2f4, rtc_v2f7, rtc_v2h7, rtc_v2l0, rtc_v2l1, rtc_v2l4, rtc_v2wb, rtc_v3,
        rtc_v3u5
    ))]
    #[allow(dead_code, unused_variables)]
    fn modify<R>(f: impl FnOnce(&mut Bdcr) -> R) -> R {
        #[cfg(any(rtc_v2f2, rtc_v2f3, rtc_v2l1))]
        let cr = crate::pac::PWR.cr();
        #[cfg(any(rtc_v2f4, rtc_v2f7, rtc_v2h7, rtc_v2l4, rtc_v2wb, rtc_v3, rtc_v3u5))]
        let cr = crate::pac::PWR.cr1();

        // TODO: Missing from PAC for l0 and f0?
        #[cfg(not(any(rtc_v2f0, rtc_v2l0, rtc_v3u5)))]
        {
            cr.modify(|w| w.set_dbp(true));
            while !cr.read().dbp() {}
        }

        #[cfg(any(rtc_v2l0, rtc_v2l1))]
        let cr = crate::pac::RCC.csr();

        #[cfg(not(any(rtc_v2l0, rtc_v2l1)))]
        let cr = crate::pac::RCC.bdcr();

        cr.modify(|w| f(w))
    }

    #[cfg(any(
        rtc_v2f0, rtc_v2f2, rtc_v2f3, rtc_v2f4, rtc_v2f7, rtc_v2h7, rtc_v2l0, rtc_v2l1, rtc_v2l4, rtc_v2wb, rtc_v3,
        rtc_v3u5
    ))]
    #[allow(dead_code)]
    fn read() -> Bdcr {
        #[cfg(any(rtc_v2l0, rtc_v2l1))]
        let r = crate::pac::RCC.csr().read();

        #[cfg(not(any(rtc_v2l0, rtc_v2l1)))]
        let r = crate::pac::RCC.bdcr().read();

        r
    }

    #[cfg(any(
        rtc_v2f0, rtc_v2f2, rtc_v2f3, rtc_v2f4, rtc_v2f7, rtc_v2h7, rtc_v2l0, rtc_v2l1, rtc_v2l4, rtc_v2wb, rtc_v3,
        rtc_v3u5
    ))]
    #[allow(dead_code, unused_variables)]
    pub fn set_rtc_clock_source(clock_source: RtcClockSource) {
        let clock_source = clock_source as u8;
        #[cfg(any(
            all(not(any(rtc_v3, rtc_v3u5)), not(rtc_v2wb)),
            all(any(rtc_v3, rtc_v3u5), not(any(rcc_wl5, rcc_wle)))
        ))]
        let clock_source = crate::pac::rcc::vals::Rtcsel::from_bits(clock_source);

        #[cfg(not(rtc_v2wb))]
        Self::modify(|w| {
            // Select RTC source
            w.set_rtcsel(clock_source);
        });
    }

    #[cfg(any(
        rtc_v2f0, rtc_v2f2, rtc_v2f3, rtc_v2f4, rtc_v2f7, rtc_v2h7, rtc_v2l0, rtc_v2l1, rtc_v2l4, rtc_v2wb
    ))]
    #[allow(dead_code)]
    pub fn enable_rtc() {
        let reg = Self::read();

        #[cfg(any(rtc_v2h7, rtc_v2l4, rtc_v2wb))]
        assert!(!reg.lsecsson(), "RTC is not compatible with LSE CSS, yet.");

        if !reg.rtcen() {
            #[cfg(not(any(rtc_v2l0, rtc_v2l1, rtc_v2f2)))]
            Self::modify(|w| w.set_bdrst(true));

            Self::modify(|w| {
                // Reset
                #[cfg(not(any(rtc_v2l0, rtc_v2l1)))]
                w.set_bdrst(false);

                w.set_rtcen(true);
                w.set_rtcsel(reg.rtcsel());

                // Restore bcdr
                #[cfg(any(rtc_v2l4, rtc_v2wb))]
                w.set_lscosel(reg.lscosel());
                #[cfg(any(rtc_v2l4, rtc_v2wb))]
                w.set_lscoen(reg.lscoen());

                w.set_lseon(reg.lseon());

                #[cfg(any(rtc_v2f0, rtc_v2f7, rtc_v2h7, rtc_v2l4, rtc_v2wb))]
                w.set_lsedrv(reg.lsedrv());
                w.set_lsebyp(reg.lsebyp());
            });
        }
    }

    #[cfg(any(rtc_v3, rtc_v3u5))]
    #[allow(dead_code)]
    pub fn enable_rtc() {
        let reg = Self::read();
        assert!(!reg.lsecsson(), "RTC is not compatible with LSE CSS, yet.");

        if !reg.rtcen() {
            Self::modify(|w| w.set_bdrst(true));

            Self::modify(|w| {
                w.set_bdrst(false);

                w.set_rtcen(true);
                w.set_rtcsel(reg.rtcsel());

                // Restore bcdr
                w.set_lscosel(reg.lscosel());
                w.set_lscoen(reg.lscoen());

                w.set_lseon(reg.lseon());
                w.set_lsedrv(reg.lsedrv());
                w.set_lsebyp(reg.lsebyp());
            });
        }
    }
}