h7: implement RTC and LSE clock configuration

2 files changed, 49 insertions, 18 deletions

diff --git a/embassy-stm32/src/rtc/mod.rs b/embassy-stm32/src/rtc/mod.rs
index 73b78f253..28dde2eb1 100644
--- a/embassy-stm32/src/rtc/mod.rs
+++ b/embassy-stm32/src/rtc/mod.rs
@@ -93,21 +93,50 @@ impl RtcTimeProvider {
     ///
     /// Will return an `RtcError::InvalidDateTime` if the stored value in the system is not a valid [`DayOfWeek`].
     pub fn now(&self) -> Result<DateTime, RtcError> {
-        let r = RTC::regs();
-        let tr = r.tr().read();
-        let second = bcd2_to_byte((tr.st(), tr.su()));
-        let minute = bcd2_to_byte((tr.mnt(), tr.mnu()));
-        let hour = bcd2_to_byte((tr.ht(), tr.hu()));
-        // Reading either RTC_SSR or RTC_TR locks the values in the higher-order
-        // calendar shadow registers until RTC_DR is read.
-        let dr = r.dr().read();
-
-        let weekday = dr.wdu();
-        let day = bcd2_to_byte((dr.dt(), dr.du()));
-        let month = bcd2_to_byte((dr.mt() as u8, dr.mu()));
-        let year = bcd2_to_byte((dr.yt(), dr.yu())) as u16 + 1970_u16;
-
-        self::datetime::datetime(year, month, day, weekday, hour, minute, second).map_err(RtcError::InvalidDateTime)
+        // For RM0433 we use BYPSHAD=1 to work around errata ES0392 2.19.1
+        #[cfg(rcc_h7rm0433)]
+        loop {
+            let r = RTC::regs();
+            let ss = r.ssr().read().ss();
+            let dr = r.dr().read();
+            let tr = r.tr().read();
+
+            // If an RTCCLK edge occurs during read we may see inconsistent values
+            // so read ssr again and see if it has changed. (see RM0433 Rev 7 46.3.9)
+            let ss_after = r.ssr().read().ss();
+            if ss == ss_after {
+                let second = bcd2_to_byte((tr.st(), tr.su()));
+                let minute = bcd2_to_byte((tr.mnt(), tr.mnu()));
+                let hour = bcd2_to_byte((tr.ht(), tr.hu()));
+
+                let weekday = dr.wdu();
+                let day = bcd2_to_byte((dr.dt(), dr.du()));
+                let month = bcd2_to_byte((dr.mt() as u8, dr.mu()));
+                let year = bcd2_to_byte((dr.yt(), dr.yu())) as u16 + 1970_u16;
+
+                return self::datetime::datetime(year, month, day, weekday, hour, minute, second)
+                    .map_err(RtcError::InvalidDateTime);
+            }
+        }
+
+        #[cfg(not(rcc_h7rm0433))]
+        {
+            let r = RTC::regs();
+            let tr = r.tr().read();
+            let second = bcd2_to_byte((tr.st(), tr.su()));
+            let minute = bcd2_to_byte((tr.mnt(), tr.mnu()));
+            let hour = bcd2_to_byte((tr.ht(), tr.hu()));
+            // Reading either RTC_SSR or RTC_TR locks the values in the higher-order
+            // calendar shadow registers until RTC_DR is read.
+            let dr = r.dr().read();
+
+            let weekday = dr.wdu();
+            let day = bcd2_to_byte((dr.dt(), dr.du()));
+            let month = bcd2_to_byte((dr.mt() as u8, dr.mu()));
+            let year = bcd2_to_byte((dr.yt(), dr.yu())) as u16 + 1970_u16;
+
+            self::datetime::datetime(year, month, day, weekday, hour, minute, second).map_err(RtcError::InvalidDateTime)
+        }
     }
 }
 
@@ -175,18 +204,18 @@ impl Rtc {
     }
 
     fn frequency() -> Hertz {
-        #[cfg(any(rcc_wb, rcc_f4, rcc_f410))]
+        #[cfg(any(rcc_wb, rcc_f4, rcc_f410, rcc_h5, rcc_h50, rcc_h7, rcc_h7rm0433, rcc_h7ab))]
         let freqs = unsafe { crate::rcc::get_freqs() };
 
         // Load the clock frequency from the rcc mod, if supported
-        #[cfg(any(rcc_wb, rcc_f4, rcc_f410))]
+        #[cfg(any(rcc_wb, rcc_f4, rcc_f410, rcc_h5, rcc_h50, rcc_h7, rcc_h7rm0433, rcc_h7ab))]
         match freqs.rtc {
             Some(hertz) => hertz,
             None => freqs.rtc_hse.unwrap(),
         }
 
         // Assume the  default value, if not supported
-        #[cfg(not(any(rcc_wb, rcc_f4, rcc_f410)))]
+        #[cfg(not(any(rcc_wb, rcc_f4, rcc_f410, rcc_h5, rcc_h50, rcc_h7, rcc_h7rm0433, rcc_h7ab)))]
         Hertz(32_768)
     }
 
diff --git a/embassy-stm32/src/rtc/v2.rs b/embassy-stm32/src/rtc/v2.rs
index 4974f6ee6..eeb23e1f1 100644
--- a/embassy-stm32/src/rtc/v2.rs
+++ b/embassy-stm32/src/rtc/v2.rs
@@ -157,6 +157,8 @@ impl super::Rtc {
                 w.set_fmt(stm32_metapac::rtc::vals::Fmt::TWENTY_FOUR_HOUR);
                 w.set_osel(Osel::DISABLED);
                 w.set_pol(Pol::HIGH);
+                #[cfg(rcc_h7rm0433)]
+                w.set_bypshad(true);
             });
 
             rtc.prer().modify(|w| {