5 files changed, 172 insertions, 141 deletions

diff --git a/embassy-stm32/Cargo.toml b/embassy-stm32/Cargo.toml
index 01a9d482f..7b3a6c2bb 100644
--- a/embassy-stm32/Cargo.toml
+++ b/embassy-stm32/Cargo.toml
@@ -18,7 +18,7 @@ flavors = [
     { regex_feature = "stm32f7.*", target = "thumbv7em-none-eabi" },
     { regex_feature = "stm32c0.*", target = "thumbv6m-none-eabi" },
     { regex_feature = "stm32g0.*", target = "thumbv6m-none-eabi" },
-    { regex_feature = "stm32g4.*", target = "thumbv7em-none-eabi" },
+    { regex_feature = "stm32g4.*", target = "thumbv7em-none-eabi", features = ["low-power"] },
     { regex_feature = "stm32h5.*", target = "thumbv8m.main-none-eabihf" },
     { regex_feature = "stm32h7.*", target = "thumbv7em-none-eabi" },
     { regex_feature = "stm32l0.*", target = "thumbv6m-none-eabi", features = ["low-power"] },
diff --git a/embassy-stm32/src/rtc/mod.rs b/embassy-stm32/src/rtc/mod.rs
index e94a58575..b4315f535 100644
--- a/embassy-stm32/src/rtc/mod.rs
+++ b/embassy-stm32/src/rtc/mod.rs
@@ -33,6 +33,61 @@ use embassy_hal_internal::Peripheral;
 use crate::peripherals::RTC;
 use crate::rtc::sealed::Instance;
 
+#[allow(dead_code)]
+#[repr(u8)]
+#[derive(Clone, Copy, Debug)]
+pub(crate) enum WakeupPrescaler {
+    Div2 = 2,
+    Div4 = 4,
+    Div8 = 8,
+    Div16 = 16,
+}
+
+#[cfg(any(stm32wb, stm32f4, stm32l0, stm32g4))]
+impl From<WakeupPrescaler> for crate::pac::rtc::vals::Wucksel {
+    fn from(val: WakeupPrescaler) -> Self {
+        use crate::pac::rtc::vals::Wucksel;
+
+        match val {
+            WakeupPrescaler::Div2 => Wucksel::DIV2,
+            WakeupPrescaler::Div4 => Wucksel::DIV4,
+            WakeupPrescaler::Div8 => Wucksel::DIV8,
+            WakeupPrescaler::Div16 => Wucksel::DIV16,
+        }
+    }
+}
+
+#[cfg(any(stm32wb, stm32f4, stm32l0, stm32g4))]
+impl From<crate::pac::rtc::vals::Wucksel> for WakeupPrescaler {
+    fn from(val: crate::pac::rtc::vals::Wucksel) -> Self {
+        use crate::pac::rtc::vals::Wucksel;
+
+        match val {
+            Wucksel::DIV2 => WakeupPrescaler::Div2,
+            Wucksel::DIV4 => WakeupPrescaler::Div4,
+            Wucksel::DIV8 => WakeupPrescaler::Div8,
+            Wucksel::DIV16 => WakeupPrescaler::Div16,
+            _ => unreachable!(),
+        }
+    }
+}
+
+#[cfg(feature = "low-power")]
+impl WakeupPrescaler {
+    pub fn compute_min(val: u32) -> Self {
+        *[
+            WakeupPrescaler::Div2,
+            WakeupPrescaler::Div4,
+            WakeupPrescaler::Div8,
+            WakeupPrescaler::Div16,
+        ]
+        .iter()
+        .skip_while(|psc| **psc as u32 <= val)
+        .next()
+        .unwrap_or(&WakeupPrescaler::Div16)
+    }
+}
+
 /// Errors that can occur on methods on [RtcClock]
 #[non_exhaustive]
 #[derive(Clone, Debug, PartialEq, Eq)]
@@ -277,6 +332,114 @@ impl Rtc {
     pub fn write_backup_register(&self, register: usize, value: u32) {
         RTC::write_backup_register(&RTC::regs(), register, value)
     }
+
+    #[cfg(feature = "low-power")]
+    /// start the wakeup alarm and wtih a duration that is as close to but less than
+    /// the requested duration, and record the instant the wakeup alarm was started
+    pub(crate) fn start_wakeup_alarm(
+        &self,
+        requested_duration: embassy_time::Duration,
+        cs: critical_section::CriticalSection,
+    ) {
+        use embassy_time::{Duration, TICK_HZ};
+
+        #[cfg(any(rtc_v3, rtc_v3u5))]
+        use crate::pac::rtc::vals::Calrf;
+
+        // Panic if the rcc mod knows we're not using low-power rtc
+        #[cfg(any(rcc_wb, rcc_f4, rcc_f410))]
+        unsafe { crate::rcc::get_freqs() }.rtc.unwrap();
+
+        let requested_duration = requested_duration.as_ticks().clamp(0, u32::MAX as u64);
+        let rtc_hz = Self::frequency().0 as u64;
+        let rtc_ticks = requested_duration * rtc_hz / TICK_HZ;
+        let prescaler = WakeupPrescaler::compute_min((rtc_ticks / u16::MAX as u64) as u32);
+
+        // adjust the rtc ticks to the prescaler and subtract one rtc tick
+        let rtc_ticks = rtc_ticks / prescaler as u64;
+        let rtc_ticks = rtc_ticks.clamp(0, (u16::MAX - 1) as u64).saturating_sub(1) as u16;
+
+        self.write(false, |regs| {
+            regs.cr().modify(|w| w.set_wute(false));
+
+            #[cfg(any(
+                rtc_v2f0, rtc_v2f2, rtc_v2f3, rtc_v2f4, rtc_v2f7, rtc_v2h7, rtc_v2l0, rtc_v2l1, rtc_v2l4, rtc_v2wb
+            ))]
+            {
+                regs.isr().modify(|w| w.set_wutf(false));
+                while !regs.isr().read().wutwf() {}
+            }
+
+            #[cfg(any(rtc_v3, rtc_v3u5))]
+            {
+                regs.scr().write(|w| w.set_cwutf(Calrf::CLEAR));
+                while !regs.icsr().read().wutwf() {}
+            }
+
+            regs.cr().modify(|w| w.set_wucksel(prescaler.into()));
+            regs.wutr().write(|w| w.set_wut(rtc_ticks));
+            regs.cr().modify(|w| w.set_wute(true));
+            regs.cr().modify(|w| w.set_wutie(true));
+        });
+
+        let instant = self.instant().unwrap();
+        trace!(
+            "rtc: start wakeup alarm for {} ms (psc: {}, ticks: {}) at {}",
+            Duration::from_ticks(rtc_ticks as u64 * TICK_HZ * prescaler as u64 / rtc_hz).as_millis(),
+            prescaler as u32,
+            rtc_ticks,
+            instant,
+        );
+
+        assert!(self.stop_time.borrow(cs).replace(Some(instant)).is_none())
+    }
+
+    #[cfg(feature = "low-power")]
+    /// stop the wakeup alarm and return the time elapsed since `start_wakeup_alarm`
+    /// was called, otherwise none
+    pub(crate) fn stop_wakeup_alarm(&self, cs: critical_section::CriticalSection) -> Option<embassy_time::Duration> {
+        use crate::interrupt::typelevel::Interrupt;
+        #[cfg(any(rtc_v3, rtc_v3u5))]
+        use crate::pac::rtc::vals::Calrf;
+
+        let instant = self.instant().unwrap();
+        if RTC::regs().cr().read().wute() {
+            trace!("rtc: stop wakeup alarm at {}", instant);
+
+            self.write(false, |regs| {
+                regs.cr().modify(|w| w.set_wutie(false));
+                regs.cr().modify(|w| w.set_wute(false));
+
+                #[cfg(any(
+                    rtc_v2f0, rtc_v2f2, rtc_v2f3, rtc_v2f4, rtc_v2f7, rtc_v2h7, rtc_v2l0, rtc_v2l1, rtc_v2l4, rtc_v2wb
+                ))]
+                regs.isr().modify(|w| w.set_wutf(false));
+
+                #[cfg(any(rtc_v3, rtc_v3u5))]
+                regs.scr().write(|w| w.set_cwutf(Calrf::CLEAR));
+
+                crate::pac::EXTI
+                    .pr(0)
+                    .modify(|w| w.set_line(RTC::EXTI_WAKEUP_LINE, true));
+
+                <RTC as crate::rtc::sealed::Instance>::WakeupInterrupt::unpend();
+            });
+        }
+
+        self.stop_time.borrow(cs).take().map(|stop_time| instant - stop_time)
+    }
+
+    #[cfg(feature = "low-power")]
+    pub(crate) fn enable_wakeup_line(&self) {
+        use crate::interrupt::typelevel::Interrupt;
+        use crate::pac::EXTI;
+
+        <RTC as crate::rtc::sealed::Instance>::WakeupInterrupt::unpend();
+        unsafe { <RTC as crate::rtc::sealed::Instance>::WakeupInterrupt::enable() };
+
+        EXTI.rtsr(0).modify(|w| w.set_line(RTC::EXTI_WAKEUP_LINE, true));
+        EXTI.imr(0).modify(|w| w.set_line(RTC::EXTI_WAKEUP_LINE, true));
+    }
 }
 
 pub(crate) fn byte_to_bcd2(byte: u8) -> (u8, u8) {
diff --git a/embassy-stm32/src/rtc/v2.rs b/embassy-stm32/src/rtc/v2.rs
index 006fd63f4..91f08fae4 100644
--- a/embassy-stm32/src/rtc/v2.rs
+++ b/embassy-stm32/src/rtc/v2.rs
@@ -6,145 +6,7 @@ use crate::peripherals::RTC;
 use crate::rtc::sealed::Instance;
 
 #[allow(dead_code)]
-#[repr(u8)]
-#[derive(Clone, Copy, Debug)]
-pub(crate) enum WakeupPrescaler {
-    Div2 = 2,
-    Div4 = 4,
-    Div8 = 8,
-    Div16 = 16,
-}
-
-#[cfg(any(stm32wb, stm32f4, stm32l0))]
-impl From<WakeupPrescaler> for crate::pac::rtc::vals::Wucksel {
-    fn from(val: WakeupPrescaler) -> Self {
-        use crate::pac::rtc::vals::Wucksel;
-
-        match val {
-            WakeupPrescaler::Div2 => Wucksel::DIV2,
-            WakeupPrescaler::Div4 => Wucksel::DIV4,
-            WakeupPrescaler::Div8 => Wucksel::DIV8,
-            WakeupPrescaler::Div16 => Wucksel::DIV16,
-        }
-    }
-}
-
-#[cfg(any(stm32wb, stm32f4, stm32l0))]
-impl From<crate::pac::rtc::vals::Wucksel> for WakeupPrescaler {
-    fn from(val: crate::pac::rtc::vals::Wucksel) -> Self {
-        use crate::pac::rtc::vals::Wucksel;
-
-        match val {
-            Wucksel::DIV2 => WakeupPrescaler::Div2,
-            Wucksel::DIV4 => WakeupPrescaler::Div4,
-            Wucksel::DIV8 => WakeupPrescaler::Div8,
-            Wucksel::DIV16 => WakeupPrescaler::Div16,
-            _ => unreachable!(),
-        }
-    }
-}
-
-#[allow(dead_code)]
-impl WakeupPrescaler {
-    pub fn compute_min(val: u32) -> Self {
-        *[
-            WakeupPrescaler::Div2,
-            WakeupPrescaler::Div4,
-            WakeupPrescaler::Div8,
-            WakeupPrescaler::Div16,
-        ]
-        .iter()
-        .skip_while(|psc| **psc as u32 <= val)
-        .next()
-        .unwrap_or(&WakeupPrescaler::Div16)
-    }
-}
-
 impl super::Rtc {
-    #[cfg(feature = "low-power")]
-    /// start the wakeup alarm and wtih a duration that is as close to but less than
-    /// the requested duration, and record the instant the wakeup alarm was started
-    pub(crate) fn start_wakeup_alarm(
-        &self,
-        requested_duration: embassy_time::Duration,
-        cs: critical_section::CriticalSection,
-    ) {
-        use embassy_time::{Duration, TICK_HZ};
-
-        // Panic if the rcc mod knows we're not using low-power rtc
-        #[cfg(any(rcc_wb, rcc_f4, rcc_f410))]
-        unsafe { crate::rcc::get_freqs() }.rtc.unwrap();
-
-        let requested_duration = requested_duration.as_ticks().clamp(0, u32::MAX as u64);
-        let rtc_hz = Self::frequency().0 as u64;
-        let rtc_ticks = requested_duration * rtc_hz / TICK_HZ;
-        let prescaler = WakeupPrescaler::compute_min((rtc_ticks / u16::MAX as u64) as u32);
-
-        // adjust the rtc ticks to the prescaler and subtract one rtc tick
-        let rtc_ticks = rtc_ticks / prescaler as u64;
-        let rtc_ticks = rtc_ticks.clamp(0, (u16::MAX - 1) as u64).saturating_sub(1) as u16;
-
-        self.write(false, |regs| {
-            regs.cr().modify(|w| w.set_wute(false));
-            regs.isr().modify(|w| w.set_wutf(false));
-            while !regs.isr().read().wutwf() {}
-
-            regs.cr().modify(|w| w.set_wucksel(prescaler.into()));
-            regs.wutr().write(|w| w.set_wut(rtc_ticks));
-            regs.cr().modify(|w| w.set_wute(true));
-            regs.cr().modify(|w| w.set_wutie(true));
-        });
-
-        let instant = self.instant().unwrap();
-        trace!(
-            "rtc: start wakeup alarm for {} ms (psc: {}, ticks: {}) at {}",
-            Duration::from_ticks(rtc_ticks as u64 * TICK_HZ * prescaler as u64 / rtc_hz).as_millis(),
-            prescaler as u32,
-            rtc_ticks,
-            instant,
-        );
-
-        assert!(self.stop_time.borrow(cs).replace(Some(instant)).is_none())
-    }
-
-    #[cfg(feature = "low-power")]
-    /// stop the wakeup alarm and return the time elapsed since `start_wakeup_alarm`
-    /// was called, otherwise none
-    pub(crate) fn stop_wakeup_alarm(&self, cs: critical_section::CriticalSection) -> Option<embassy_time::Duration> {
-        use crate::interrupt::typelevel::Interrupt;
-
-        let instant = self.instant().unwrap();
-        if RTC::regs().cr().read().wute() {
-            trace!("rtc: stop wakeup alarm at {}", instant);
-
-            self.write(false, |regs| {
-                regs.cr().modify(|w| w.set_wutie(false));
-                regs.cr().modify(|w| w.set_wute(false));
-                regs.isr().modify(|w| w.set_wutf(false));
-
-                crate::pac::EXTI
-                    .pr(0)
-                    .modify(|w| w.set_line(RTC::EXTI_WAKEUP_LINE, true));
-
-                <RTC as crate::rtc::sealed::Instance>::WakeupInterrupt::unpend();
-            });
-        }
-
-        self.stop_time.borrow(cs).take().map(|stop_time| instant - stop_time)
-    }
-
-    #[cfg(feature = "low-power")]
-    pub(crate) fn enable_wakeup_line(&self) {
-        use crate::interrupt::typelevel::Interrupt;
-        use crate::pac::EXTI;
-
-        <RTC as crate::rtc::sealed::Instance>::WakeupInterrupt::unpend();
-        unsafe { <RTC as crate::rtc::sealed::Instance>::WakeupInterrupt::enable() };
-
-        EXTI.rtsr(0).modify(|w| w.set_line(RTC::EXTI_WAKEUP_LINE, true));
-        EXTI.imr(0).modify(|w| w.set_line(RTC::EXTI_WAKEUP_LINE, true));
-    }
-
     /// Applies the RTC config
     /// It this changes the RTC clock source the time will be reset
     pub(super) fn configure(&mut self, async_psc: u8, sync_psc: u16) {
diff --git a/embassy-stm32/src/rtc/v3.rs b/embassy-stm32/src/rtc/v3.rs
index 7bf757e7d..d2d0d9309 100644
--- a/embassy-stm32/src/rtc/v3.rs
+++ b/embassy-stm32/src/rtc/v3.rs
@@ -95,7 +95,7 @@ impl super::Rtc {
         })
     }
 
-    pub(super) fn write<F, R>(&mut self, init_mode: bool, f: F) -> R
+    pub(super) fn write<F, R>(&self, init_mode: bool, f: F) -> R
     where
         F: FnOnce(&crate::pac::rtc::Rtc) -> R,
     {
@@ -129,6 +129,12 @@ impl super::Rtc {
 impl sealed::Instance for crate::peripherals::RTC {
     const BACKUP_REGISTER_COUNT: usize = 32;
 
+    #[cfg(all(feature = "low-power", stm32g4))]
+    const EXTI_WAKEUP_LINE: usize = 20;
+
+    #[cfg(all(feature = "low-power", stm32g4))]
+    type WakeupInterrupt = crate::interrupt::typelevel::RTC_WKUP;
+
     fn read_backup_register(_rtc: &Rtc, register: usize) -> Option<u32> {
         #[allow(clippy::if_same_then_else)]
         if register < Self::BACKUP_REGISTER_COUNT {
diff --git a/tests/stm32/Cargo.toml b/tests/stm32/Cargo.toml
index 4b769b1cb..9b9273a5c 100644
--- a/tests/stm32/Cargo.toml
+++ b/tests/stm32/Cargo.toml
@@ -10,7 +10,7 @@ stm32f103c8 = ["embassy-stm32/stm32f103c8", "not-gpdma"]
 stm32f429zi = ["embassy-stm32/stm32f429zi", "chrono", "eth", "stop", "can", "not-gpdma", "dac-adc-pin", "rng"]
 stm32g071rb = ["embassy-stm32/stm32g071rb", "cm0", "not-gpdma", "dac-adc-pin"]
 stm32c031c6 = ["embassy-stm32/stm32c031c6", "cm0", "not-gpdma"]
-stm32g491re = ["embassy-stm32/stm32g491re", "chrono", "not-gpdma", "rng"]
+stm32g491re = ["embassy-stm32/stm32g491re", "chrono", "stop", "not-gpdma", "rng"]
 stm32h755zi = ["embassy-stm32/stm32h755zi-cm7", "chrono", "not-gpdma", "eth", "dac-adc-pin", "rng"]
 stm32h753zi = ["embassy-stm32/stm32h753zi", "chrono", "not-gpdma", "eth", "rng"]
 stm32h7a3zi = ["embassy-stm32/stm32h7a3zi", "not-gpdma", "rng"]