Merge pull request #2116 from xoviat/rtc-2

stm32/low-power: refactor refcount

4 files changed, 23 insertions, 29 deletions

diff --git a/embassy-stm32/src/lib.rs b/embassy-stm32/src/lib.rs
index 372246f87..5c7067d2d 100644
--- a/embassy-stm32/src/lib.rs
+++ b/embassy-stm32/src/lib.rs
@@ -226,9 +226,9 @@ pub fn init(config: Config) -> Peripherals {
             time_driver::init(cs);
 
             #[cfg(feature = "low-power")]
-            while !crate::rcc::low_power_ready() {
-                crate::rcc::clock_refcount_sub(cs);
-            }
+            {
+                crate::rcc::REFCOUNT_STOP2 = 0
+            };
         }
 
         p
diff --git a/embassy-stm32/src/low_power.rs b/embassy-stm32/src/low_power.rs
index 861a59d7b..d5846f530 100644
--- a/embassy-stm32/src/low_power.rs
+++ b/embassy-stm32/src/low_power.rs
@@ -6,7 +6,6 @@ use cortex_m::peripheral::SCB;
 use embassy_executor::*;
 
 use crate::interrupt;
-use crate::rcc::low_power_ready;
 use crate::time_driver::{get_driver, RtcDriver};
 
 const THREAD_PENDER: usize = usize::MAX;
@@ -33,6 +32,15 @@ pub fn stop_with_rtc(rtc: &'static Rtc) {
     unsafe { EXECUTOR.as_mut().unwrap() }.stop_with_rtc(rtc)
 }
 
+pub fn stop_ready(stop_mode: StopMode) -> bool {
+    unsafe { EXECUTOR.as_mut().unwrap() }.stop_ready(stop_mode)
+}
+
+#[non_exhaustive]
+pub enum StopMode {
+    Stop2,
+}
+
 /// Thread mode executor, using WFE/SEV.
 ///
 /// This is the simplest and most common kind of executor. It runs on
@@ -80,12 +88,18 @@ impl Executor {
         trace!("low power: stop with rtc configured");
     }
 
+    fn stop_ready(&self, stop_mode: StopMode) -> bool {
+        match stop_mode {
+            StopMode::Stop2 => unsafe { crate::rcc::REFCOUNT_STOP2 == 0 },
+        }
+    }
+
     fn configure_pwr(&mut self) {
         self.scb.clear_sleepdeep();
 
         compiler_fence(Ordering::SeqCst);
 
-        if !low_power_ready() {
+        if !self.stop_ready(StopMode::Stop2) {
             trace!("low power: not ready to stop");
         } else if self.time_driver.pause_time().is_err() {
             trace!("low power: failed to pause time");
diff --git a/embassy-stm32/src/rcc/mod.rs b/embassy-stm32/src/rcc/mod.rs
index 8cf2d6ab0..3b19e4b95 100644
--- a/embassy-stm32/src/rcc/mod.rs
+++ b/embassy-stm32/src/rcc/mod.rs
@@ -23,8 +23,6 @@ pub use mco::*;
 #[cfg_attr(rcc_u5, path = "u5.rs")]
 #[cfg_attr(rcc_wba, path = "wba.rs")]
 mod _version;
-#[cfg(feature = "low-power")]
-use core::sync::atomic::{AtomicU32, Ordering};
 
 pub use _version::*;
 
@@ -183,27 +181,7 @@ pub struct Clocks {
 }
 
 #[cfg(feature = "low-power")]
-static CLOCK_REFCOUNT: AtomicU32 = AtomicU32::new(0);
-
-#[cfg(feature = "low-power")]
-pub fn low_power_ready() -> bool {
-    // trace!("clock refcount: {}", CLOCK_REFCOUNT.load(Ordering::SeqCst));
-    CLOCK_REFCOUNT.load(Ordering::SeqCst) == 0
-}
-
-#[cfg(feature = "low-power")]
-pub(crate) fn clock_refcount_add(_cs: critical_section::CriticalSection) {
-    // We don't check for overflow because constructing more than u32 peripherals is unlikely
-    let n = CLOCK_REFCOUNT.load(Ordering::Relaxed);
-    CLOCK_REFCOUNT.store(n + 1, Ordering::Relaxed);
-}
-
-#[cfg(feature = "low-power")]
-pub(crate) fn clock_refcount_sub(_cs: critical_section::CriticalSection) {
-    let n = CLOCK_REFCOUNT.load(Ordering::Relaxed);
-    assert!(n != 0);
-    CLOCK_REFCOUNT.store(n - 1, Ordering::Relaxed);
-}
+pub(crate) static mut REFCOUNT_STOP2: u32 = 0;
 
 /// Frozen clock frequencies
 ///
diff --git a/embassy-stm32/src/rtc/mod.rs b/embassy-stm32/src/rtc/mod.rs
index d77443a9c..3334262f9 100644
--- a/embassy-stm32/src/rtc/mod.rs
+++ b/embassy-stm32/src/rtc/mod.rs
@@ -187,7 +187,9 @@ impl Rtc {
         critical_section::with(|cs| {
             <RTC as crate::rcc::sealed::RccPeripheral>::enable_and_reset_with_cs(cs);
             #[cfg(feature = "low-power")]
-            crate::rcc::clock_refcount_sub(cs);
+            unsafe {
+                crate::rcc::REFCOUNT_STOP2 -= 1
+            };
         });
 
         let mut this = Self {