stm32/rcc: add ClockEnableBit struct.

1 files changed, 49 insertions, 1 deletions

diff --git a/embassy-stm32/src/rcc/mod.rs b/embassy-stm32/src/rcc/mod.rs
index a585940bc..c413b62ef 100644
--- a/embassy-stm32/src/rcc/mod.rs
+++ b/embassy-stm32/src/rcc/mod.rs
@@ -31,6 +31,7 @@ pub use hsi48::*;
 mod _version;
 
 pub use _version::*;
+use stm32_metapac::RCC;
 
 pub use crate::_generated::{mux, Clocks};
 use crate::time::Hertz;
@@ -66,9 +67,10 @@ pub(crate) unsafe fn get_freqs() -> &'static Clocks {
 }
 
 pub(crate) trait SealedRccPeripheral {
-    fn frequency() -> crate::time::Hertz;
+    fn frequency() -> Hertz;
     fn enable_and_reset_with_cs(cs: CriticalSection);
     fn disable_with_cs(cs: CriticalSection);
+    fn enable_bit() -> ClockEnableBit;
 
     fn enable_and_reset() {
         critical_section::with(|cs| Self::enable_and_reset_with_cs(cs))
@@ -137,3 +139,49 @@ pub unsafe fn enable_and_reset<T: RccPeripheral>() {
 pub unsafe fn disable<T: RccPeripheral>() {
     T::disable();
 }
+
+/// Struct representing some clock enable bit (xxxENR.xxEN), only known at runtime.
+#[derive(Clone, Copy)]
+pub(crate) struct ClockEnableBit {
+    /// offset in 32bit words of the xxxENR register into the RCC register block.
+    offset: u8,
+    /// bit within the register (0..=31)
+    bit: u8,
+}
+
+impl ClockEnableBit {
+    /// Safety: offset+bit must correspond to a valid xxxEN bit.
+    pub(crate) unsafe fn new(offset: u8, bit: u8) -> Self {
+        Self { offset, bit }
+    }
+
+    fn ptr(self) -> *mut u32 {
+        unsafe { (RCC.as_ptr() as *mut u32).add(self.offset as _) }
+    }
+
+    #[allow(unused)]
+    pub(crate) fn enable_with_cs(self, _cs: CriticalSection) {
+        let p = self.ptr();
+        unsafe {
+            let val = p.read_volatile();
+            p.write_volatile(val | 1u32 << self.bit);
+        }
+    }
+
+    pub(crate) fn disable_with_cs(self, _cs: CriticalSection) {
+        let p = self.ptr();
+        unsafe {
+            let val = p.read_volatile();
+            p.write_volatile(val & !(1u32 << self.bit));
+        }
+    }
+
+    #[allow(unused)]
+    pub(crate) fn enable(self) {
+        critical_section::with(|cs| self.enable_with_cs(cs))
+    }
+
+    pub(crate) fn disable(self) {
+        critical_section::with(|cs| self.disable_with_cs(cs))
+    }
+}