fix HardwareSemaphore (HSEM) implementation

Author: Legorooj

embassy-stm32/src/hsem.rs

@@ -0,0 +1,159 @@
+//! Hardware Semaphore (HSEM)
+const HSEM: crate::pac::hsem::Hsem = crate::pac::HSEM;
+
+/// Locking the HardwareSemaphore failed.
+#[derive(Debug)]
+pub struct HsemLockFailed;
+
+/// CPU Core.
+///
+/// The enum values are identical to the bus master IDs defined for each chip family.
+///
+/// On some chips, the Reference Manual calls this value MASTERID instead of COREID.
+#[repr(u8)]
+pub enum CoreId {
+    #[cfg(any(stm32h7a3, stm32h7b3, stm32h7b0))]
+    /// Cortex-M7, core 1. MASTERID = 1
+    Core0 = 1,
+
+    #[cfg(any(
+        stm32h723, stm32h725, stm32h730, stm32h733, stm32h735, stm32h742, stm32h743, stm32h745, stm32h747, stm32h750,
+        stm32h753, stm32h755, stm32h757,
+    ))]
+    /// Cortex-M7, core 1. MASTERID = 3
+    Core0 = 3,
+
+    #[cfg(any(stm32wb, stm32wl))]
+    /// Cortex-M4, core 1
+    Core0 = 4,
+
+    #[cfg(not(any(stm32wb, stm32wl, stm32h7a3, stm32h7b3, stm32h7b0)))]
+    /// Cortex-M4, core 2
+    Core1 = 1,
+
+    #[cfg(any(stm32wb, stm32wl))]
+    /// Cortex M0+, core 2
+    Core1 = 8,
+}
+
+impl CoreId {
+    #[cfg(any(feature = "_core-cm7", not(feature = "_core-cm4")))]
+    const fn current() -> CoreId {
+        CoreId::Core0
+    }
+
+    #[cfg(feature = "_core-cm4")]
+    const fn current() -> CoreId {
+        CoreId::Core1
+    }
+
+    fn as_index(&self) -> usize {
+        match self {
+            CoreId::Core0 => 0,
+            #[cfg(not(any(stm32h7a3, stm32h7b3, stm32h7b0)))]
+            CoreId::Core1 => 1,
+        }
+    }
+}
+
+/// TODO
+pub struct HardwareSemaphore<'d> {
+    _peri: crate::Peri<'d, crate::peripherals::HSEM>,
+}
+
+impl<'d> HardwareSemaphore<'d> {
+    /// Create a new HardwareSemaphore instance.
+    pub fn new(peri: crate::Peri<'d, crate::peripherals::HSEM>) -> Self {
+        HardwareSemaphore { _peri: peri }
+    }
+
+    /// Locks the semaphore via the 2-step (write) lock procedure
+    ///
+    /// The two-step procedure consists of a write to lock the semaphore, followed by a read
+    /// to check if the lock has been successful, carried out from the HSEM_Rx retgister.
+    pub fn two_step_lock(&mut self, sem_id: u8, process_id: u8) -> Result<(), HsemLockFailed> {
+        HSEM.r(sem_id as usize).write(|w| {
+            w.set_procid(process_id);
+            w.set_coreid(CoreId::current() as u8);
+            w.set_lock(true);
+        });
+
+        let reg = HSEM.r(sem_id as usize).read();
+
+        match (
+            reg.lock(),
+            reg.coreid() == CoreId::current() as u8,
+            reg.procid() == process_id,
+        ) {
+            (true, true, true) => Ok(()),
+            _ => Err(HsemLockFailed),
+        }
+    }
+
+    /// Locks the semaphore via the 1-step (read) lock procedure
+    ///
+    /// The one-step procedure consists of a read to lock and check the semaphore in a single
+    /// step, carried out from the HSEM_RLRx register.
+    pub fn one_step_lock(&mut self, sem_id: u8) -> Result<(), HsemLockFailed> {
+        let reg = HSEM.rlr(sem_id as usize).read();
+
+        match (reg.lock(), reg.coreid() == CoreId::current() as u8, reg.procid()) {
+            (_, true, 0) => Ok(()),
+            _ => Err(HsemLockFailed),
+        }
+    }
+
+    /// Unlocks the semaphore
+    ///
+    /// Unlocking a semaphore is a protected process, to prevent accidental clearing by an AHB
+    /// bus core ID or by a process not having the semaphore lock right.
+    pub fn unlock(&mut self, sem_id: u8, process_id: u8) {
+        HSEM.r(sem_id as usize).write(|w| {
+            w.set_procid(process_id);
+            w.set_coreid(CoreId::current() as u8);
+            w.set_lock(false);
+        });
+    }
+
+    /// Unlocks all semahpores.
+    ///
+    /// All semaphores locked by a COREID can be unlocked at once by using the HSEM_CR register.
+    /// Write COREID and correct KEY value in HSEM_CR. All locked semaphores with a matching
+    /// COREID are unlocked, and may generate an interrupt if enabled.
+    pub fn unlock_all(&mut self, key: u16, core_id: u8) {
+        HSEM.cr().write(|w| {
+            w.set_key(key);
+            w.set_coreid(core_id);
+        })
+    }
+
+    /// Checks if the semaphore is locked.
+    pub fn is_semaphore_locked(&self, sem_id: u8) -> bool {
+        HSEM.r(sem_id as usize).read().lock()
+    }
+
+    /// Sets the clear (unlock) key
+    pub fn set_clear_key(&mut self, key: u16) {
+        HSEM.keyr().modify(|w| w.set_key(key));
+    }
+
+    /// Gets the clear (unlock) key
+    pub fn get_clear_key(&mut self) -> u16 {
+        HSEM.keyr().read().key()
+    }
+
+    /// Sets the interrupt enable bit for the semaphore.
+    pub fn enable_interrupt(&mut self, core_id: CoreId, sem_x: usize, enable: bool) {
+        HSEM.ier(core_id.as_index()).modify(|w| w.set_ise(sem_x, enable));
+    }
+
+    /// Clears the interrupt flag for the semaphore.
+    pub fn clear_interrupt(&mut self, core_id: CoreId, sem_x: usize) {
+        HSEM.icr(core_id.as_index()).write(|w| w.set_isc(sem_x, false));
+    }
+
+    /// Gets the interrupt flag for the semaphore.
+    pub fn is_interrupt_active(&mut self, core_id: CoreId, sem_x: usize) -> bool {
+        HSEM.isr(core_id.as_index()).read().isf(sem_x)
+    }
+}

embassy-stm32/src/hsem/mod.rs renamed to embassy-stm32/src/hsem/old.rs

@@ -14,7 +14,8 @@ async fn main(_spawner: Spawner) {
     let p: embassy_stm32::Peripherals = init();
 
     let mut hsem = HardwareSemaphore::new(p.HSEM);
-    hsem.one_step_lock(5).unwrap();
+    hsem.one_step_lock(1).unwrap();
+    hsem.two_step_lock(1, 0).unwrap();
 
     info!("Test OK");
     cortex_m::asm::bkpt();