[UCPD] Split into CC and PD phy

PD3.0 spec requires concurrent control of CC resistors for collision avoidance.
Needed to introduce some "ref counting" (its just a bool) for drop code.

2 files changed, 144 insertions, 84 deletions

diff --git a/embassy-stm32/src/ucpd.rs b/embassy-stm32/src/ucpd.rs
index d1b793e26..2120716ef 100644
--- a/embassy-stm32/src/ucpd.rs
+++ b/embassy-stm32/src/ucpd.rs
@@ -16,11 +16,11 @@
 
 use core::future::poll_fn;
 use core::marker::PhantomData;
+use core::sync::atomic::Ordering;
 use core::task::Poll;
 
 use embassy_hal_internal::drop::OnDrop;
 use embassy_hal_internal::{into_ref, Peripheral, PeripheralRef};
-use embassy_sync::waitqueue::AtomicWaker;
 
 use crate::dma::{AnyChannel, Request, Transfer, TransferOptions};
 use crate::interrupt;
@@ -53,22 +53,15 @@ pub enum CcPull {
 
 /// UCPD driver.
 pub struct Ucpd<'d, T: Instance> {
-    _peri: PeripheralRef<'d, T>,
-}
-
-impl<'d, T: Instance> Drop for Ucpd<'d, T> {
-    fn drop(&mut self) {
-        T::REGS.cfgr1().write(|w| w.set_ucpden(false));
-    }
+    cc_phy: CcPhy<'d, T>,
 }
 
 impl<'d, T: Instance> Ucpd<'d, T> {
     /// Creates a new UCPD driver instance.
     pub fn new(
-        peri: impl Peripheral<P = T> + 'd,
+        _peri: impl Peripheral<P = T> + 'd,
         _cc1: impl Peripheral<P = impl Cc1Pin<T>> + 'd,
         _cc2: impl Peripheral<P = impl Cc2Pin<T>> + 'd,
-        cc_pull: CcPull,
     ) -> Self {
         T::enable_and_reset();
 
@@ -99,7 +92,94 @@ impl<'d, T: Instance> Ucpd<'d, T> {
             w.set_ucpden(true);
         });
 
-        r.cr().write(|w| {
+        Self {
+            cc_phy: CcPhy { _lifetime: PhantomData },
+        }
+    }
+
+    /// Returns the TypeC CC PHY.
+    pub fn cc_phy(&mut self) -> &mut CcPhy<'d, T> {
+        &mut self.cc_phy
+    }
+
+    /// Splits the UCPD driver into a TypeC PHY to control and monitor CC voltage
+    /// and a Power Delivery (PD) PHY with receiver and transmitter.
+    pub fn split_pd_phy(
+        self,
+        rx_dma: impl Peripheral<P = impl RxDma<T>> + 'd,
+        tx_dma: impl Peripheral<P = impl TxDma<T>> + 'd,
+        cc_sel: CcSel,
+    ) -> (CcPhy<'d, T>, PdPhy<'d, T>) {
+        let r = T::REGS;
+
+        // TODO: Currently only SOP messages are supported.
+        r.tx_ordsetr().write(|w| w.set_txordset(0b10001_11000_11000_11000));
+
+        r.cfgr1().modify(|w| {
+            // TODO: Currently only hard reset and SOP messages can be received.
+            w.set_rxordseten(0b1001);
+
+            // Enable DMA
+            w.set_txdmaen(true);
+            w.set_rxdmaen(true);
+        });
+
+        // Enable the receiver on one of the two CC lines.
+        r.cr().modify(|w| {
+            w.set_phyccsel(cc_sel);
+            w.set_phyrxen(true);
+        });
+
+        // Enable hard reset receive interrupt.
+        r.imr().modify(|w| w.set_rxhrstdetie(true));
+
+        // Both parts must be dropped before the peripheral can be disabled.
+        T::state().drop_not_ready.store(true, Ordering::Relaxed);
+
+        into_ref!(rx_dma, tx_dma);
+        let rx_dma_req = rx_dma.request();
+        let tx_dma_req = tx_dma.request();
+        (
+            self.cc_phy,
+            PdPhy {
+                _lifetime: PhantomData,
+                rx_dma_ch: rx_dma.map_into(),
+                rx_dma_req,
+                tx_dma_ch: tx_dma.map_into(),
+                tx_dma_req,
+            },
+        )
+    }
+}
+
+/// Control and monitoring of TypeC CC pin functionailty.
+pub struct CcPhy<'d, T: Instance> {
+    _lifetime: PhantomData<&'d mut T>,
+}
+
+impl<'d, T: Instance> Drop for CcPhy<'d, T> {
+    fn drop(&mut self) {
+        let r = T::REGS;
+        r.cr().modify(|w| {
+            w.set_cc1tcdis(true);
+            w.set_cc2tcdis(true);
+            w.set_ccenable(Ccenable::DISABLED);
+        });
+
+        // Check if the PdPhy part was dropped already.
+        let drop_not_ready = &T::state().drop_not_ready;
+        if drop_not_ready.load(Ordering::Relaxed) {
+            drop_not_ready.store(true, Ordering::Relaxed);
+        } else {
+            r.cfgr1().write(|w| w.set_ucpden(false));
+        }
+    }
+}
+
+impl<'d, T: Instance> CcPhy<'d, T> {
+    /// Sets the pull-up/pull-down resistor values exposed on the CC pins.
+    pub fn set_pull(&mut self, cc_pull: CcPull) {
+        T::REGS.cr().write(|w| {
             w.set_anamode(if cc_pull == CcPull::Sink {
                 Anamode::SINK
             } else {
@@ -116,10 +196,6 @@ impl<'d, T: Instance> Ucpd<'d, T> {
             } else {
                 Ccenable::DISABLED
             });
-
-            // Make sure detector is enabled on both pins.
-            w.set_cc1tcdis(false);
-            w.set_cc2tcdis(false);
         });
 
         // Disable dead-battery pull-down resistors which are enabled by default on boot.
@@ -130,30 +206,27 @@ impl<'d, T: Instance> Ucpd<'d, T> {
                 .cr3()
                 .modify(|w| w.set_ucpd1_dbdis(cc_pull != CcPull::SinkDeadBattery));
         });
-
-        into_ref!(peri);
-        Self { _peri: peri }
     }
 
     /// Returns the current voltage level of CC1 and CC2 pin as tuple.
     ///
     /// Interpretation of the voltage levels depends on the configured CC line
     /// pull-up/pull-down resistance.
-    pub fn cc_vstate(&self) -> (CcVState, CcVState) {
+    pub fn vstate(&self) -> (CcVState, CcVState) {
         let sr = T::REGS.sr().read();
         (sr.typec_vstate_cc1(), sr.typec_vstate_cc2())
     }
 
     /// Waits for a change in voltage state on either CC line.
-    pub async fn wait_for_cc_vstate_change(&self) -> (CcVState, CcVState) {
+    pub async fn wait_for_vstate_change(&self) -> (CcVState, CcVState) {
         let _on_drop = OnDrop::new(|| self.enable_cc_interrupts(false));
-        let prev_vstate = self.cc_vstate();
+        let prev_vstate = self.vstate();
         poll_fn(|cx| {
-            let vstate = self.cc_vstate();
+            let vstate = self.vstate();
             if vstate != prev_vstate {
                 Poll::Ready(vstate)
             } else {
-                T::waker().register(cx.waker());
+                T::state().waker.register(cx.waker());
                 self.enable_cc_interrupts(true);
                 Poll::Pending
             }
@@ -167,48 +240,6 @@ impl<'d, T: Instance> Ucpd<'d, T> {
             w.set_typecevt2ie(enable);
         });
     }
-
-    /// Returns PD receiver and transmitter.
-    pub fn pd_phy(
-        &mut self,
-        rx_dma: impl Peripheral<P = impl RxDma<T>> + 'd,
-        tx_dma: impl Peripheral<P = impl TxDma<T>> + 'd,
-        cc_sel: CcSel,
-    ) -> PdPhy<'_, T> {
-        let r = T::REGS;
-
-        // TODO: Currently only SOP messages are supported.
-        r.tx_ordsetr().write(|w| w.set_txordset(0b10001_11000_11000_11000));
-
-        r.cfgr1().modify(|w| {
-            // TODO: Currently only hard reset and SOP messages can be received.
-            w.set_rxordseten(0b1001);
-
-            // Enable DMA
-            w.set_txdmaen(true);
-            w.set_rxdmaen(true);
-        });
-
-        // Enable the receiver on one of the two CC lines.
-        r.cr().modify(|w| {
-            w.set_phyccsel(cc_sel);
-            w.set_phyrxen(true);
-        });
-
-        // Enable hard reset receive interrupt.
-        r.imr().modify(|w| w.set_rxhrstdetie(true));
-
-        into_ref!(rx_dma, tx_dma);
-        let rx_dma_req = rx_dma.request();
-        let tx_dma_req = tx_dma.request();
-        PdPhy {
-            _ucpd: self,
-            rx_dma_ch: rx_dma.map_into(),
-            rx_dma_req,
-            tx_dma_ch: tx_dma.map_into(),
-            tx_dma_req,
-        }
-    }
 }
 
 /// Receive Error.
@@ -238,7 +269,7 @@ pub enum TxError {
 
 /// Power Delivery (PD) PHY.
 pub struct PdPhy<'d, T: Instance> {
-    _ucpd: &'d Ucpd<'d, T>,
+    _lifetime: PhantomData<&'d mut T>,
     rx_dma_ch: PeripheralRef<'d, AnyChannel>,
     rx_dma_req: Request,
     tx_dma_ch: PeripheralRef<'d, AnyChannel>,
@@ -247,7 +278,16 @@ pub struct PdPhy<'d, T: Instance> {
 
 impl<'d, T: Instance> Drop for PdPhy<'d, T> {
     fn drop(&mut self) {
-        T::REGS.cr().modify(|w| w.set_phyrxen(false));
+        let r = T::REGS;
+        r.cr().modify(|w| w.set_phyrxen(false));
+
+        // Check if the Type-C part was dropped already.
+        let drop_not_ready = &T::state().drop_not_ready;
+        if drop_not_ready.load(Ordering::Relaxed) {
+            drop_not_ready.store(true, Ordering::Relaxed);
+        } else {
+            r.cfgr1().write(|w| w.set_ucpden(false));
+        }
     }
 }
 
@@ -316,7 +356,7 @@ impl<'d, T: Instance> PdPhy<'d, T> {
                 });
                 Poll::Ready(ret)
             } else {
-                T::waker().register(cx.waker());
+                T::state().waker.register(cx.waker());
                 self.enable_rx_interrupt(true);
                 Poll::Pending
             }
@@ -383,7 +423,7 @@ impl<'d, T: Instance> PdPhy<'d, T> {
             } else if sr.txmsgsent() {
                 Poll::Ready(Ok(()))
             } else {
-                T::waker().register(cx.waker());
+                T::state().waker.register(cx.waker());
                 self.enable_tx_interrupts(true);
                 Poll::Pending
             }
@@ -427,7 +467,7 @@ impl<'d, T: Instance> PdPhy<'d, T> {
             } else if sr.hrstsent() {
                 Poll::Ready(Ok(()))
             } else {
-                T::waker().register(cx.waker());
+                T::state().waker.register(cx.waker());
                 self.enable_hardreset_interrupts(true);
                 Poll::Pending
             }
@@ -483,18 +523,37 @@ impl<T: Instance> interrupt::typelevel::Handler<T::Interrupt> for InterruptHandl
         }
 
         // Wake the task to clear and re-enabled interrupts.
-        T::waker().wake();
+        T::state().waker.wake();
     }
 }
 
 /// UCPD instance trait.
 pub trait Instance: sealed::Instance + RccPeripheral {}
 
-pub(crate) mod sealed {
+mod sealed {
+    use core::sync::atomic::AtomicBool;
+
+    use embassy_sync::waitqueue::AtomicWaker;
+
+    pub struct State {
+        pub waker: AtomicWaker,
+        // Inverted logic for a default state of 0 so that the data goes into the .bss section.
+        pub drop_not_ready: AtomicBool,
+    }
+
+    impl State {
+        pub const fn new() -> Self {
+            Self {
+                waker: AtomicWaker::new(),
+                drop_not_ready: AtomicBool::new(false),
+            }
+        }
+    }
+
     pub trait Instance {
         type Interrupt: crate::interrupt::typelevel::Interrupt;
         const REGS: crate::pac::ucpd::Ucpd;
-        fn waker() -> &'static embassy_sync::waitqueue::AtomicWaker;
+        fn state() -> &'static crate::ucpd::sealed::State;
     }
 }
 
@@ -505,9 +564,9 @@ foreach_interrupt!(
 
             const REGS: crate::pac::ucpd::Ucpd = crate::pac::$inst;
 
-            fn waker() -> &'static AtomicWaker {
-                static WAKER: AtomicWaker = AtomicWaker::new();
-                &WAKER
+            fn state() -> &'static crate::ucpd::sealed::State {
+                static STATE: crate::ucpd::sealed::State = crate::ucpd::sealed::State::new();
+                &STATE
             }
         }
 
diff --git a/examples/stm32g4/src/bin/usb_c_pd.rs b/examples/stm32g4/src/bin/usb_c_pd.rs
index 14abd542f..0e80840df 100644
--- a/examples/stm32g4/src/bin/usb_c_pd.rs
+++ b/examples/stm32g4/src/bin/usb_c_pd.rs
@@ -3,7 +3,7 @@
 
 use defmt::{error, info, Format};
 use embassy_executor::Spawner;
-use embassy_stm32::ucpd::{self, CcPull, CcSel, CcVState, Ucpd};
+use embassy_stm32::ucpd::{self, CcPhy, CcPull, CcSel, CcVState, Ucpd};
 use embassy_stm32::Config;
 use embassy_time::{with_timeout, Duration};
 use {defmt_rtt as _, panic_probe as _};
@@ -16,17 +16,17 @@ enum CableOrientation {
 }
 
 // Returns true when the cable
-async fn wait_attached<T: ucpd::Instance>(ucpd: &mut Ucpd<'_, T>) -> CableOrientation {
+async fn wait_attached<T: ucpd::Instance>(cc_phy: &mut CcPhy<'_, T>) -> CableOrientation {
     loop {
-        let (cc1, cc2) = ucpd.cc_vstate();
+        let (cc1, cc2) = cc_phy.vstate();
         if cc1 == CcVState::LOWEST && cc2 == CcVState::LOWEST {
             // Detached, wait until attached by monitoring the CC lines.
-            ucpd.wait_for_cc_vstate_change().await;
+            cc_phy.wait_for_vstate_change().await;
             continue;
         }
 
         // Attached, wait for CC lines to be stable for tCCDebounce (100..200ms).
-        if with_timeout(Duration::from_millis(100), ucpd.wait_for_cc_vstate_change())
+        if with_timeout(Duration::from_millis(100), cc_phy.wait_for_vstate_change())
             .await
             .is_ok()
         {
@@ -50,10 +50,11 @@ async fn main(_spawner: Spawner) {
 
     info!("Hello World!");
 
-    let mut ucpd = Ucpd::new(p.UCPD1, p.PB6, p.PB4, CcPull::Sink);
+    let mut ucpd = Ucpd::new(p.UCPD1, p.PB6, p.PB4);
+    ucpd.cc_phy().set_pull(CcPull::Sink);
 
     info!("Waiting for USB connection...");
-    let cable_orientation = wait_attached(&mut ucpd).await;
+    let cable_orientation = wait_attached(ucpd.cc_phy()).await;
     info!("USB cable connected, orientation: {}", cable_orientation);
 
     let cc_sel = match cable_orientation {
@@ -67,7 +68,7 @@ async fn main(_spawner: Spawner) {
         }
         CableOrientation::DebugAccessoryMode => panic!("No PD communication in DAM"),
     };
-    let mut pd_phy = ucpd.pd_phy(p.DMA1_CH1, p.DMA1_CH2, cc_sel);
+    let (_cc_phy, mut pd_phy) = ucpd.split_pd_phy(p.DMA1_CH1, p.DMA1_CH2, cc_sel);
 
     loop {
         // Enough space for the longest non-extended data message.