[UCPD] Configuration Channel (CC) handling

2 files changed, 227 insertions, 4 deletions

diff --git a/embassy-stm32/src/ucpd.rs b/embassy-stm32/src/ucpd.rs
index a3f01c629..98b82bacc 100644
--- a/embassy-stm32/src/ucpd.rs
+++ b/embassy-stm32/src/ucpd.rs
@@ -1,10 +1,165 @@
 //! USB Type-C/USB Power Delivery Interface (UCPD)
 
+// Implementation Notes
+//
+// As of Feb. 2024 the UCPD peripheral is availalbe on: G0, G4, H5, L5, U5
+//
+// Cube HAL LL Driver (g0):
+// https://github.com/STMicroelectronics/stm32g0xx_hal_driver/blob/v1.4.6/Inc/stm32g0xx_ll_ucpd.h
+// https://github.com/STMicroelectronics/stm32g0xx_hal_driver/blob/v1.4.6/Src/stm32g0xx_ll_ucpd.c
+// Except for a the `LL_UCPD_RxAnalogFilterEnable/Disable()` functions the Cube HAL implementation of
+// all families is the same.
+//
+// Dead battery pull-down resistors functionality is enabled by default on startup and must
+// be disabled by setting a bit in PWR/SYSCFG registers. The exact name and location for that
+// bit is different for each familily.
+
+use core::future::poll_fn;
 use core::marker::PhantomData;
+use core::task::Poll;
 
-use crate::interrupt;
 use crate::rcc::RccPeripheral;
+use crate::{interrupt, pac};
+use embassy_hal_internal::{into_ref, Peripheral, PeripheralRef};
 use embassy_sync::waitqueue::AtomicWaker;
+use pac::ucpd::vals::{Anamode, Ccenable, PscUsbpdclk};
+
+pub use pac::ucpd::vals::TypecVstateCc as CcVState;
+
+/// Pull-up or Pull-down resistor state of both CC lines.
+#[derive(Debug, Clone, Copy, PartialEq)]
+pub enum CcPull {
+    /// Analog PHY for CC pin disabled.
+    Disabled,
+
+    /// Rd=5.1k pull-down resistor enabled when the corresponding DBCC pin is high.
+    SinkDeadBattery,
+
+    /// Rd=5.1k pull-down resistor.
+    Sink,
+
+    /// Rp=56k pull-up resistor to indicate default USB power.
+    SourceDefaultUsb,
+
+    /// Rp=22k pull-up resistor to indicate support for up to 1.5A.
+    Source1_5A,
+
+    /// Rp=10k pull-up resistor to indicate support for up to 3.0A.
+    Source3_0A,
+}
+
+/// UCPD driver.
+pub struct Ucpd<'d, T: Instance> {
+    _peri: PeripheralRef<'d, T>,
+}
+
+impl<'d, T: Instance> Ucpd<'d, T> {
+    /// Creates a new UCPD driver instance.
+    pub fn new(
+        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();
+
+        let r = T::REGS;
+        r.cfgr1().write(|w| {
+            // "The receiver is designed to work in the clock frequency range from 6 to 18 MHz.
+            // However, the optimum performance is ensured in the range from 6 to 12 MHz"
+            // UCPD is driven by HSI16 (16MHz internal oscillator), which we need to divide by 2.
+            w.set_psc_usbpdclk(PscUsbpdclk::DIV2);
+
+            // Prescaler to produce a target half-bit frequency of 600kHz which is required
+            // to produce transmit with a nominal nominal bit rate of 300Kbps+-10% using
+            // biphase mark coding (BMC, aka differential manchester coding).
+            // A divider of 13 gives the target frequency closest to spec (~615kHz, 1.625us)
+            // but we go with the (hopefully well tested) default value used by the Cube HAL
+            // which is 14 divides the clock down to ~571kHz, 1.75us.
+            w.set_hbitclkdiv(14 - 1);
+
+            // Time window for detecting non-idle (12-20us).
+            // 1.75us * 8 = 14us.
+            w.set_transwin(8 - 1);
+
+            // Time from the end of last bit of a Frame until the start of the first bit of the
+            // next Preamble (min 25us).
+            // 1.75us * 17 = ~30us
+            w.set_ifrgap(17 - 1);
+
+            // TODO: Only receive SOP messages
+            w.set_rxordseten(0x1);
+
+            // Enable DMA and the peripheral
+            w.set_txdmaen(true);
+            w.set_rxdmaen(true);
+            w.set_ucpden(true);
+        });
+
+        r.cr().write(|w| {
+            w.set_anamode(if cc_pull == CcPull::Sink {
+                Anamode::SINK
+            } else {
+                Anamode::SOURCE
+            });
+            w.set_anasubmode(match cc_pull {
+                CcPull::SourceDefaultUsb => 1,
+                CcPull::Source1_5A => 2,
+                CcPull::Source3_0A => 3,
+                _ => 0,
+            });
+            w.set_ccenable(if cc_pull != CcPull::SinkDeadBattery {
+                Ccenable::BOTH
+            } else {
+                Ccenable::DISABLED
+            });
+        });
+
+        // Disable dead-battery pull-down resistors which are enabled by default on boot.
+        critical_section::with(|_| {
+            // TODO: other families
+            #[cfg(stm32g4)]
+            pac::PWR
+                .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) {
+        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_change(&mut self) {
+        let r = T::REGS;
+        poll_fn(|cx| {
+            let sr = r.sr().read();
+            if sr.typecevt1() || sr.typecevt2() {
+                r.icr().write(|w| {
+                    w.set_typecevt1cf(true);
+                    w.set_typecevt2cf(true);
+                });
+                Poll::Ready(())
+            } else {
+                T::waker().register(cx.waker());
+                r.imr().modify(|w| {
+                    w.set_typecevt1ie(true);
+                    w.set_typecevt2ie(true);
+                });
+                Poll::Pending
+            }
+        })
+        .await;
+    }
+}
 
 /// Interrupt handler.
 pub struct InterruptHandler<T: Instance> {
@@ -13,11 +168,17 @@ pub struct InterruptHandler<T: Instance> {
 
 impl<T: Instance> interrupt::typelevel::Handler<T::Interrupt> for InterruptHandler<T> {
     unsafe fn on_interrupt() {
-        let sr = T::REGS.sr().read();
+        let r = T::REGS;
+        let sr = r.sr().read();
 
-        // TODO: Disable interrupt which have fired.
+        if sr.typecevt1() || sr.typecevt2() {
+            r.imr().modify(|w| {
+                w.set_typecevt1ie(true);
+                w.set_typecevt2ie(true);
+            });
+        }
 
-        // Wake the task to handle and re-enabled interrupts.
+        // Wake the task to clear and re-enabled interrupts.
         T::waker().wake();
     }
 }
diff --git a/examples/stm32g4/src/bin/usb_c_pd.rs b/examples/stm32g4/src/bin/usb_c_pd.rs
new file mode 100644
index 000000000..c442ab0a7
--- /dev/null
+++ b/examples/stm32g4/src/bin/usb_c_pd.rs
@@ -0,0 +1,62 @@
+#![no_std]
+#![no_main]
+
+use defmt::{info, Format};
+use embassy_executor::Spawner;
+use embassy_stm32::{
+    ucpd::{self, CcPull, CcVState, Ucpd},
+    Config,
+};
+use embassy_time::{with_timeout, Duration};
+use {defmt_rtt as _, panic_probe as _};
+
+#[derive(Debug, Format)]
+enum CableOrientation {
+    Normal,
+    Flipped,
+    DebugAccessoryMode,
+}
+
+// Returns true when the cable
+async fn wait_attached<'d, T: ucpd::Instance>(ucpd: &mut Ucpd<'d, T>) -> CableOrientation {
+    loop {
+        let (cc1, cc2) = ucpd.cc_vstate();
+        if cc1 == CcVState::LOWEST && cc2 == CcVState::LOWEST {
+            // Detached, wait until attached by monitoring the CC lines.
+            ucpd.wait_for_cc_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_change())
+            .await
+            .is_ok()
+        {
+            // State has changed, restart detection procedure.
+            continue;
+        };
+
+        // State was stable for the complete debounce period, check orientation.
+        return match (cc1, cc2) {
+            (_, CcVState::LOWEST) => CableOrientation::Normal,  // CC1 connected
+            (CcVState::LOWEST, _) => CableOrientation::Flipped, // CC2 connected
+            _ => CableOrientation::DebugAccessoryMode,          // Both connected (special cable)
+        };
+    }
+}
+
+#[embassy_executor::main]
+async fn main(_spawner: Spawner) {
+    // TODO: Disable DBCC pin functionality by default but have flag in the config to keep it enabled when required.
+    let p = embassy_stm32::init(Config::default());
+
+    info!("Hello World!");
+
+    let mut ucpd = Ucpd::new(p.UCPD1, p.PB6, p.PB4, CcPull::Sink);
+
+    info!("Waiting for USB connection...");
+    let cable_orientation = wait_attached(&mut ucpd).await;
+    info!("USB cable connected, orientation: {}", cable_orientation);
+
+    loop {}
+}