3 files changed, 209 insertions, 34 deletions

diff --git a/embassy-stm32/build.rs b/embassy-stm32/build.rs
index 276c1d637..35c3f23b4 100644
--- a/embassy-stm32/build.rs
+++ b/embassy-stm32/build.rs
@@ -944,17 +944,25 @@ fn main() {
                 }
 
                 if regs.kind == "opamp" {
-                    if !pin.signal.starts_with("VP") {
-                        continue;
-                    }
+                    println!("{}", pin.signal);
 
-                    let peri = format_ident!("{}", p.name);
-                    let pin_name = format_ident!("{}", pin.pin);
-                    let ch: u8 = pin.signal.strip_prefix("VP").unwrap().parse().unwrap();
+                    if pin.signal.starts_with("VP") {
+                        // Impl NonInvertingPin for the VP* signals (VP0, VP1, VP2, etc)
+                        let peri = format_ident!("{}", p.name);
+                        let pin_name = format_ident!("{}", pin.pin);
+                        let ch: u8 = pin.signal.strip_prefix("VP").unwrap().parse().unwrap();
 
-                    g.extend(quote! {
-                        impl_opamp_pin!( #peri, #pin_name, #ch);
-                    })
+                        g.extend(quote! {
+                            impl_opamp_vp_pin!( #peri, #pin_name, #ch);
+                        })
+                    } else if pin.signal == "VOUT" {
+                        // Impl OutputPin for the VOUT pin
+                        let peri = format_ident!("{}", p.name);
+                        let pin_name = format_ident!("{}", pin.pin);
+                        g.extend(quote! {
+                            impl_opamp_vout_pin!( #peri, #pin_name );
+                        })
+                    }
                 }
 
                 // DAC is special
diff --git a/embassy-stm32/src/opamp.rs b/embassy-stm32/src/opamp.rs
index cb55cbe19..89db6d14d 100644
--- a/embassy-stm32/src/opamp.rs
+++ b/embassy-stm32/src/opamp.rs
@@ -13,21 +13,50 @@ pub enum OpAmpGain {
     Mul16,
 }
 
-pub struct OpAmpOutput<'d, 'p, T: Instance, P: NonInvertingPin<T>> {
+#[derive(Clone, Copy)]
+pub enum OpAmpSpeed {
+    Normal,
+    HighSpeed,
+}
+
+#[cfg(opamp_g4)]
+impl From<OpAmpSpeed> for crate::pac::opamp::vals::OpampCsrOpahsm {
+    fn from(v: OpAmpSpeed) -> Self {
+        match v {
+            OpAmpSpeed::Normal => crate::pac::opamp::vals::OpampCsrOpahsm::NORMAL,
+            OpAmpSpeed::HighSpeed => crate::pac::opamp::vals::OpampCsrOpahsm::HIGHSPEED,
+        }
+    }
+}
+
+/// OpAmp external outputs, wired to a GPIO pad.
+///
+/// The GPIO output pad is held by this struct to ensure it cannot be used elsewhere.
+///
+/// This struct can also be used as an ADC input.
+pub struct OpAmpOutput<'d, 'p, T: Instance, P: OutputPin<T>> {
     _inner: &'d OpAmp<'d, T>,
-    _input: &'p mut P,
+    _output: &'p mut P,
 }
 
+/// OpAmp internal outputs, wired directly to ADC inputs.
+///
+/// This struct can be used as an ADC input.
+pub struct OpAmpInternalOutput<'d, T: Instance> {
+    _inner: &'d OpAmp<'d, T>,
+}
+
+/// OpAmp driver.
 pub struct OpAmp<'d, T: Instance> {
     _inner: PeripheralRef<'d, T>,
 }
 
 impl<'d, T: Instance> OpAmp<'d, T> {
-    pub fn new(opamp: impl Peripheral<P = T> + 'd) -> Self {
-        Self::new_inner(opamp)
-    }
-
-    fn new_inner(opamp: impl Peripheral<P = T> + 'd) -> Self {
+    /// Create a new driver instance.
+    ///
+    /// Enables the OpAmp and configures the speed, but
+    /// does not set any other configuration.
+    pub fn new(opamp: impl Peripheral<P = T> + 'd, #[cfg(opamp_g4)] speed: OpAmpSpeed) -> Self {
         into_ref!(opamp);
 
         #[cfg(opamp_f3)]
@@ -38,15 +67,34 @@ impl<'d, T: Instance> OpAmp<'d, T> {
         #[cfg(opamp_g4)]
         T::regs().opamp_csr().modify(|w| {
             w.set_opaen(true);
+            w.set_opahsm(speed.into());
         });
 
         Self { _inner: opamp }
     }
 
-    pub fn buffer_for<'a, 'b, P>(&'a mut self, pin: &'b mut P, gain: OpAmpGain) -> OpAmpOutput<'a, 'b, T, P>
+    /// Configure the OpAmp as a buffer for the provided input pin,
+    /// outputting to the provided output pin.
+    ///
+    /// The input pin is configured for analogue mode but not consumed,
+    /// so it may subsequently be used for ADC or comparator inputs.
+    ///
+    /// The output pin is held within the returned [`OpAmpOutput`] struct,
+    /// preventing it being used elsewhere. The `OpAmpOutput` can then be
+    /// directly used as an ADC input.
+    pub fn buffer_ext<'a, 'b, IP, OP>(
+        &'a mut self,
+        in_pin: &IP,
+        out_pin: &'b mut OP,
+        gain: OpAmpGain,
+    ) -> OpAmpOutput<'a, 'b, T, OP>
     where
-        P: NonInvertingPin<T>,
+        IP: NonInvertingPin<T> + crate::gpio::sealed::Pin,
+        OP: OutputPin<T> + crate::gpio::sealed::Pin,
     {
+        in_pin.set_as_analog();
+        out_pin.set_as_analog();
+
         let (vm_sel, pga_gain) = match gain {
             OpAmpGain::Mul1 => (0b11, 0b00),
             OpAmpGain::Mul2 => (0b10, 0b00),
@@ -57,25 +105,76 @@ impl<'d, T: Instance> OpAmp<'d, T> {
 
         #[cfg(opamp_f3)]
         T::regs().opampcsr().modify(|w| {
-            w.set_vp_sel(pin.channel());
+            w.set_vp_sel(in_pin.channel());
             w.set_vm_sel(vm_sel);
             w.set_pga_gain(pga_gain);
+            w.set_opampen(true);
         });
 
         #[cfg(opamp_g4)]
         T::regs().opamp_csr().modify(|w| {
             use crate::pac::opamp::vals::*;
 
-            w.set_vp_sel(OpampCsrVpSel::from_bits(pin.channel()));
+            w.set_vp_sel(OpampCsrVpSel::from_bits(in_pin.channel()));
             w.set_vm_sel(OpampCsrVmSel::from_bits(vm_sel));
             w.set_pga_gain(OpampCsrPgaGain::from_bits(pga_gain));
+            w.set_opaintoen(OpampCsrOpaintoen::OUTPUTPIN);
+            w.set_opaen(true);
         });
 
         OpAmpOutput {
             _inner: self,
-            _input: pin,
+            _output: out_pin,
         }
     }
+
+    /// Configure the OpAmp as a buffer for the provided input pin,
+    /// with the output only used internally.
+    ///
+    /// The input pin is configured for analogue mode but not consumed,
+    /// so it may be subsequently used for ADC or comparator inputs.
+    ///
+    /// The returned `OpAmpInternalOutput` struct may be used as an ADC input.
+    #[cfg(opamp_g4)]
+    pub fn buffer_int<'a, P>(&'a mut self, pin: &P, gain: OpAmpGain) -> OpAmpInternalOutput<'a, T>
+    where
+        P: NonInvertingPin<T> + crate::gpio::sealed::Pin,
+    {
+        pin.set_as_analog();
+
+        let (vm_sel, pga_gain) = match gain {
+            OpAmpGain::Mul1 => (0b11, 0b00),
+            OpAmpGain::Mul2 => (0b10, 0b00),
+            OpAmpGain::Mul4 => (0b10, 0b01),
+            OpAmpGain::Mul8 => (0b10, 0b10),
+            OpAmpGain::Mul16 => (0b10, 0b11),
+        };
+
+        T::regs().opamp_csr().modify(|w| {
+            use crate::pac::opamp::vals::*;
+            w.set_vp_sel(OpampCsrVpSel::from_bits(pin.channel()));
+            w.set_vm_sel(OpampCsrVmSel::from_bits(vm_sel));
+            w.set_pga_gain(OpampCsrPgaGain::from_bits(pga_gain));
+            w.set_opaintoen(OpampCsrOpaintoen::ADCCHANNEL);
+            w.set_opaen(true);
+        });
+
+        OpAmpInternalOutput { _inner: self }
+    }
+}
+
+impl<'d, T: Instance> Drop for OpAmp<'d, T> {
+    fn drop(&mut self) {
+        #[cfg(opamp_f3)]
+        T::regs().opampcsr().modify(|w| {
+            w.set_opampen(false);
+        });
+
+        #[cfg(opamp_g4)]
+        T::regs().opamp_csr().modify(|w| {
+            w.set_opaen(false);
+        });
+    }
 }
 
 pub trait Instance: sealed::Instance + 'static {}
@@ -92,18 +191,19 @@ pub(crate) mod sealed {
     pub trait InvertingPin<T: Instance> {
         fn channel(&self) -> u8;
     }
+
+    pub trait OutputPin<T: Instance> {}
 }
 
 pub trait NonInvertingPin<T: Instance>: sealed::NonInvertingPin<T> {}
-
 pub trait InvertingPin<T: Instance>: sealed::InvertingPin<T> {}
+pub trait OutputPin<T: Instance>: sealed::OutputPin<T> {}
 
-#[cfg(opamp_f3)]
-macro_rules! impl_opamp_output {
+macro_rules! impl_opamp_external_output {
     ($inst:ident, $adc:ident, $ch:expr) => {
         foreach_adc!(
             ($adc, $common_inst:ident, $adc_clock:ident) => {
-                impl<'d, 'p, P: NonInvertingPin<crate::peripherals::$inst>> crate::adc::sealed::AdcPin<crate::peripherals::$adc>
+                impl<'d, 'p, P: OutputPin<crate::peripherals::$inst>> crate::adc::sealed::AdcPin<crate::peripherals::$adc>
                     for OpAmpOutput<'d, 'p, crate::peripherals::$inst, P>
                 {
                     fn channel(&self) -> u8 {
@@ -111,7 +211,7 @@ macro_rules! impl_opamp_output {
                     }
                 }
 
-                impl<'d, 'p, P: NonInvertingPin<crate::peripherals::$inst>> crate::adc::AdcPin<crate::peripherals::$adc>
+                impl<'d, 'p, P: OutputPin<crate::peripherals::$inst>> crate::adc::AdcPin<crate::peripherals::$adc>
                     for OpAmpOutput<'d, 'p, crate::peripherals::$inst, P>
                 {
                 }
@@ -120,19 +220,79 @@ macro_rules! impl_opamp_output {
     };
 }
 
-#[cfg(opamp_f3)]
 foreach_peripheral!(
     (opamp, OPAMP1) => {
-        impl_opamp_output!(OPAMP1, ADC1, 3);
+        impl_opamp_external_output!(OPAMP1, ADC1, 3);
+    };
+    (opamp, OPAMP2) => {
+        impl_opamp_external_output!(OPAMP2, ADC2, 3);
+    };
+    (opamp, OPAMP3) => {
+        impl_opamp_external_output!(OPAMP3, ADC3, 1);
+    };
+    // OPAMP4 only in STM32G4 Cat 3 devices
+    (opamp, OPAMP4) => {
+        impl_opamp_external_output!(OPAMP4, ADC4, 3);
+    };
+    // OPAMP5 only in STM32G4 Cat 3 devices
+    (opamp, OPAMP5) => {
+        impl_opamp_external_output!(OPAMP5, ADC5, 1);
+    };
+    // OPAMP6 only in STM32G4 Cat 3/4 devices
+    (opamp, OPAMP6) => {
+        impl_opamp_external_output!(OPAMP6, ADC1, 14);
+    };
+);
+
+#[cfg(opamp_g4)]
+macro_rules! impl_opamp_internal_output {
+    ($inst:ident, $adc:ident, $ch:expr) => {
+        foreach_adc!(
+            ($adc, $common_inst:ident, $adc_clock:ident) => {
+                impl<'d> crate::adc::sealed::AdcPin<crate::peripherals::$adc>
+                    for OpAmpInternalOutput<'d, crate::peripherals::$inst>
+                {
+                    fn channel(&self) -> u8 {
+                        $ch
+                    }
+                }
+
+                impl<'d> crate::adc::AdcPin<crate::peripherals::$adc>
+                    for OpAmpInternalOutput<'d, crate::peripherals::$inst>
+                {
+                }
+            };
+        );
+    };
+}
+
+#[cfg(opamp_g4)]
+foreach_peripheral!(
+    (opamp, OPAMP1) => {
+        impl_opamp_internal_output!(OPAMP1, ADC1, 13);
     };
     (opamp, OPAMP2) => {
-        impl_opamp_output!(OPAMP2, ADC2, 3);
+        impl_opamp_internal_output!(OPAMP2, ADC2, 16);
     };
     (opamp, OPAMP3) => {
-        impl_opamp_output!(OPAMP3, ADC3, 1);
+        impl_opamp_internal_output!(OPAMP3, ADC2, 18);
+        // Only in Cat 3/4 devices
+        impl_opamp_internal_output!(OPAMP3, ADC3, 13);
     };
+    // OPAMP4 only in Cat 3 devices
     (opamp, OPAMP4) => {
-        impl_opamp_output!(OPAMP4, ADC4, 3);
+        impl_opamp_internal_output!(OPAMP4, ADC5, 5);
+    };
+    // OPAMP5 only in Cat 3 devices
+    (opamp, OPAMP5) => {
+        impl_opamp_internal_output!(OPAMP5, ADC5, 3);
+    };
+    // OPAMP6 only in Cat 3/4 devices
+    (opamp, OPAMP6) => {
+        // Only in Cat 3 devices
+        impl_opamp_internal_output!(OPAMP6, ADC4, 17);
+        // Only in Cat 4 devices
+        impl_opamp_internal_output!(OPAMP6, ADC3, 17);
     };
 );
 
@@ -145,13 +305,12 @@ foreach_peripheral! {
         }
 
         impl Instance for crate::peripherals::$inst {
-
         }
     };
 }
 
 #[allow(unused_macros)]
-macro_rules! impl_opamp_pin {
+macro_rules! impl_opamp_vp_pin {
     ($inst:ident, $pin:ident, $ch:expr) => {
         impl crate::opamp::NonInvertingPin<peripherals::$inst> for crate::peripherals::$pin {}
         impl crate::opamp::sealed::NonInvertingPin<peripherals::$inst> for crate::peripherals::$pin {
@@ -161,3 +320,11 @@ macro_rules! impl_opamp_pin {
         }
     };
 }
+
+#[allow(unused_macros)]
+macro_rules! impl_opamp_vout_pin {
+    ($inst:ident, $pin:ident) => {
+        impl crate::opamp::OutputPin<peripherals::$inst> for crate::peripherals::$pin {}
+        impl crate::opamp::sealed::OutputPin<peripherals::$inst> for crate::peripherals::$pin {}
+    };
+}
diff --git a/examples/stm32f334/src/bin/opamp.rs b/examples/stm32f334/src/bin/opamp.rs
index 128001bf2..137fc9e66 100644
--- a/examples/stm32f334/src/bin/opamp.rs
+++ b/examples/stm32f334/src/bin/opamp.rs
@@ -39,7 +39,7 @@ async fn main(_spawner: Spawner) -> ! {
 
     let mut vrefint = adc.enable_vref(&mut Delay);
     let mut temperature = adc.enable_temperature();
-    let mut buffer = opamp.buffer_for(&mut p.PA7, OpAmpGain::Mul1);
+    let mut buffer = opamp.buffer_ext(&p.PA7, &mut p.PA6, OpAmpGain::Mul1);
 
     loop {
         let vref = adc.read(&mut vrefint).await;