rp: generalize adc inputs from pins to channels

this lets us treat pins and the temperature sensor uniformly using the
same interface. uniformity in turn lets us add more adc features without
combinatorial explosion of methods and types needed to handle them all.

embassy-rp/src/adc.rs

@@ -10,8 +10,8 @@ use crate::gpio::sealed::Pin as GpioPin;
 use crate::gpio::{self, AnyPin, Pull};
 use crate::interrupt::typelevel::Binding;
 use crate::interrupt::InterruptExt;
-use crate::peripherals::ADC;
-use crate::{interrupt, pac, peripherals, Peripheral};
+use crate::peripherals::{ADC, ADC_TEMP_SENSOR};
+use crate::{interrupt, pac, peripherals, Peripheral, RegExt};
 
 static WAKER: AtomicWaker = AtomicWaker::new();
 
@@ -24,12 +24,15 @@ impl Default for Config {
     }
 }
 
-pub struct Pin<'p> {
-    pin: PeripheralRef<'p, AnyPin>,
+enum Source<'p> {
+    Pin(PeripheralRef<'p, AnyPin>),
+    TempSensor(PeripheralRef<'p, ADC_TEMP_SENSOR>),
 }
 
-impl<'p> Pin<'p> {
-    pub fn new(pin: impl Peripheral<P = impl AdcPin + 'p> + 'p, pull: Pull) -> Self {
+pub struct Channel<'p>(Source<'p>);
+
+impl<'p> Channel<'p> {
+    pub fn new_pin(pin: impl Peripheral<P = impl AdcPin + 'p> + 'p, pull: Pull) -> Self {
         into_ref!(pin);
         pin.pad_ctrl().modify(|w| {
             // manual says:
@@ -42,24 +45,40 @@ impl<'p> Pin<'p> {
             w.set_pue(pull == Pull::Up);
             w.set_pde(pull == Pull::Down);
         });
-        Self { pin: pin.map_into() }
+        Self(Source::Pin(pin.map_into()))
+    }
+
+    pub fn new_sensor(s: impl Peripheral<P = ADC_TEMP_SENSOR> + 'p) -> Self {
+        let r = pac::ADC;
+        r.cs().write_set(|w| w.set_ts_en(true));
+        Self(Source::TempSensor(s.into_ref()))
     }
 
     fn channel(&self) -> u8 {
-        // this requires adc pins to be sequential and matching the adc channels,
-        // which is the case for rp2040
-        self.pin._pin() - 26
+        match &self.0 {
+            // this requires adc pins to be sequential and matching the adc channels,
+            // which is the case for rp2040
+            Source::Pin(p) => p._pin() - 26,
+            Source::TempSensor(_) => 4,
+        }
     }
 }
 
-impl<'d> Drop for Pin<'d> {
+impl<'p> Drop for Source<'p> {
     fn drop(&mut self) {
-        self.pin.pad_ctrl().modify(|w| {
-            w.set_ie(true);
-            w.set_od(false);
-            w.set_pue(false);
-            w.set_pde(true);
-        });
+        match self {
+            Source::Pin(p) => {
+                p.pad_ctrl().modify(|w| {
+                    w.set_ie(true);
+                    w.set_od(false);
+                    w.set_pue(false);
+                    w.set_pde(true);
+                });
+            }
+            Source::TempSensor(_) => {
+                pac::ADC.cs().write_clear(|w| w.set_ts_en(true));
+            }
+        }
     }
 }
 
@@ -115,10 +134,10 @@ impl<'d, M: Mode> Adc<'d, M> {
         while !r.cs().read().ready() {}
     }
 
-    fn sample_blocking(channel: u8) -> Result<u16, Error> {
+    pub fn blocking_read(&mut self, ch: &mut Channel) -> Result<u16, Error> {
         let r = Self::regs();
         r.cs().modify(|w| {
-            w.set_ainsel(channel);
+            w.set_ainsel(ch.channel());
             w.set_start_once(true);
             w.set_err(true);
         });
@@ -128,19 +147,6 @@ impl<'d, M: Mode> Adc<'d, M> {
             false => Ok(r.result().read().result().into()),
         }
     }
-
-    pub fn blocking_read(&mut self, pin: &mut Pin) -> Result<u16, Error> {
-        Self::sample_blocking(pin.channel())
-    }
-
-    pub fn blocking_read_temperature(&mut self) -> Result<u16, Error> {
-        let r = Self::regs();
-        r.cs().modify(|w| w.set_ts_en(true));
-        while !r.cs().read().ready() {}
-        let result = Self::sample_blocking(4);
-        r.cs().modify(|w| w.set_ts_en(false));
-        result
-    }
 }
 
 impl<'d> Adc<'d, Async> {
@@ -172,10 +178,10 @@ impl<'d> Adc<'d, Async> {
         .await;
     }
 
-    async fn sample_async(channel: u8) -> Result<u16, Error> {
+    pub async fn read(&mut self, ch: &mut Channel<'_>) -> Result<u16, Error> {
         let r = Self::regs();
         r.cs().modify(|w| {
-            w.set_ainsel(channel);
+            w.set_ainsel(ch.channel());
             w.set_start_once(true);
             w.set_err(true);
         });
@@ -185,21 +191,6 @@ impl<'d> Adc<'d, Async> {
             false => Ok(r.result().read().result().into()),
         }
     }
-
-    pub async fn read(&mut self, pin: &mut Pin<'_>) -> Result<u16, Error> {
-        Self::sample_async(pin.channel()).await
-    }
-
-    pub async fn read_temperature(&mut self) -> Result<u16, Error> {
-        let r = Self::regs();
-        r.cs().modify(|w| w.set_ts_en(true));
-        if !r.cs().read().ready() {
-            Self::wait_for_ready().await;
-        }
-        let result = Self::sample_async(4).await;
-        r.cs().modify(|w| w.set_ts_en(false));
-        result
-    }
 }
 
 impl<'d> Adc<'d, Blocking> {
@@ -230,14 +221,17 @@ pub trait AdcChannel: sealed::AdcChannel {}
 pub trait AdcPin: AdcChannel + gpio::Pin {}
 
 macro_rules! impl_pin {
-    ($pin:ident) => {
+    ($pin:ident, $channel:expr) => {
         impl sealed::AdcChannel for peripherals::$pin {}
         impl AdcChannel for peripherals::$pin {}
         impl AdcPin for peripherals::$pin {}
     };
 }
 
-impl_pin!(PIN_26);
-impl_pin!(PIN_27);
-impl_pin!(PIN_28);
-impl_pin!(PIN_29);
+impl_pin!(PIN_26, 0);
+impl_pin!(PIN_27, 1);
+impl_pin!(PIN_28, 2);
+impl_pin!(PIN_29, 3);
+
+impl sealed::AdcChannel for peripherals::ADC_TEMP_SENSOR {}
+impl AdcChannel for peripherals::ADC_TEMP_SENSOR {}

embassy-rp/src/lib.rs

@@ -183,6 +183,7 @@ embassy_hal_internal::peripherals! {
     FLASH,
 
     ADC,
+    ADC_TEMP_SENSOR,
 
     CORE1,