[DMA 6/8] More helper types & working split

esp-hal/CHANGELOG.md

@@ -12,7 +12,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - ESP32-S3: Added SDMMC signals (#2556)
 - Added `set_priority` to the `DmaChannel` trait on GDMA devices (#2403, #2526)
 - Added `into_async` and `into_blocking` functions for `ParlIoTxOnly`, `ParlIoRxOnly` (#2526)
-- ESP32-C6, H2, S3: Added `split` function to the `DmaChannel` trait. (#2526)
+- ESP32-C6, H2, S3: Added `split` function to the `DmaChannel` trait. (#2526, #2532)
+- DMA: `CompatibleWith` traits and `ChannelFor` type aliasses to improve usability. (#2532)
 
 ### Changed
 

esp-hal/MIGRATING-0.22.md

@@ -1,6 +1,8 @@
 # Migration Guide from 0.22.x to v1.0.0-beta.0
 
-## DMA configuration changes
+## DMA changes
+
+### Configuration changes
 
 - `configure_for_async` and `configure` have been removed
 - PDMA devices (ESP32, ESP32-S2) provide no configurability
@@ -27,6 +29,65 @@
 +.with_dma(dma_channel);
 ```
 
+### Usability changes affecting applications
+
+It is now simpler to work with DMA channels in generic contexts. esp-hal now provides convenience
+traits and type aliasses to specify peripheral compatibility. The `ChannelCreator` types have been
+removed and individual channels are no longer wrapped in `Channel`, further simplifying use.
+
+The `Channel` types remain available for use in peripheral drivers.
+
+For example, previously you may have needed to write something like this to accept a DMA channel
+in a generic function:
+
+```rust
+fn new_foo<'d, T>(
+    dma_channel: ChannelCreator<2>, // It wasn't possible to accept a generic ChannelCreator.
+    peripheral: impl Peripheral<P = T> + 'd,
+)
+where
+    T: SomePeripheralInstance,
+    ChannelCreator<2>: DmaChannelConvert<<T as DmaEligible>::Dma>,
+{
+    let dma_channel = dma_channel.configure_for_async(false, DmaPriority::Priority0);
+
+    let driver = PeripheralDriver::new(peripheral, config).with_dma(dma_channel);
+
+    // ...
+}
+```
+
+From now on a similar, but more flexible implementation may look like:
+
+```rust
+fn new_foo<'d, T, CH>(
+    dma_channel: impl Peripheral<P = CH> + 'd,
+    peripheral: impl Peripheral<P = T> + 'd,
+)
+where
+    T: SomePeripheralInstance,
+    CH: CompatibleWith<T>,
+{
+    // Optionally: dma_channel.set_priority(DmaPriority::Priority2);
+
+    let driver = PeripheralDriver::new(peripheral, config).with_dma(dma_channel);
+
+    // ...
+}
+```
+
+### Usability changes affecting third party peripheral drivers
+
+If you are writing a driver and need to store a channel in a structure, you can use one of the
+`ChannelFor` type aliasses.
+
+```diff
+ struct Aes<'d> {
+-    channel: ChannelTx<'d, Blocking, <AES as DmaEligible>::Dma>,
++    channel: ChannelTx<'d, Blocking, TxChannelFor<AES>>,
+ }
+```
+
 ## Timer changes
 
 The low level timers, `SystemTimer` and `TimerGroup` are now "dumb". They contain no logic for operating modes or trait implementations (except the low level `Timer` trait).

esp-hal/src/aes/mod.rs

@@ -240,8 +240,8 @@ pub mod dma {
             Channel,
             ChannelRx,
             ChannelTx,
+            CompatibleWith,
             DescriptorChain,
-            DmaChannelConvert,
             DmaChannelFor,
             DmaDescriptor,
             DmaPeripheral,
@@ -295,7 +295,7 @@ pub mod dma {
             tx_descriptors: &'static mut [DmaDescriptor],
         ) -> AesDma<'d>
         where
-            CH: DmaChannelConvert<DmaChannelFor<AES>>,
+            CH: CompatibleWith<AES>,
         {
             let channel = Channel::new(channel.map(|ch| ch.degrade()));
             channel.runtime_ensure_compatible(&self.aes);

esp-hal/src/dma/gdma.rs

@@ -60,6 +60,12 @@ impl Peripheral for AnyGdmaRxChannel {
     }
 }
 
+impl DmaChannelConvert<AnyGdmaRxChannel> for AnyGdmaRxChannel {
+    fn degrade(self) -> AnyGdmaRxChannel {
+        self
+    }
+}
+
 /// An arbitrary GDMA TX channel
 pub struct AnyGdmaTxChannel(u8);
 
@@ -71,6 +77,12 @@ impl Peripheral for AnyGdmaTxChannel {
     }
 }
 
+impl DmaChannelConvert<AnyGdmaTxChannel> for AnyGdmaTxChannel {
+    fn degrade(self) -> AnyGdmaTxChannel {
+        self
+    }
+}
+
 use embassy_sync::waitqueue::AtomicWaker;
 
 static TX_WAKERS: [AtomicWaker; CHANNEL_COUNT] = [const { AtomicWaker::new() }; CHANNEL_COUNT];

esp-hal/src/dma/mod.rs

@@ -1647,7 +1647,7 @@ pub trait DmaChannelExt: DmaChannel {
     note = "Not all channels are useable with all peripherals"
 )]
 #[doc(hidden)]
-pub trait DmaChannelConvert<DEG>: DmaChannel {
+pub trait DmaChannelConvert<DEG> {
     fn degrade(self) -> DEG;
 }
 
@@ -1657,6 +1657,91 @@ impl<DEG: DmaChannel> DmaChannelConvert<DEG> for DEG {
     }
 }
 
+/// Trait implemented for DMA channels that are compatible with a particular
+/// peripheral.
+///
+/// You can use this in places where a peripheral driver would expect a
+/// `DmaChannel` implementation.
+#[cfg_attr(pdma, doc = "")]
+#[cfg_attr(
+    pdma,
+    doc = "Note that using mismatching channels (e.g. trying to use `spi2channel` with SPI3) may compile, but will panic in runtime."
+)]
+#[cfg_attr(pdma, doc = "")]
+/// ## Example
+///
+/// The following example demonstrates how this trait can be used to only accept
+/// types compatible with a specific peripheral.
+///
+/// ```rust,no_run
+#[doc = crate::before_snippet!()]
+/// use esp_hal::spi::master::{Spi, SpiDma, Config, Instance as SpiInstance};
+/// use esp_hal::dma::CompatibleWith;
+/// use esp_hal::peripheral::Peripheral;
+/// use esp_hal::Blocking;
+/// use esp_hal::dma::Dma;
+///
+/// fn configures_spi_dma<'d, S, CH>(
+///     spi: Spi<'d, Blocking, S>,
+///     channel: impl Peripheral<P = CH> + 'd,
+/// ) -> SpiDma<'d, Blocking, S>
+/// where
+///     S: SpiInstance,
+///     CH: CompatibleWith<S> + 'd,
+///  {
+///     spi.with_dma(channel)
+/// }
+///
+/// let dma = Dma::new(peripherals.DMA);
+#[cfg_attr(pdma, doc = "let dma_channel = dma.spi2channel;")]
+#[cfg_attr(gdma, doc = "let dma_channel = dma.channel0;")]
+#[doc = ""]
+/// let spi = Spi::new_with_config(
+///     peripherals.SPI2,
+///     Config::default(),
+/// );
+///
+/// let spi_dma = configures_spi_dma(spi, dma_channel);
+/// # }
+/// ```
+pub trait CompatibleWith<P: DmaEligible>: DmaChannel + DmaChannelConvert<DmaChannelFor<P>> {}
+impl<P, CH> CompatibleWith<P> for CH
+where
+    P: DmaEligible,
+    CH: DmaChannel + DmaChannelConvert<DmaChannelFor<P>>,
+{
+}
+
+/// Trait implemented for the RX half of split DMA channels that are compatible
+/// with a particular peripheral. Accepts complete DMA channels or split halves.
+///
+/// This trait is similar in use to [`CompatibleWith`].
+///
+/// You can use this in places where a peripheral driver would expect a
+/// `DmaRxChannel` implementation.
+pub trait RxCompatibleWith<P: DmaEligible>: DmaChannelConvert<RxChannelFor<P>> {}
+impl<P, RX> RxCompatibleWith<P> for RX
+where
+    P: DmaEligible,
+    RX: DmaChannelConvert<RxChannelFor<P>>,
+{
+}
+
+/// Trait implemented for the TX half of split DMA channels that are compatible
+/// with a particular peripheral. Accepts complete DMA channels or split halves.
+///
+/// This trait is similar in use to [`CompatibleWith`].
+///
+/// You can use this in places where a peripheral driver would expect a
+/// `DmaTxChannel` implementation.
+pub trait TxCompatibleWith<PER: DmaEligible>: DmaChannelConvert<TxChannelFor<PER>> {}
+impl<P, TX> TxCompatibleWith<P> for TX
+where
+    P: DmaEligible,
+    TX: DmaChannelConvert<TxChannelFor<P>>,
+{
+}
+
 /// The functions here are not meant to be used outside the HAL
 #[doc(hidden)]
 pub trait Rx: crate::private::Sealed {

esp-hal/src/i2s/master.rs

@@ -80,8 +80,8 @@ use crate::{
         Channel,
         ChannelRx,
         ChannelTx,
+        CompatibleWith,
         DescriptorChain,
-        DmaChannelConvert,
         DmaChannelFor,
         DmaDescriptor,
         DmaEligible,
@@ -377,7 +377,7 @@ impl<'d> I2s<'d, Blocking> {
         tx_descriptors: &'static mut [DmaDescriptor],
     ) -> Self
     where
-        CH: DmaChannelConvert<DmaChannelFor<AnyI2s>>,
+        CH: CompatibleWith<AnyI2s>,
     {
         Self::new_typed(
             i2s.map_into(),
@@ -408,7 +408,7 @@ where
         tx_descriptors: &'static mut [DmaDescriptor],
     ) -> Self
     where
-        CH: DmaChannelConvert<DmaChannelFor<T>>,
+        CH: CompatibleWith<T>,
     {
         crate::into_ref!(i2s);
         Self::new_internal(

esp-hal/src/i2s/parallel.rs

@@ -46,8 +46,7 @@ use crate::{
         asynch::DmaTxFuture,
         Channel,
         ChannelTx,
-        DmaChannelConvert,
-        DmaChannelFor,
+        CompatibleWith,
         DmaEligible,
         DmaError,
         DmaPeripheral,
@@ -193,7 +192,7 @@ impl<'d> I2sParallel<'d, Blocking> {
         clock_pin: impl Peripheral<P = impl PeripheralOutput> + 'd,
     ) -> Self
     where
-        CH: DmaChannelConvert<DmaChannelFor<AnyI2s>>,
+        CH: CompatibleWith<AnyI2s>,
     {
         Self::new_typed(i2s.map_into(), channel, frequency, pins, clock_pin)
     }
@@ -212,7 +211,7 @@ where
         clock_pin: impl Peripheral<P = impl PeripheralOutput> + 'd,
     ) -> Self
     where
-        CH: DmaChannelConvert<DmaChannelFor<I>>,
+        CH: CompatibleWith<I>,
     {
         crate::into_ref!(i2s);
         crate::into_mapped_ref!(clock_pin);

esp-hal/src/lcd_cam/cam.rs

@@ -67,7 +67,7 @@ use fugit::HertzU32;
 
 use crate::{
     clock::Clocks,
-    dma::{ChannelRx, DmaChannelConvert, DmaError, DmaPeripheral, DmaRxBuffer, Rx, RxChannelFor},
+    dma::{ChannelRx, DmaError, DmaPeripheral, DmaRxBuffer, Rx, RxChannelFor, RxCompatibleWith},
     gpio::{
         interconnect::{PeripheralInput, PeripheralOutput},
         InputSignal,
@@ -136,7 +136,7 @@ impl<'d> Camera<'d> {
         frequency: HertzU32,
     ) -> Self
     where
-        CH: DmaChannelConvert<RxChannelFor<LCD_CAM>>,
+        CH: RxCompatibleWith<LCD_CAM>,
         P: RxPins,
     {
         let rx_channel = ChannelRx::new(channel.map(|ch| ch.degrade()));

esp-hal/src/lcd_cam/lcd/dpi.rs

@@ -106,7 +106,7 @@ use fugit::HertzU32;
 
 use crate::{
     clock::Clocks,
-    dma::{ChannelTx, DmaChannelConvert, DmaError, DmaPeripheral, DmaTxBuffer, Tx, TxChannelFor},
+    dma::{ChannelTx, DmaError, DmaPeripheral, DmaTxBuffer, Tx, TxChannelFor, TxCompatibleWith},
     gpio::{interconnect::PeripheralOutput, Level, OutputSignal},
     lcd_cam::{
         calculate_clkm,
@@ -139,7 +139,7 @@ where
         config: Config,
     ) -> Self
     where
-        CH: DmaChannelConvert<TxChannelFor<LCD_CAM>>,
+        CH: TxCompatibleWith<LCD_CAM>,
     {
         let tx_channel = ChannelTx::new(channel.map(|ch| ch.degrade()));
         let lcd_cam = lcd.lcd_cam;

esp-hal/src/lcd_cam/lcd/i8080.rs

@@ -62,7 +62,7 @@ use fugit::HertzU32;
 
 use crate::{
     clock::Clocks,
-    dma::{ChannelTx, DmaChannelConvert, DmaError, DmaPeripheral, DmaTxBuffer, Tx, TxChannelFor},
+    dma::{ChannelTx, DmaError, DmaPeripheral, DmaTxBuffer, Tx, TxChannelFor, TxCompatibleWith},
     gpio::{
         interconnect::{OutputConnection, PeripheralOutput},
         OutputSignal,
@@ -102,7 +102,7 @@ where
         config: Config,
     ) -> Self
     where
-        CH: DmaChannelConvert<TxChannelFor<LCD_CAM>>,
+        CH: TxCompatibleWith<LCD_CAM>,
         P: TxPins,
     {
         let tx_channel = ChannelTx::new(channel.map(|ch| ch.degrade()));

esp-hal/src/parl_io.rs

@@ -34,9 +34,8 @@ use crate::{
         Channel,
         ChannelRx,
         ChannelTx,
+        CompatibleWith,
         DescriptorChain,
-        DmaChannelConvert,
-        DmaChannelFor,
         DmaDescriptor,
         DmaError,
         DmaPeripheral,
@@ -45,8 +44,10 @@ use crate::{
         ReadBuffer,
         Rx,
         RxChannelFor,
+        RxCompatibleWith,
         Tx,
         TxChannelFor,
+        TxCompatibleWith,
         WriteBuffer,
     },
     gpio::{
@@ -1013,7 +1014,7 @@ impl<'d> ParlIoFullDuplex<'d, Blocking> {
         frequency: HertzU32,
     ) -> Result<Self, Error>
     where
-        CH: DmaChannelConvert<DmaChannelFor<PARL_IO>>,
+        CH: CompatibleWith<PARL_IO>,
     {
         let tx_guard = GenericPeripheralGuard::new();
         let rx_guard = GenericPeripheralGuard::new();
@@ -1135,7 +1136,7 @@ impl<'d> ParlIoTxOnly<'d, Blocking> {
         frequency: HertzU32,
     ) -> Result<Self, Error>
     where
-        CH: DmaChannelConvert<TxChannelFor<PARL_IO>>,
+        CH: TxCompatibleWith<PARL_IO>,
     {
         let guard = GenericPeripheralGuard::new();
         let tx_channel = ChannelTx::new(dma_channel.map(|ch| ch.degrade()));
@@ -1241,7 +1242,7 @@ impl<'d> ParlIoRxOnly<'d, Blocking> {
         frequency: HertzU32,
     ) -> Result<Self, Error>
     where
-        CH: DmaChannelConvert<RxChannelFor<PARL_IO>>,
+        CH: RxCompatibleWith<PARL_IO>,
     {
         let guard = GenericPeripheralGuard::new();
         let rx_channel = ChannelRx::new(dma_channel.map(|ch| ch.degrade()));