Async shared bus for SPI & I2C + rename embassy-traits (#769)

* Rename embassy-traits to embassy-embedded-hal

* Rename embassy-traits to embassy-embedded-hal

* Add shared bus for SPI and I2C

* rustfmt

* EHA alpha 1

* Rename embedded-traits in examples

* rustfmt

* rustfmt

Co-authored-by: Henrik Alsér <[email protected]>

3 files changed, 234 insertions, 0 deletions

diff --git a/embassy-embedded-hal/src/shared_bus/i2c.rs b/embassy-embedded-hal/src/shared_bus/i2c.rs
new file mode 100644
index 000000000..5a180e897
--- /dev/null
+++ b/embassy-embedded-hal/src/shared_bus/i2c.rs
@@ -0,0 +1,120 @@
+//! Asynchronous shared I2C bus
+//!
+//! # Example (nrf52)
+//!
+//! ```rust
+//! use embassy_embedded_hal::shared_bus::i2c::I2cBusDevice;
+//! use embassy::mutex::Mutex;
+//! use embassy::blocking_mutex::raw::ThreadModeRawMutex;
+//!
+//! static I2C_BUS: Forever<Mutex::<ThreadModeRawMutex, Twim<TWISPI0>>> = Forever::new();
+//! let config = twim::Config::default();
+//! let irq = interrupt::take!(SPIM0_SPIS0_TWIM0_TWIS0_SPI0_TWI0);
+//! let i2c = Twim::new(p.TWISPI0, irq, p.P0_03, p.P0_04, config);
+//! let i2c_bus = Mutex::<ThreadModeRawMutex, _>::new(i2c);
+//! let i2c_bus = I2C_BUS.put(i2c_bus);
+//!
+//! // Device 1, using embedded-hal-async compatible driver for QMC5883L compass
+//! let i2c_dev1 = I2cBusDevice::new(i2c_bus);
+//! let compass = QMC5883L::new(i2c_dev1).await.unwrap();
+//!
+//! // Device 2, using embedded-hal-async compatible driver for Mpu6050 accelerometer
+//! let i2c_dev2 = I2cBusDevice::new(i2c_bus);
+//! let mpu = Mpu6050::new(i2c_dev2);
+//! ```
+use core::{fmt::Debug, future::Future};
+use embassy::blocking_mutex::raw::RawMutex;
+use embassy::mutex::Mutex;
+use embedded_hal_async::i2c;
+
+#[derive(Copy, Clone, Eq, PartialEq, Debug)]
+pub enum I2cBusDeviceError<BUS> {
+    I2c(BUS),
+}
+
+impl<BUS> i2c::Error for I2cBusDeviceError<BUS>
+where
+    BUS: i2c::Error + Debug,
+{
+    fn kind(&self) -> i2c::ErrorKind {
+        match self {
+            Self::I2c(e) => e.kind(),
+        }
+    }
+}
+
+pub struct I2cBusDevice<'a, M: RawMutex, BUS> {
+    bus: &'a Mutex<M, BUS>,
+}
+
+impl<'a, M: RawMutex, BUS> I2cBusDevice<'a, M, BUS> {
+    pub fn new(bus: &'a Mutex<M, BUS>) -> Self {
+        Self { bus }
+    }
+}
+
+impl<'a, M: RawMutex, BUS> i2c::ErrorType for I2cBusDevice<'a, M, BUS>
+where
+    BUS: i2c::ErrorType,
+{
+    type Error = I2cBusDeviceError<BUS::Error>;
+}
+
+impl<M, BUS> i2c::I2c for I2cBusDevice<'_, M, BUS>
+where
+    M: RawMutex + 'static,
+    BUS: i2c::I2c + 'static,
+{
+    type ReadFuture<'a> = impl Future<Output = Result<(), Self::Error>> + 'a where Self: 'a;
+
+    fn read<'a>(&'a mut self, address: u8, buffer: &'a mut [u8]) -> Self::ReadFuture<'a> {
+        async move {
+            let mut bus = self.bus.lock().await;
+            bus.read(address, buffer)
+                .await
+                .map_err(I2cBusDeviceError::I2c)?;
+            Ok(())
+        }
+    }
+
+    type WriteFuture<'a> = impl Future<Output = Result<(), Self::Error>> + 'a where Self: 'a;
+
+    fn write<'a>(&'a mut self, address: u8, bytes: &'a [u8]) -> Self::WriteFuture<'a> {
+        async move {
+            let mut bus = self.bus.lock().await;
+            bus.write(address, bytes)
+                .await
+                .map_err(I2cBusDeviceError::I2c)?;
+            Ok(())
+        }
+    }
+
+    type WriteReadFuture<'a> = impl Future<Output = Result<(), Self::Error>> + 'a where Self: 'a;
+
+    fn write_read<'a>(
+        &'a mut self,
+        address: u8,
+        wr_buffer: &'a [u8],
+        rd_buffer: &'a mut [u8],
+    ) -> Self::WriteReadFuture<'a> {
+        async move {
+            let mut bus = self.bus.lock().await;
+            bus.write_read(address, wr_buffer, rd_buffer)
+                .await
+                .map_err(I2cBusDeviceError::I2c)?;
+            Ok(())
+        }
+    }
+
+    type TransactionFuture<'a, 'b> = impl Future<Output = Result<(), Self::Error>> + 'a where Self: 'a, 'b: 'a;
+
+    fn transaction<'a, 'b>(
+        &'a mut self,
+        address: u8,
+        operations: &'a mut [embedded_hal_async::i2c::Operation<'b>],
+    ) -> Self::TransactionFuture<'a, 'b> {
+        let _ = address;
+        let _ = operations;
+        async move { todo!() }
+    }
+}
diff --git a/embassy-embedded-hal/src/shared_bus/mod.rs b/embassy-embedded-hal/src/shared_bus/mod.rs
new file mode 100644
index 000000000..bd4fd2c31
--- /dev/null
+++ b/embassy-embedded-hal/src/shared_bus/mod.rs
@@ -0,0 +1,4 @@
+//! Shared bus implementations for embedded-hal-async
+
+pub mod i2c;
+pub mod spi;
diff --git a/embassy-embedded-hal/src/shared_bus/spi.rs b/embassy-embedded-hal/src/shared_bus/spi.rs
new file mode 100644
index 000000000..3ec064ba7
--- /dev/null
+++ b/embassy-embedded-hal/src/shared_bus/spi.rs
@@ -0,0 +1,110 @@
+//! Asynchronous shared SPI bus
+//!
+//! # Example (nrf52)
+//!
+//! ```rust
+//! use embassy_embedded_hal::shared_bus::spi::SpiBusDevice;
+//! use embassy::mutex::Mutex;
+//! use embassy::blocking_mutex::raw::ThreadModeRawMutex;
+//!
+//! static SPI_BUS: Forever<Mutex<ThreadModeRawMutex, spim::Spim<SPI3>>> = Forever::new();
+//! let mut config = spim::Config::default();
+//! config.frequency = spim::Frequency::M32;
+//! let irq = interrupt::take!(SPIM3);
+//! let spi = spim::Spim::new_txonly(p.SPI3, irq, p.P0_15, p.P0_18, config);
+//! let spi_bus = Mutex::<ThreadModeRawMutex, _>::new(spi);
+//! let spi_bus = SPI_BUS.put(spi_bus);
+//!
+//! // Device 1, using embedded-hal-async compatible driver for ST7735 LCD display
+//! let cs_pin1 = Output::new(p.P0_24, Level::Low, OutputDrive::Standard);
+//! let spi_dev1 = SpiBusDevice::new(spi_bus, cs_pin1);
+//! let display1 = ST7735::new(spi_dev1, dc1, rst1, Default::default(), 160, 128);
+//!
+//! // Device 2
+//! let cs_pin2 = Output::new(p.P0_24, Level::Low, OutputDrive::Standard);
+//! let spi_dev2 = SpiBusDevice::new(spi_bus, cs_pin2);
+//! let display2 = ST7735::new(spi_dev2, dc2, rst2, Default::default(), 160, 128);
+//! ```
+use core::{fmt::Debug, future::Future};
+use embassy::blocking_mutex::raw::RawMutex;
+use embassy::mutex::Mutex;
+
+use embedded_hal_1::digital::blocking::OutputPin;
+use embedded_hal_1::spi::ErrorType;
+use embedded_hal_async::spi;
+
+#[derive(Copy, Clone, Eq, PartialEq, Debug)]
+pub enum SpiBusDeviceError<BUS, CS> {
+    Spi(BUS),
+    Cs(CS),
+}
+
+impl<BUS, CS> spi::Error for SpiBusDeviceError<BUS, CS>
+where
+    BUS: spi::Error + Debug,
+    CS: Debug,
+{
+    fn kind(&self) -> spi::ErrorKind {
+        match self {
+            Self::Spi(e) => e.kind(),
+            Self::Cs(_) => spi::ErrorKind::Other,
+        }
+    }
+}
+
+pub struct SpiBusDevice<'a, M: RawMutex, BUS, CS> {
+    bus: &'a Mutex<M, BUS>,
+    cs: CS,
+}
+
+impl<'a, M: RawMutex, BUS, CS> SpiBusDevice<'a, M, BUS, CS> {
+    pub fn new(bus: &'a Mutex<M, BUS>, cs: CS) -> Self {
+        Self { bus, cs }
+    }
+}
+
+impl<'a, M: RawMutex, BUS, CS> spi::ErrorType for SpiBusDevice<'a, M, BUS, CS>
+where
+    BUS: spi::ErrorType,
+    CS: OutputPin,
+{
+    type Error = SpiBusDeviceError<BUS::Error, CS::Error>;
+}
+
+impl<M, BUS, CS> spi::SpiDevice for SpiBusDevice<'_, M, BUS, CS>
+where
+    M: RawMutex + 'static,
+    BUS: spi::SpiBusFlush + 'static,
+    CS: OutputPin,
+{
+    type Bus = BUS;
+
+    type TransactionFuture<'a, R, F, Fut> = impl Future<Output = Result<R, Self::Error>> + 'a
+    where
+        Self: 'a, R: 'a, F: FnOnce(*mut Self::Bus) -> Fut + 'a,
+        Fut: Future<Output =  Result<R, <Self::Bus as ErrorType>::Error>> + 'a;
+
+    fn transaction<'a, R, F, Fut>(&'a mut self, f: F) -> Self::TransactionFuture<'a, R, F, Fut>
+    where
+        R: 'a,
+        F: FnOnce(*mut Self::Bus) -> Fut + 'a,
+        Fut: Future<Output = Result<R, <Self::Bus as ErrorType>::Error>> + 'a,
+    {
+        async move {
+            let mut bus = self.bus.lock().await;
+            self.cs.set_low().map_err(SpiBusDeviceError::Cs)?;
+
+            let f_res = f(&mut *bus).await;
+
+            // On failure, it's important to still flush and deassert CS.
+            let flush_res = bus.flush().await;
+            let cs_res = self.cs.set_high();
+
+            let f_res = f_res.map_err(SpiBusDeviceError::Spi)?;
+            flush_res.map_err(SpiBusDeviceError::Spi)?;
+            cs_res.map_err(SpiBusDeviceError::Cs)?;
+
+            Ok(f_res)
+        }
+    }
+}