From 264b32d71baf471d0d36a34cc48aa10d429bed04 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Henrik=20Alse=CC=81r?= <henrik.alser@me.com>
Date: Wed, 6 Jul 2022 02:35:46 +0200
Subject: [PATCH] Add blocking shared bus for i2c and SPI

---
 .../src/shared_bus/blocking/i2c.rs            | 69 +++++++++++++++++++
 .../src/shared_bus/blocking/mod.rs            |  3 +
 .../src/shared_bus/blocking/spi.rs            | 69 +++++++++++++++++++
 embassy-embedded-hal/src/shared_bus/mod.rs    |  6 +-
 4 files changed, 145 insertions(+), 2 deletions(-)
 create mode 100644 embassy-embedded-hal/src/shared_bus/blocking/i2c.rs
 create mode 100644 embassy-embedded-hal/src/shared_bus/blocking/mod.rs
 create mode 100644 embassy-embedded-hal/src/shared_bus/blocking/spi.rs

diff --git a/embassy-embedded-hal/src/shared_bus/blocking/i2c.rs b/embassy-embedded-hal/src/shared_bus/blocking/i2c.rs
new file mode 100644
index 00000000..2a6ea6dc
--- /dev/null
+++ b/embassy-embedded-hal/src/shared_bus/blocking/i2c.rs
@@ -0,0 +1,69 @@
+//! Blocking shared I2C bus
+use core::cell::RefCell;
+use core::fmt::Debug;
+use core::future::Future;
+
+use embedded_hal_1::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, BUS> {
+    bus: &'a RefCell<BUS>,
+}
+
+impl<'a, BUS> I2cBusDevice<'a, BUS> {
+    pub fn new(bus: &'a RefCell<BUS>) -> Self {
+        Self { bus }
+    }
+}
+
+impl<'a, BUS> i2c::ErrorType for I2cBusDevice<'a, BUS>
+where
+    BUS: i2c::ErrorType,
+{
+    type Error = I2cBusDeviceError<BUS::Error>;
+}
+
+impl<M, BUS> i2c::I2c for I2cBusDevice<'_, BUS>
+where
+    BUS: i2c::I2c,
+{
+    fn read(&mut self, address: u8, buffer: &mut [u8]) -> Result<(), Self::Error> {
+        let mut bus = self.bus.borrow_mut();
+        bus.read(address, buffer).map_err(I2cBusDeviceError::I2c)?;
+        Ok(())
+    }
+
+    fn write(&mut self, address: u8, bytes: &[u8]) -> Result<(), Self::Error> {
+        let mut bus = self.bus.borrow_mut();
+        bus.write(address, bytes).map_err(I2cBusDeviceError::I2c)?;
+        Ok(())
+    }
+
+    fn write_read(&mut self, address: u8, wr_buffer: &[u8], rd_buffer: &mut [u8]) -> Result<(), Self::Error> {
+        let mut bus = self.bus.borrow_mut();
+        bus.write_read(address, wr_buffer, rd_buffer)
+            .map_err(I2cBusDeviceError::I2c)?;
+        Ok(())
+    }
+
+    fn transaction<'a>(&mut self, address: u8, operations: &mut [i2c::Operation<'a>]) -> Result<(), Self::Error> {
+        let _ = address;
+        let _ = operations;
+        todo!()
+    }
+}
diff --git a/embassy-embedded-hal/src/shared_bus/blocking/mod.rs b/embassy-embedded-hal/src/shared_bus/blocking/mod.rs
new file mode 100644
index 00000000..c2063ed2
--- /dev/null
+++ b/embassy-embedded-hal/src/shared_bus/blocking/mod.rs
@@ -0,0 +1,3 @@
+//! Blocking shared bus implementations for embedded-hal
+pub mod i2c;
+pub mod spi;
diff --git a/embassy-embedded-hal/src/shared_bus/blocking/spi.rs b/embassy-embedded-hal/src/shared_bus/blocking/spi.rs
new file mode 100644
index 00000000..0d01a590
--- /dev/null
+++ b/embassy-embedded-hal/src/shared_bus/blocking/spi.rs
@@ -0,0 +1,69 @@
+//! Blocking shared SPI bus
+use core::cell::RefCell;
+use core::fmt::Debug;
+
+use embedded_hal_1::digital::blocking::OutputPin;
+use embedded_hal_1::spi;
+use embedded_hal_1::spi::blocking::SpiDevice;
+
+#[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, BUS, CS> {
+    bus: &'a RefCell<BUS>,
+    cs: CS,
+}
+
+impl<'a, BUS, CS> SpiBusDevice<'a, BUS, CS> {
+    pub fn new(bus: &'a RefCell<BUS>, cs: CS) -> Self {
+        Self { bus, cs }
+    }
+}
+
+impl<'a, BUS, CS> spi::ErrorType for SpiBusDevice<'a, BUS, CS>
+where
+    BUS: spi::ErrorType,
+    CS: OutputPin,
+{
+    type Error = SpiBusDeviceError<BUS::Error, CS::Error>;
+}
+
+impl<BUS, CS> spi::SpiDevice for SpiBusDevice<'_, BUS, CS>
+where
+    BUS: spi::SpiBusFlush,
+    CS: OutputPin,
+{
+    type Bus = BUS;
+    fn transaction<R>(&mut self, f: impl FnOnce(&mut Self::Bus) -> Result<R, BUS::Error>) -> Result<R, Self::Error> {
+        let mut bus = self.bus.borrow_mut();
+        self.cs.set_low().map_err(SpiDeviceWithCsError::Cs)?;
+
+        let f_res = f(&mut bus);
+
+        // On failure, it's important to still flush and deassert CS.
+        let flush_res = bus.flush();
+        let cs_res = self.cs.set_high();
+
+        let f_res = f_res.map_err(SpiDeviceWithCsError::Spi)?;
+        flush_res.map_err(SpiDeviceWithCsError::Spi)?;
+        cs_res.map_err(SpiDeviceWithCsError::Cs)?;
+
+        Ok(f_res)
+    }
+}
diff --git a/embassy-embedded-hal/src/shared_bus/mod.rs b/embassy-embedded-hal/src/shared_bus/mod.rs
index bd4fd2c3..cd748cac 100644
--- a/embassy-embedded-hal/src/shared_bus/mod.rs
+++ b/embassy-embedded-hal/src/shared_bus/mod.rs
@@ -1,4 +1,6 @@
-//! Shared bus implementations for embedded-hal-async
-
+//! Shared bus implementations
+pub mod blocking;
+/// Shared i2c bus implementation for embedded-hal-async
 pub mod i2c;
+/// Shared SPI bus implementation for embedded-hal-async
 pub mod spi;