From 034a6a6399d2fa3908121a9540149083018b4f36 Mon Sep 17 00:00:00 2001
From: Diego Barrios Romero <eldruin@gmail.com>
Date: Wed, 17 Aug 2022 22:41:23 +0200
Subject: [PATCH] Add I2C exclusive device implementation

---
 embedded-hal-bus/CHANGELOG.md |  3 +-
 embedded-hal-bus/Cargo.toml   |  3 +-
 embedded-hal-bus/src/i2c.rs   | 57 +++++++++++++++++++++++++++++++++++
 embedded-hal-bus/src/lib.rs   |  1 +
 4 files changed, 62 insertions(+), 2 deletions(-)
 create mode 100644 embedded-hal-bus/src/i2c.rs

diff --git a/embedded-hal-bus/CHANGELOG.md b/embedded-hal-bus/CHANGELOG.md
index 168957e6e..f22df5f0c 100644
--- a/embedded-hal-bus/CHANGELOG.md
+++ b/embedded-hal-bus/CHANGELOG.md
@@ -7,7 +7,8 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 ## [Unreleased]
 
-...
+### Added
+- `ExclusiveDevice` implementation for I2C.
 
 ## [v0.1.0-alpha.0] - 2022-08-17
 
diff --git a/embedded-hal-bus/Cargo.toml b/embedded-hal-bus/Cargo.toml
index 17037163a..d423f227f 100644
--- a/embedded-hal-bus/Cargo.toml
+++ b/embedded-hal-bus/Cargo.toml
@@ -14,4 +14,5 @@ repository = "https://github.com/rust-embedded/embedded-hal"
 version = "0.1.0-alpha.0"
 
 [dependencies]
-embedded-hal = { version = "=1.0.0-alpha.8", path = ".." }
+#embedded-hal = { version = "=1.0.0-alpha.8", path = ".." }
+embedded-hal = {git = "http://github.com/Dirbaio/embedded-hal", branch="i2c-bus-device"}
diff --git a/embedded-hal-bus/src/i2c.rs b/embedded-hal-bus/src/i2c.rs
new file mode 100644
index 000000000..c752560f4
--- /dev/null
+++ b/embedded-hal-bus/src/i2c.rs
@@ -0,0 +1,57 @@
+//! I2C bus sharing mechanisms.
+
+/// I2C bus sharing with blocking traits
+pub mod blocking {
+    use embedded_hal::i2c::{
+        blocking::{I2cBus, I2cDevice},
+        ErrorType,
+    };
+
+    /// [`I2cDevice`] implementation with exclusive access to the bus (not shared).
+    ///
+    /// This is the most straightforward way of obtaining an [`I2cDevice`] from an [`I2cBus`],
+    /// ideal for when no sharing is required (only one I2C device is present on the bus).
+    #[derive(Debug)]
+    pub struct ExclusiveDevice<BUS> {
+        bus: BUS,
+    }
+
+    impl<BUS> ExclusiveDevice<BUS> {
+        /// Create a new `ExclusiveDevice`
+        pub fn new(bus: BUS) -> Self {
+            Self { bus }
+        }
+    }
+
+    impl<BUS> ErrorType for ExclusiveDevice<BUS>
+    where
+        BUS: ErrorType,
+    {
+        type Error = BUS::Error;
+    }
+
+    impl<BUS> I2cDevice for ExclusiveDevice<BUS>
+    where
+        BUS: I2cBus,
+    {
+        type Bus = BUS;
+
+        fn transaction<R>(
+            &mut self,
+            f: impl FnOnce(&mut Self::Bus) -> Result<R, <Self::Bus as ErrorType>::Error>,
+        ) -> Result<R, Self::Error> {
+            let f_res = f(&mut self.bus);
+
+            // On failure, it's important to still stop and flush.
+            let stop_res = self.bus.stop();
+            let flush_res = self.bus.flush();
+
+            // Note that in the case of multiple failures, only one error
+            // will be returned, in the following order.
+            let f_ok = f_res?;
+            stop_res?;
+            flush_res?;
+            Ok(f_ok)
+        }
+    }
+}
diff --git a/embedded-hal-bus/src/lib.rs b/embedded-hal-bus/src/lib.rs
index 566e74b61..297c05cb8 100644
--- a/embedded-hal-bus/src/lib.rs
+++ b/embedded-hal-bus/src/lib.rs
@@ -14,4 +14,5 @@
 #![warn(missing_docs)]
 #![no_std]
 
+pub mod i2c;
 pub mod spi;