From 91ebdc3e3d9476696257c93b9a73bf97751b24e2 Mon Sep 17 00:00:00 2001
From: Ryan Summers <ryan.summers@vertigo-designs.com>
Date: Mon, 1 Aug 2022 10:03:39 +0200
Subject: [PATCH 1/2] Leveraging shared_bus over custom mutex

---
 src/hardware/mod.rs   |  5 ++---
 src/hardware/mutex.rs | 52 -------------------------------------------
 src/hardware/setup.rs |  4 ++--
 3 files changed, 4 insertions(+), 57 deletions(-)
 delete mode 100644 src/hardware/mutex.rs

diff --git a/src/hardware/mod.rs b/src/hardware/mod.rs
index 1ccafb72..17f0c292 100644
--- a/src/hardware/mod.rs
+++ b/src/hardware/mod.rs
@@ -15,7 +15,6 @@ pub mod chassis_fans;
 pub mod delay;
 pub mod external_mac;
 pub mod metadata;
-mod mutex;
 pub mod net_interface;
 pub mod platform;
 pub mod rf_channel;
@@ -69,8 +68,8 @@ pub type NetworkManager = external_mac::Manager<'static, ExternalMac>;
 pub type NetworkStack =
     smoltcp_nal::NetworkStack<'static, external_mac::SmoltcpDevice<'static>, SystemTimer>;
 
-pub type I2cBusManager = mutex::AtomicCheckManager<I2C>;
-pub type I2cProxy = shared_bus::I2cProxy<'static, mutex::AtomicCheckMutex<I2C>>;
+pub type I2cBusManager = shared_bus::BusManagerAtomicCheck<I2C>;
+pub type I2cProxy = shared_bus::I2cProxy<'static, shared_bus::AtomicCheckMutex<I2C>>;
 pub type I2cError = hal::i2c::Error;
 
 pub type UsbBus = hal::otg_fs::UsbBus<hal::otg_fs::USB>;
diff --git a/src/hardware/mutex.rs b/src/hardware/mutex.rs
deleted file mode 100644
index 7b643b87..00000000
--- a/src/hardware/mutex.rs
+++ /dev/null
@@ -1,52 +0,0 @@
-/// A "mutex" that guarantees only a single user of a bus at a time through panicking.
-pub struct AtomicCheckMutex<BUS> {
-    bus: core::cell::UnsafeCell<BUS>,
-    busy: core::sync::atomic::AtomicBool,
-}
-
-impl<BUS> shared_bus::BusMutex for AtomicCheckMutex<BUS> {
-    type Bus = BUS;
-
-    fn create(v: BUS) -> Self {
-        Self {
-            bus: core::cell::UnsafeCell::new(v),
-            busy: core::sync::atomic::AtomicBool::from(false),
-        }
-    }
-
-    fn lock<R, F: FnOnce(&mut Self::Bus) -> R>(&self, f: F) -> R {
-        self.busy
-            .compare_exchange(
-                false,
-                true,
-                core::sync::atomic::Ordering::SeqCst,
-                core::sync::atomic::Ordering::SeqCst,
-            )
-            .expect("Bus conflict");
-        let result = f(unsafe { &mut *self.bus.get() });
-
-        self.busy.store(false, core::sync::atomic::Ordering::SeqCst);
-
-        result
-    }
-}
-
-// It is explicitly safe to share this across threads because there is a coherency check using an
-// atomic bool comparison.
-unsafe impl<BUS> Sync for AtomicCheckMutex<BUS> {}
-
-/// A convenience type for declaring use with shared-bus.
-pub type AtomicCheckManager<T> = shared_bus::BusManager<AtomicCheckMutex<T>>;
-
-/// Construct a statically allocated bus manager.
-#[macro_export]
-macro_rules! new_atomic_check_manager {
-    ($bus_type:ty = $bus:expr) => {{
-        let m: Option<&'static mut _> = cortex_m::singleton!(
-            : $crate::hardware::mutex::AtomicCheckManager<$bus_type> =
-                $crate::hardware::mutex::AtomicCheckManager::new($bus)
-        );
-
-        m
-    }};
-}
diff --git a/src/hardware/setup.rs b/src/hardware/setup.rs
index e8acafe6..dcfbd07b 100644
--- a/src/hardware/setup.rs
+++ b/src/hardware/setup.rs
@@ -17,7 +17,7 @@ use super::{
     HardwareVersion, NetworkManager, NetworkStack, SystemTimer, Systick, UsbBus, CPU_FREQ, I2C,
 };
 
-use crate::{new_atomic_check_manager, settings::BoosterSettings};
+use crate::settings::BoosterSettings;
 
 use stm32f4xx_hal as hal;
 
@@ -189,7 +189,7 @@ pub fn setup(
             hal::i2c::I2c::i2c1(i2c_peripheral, (scl, sda), 100.khz(), clocks)
         };
 
-        new_atomic_check_manager!(I2C = i2c).unwrap()
+        shared_bus::new_atomic_check!(I2C = i2c).unwrap()
     };
 
     // Instantiate the I2C interface to the I2C mux. Use a shared-bus so we can share the I2C

From 82ca34ca84a27b33c13d01d1d93378f156a805c0 Mon Sep 17 00:00:00 2001
From: Ryan Summers <ryan.summers@vertigo-designs.com>
Date: Mon, 1 Aug 2022 12:22:13 +0200
Subject: [PATCH 2/2] Adding CHANGELOG entry

---
 CHANGELOG.md | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 94db779c..5164e46f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -12,6 +12,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   Settings are backwards compatible with previous Booster releases.
 * Fan speed is now stored in EEPROM and configurable via the serial interface.
 
+### Changed
+* Removed custom `mutex` implementation in favor of leveraging `shared-bus`
+
 ### Fixed
 * A few dependencies were deprecated because changes landed upstream. These dependencies were
   corrected to point upstream.