From e229494bbf36173d0abde91055b435a4f2c80329 Mon Sep 17 00:00:00 2001
From: 9names <60134748+9names@users.noreply.github.com>
Date: Sat, 8 Jun 2024 21:37:28 +1000
Subject: [PATCH 01/11] Feature gate embedded-hal-bus atomic impls

---
 embedded-hal-bus/Cargo.toml     | 3 ++-
 embedded-hal-bus/src/i2c/mod.rs | 2 ++
 embedded-hal-bus/src/spi/mod.rs | 2 ++
 embedded-hal-bus/src/util.rs    | 6 +++++-
 4 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/embedded-hal-bus/Cargo.toml b/embedded-hal-bus/Cargo.toml
index 2c54bfbd..3460062e 100644
--- a/embedded-hal-bus/Cargo.toml
+++ b/embedded-hal-bus/Cargo.toml
@@ -16,6 +16,7 @@ version = "0.2.0"
 
 [features]
 std = []
+atomic-device = []
 async = ["dep:embedded-hal-async"]
 defmt-03 = ["dep:defmt-03", "embedded-hal/defmt-03", "embedded-hal-async?/defmt-03"]
 
@@ -27,5 +28,5 @@ defmt-03 = { package = "defmt", version = "0.3", optional = true }
 portable-atomic = {version = "1", default-features = false}
 
 [package.metadata.docs.rs]
-features = ["std", "async"]
+features = ["std", "async", "atomic-device"]
 rustdoc-args = ["--cfg", "docsrs"]
diff --git a/embedded-hal-bus/src/i2c/mod.rs b/embedded-hal-bus/src/i2c/mod.rs
index 5295492f..5e2c1402 100644
--- a/embedded-hal-bus/src/i2c/mod.rs
+++ b/embedded-hal-bus/src/i2c/mod.rs
@@ -8,5 +8,7 @@ mod mutex;
 pub use mutex::*;
 mod critical_section;
 pub use self::critical_section::*;
+#[cfg(feature = "atomic-device")]
 mod atomic;
+#[cfg(feature = "atomic-device")]
 pub use atomic::*;
diff --git a/embedded-hal-bus/src/spi/mod.rs b/embedded-hal-bus/src/spi/mod.rs
index d55fa5ea..23cd824d 100644
--- a/embedded-hal-bus/src/spi/mod.rs
+++ b/embedded-hal-bus/src/spi/mod.rs
@@ -11,9 +11,11 @@ pub use refcell::*;
 mod mutex;
 #[cfg(feature = "std")]
 pub use mutex::*;
+#[cfg(feature = "atomic-device")]
 mod atomic;
 mod critical_section;
 mod shared;
+#[cfg(feature = "atomic-device")]
 pub use atomic::*;
 
 pub use self::critical_section::*;
diff --git a/embedded-hal-bus/src/util.rs b/embedded-hal-bus/src/util.rs
index 739f4b1b..70dac74e 100644
--- a/embedded-hal-bus/src/util.rs
+++ b/embedded-hal-bus/src/util.rs
@@ -1,7 +1,9 @@
 //! Utilities shared by all bus types.
 
+#[allow(unused_imports)]
 use core::cell::UnsafeCell;
 
+#[cfg(feature = "atomic-device")]
 /// Cell type used by [`spi::AtomicDevice`](crate::spi::AtomicDevice) and [`i2c::AtomicDevice`](crate::i2c::AtomicDevice).
 ///
 /// To use `AtomicDevice`, you must wrap the bus with this struct, and then
@@ -10,10 +12,12 @@ pub struct AtomicCell<BUS> {
     pub(crate) bus: UnsafeCell<BUS>,
     pub(crate) busy: portable_atomic::AtomicBool,
 }
-
+#[cfg(feature = "atomic-device")]
 unsafe impl<BUS: Send> Send for AtomicCell<BUS> {}
+#[cfg(feature = "atomic-device")]
 unsafe impl<BUS: Send> Sync for AtomicCell<BUS> {}
 
+#[cfg(feature = "atomic-device")]
 impl<BUS> AtomicCell<BUS> {
     /// Create a new `AtomicCell`
     pub fn new(bus: BUS) -> Self {

From f0eec219bb1ff9a5642e12b8e92dcc98c4d1640c Mon Sep 17 00:00:00 2001
From: 9names <60134748+9names@users.noreply.github.com>
Date: Sat, 8 Jun 2024 21:38:28 +1000
Subject: [PATCH 02/11] Add features for selecting portable-atomic features

---
 embedded-hal-bus/Cargo.toml | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/embedded-hal-bus/Cargo.toml b/embedded-hal-bus/Cargo.toml
index 3460062e..44b9a028 100644
--- a/embedded-hal-bus/Cargo.toml
+++ b/embedded-hal-bus/Cargo.toml
@@ -19,6 +19,8 @@ std = []
 atomic-device = []
 async = ["dep:embedded-hal-async"]
 defmt-03 = ["dep:defmt-03", "embedded-hal/defmt-03", "embedded-hal-async?/defmt-03"]
+portable-atomic-critical-section = ["atomic-device", "portable-atomic/critical-section"]
+portable-atomic-unsafe-assume-single-core = ["atomic-device", "portable-atomic/unsafe-assume-single-core"]
 
 [dependencies]
 embedded-hal = { version = "1.0.0", path = "../embedded-hal" }

From 797dc9559040df979aab69dc876b1c22f5499fc5 Mon Sep 17 00:00:00 2001
From: 9names <60134748+9names@users.noreply.github.com>
Date: Sat, 8 Jun 2024 21:47:41 +1000
Subject: [PATCH 03/11] Document embedded-hal-bus features in README.md and
 Cargo.toml

---
 embedded-hal-bus/Cargo.toml | 13 +++++++++++++
 embedded-hal-bus/README.md  | 14 ++++++++++++--
 2 files changed, 25 insertions(+), 2 deletions(-)

diff --git a/embedded-hal-bus/Cargo.toml b/embedded-hal-bus/Cargo.toml
index 44b9a028..07bff536 100644
--- a/embedded-hal-bus/Cargo.toml
+++ b/embedded-hal-bus/Cargo.toml
@@ -15,11 +15,24 @@ repository = "https://github.com/rust-embedded/embedded-hal"
 version = "0.2.0"
 
 [features]
+# Enable shared bus implementations using `std::sync::Mutex`, and implement `std::error::Error` for `DeviceError`
 std = []
+# Enable shared bus implementations that require Atomic CAS operations
 atomic-device = []
+# Enable `embedded-hal-async` support.
 async = ["dep:embedded-hal-async"]
+# Derive `defmt::Format` from `defmt` 0.3 for enums and structs. See https://github.com/knurling-rs/defmt for more info
 defmt-03 = ["dep:defmt-03", "embedded-hal/defmt-03", "embedded-hal-async?/defmt-03"]
+# Enable critical-section feature in portable-atomic.
+#
+# `portable-atomic` emulates atomic CAS functionality, allowing `embedded-hal-bus` to use `atomic-device` on hardware that does not natively support atomic CAS.
+# This feature requires a critical-section implementation, which is most often provided by your arch crate (cortex-m / riscv / msp430 / avr-device / etc) when the `critical-section-single-core` feature is enabled.
+# A list of critical-section impls is available [in the critical section docs](https://github.com/rust-embedded/critical-section?tab=readme-ov-file#usage-in-no-std-binaries)
 portable-atomic-critical-section = ["atomic-device", "portable-atomic/critical-section"]
+# Enable unsafe-assume-single-core feature of portable-atomic.
+# 
+# `portable-atomic` emulates atomic CAS functionality, allowing `embedded-hal-bus` to use `atomic-device` on hardware that does not natively support atomic CAS.
+#  This feature is only safe on single core systems
 portable-atomic-unsafe-assume-single-core = ["atomic-device", "portable-atomic/unsafe-assume-single-core"]
 
 [dependencies]
diff --git a/embedded-hal-bus/README.md b/embedded-hal-bus/README.md
index ce71eec9..4922c7f5 100644
--- a/embedded-hal-bus/README.md
+++ b/embedded-hal-bus/README.md
@@ -30,10 +30,20 @@ provides mechanisms to obtain multiple `I2c` instances out of a single `I2c` ins
 
 ## Optional Cargo features
 
-- **`std`**: enable shared bus implementations using `std::sync::Mutex`, and implement
-  `std::error::Error` for `DeviceError`.
 - **`async`**: enable `embedded-hal-async` support.
+- **`atomic-device`**: enable shared bus implementations that require Atomic CAS operations.
 - **`defmt-03`**: Derive `defmt::Format` from `defmt` 0.3 for enums and structs.
+- **`portable-atomic-critical-section`**: Enable critical-section feature in portable-atomic.
+
+  `portable-atomic` emulates atomic CAS functionality, allowing `embedded-hal-bus` to use `atomic-device` on hardware that does not natively support atomic CAS.
+  This feature requires a critical-section implementation, which is most often provided by your arch crate (cortex-m / riscv / msp430 / avr-device / etc) when the `critical-section-single-core` feature is enabled.
+  A list of critical-section impls is available [in the critical section docs](https://github.com/rust-embedded/critical-section?tab=readme-ov-file#usage-in-no-std-binaries)
+- **`portable-atomic-unsafe-assume-single-core`**: Enable unsafe-assume-single-core feature of portable-atomic.
+
+  `portable-atomic` emulates atomic CAS functionality, allowing `embedded-hal-bus` to use `atomic-device` on hardware that does not natively support atomic CAS.
+  This feature is only safe on single core systems
+- **`std`**: enable shared bus implementations using `std::sync::Mutex`, and implement
+  `std::error::Error` for `DeviceError`.
 
 ## Minimum Supported Rust Version (MSRV)
 

From d346553c0cc8a0ad6fde4551af8d62a733633770 Mon Sep 17 00:00:00 2001
From: 9names <60134748+9names@users.noreply.github.com>
Date: Sat, 8 Jun 2024 22:03:05 +1000
Subject: [PATCH 04/11] Also enable Atomic* when target_has_atomic=8

---
 embedded-hal-bus/src/i2c/mod.rs | 4 ++--
 embedded-hal-bus/src/spi/mod.rs | 4 ++--
 embedded-hal-bus/src/util.rs    | 8 ++++----
 3 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/embedded-hal-bus/src/i2c/mod.rs b/embedded-hal-bus/src/i2c/mod.rs
index 5e2c1402..ef8f7ae9 100644
--- a/embedded-hal-bus/src/i2c/mod.rs
+++ b/embedded-hal-bus/src/i2c/mod.rs
@@ -8,7 +8,7 @@ mod mutex;
 pub use mutex::*;
 mod critical_section;
 pub use self::critical_section::*;
-#[cfg(feature = "atomic-device")]
+#[cfg(any(feature = "atomic-device", target_has_atomic = "8"))]
 mod atomic;
-#[cfg(feature = "atomic-device")]
+#[cfg(any(feature = "atomic-device", target_has_atomic = "8"))]
 pub use atomic::*;
diff --git a/embedded-hal-bus/src/spi/mod.rs b/embedded-hal-bus/src/spi/mod.rs
index 23cd824d..a7ad6b98 100644
--- a/embedded-hal-bus/src/spi/mod.rs
+++ b/embedded-hal-bus/src/spi/mod.rs
@@ -11,11 +11,11 @@ pub use refcell::*;
 mod mutex;
 #[cfg(feature = "std")]
 pub use mutex::*;
-#[cfg(feature = "atomic-device")]
+#[cfg(any(feature = "atomic-device", target_has_atomic = "8"))]
 mod atomic;
 mod critical_section;
 mod shared;
-#[cfg(feature = "atomic-device")]
+#[cfg(any(feature = "atomic-device", target_has_atomic = "8"))]
 pub use atomic::*;
 
 pub use self::critical_section::*;
diff --git a/embedded-hal-bus/src/util.rs b/embedded-hal-bus/src/util.rs
index 70dac74e..f0cb8f16 100644
--- a/embedded-hal-bus/src/util.rs
+++ b/embedded-hal-bus/src/util.rs
@@ -3,7 +3,7 @@
 #[allow(unused_imports)]
 use core::cell::UnsafeCell;
 
-#[cfg(feature = "atomic-device")]
+#[cfg(any(feature = "atomic-device", target_has_atomic = "8"))]
 /// Cell type used by [`spi::AtomicDevice`](crate::spi::AtomicDevice) and [`i2c::AtomicDevice`](crate::i2c::AtomicDevice).
 ///
 /// To use `AtomicDevice`, you must wrap the bus with this struct, and then
@@ -12,12 +12,12 @@ pub struct AtomicCell<BUS> {
     pub(crate) bus: UnsafeCell<BUS>,
     pub(crate) busy: portable_atomic::AtomicBool,
 }
-#[cfg(feature = "atomic-device")]
+#[cfg(any(feature = "atomic-device", target_has_atomic = "8"))]
 unsafe impl<BUS: Send> Send for AtomicCell<BUS> {}
-#[cfg(feature = "atomic-device")]
+#[cfg(any(feature = "atomic-device", target_has_atomic = "8"))]
 unsafe impl<BUS: Send> Sync for AtomicCell<BUS> {}
 
-#[cfg(feature = "atomic-device")]
+#[cfg(any(feature = "atomic-device", target_has_atomic = "8"))]
 impl<BUS> AtomicCell<BUS> {
     /// Create a new `AtomicCell`
     pub fn new(bus: BUS) -> Self {

From 3ddc31a81087b92effcc00cee5f0a0003f73fbd4 Mon Sep 17 00:00:00 2001
From: 9names <60134748+9names@users.noreply.github.com>
Date: Sat, 27 Jul 2024 21:03:20 +1000
Subject: [PATCH 05/11] Remove features that enable atomic-polyfill flags

---
 embedded-hal-bus/Cargo.toml     | 20 +++++++-------------
 embedded-hal-bus/README.md      | 14 +++++---------
 embedded-hal-bus/src/i2c/mod.rs |  4 ++--
 embedded-hal-bus/src/spi/mod.rs |  4 ++--
 embedded-hal-bus/src/util.rs    |  8 ++++----
 5 files changed, 20 insertions(+), 30 deletions(-)

diff --git a/embedded-hal-bus/Cargo.toml b/embedded-hal-bus/Cargo.toml
index 07bff536..1ef572e9 100644
--- a/embedded-hal-bus/Cargo.toml
+++ b/embedded-hal-bus/Cargo.toml
@@ -17,23 +17,17 @@ version = "0.2.0"
 [features]
 # Enable shared bus implementations using `std::sync::Mutex`, and implement `std::error::Error` for `DeviceError`
 std = []
-# Enable shared bus implementations that require Atomic CAS operations
-atomic-device = []
+# Use `portable-atomic` to enable `atomic-device` on devices without native atomic CAS
+#
+# `portable-atomic` emulates atomic CAS functionality, allowing `embedded-hal-bus` to use `atomic-device` on hardware
+# that does not natively support atomic CAS. If you enable this, you must also add `portable-atomic` to your crate with
+# a feature flag such as `unsafe-assume-single-core` or `critical-section` to choose how atomic CAS is implemented.
+# See https://docs.rs/portable-atomic/1.7.0/portable_atomic/#optional-features for more info.
+portable-atomic = []
 # Enable `embedded-hal-async` support.
 async = ["dep:embedded-hal-async"]
 # Derive `defmt::Format` from `defmt` 0.3 for enums and structs. See https://github.com/knurling-rs/defmt for more info
 defmt-03 = ["dep:defmt-03", "embedded-hal/defmt-03", "embedded-hal-async?/defmt-03"]
-# Enable critical-section feature in portable-atomic.
-#
-# `portable-atomic` emulates atomic CAS functionality, allowing `embedded-hal-bus` to use `atomic-device` on hardware that does not natively support atomic CAS.
-# This feature requires a critical-section implementation, which is most often provided by your arch crate (cortex-m / riscv / msp430 / avr-device / etc) when the `critical-section-single-core` feature is enabled.
-# A list of critical-section impls is available [in the critical section docs](https://github.com/rust-embedded/critical-section?tab=readme-ov-file#usage-in-no-std-binaries)
-portable-atomic-critical-section = ["atomic-device", "portable-atomic/critical-section"]
-# Enable unsafe-assume-single-core feature of portable-atomic.
-# 
-# `portable-atomic` emulates atomic CAS functionality, allowing `embedded-hal-bus` to use `atomic-device` on hardware that does not natively support atomic CAS.
-#  This feature is only safe on single core systems
-portable-atomic-unsafe-assume-single-core = ["atomic-device", "portable-atomic/unsafe-assume-single-core"]
 
 [dependencies]
 embedded-hal = { version = "1.0.0", path = "../embedded-hal" }
diff --git a/embedded-hal-bus/README.md b/embedded-hal-bus/README.md
index 4922c7f5..c2d9a77c 100644
--- a/embedded-hal-bus/README.md
+++ b/embedded-hal-bus/README.md
@@ -31,17 +31,13 @@ provides mechanisms to obtain multiple `I2c` instances out of a single `I2c` ins
 ## Optional Cargo features
 
 - **`async`**: enable `embedded-hal-async` support.
-- **`atomic-device`**: enable shared bus implementations that require Atomic CAS operations.
 - **`defmt-03`**: Derive `defmt::Format` from `defmt` 0.3 for enums and structs.
-- **`portable-atomic-critical-section`**: Enable critical-section feature in portable-atomic.
+- **`portable-atomic`**: Use `portable-atomic` to enable `atomic-device` on devices without native atomic CAS
 
-  `portable-atomic` emulates atomic CAS functionality, allowing `embedded-hal-bus` to use `atomic-device` on hardware that does not natively support atomic CAS.
-  This feature requires a critical-section implementation, which is most often provided by your arch crate (cortex-m / riscv / msp430 / avr-device / etc) when the `critical-section-single-core` feature is enabled.
-  A list of critical-section impls is available [in the critical section docs](https://github.com/rust-embedded/critical-section?tab=readme-ov-file#usage-in-no-std-binaries)
-- **`portable-atomic-unsafe-assume-single-core`**: Enable unsafe-assume-single-core feature of portable-atomic.
-
-  `portable-atomic` emulates atomic CAS functionality, allowing `embedded-hal-bus` to use `atomic-device` on hardware that does not natively support atomic CAS.
-  This feature is only safe on single core systems
+  `portable-atomic` emulates atomic CAS functionality, allowing `embedded-hal-bus` to use `atomic-device` on hardware
+  that does not natively support atomic CAS. If you enable this, you must also add `portable-atomic` to your crate with
+  a feature flag such as `unsafe-assume-single-core` or `critical-section` to choose how atomic CAS is implemented.
+  See https://docs.rs/portable-atomic/1.7.0/portable_atomic/#optional-features for more info.
 - **`std`**: enable shared bus implementations using `std::sync::Mutex`, and implement
   `std::error::Error` for `DeviceError`.
 
diff --git a/embedded-hal-bus/src/i2c/mod.rs b/embedded-hal-bus/src/i2c/mod.rs
index ef8f7ae9..0353ea71 100644
--- a/embedded-hal-bus/src/i2c/mod.rs
+++ b/embedded-hal-bus/src/i2c/mod.rs
@@ -8,7 +8,7 @@ mod mutex;
 pub use mutex::*;
 mod critical_section;
 pub use self::critical_section::*;
-#[cfg(any(feature = "atomic-device", target_has_atomic = "8"))]
+#[cfg(any(feature = "portable-atomic", target_has_atomic = "8"))]
 mod atomic;
-#[cfg(any(feature = "atomic-device", target_has_atomic = "8"))]
+#[cfg(any(feature = "portable-atomic", target_has_atomic = "8"))]
 pub use atomic::*;
diff --git a/embedded-hal-bus/src/spi/mod.rs b/embedded-hal-bus/src/spi/mod.rs
index a7ad6b98..c14c8fdc 100644
--- a/embedded-hal-bus/src/spi/mod.rs
+++ b/embedded-hal-bus/src/spi/mod.rs
@@ -11,11 +11,11 @@ pub use refcell::*;
 mod mutex;
 #[cfg(feature = "std")]
 pub use mutex::*;
-#[cfg(any(feature = "atomic-device", target_has_atomic = "8"))]
+#[cfg(any(feature = "portable-atomic", target_has_atomic = "8"))]
 mod atomic;
 mod critical_section;
 mod shared;
-#[cfg(any(feature = "atomic-device", target_has_atomic = "8"))]
+#[cfg(any(feature = "portable-atomic", target_has_atomic = "8"))]
 pub use atomic::*;
 
 pub use self::critical_section::*;
diff --git a/embedded-hal-bus/src/util.rs b/embedded-hal-bus/src/util.rs
index f0cb8f16..91add232 100644
--- a/embedded-hal-bus/src/util.rs
+++ b/embedded-hal-bus/src/util.rs
@@ -3,7 +3,7 @@
 #[allow(unused_imports)]
 use core::cell::UnsafeCell;
 
-#[cfg(any(feature = "atomic-device", target_has_atomic = "8"))]
+#[cfg(any(feature = "portable-atomic", target_has_atomic = "8"))]
 /// Cell type used by [`spi::AtomicDevice`](crate::spi::AtomicDevice) and [`i2c::AtomicDevice`](crate::i2c::AtomicDevice).
 ///
 /// To use `AtomicDevice`, you must wrap the bus with this struct, and then
@@ -12,12 +12,12 @@ pub struct AtomicCell<BUS> {
     pub(crate) bus: UnsafeCell<BUS>,
     pub(crate) busy: portable_atomic::AtomicBool,
 }
-#[cfg(any(feature = "atomic-device", target_has_atomic = "8"))]
+#[cfg(any(feature = "portable-atomic", target_has_atomic = "8"))]
 unsafe impl<BUS: Send> Send for AtomicCell<BUS> {}
-#[cfg(any(feature = "atomic-device", target_has_atomic = "8"))]
+#[cfg(any(feature = "portable-atomic", target_has_atomic = "8"))]
 unsafe impl<BUS: Send> Sync for AtomicCell<BUS> {}
 
-#[cfg(any(feature = "atomic-device", target_has_atomic = "8"))]
+#[cfg(any(feature = "portable-atomic", target_has_atomic = "8"))]
 impl<BUS> AtomicCell<BUS> {
     /// Create a new `AtomicCell`
     pub fn new(bus: BUS) -> Self {

From 33f5255ce8fe88f33755078c0386eb46d2ee0a08 Mon Sep 17 00:00:00 2001
From: 9names <60134748+9names@users.noreply.github.com>
Date: Sat, 27 Jul 2024 21:18:37 +1000
Subject: [PATCH 06/11] Fix broken URL in README.md

---
 embedded-hal-bus/README.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/embedded-hal-bus/README.md b/embedded-hal-bus/README.md
index 02761264..2e6d9db0 100644
--- a/embedded-hal-bus/README.md
+++ b/embedded-hal-bus/README.md
@@ -38,7 +38,7 @@ provides mechanisms to obtain multiple `I2c` instances out of a single `I2c` ins
   `portable-atomic` emulates atomic CAS functionality, allowing `embedded-hal-bus` to use `atomic-device` on hardware
   that does not natively support atomic CAS. If you enable this, you must also add `portable-atomic` to your crate with
   a feature flag such as `unsafe-assume-single-core` or `critical-section` to choose how atomic CAS is implemented.
-  See https://docs.rs/portable-atomic/1.7.0/portable_atomic/#optional-features for more info.
+  See <https://docs.rs/portable-atomic/1.7.0/portable_atomic/#optional-features> for more info.
 - **`std`**: enable shared bus implementations using `std::sync::Mutex`, and implement
   `std::error::Error` for `DeviceError`.
 

From 54fa71e32ae3334088b9f8c9e59dfca5fe4e8e53 Mon Sep 17 00:00:00 2001
From: 9names <60134748+9names@users.noreply.github.com>
Date: Sat, 27 Jul 2024 21:20:52 +1000
Subject: [PATCH 07/11] Add feature require-cas to portable-atomic

---
 embedded-hal-bus/Cargo.toml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/embedded-hal-bus/Cargo.toml b/embedded-hal-bus/Cargo.toml
index 61f59f3e..8898d961 100644
--- a/embedded-hal-bus/Cargo.toml
+++ b/embedded-hal-bus/Cargo.toml
@@ -36,7 +36,7 @@ embedded-hal = { version = "1.0.0", path = "../embedded-hal" }
 embedded-hal-async = { version = "1.0.0", path = "../embedded-hal-async", optional = true }
 critical-section = { version = "1.0" }
 defmt-03 = { package = "defmt", version = "0.3", optional = true }
-portable-atomic = {version = "1", default-features = false}
+portable-atomic = {version = "1", default-features = false, features = ["require-cas"]}
 
 [package.metadata.docs.rs]
 features = ["std", "async", "atomic-device"]

From a6be9a76bb09aba26337fb0c42990f4ea4537f43 Mon Sep 17 00:00:00 2001
From: 9names <60134748+9names@users.noreply.github.com>
Date: Sat, 27 Jul 2024 21:24:46 +1000
Subject: [PATCH 08/11] Set minimum portable-atomic version to allow
 'require-cas'

---
 embedded-hal-bus/Cargo.toml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/embedded-hal-bus/Cargo.toml b/embedded-hal-bus/Cargo.toml
index 8898d961..333aef89 100644
--- a/embedded-hal-bus/Cargo.toml
+++ b/embedded-hal-bus/Cargo.toml
@@ -36,7 +36,7 @@ embedded-hal = { version = "1.0.0", path = "../embedded-hal" }
 embedded-hal-async = { version = "1.0.0", path = "../embedded-hal-async", optional = true }
 critical-section = { version = "1.0" }
 defmt-03 = { package = "defmt", version = "0.3", optional = true }
-portable-atomic = {version = "1", default-features = false, features = ["require-cas"]}
+portable-atomic = {version = "1.3", default-features = false, features = ["require-cas"]}
 
 [package.metadata.docs.rs]
 features = ["std", "async", "atomic-device"]

From e7cbd52fb889de617566495dc405abac7de7c52d Mon Sep 17 00:00:00 2001
From: 9names <60134748+9names@users.noreply.github.com>
Date: Sat, 27 Jul 2024 21:27:29 +1000
Subject: [PATCH 09/11] Remove atomic-device feature from docs.rs metadata

---
 embedded-hal-bus/Cargo.toml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/embedded-hal-bus/Cargo.toml b/embedded-hal-bus/Cargo.toml
index 333aef89..0b3d444c 100644
--- a/embedded-hal-bus/Cargo.toml
+++ b/embedded-hal-bus/Cargo.toml
@@ -39,5 +39,5 @@ defmt-03 = { package = "defmt", version = "0.3", optional = true }
 portable-atomic = {version = "1.3", default-features = false, features = ["require-cas"]}
 
 [package.metadata.docs.rs]
-features = ["std", "async", "atomic-device"]
+features = ["std", "async"]
 rustdoc-args = ["--cfg", "docsrs"]

From cc868a31cd9999bd86467463e62cae8eeeb4e9c3 Mon Sep 17 00:00:00 2001
From: 9names <60134748+9names@users.noreply.github.com>
Date: Sun, 28 Jul 2024 10:13:26 +1000
Subject: [PATCH 10/11] Make portable-atomic optional

---
 embedded-hal-bus/Cargo.toml | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/embedded-hal-bus/Cargo.toml b/embedded-hal-bus/Cargo.toml
index 0b3d444c..d0ebecf7 100644
--- a/embedded-hal-bus/Cargo.toml
+++ b/embedded-hal-bus/Cargo.toml
@@ -23,7 +23,7 @@ std = ["alloc"]
 # that does not natively support atomic CAS. If you enable this, you must also add `portable-atomic` to your crate with
 # a feature flag such as `unsafe-assume-single-core` or `critical-section` to choose how atomic CAS is implemented.
 # See https://docs.rs/portable-atomic/1.7.0/portable_atomic/#optional-features for more info.
-portable-atomic = []
+portable-atomic = ["dep:portable-atomic"]
 # Enable `embedded-hal-async` support.
 async = ["dep:embedded-hal-async"]
 # Derive `defmt::Format` from `defmt` 0.3 for enums and structs. See https://github.com/knurling-rs/defmt for more info
@@ -36,7 +36,7 @@ embedded-hal = { version = "1.0.0", path = "../embedded-hal" }
 embedded-hal-async = { version = "1.0.0", path = "../embedded-hal-async", optional = true }
 critical-section = { version = "1.0" }
 defmt-03 = { package = "defmt", version = "0.3", optional = true }
-portable-atomic = {version = "1.3", default-features = false, features = ["require-cas"]}
+portable-atomic = {version = "1.3", default-features = false, optional = true, features = ["require-cas"]}
 
 [package.metadata.docs.rs]
 features = ["std", "async"]

From 2acbd7773cb30b3c8c5e78720a9fbc6b304954d8 Mon Sep 17 00:00:00 2001
From: 9names <60134748+9names@users.noreply.github.com>
Date: Sun, 28 Jul 2024 10:19:09 +1000
Subject: [PATCH 11/11] Use AtomicBool from core if not using portable-atomic

---
 embedded-hal-bus/src/util.rs | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/embedded-hal-bus/src/util.rs b/embedded-hal-bus/src/util.rs
index 91add232..bb16577c 100644
--- a/embedded-hal-bus/src/util.rs
+++ b/embedded-hal-bus/src/util.rs
@@ -3,6 +3,11 @@
 #[allow(unused_imports)]
 use core::cell::UnsafeCell;
 
+#[cfg(not(feature = "portable-atomic"))]
+use core::sync::atomic::AtomicBool;
+#[cfg(feature = "portable-atomic")]
+use portable_atomic::AtomicBool;
+
 #[cfg(any(feature = "portable-atomic", target_has_atomic = "8"))]
 /// Cell type used by [`spi::AtomicDevice`](crate::spi::AtomicDevice) and [`i2c::AtomicDevice`](crate::i2c::AtomicDevice).
 ///
@@ -10,7 +15,7 @@ use core::cell::UnsafeCell;
 /// construct multiple `AtomicDevice` instances with references to it.
 pub struct AtomicCell<BUS> {
     pub(crate) bus: UnsafeCell<BUS>,
-    pub(crate) busy: portable_atomic::AtomicBool,
+    pub(crate) busy: AtomicBool,
 }
 #[cfg(any(feature = "portable-atomic", target_has_atomic = "8"))]
 unsafe impl<BUS: Send> Send for AtomicCell<BUS> {}
@@ -23,7 +28,7 @@ impl<BUS> AtomicCell<BUS> {
     pub fn new(bus: BUS) -> Self {
         Self {
             bus: UnsafeCell::new(bus),
-            busy: portable_atomic::AtomicBool::from(false),
+            busy: AtomicBool::from(false),
         }
     }
 }