use Hal trait to combine Ui, Sd and future traits

We want to inject deps into, for BB02, testing and in the future for
other BitBox products.

For this we create a Hal trait that can be used anywhere with
`&mut impl Hal`, without needing to repeat the trait bounds in
every function.

The alternative was to have a trait that contains all functions, which
did not seem like a good thing for modularity.

Another alternative was to colour every function with `<U: Ui,
S: Sd, ...>` trait bounds, which is ugly and does not scale to more
traits easily.

The `Workflows` trait is renamed to `Ui` (in the `hal` module only for
now, later we will untangle the workflows module and rename things
there too).

Author: benma

src/rust/bitbox02-rust-c/src/workflow.rs

@@ -40,13 +40,12 @@ static mut CONFIRM_TITLE: Option<String> = None;
 static mut CONFIRM_BODY: Option<String> = None;
 static mut CONFIRM_PARAMS: Option<confirm::Params> = None;
 static mut CONFIRM_STATE: TaskState<'static, Result<(), confirm::UserAbort>> = TaskState::Nothing;
-static mut REAL_WORKFLOWS: bitbox02_rust::workflow::RealWorkflows =
-    bitbox02_rust::workflow::RealWorkflows;
+static mut BITBOX02_HAL: bitbox02_rust::hal::BitBox02Hal = bitbox02_rust::hal::BitBox02Hal::new();
 
 #[no_mangle]
 pub unsafe extern "C" fn rust_workflow_spawn_unlock() {
     UNLOCK_STATE = TaskState::Running(Box::pin(bitbox02_rust::workflow::unlock::unlock(
-        &mut REAL_WORKFLOWS,
+        &mut BITBOX02_HAL,
     )));
 }
 

src/rust/bitbox02-rust/src/hal.rs

@@ -0,0 +1,98 @@
+// Copyright 2025 Shift Crypto AG
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+use crate::workflow::RealWorkflows;
+pub use crate::workflow::Workflows as Ui;
+
+pub trait Sd {
+    fn sdcard_inserted(&mut self) -> bool;
+}
+
+/// Hardware abstraction layer for BitBox devices.
+pub trait Hal {
+    fn ui(&mut self) -> &mut impl Ui;
+    fn sd(&mut self) -> &mut impl Sd;
+}
+
+pub struct BitBox02Sd;
+
+impl Sd for BitBox02Sd {
+    fn sdcard_inserted(&mut self) -> bool {
+        bitbox02::sd::sdcard_inserted()
+    }
+}
+
+pub struct BitBox02Hal {
+    ui: RealWorkflows,
+    sd: BitBox02Sd,
+}
+
+impl BitBox02Hal {
+    pub const fn new() -> Self {
+        Self {
+            ui: crate::workflow::RealWorkflows,
+            sd: BitBox02Sd,
+        }
+    }
+}
+
+impl Hal for BitBox02Hal {
+    fn ui(&mut self) -> &mut impl Ui {
+        &mut self.ui
+    }
+    fn sd(&mut self) -> &mut impl Sd {
+        &mut self.sd
+    }
+}
+
+#[cfg(feature = "testing")]
+pub mod testing {
+    pub struct TestingSd {
+        pub inserted: Option<bool>,
+    }
+
+    impl TestingSd {
+        pub fn new() -> Self {
+            Self { inserted: None }
+        }
+    }
+    pub struct TestingHal<'a> {
+        pub ui: crate::workflow::testing::TestingWorkflows<'a>,
+        pub sd: TestingSd,
+    }
+
+    impl super::Sd for TestingSd {
+        fn sdcard_inserted(&mut self) -> bool {
+            self.inserted.unwrap()
+        }
+    }
+
+    impl TestingHal<'_> {
+        pub fn new() -> Self {
+            Self {
+                ui: crate::workflow::testing::TestingWorkflows::new(),
+                sd: TestingSd::new(),
+            }
+        }
+    }
+
+    impl super::Hal for TestingHal<'_> {
+        fn ui(&mut self) -> &mut impl super::Ui {
+            &mut self.ui
+        }
+        fn sd(&mut self) -> &mut impl super::Sd {
+            &mut self.sd
+        }
+    }
+}