Add CI workflow

.github/workflows/ci.yml

@@ -0,0 +1,52 @@
+name: CI
+
+on: [push, pull_request]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    strategy:
+      matrix:
+        target:
+          - thumbv7em-none-eabi
+          - thumbv6m-none-eabi # like the Cortex-M0+
+          - x86_64-unknown-linux-gnu
+
+    env:
+      CARGO_BUILD_TARGET: ${{ matrix.target }}
+
+    steps:
+      - name: Install build dependencies
+        shell: bash
+        run: |
+          env && pwd && sudo apt-get update -y -qq && sudo apt-get install -y -qq llvm libc6-dev-i386 libclang-dev
+      - uses: fiam/arm-none-eabi-gcc@v1
+        with:
+          release: "9-2020-q2"
+      - uses: actions-rs/toolchain@v1
+        with:
+          profile: minimal
+          toolchain: stable
+          target: ${{ matrix.target }}
+          override: true
+
+      - uses: actions/checkout@v3
+        with:
+          submodules: true
+
+      - name: Check
+        run: |
+          cargo check
+          cargo check --all-features
+
+      - name: Build
+        run: cargo build --release --verbose
+
+      - name: Run clippy
+        if: matrix.target == 'x86_64-unknown-linux-gnu'
+        run: cargo clippy --workspace --all-features --all-targets -- --deny warnings
+
+      - name: Check code format
+        if: matrix.target == 'x86_64-unknown-linux-gnu'
+        run: cargo fmt --all -- --check