add github workflow

.github/workflows/ci.yml

@@ -0,0 +1,67 @@
+on: [push]
+
+name: ci
+
+jobs:
+  check:
+    name: Check
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        target:
+          - armv7-unknown-linux-gnueabihf
+          - x86_64-unknown-linux-gnu
+          - thumbv7em-none-eabihf
+    steps:
+      - uses: actions/checkout@v2
+      - uses: actions-rs/toolchain@v1
+        with:
+          profile: minimal
+          toolchain: stable
+          target: ${{ matrix.target }}
+          override: true
+      - uses: actions-rs/cargo@v1
+        with:
+          use-cross: true
+          command: build
+          args: --release --target=${{ matrix.target }}
+
+  fmt:
+    name: Rustfmt
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: actions-rs/toolchain@v1
+        with:
+          profile: minimal
+          toolchain: stable
+          override: true
+      - run: rustup component add rustfmt
+      - uses: actions-rs/cargo@v1
+        with:
+          command: fmt
+          args: --all -- --check
+
+  clippy:
+    name: Clippy
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: actions-rs/toolchain@v1
+        with:
+          profile: minimal
+          toolchain: stable
+      - run: rustup component add clippy
+      - uses: actions-rs/cargo@v1
+        with:
+          command: clippy
+          args: -- -D warnings
+
+  ci:
+      if: ${{ success() }}
+      # all new jobs must be added to this list
+      needs: [check, fmt, clippy]
+      runs-on: ubuntu-latest
+      steps:
+        - name: CI succeeded
+          run: exit 0