Move Chipyard CI to Github Actions

- As similar as possible to the circle ci code.
- The `.github/README.md` file has a fair amount of documentation for this.
- Creates a worfklow file
  - re-uses most of the circleci/scipts unchanged
  - defines a number of *Composite Actions* which are like YML subroutines
- Removes the circle-ci code
- Points the CI badge in the top level README to use the GA test result

.github/actions/build-extra-tests/action.yml

@@ -0,0 +1,28 @@
+name: build-extra-tests
+description: 'Builds extra test required for some flows'
+
+inputs:
+  tools-version:
+    description: Which toolchain to build
+    required: false
+    default: 'riscv-tools'
+  cache-key:
+    description: Use this for caching
+    required: true
+runs:
+  using: "composite"
+  steps:
+    - uses: actions/cache@v2
+      id: build-extra-tools-cache
+      with:
+        path: extra-tests-install
+        key: ${{ needs.make-keys.outputs.extra-tests-cache-key }}
+        restore-keys: ${{ needs.make-keys.outputs.extra-tests-cache-key }}
+    - name: Build extra tests if not cached
+      run: |
+        export RISCV="/__w/chipyard/chipyard/riscv-tools-install"
+        export LD_LIBRARY_PATH="$RISCV/lib"
+        export PATH="$RISCV/bin:$PATH"
+        .github/scripts/build-extra-tests.sh
+      shell: bash
+

.github/actions/prepare-rtl/action.yml

@@ -0,0 +1,41 @@
+name: prepare-rtl
+description: 'Builds RTL based on parameters, caches the entire chipyard root dir when done'
+
+inputs:
+  tools-version:
+    description: Which toolchain to build
+    required: false
+    default: 'riscv-tools'
+  group-key:
+    description: group key
+    required: true
+  build-script:
+    description: rtl build script to use
+    required: false
+    default: "do-rtl-build.sh"
+  build-type:
+    description: type of build
+    required: false
+    default: "sim"
+
+runs:
+  using: "composite"
+  steps:
+    - uses: actions/cache@v2
+      id: rtl-build-id
+      with:
+        path: |
+          sims/verilator
+          sims/firesim/sim
+          generators/gemmini/software/gemmini-rocc-tests
+        key: ${{ inputs.group-key }}-${{ github.ref }}-${{ github.sha }}
+    - name: run rtl build script if not cached
+      run: |
+        if [[ "${{ steps.rtl-build-id.outputs.cache-hit }}" != 'true' ]]; then
+          echo "Cache miss on ${{ inputs.group-key }}-${{ github.ref }}-${{ github.sha }}"
+          ./.github/scripts/${{ inputs.build-script }} ${{ inputs.group-key }} ${{ inputs.build-type }}
+        else
+          echo "cache hit do not prepare rtl"
+        fi
+      shell: bash
+

.github/actions/run-tests/action.yml

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+name: run-tests
+description: 'Runs tests according to input parameters'
+
+inputs:
+  tools-version:
+    description: Which toolchain to build
+    required: false
+    default: 'riscv-tools'
+  group-key:
+    description: group key
+    required: true
+  project-key:
+    description: project key
+    required: true
+  run-script:
+    description: rtl build script to use
+    required: false
+    default: "run-tests.sh"
+
+runs:
+  using: "composite"
+  steps:
+    - name: run rtl build script cache of chipyard root should have been loaded by prepare-rtl
+      run: |
+        export RISCV="/__w/chipyard/chipyard/riscv-tools-install"
+        export LD_LIBRARY_PATH="$RISCV/lib"
+        export PATH="$RISCV/bin:$PATH"
+        ./.github/scripts/${{ inputs.run-script }} ${{ inputs.project-key }}
+      shell: bash
+

.github/actions/toolchain-build/action.yml

@@ -0,0 +1,29 @@
+name: toolchain-build
+description: 'Builds the selected toolchain'
+
+inputs:
+  tools-version:
+    description: Which toolchain to build
+    required: false
+    default: 'riscv-tools'
+  cache-key:
+    description: Use this for caching
+    required: true
+runs:
+  using: "composite"
+  steps:
+    - uses: actions/cache@v2
+      id: toolchain-build-id
+      with:
+        path: ${{ inputs.tools-version }}-install
+        key: ${{ inputs.cache-key }}
+    - name: run build toolchain if not cached
+      run: |
+        if [[ "${{ steps.toolchain-build-id.outputs.cache-hit }}" != 'true' ]]; then
+          echo "Cache miss on ${{ inputs.tools-version }}-install"
+          ./.github/scripts/build-toolchains.sh ${{ inputs.tools-version }}
+        else
+          echo "cache hit do not generate build ${{ inputs.tools-version }}"
+        fi
+      shell: bash
+