ci: add action for bumping platform repos

.github/actions/bump-platform/action.yml

@@ -0,0 +1,90 @@
+name: Bump platform revision
+description: Refreshes patches, updates the platform revision and submodule
+
+inputs:
+  token:
+    description: 'GitHub access token'
+    required: true
+
+runs:
+  using: composite
+  steps:
+    - name: Prepare
+      shell: bash
+      run: sudo apt install quilt
+
+    - name: Bump revision and make PR
+      shell: bash
+      env:
+        GH_TOKEN: ${{ inputs.token }}
+      run: |
+        set -euxo pipefail
+
+        PLATFORM_DIR="$PWD"
+        HELIUM_DIR="$PLATFORM_DIR/helium-chromium"
+
+        run_upstream() {
+          python3 "$HELIUM_DIR/$1" "${@:2}"
+        }
+
+        get_version() {
+          run_upstream utils/helium_version.py \
+            --tree "$HELIUM_DIR" \
+            --platform-tree "$PLATFORM_DIR" \
+            --print
+        }
+
+        # get versions and compare them after submodule update
+        version_before=$(get_version)
+
+        pushd "$HELIUM_DIR"
+          git fetch origin main
+          git checkout origin/main
+        popd
+
+        git switch update || git switch -c update
+        version_after=$(get_version)
+
+        # reset or bump revision counter depending on version change
+        if [ "$version_before" != "$version_after" ]; then
+          echo "main version changed, resetting platform revision"
+          echo 1 > "$PLATFORM_DIR/revision.txt"
+        else
+          echo "no change in main version, bumping platform revision"
+          revision=$(cat "$PLATFORM_DIR/revision.txt")
+          echo $((revision + 1)) > "$PLATFORM_DIR/revision.txt"
+        fi
+
+        version_after=$(get_version)
+
+        mkdir -p build/{src,download_cache}
+
+        # fetch soures, expect that patches apply cleanly (or die)
+        run_upstream utils/downloads.py retrieve \
+          -i "$HELIUM_DIR/downloads.ini" -c build/download_cache
+
+        run_upstream utils/downloads.py unpack \
+          -i "$HELIUM_DIR/downloads.ini" -c build/download_cache build/src
+
+        run_upstream utils/patches.py apply \
+          --no-fuzz build/src "$HELIUM_DIR/patches"
+
+        # refresh platform patches if necessary
+        source "$HELIUM_DIR/devutils/set_quilt_vars.sh"
+        export QUILT_PATCHES="$PLATFORM_DIR/patches"
+
+        pushd build/src
+          quilt --quiltrc - push -a --refresh
+        popd
+
+        # commit, push, make pr
+        TITLE="update: helium-chromium $version_after"
+
+        git config user.name "github-actions[bot]"
+        git config user.email "41898282+github-actions[bot]@users.noreply.github.com"
+        git add -u patches helium-chromium revision.txt
+        if ! git status | tail -1 | grep -q 'nothing to commit'; then
+            git commit -m "$TITLE"
+            git push origin update
+            gh pr create --title "$TITLE" --body "" || :
+        fi