github/workflows: Add CI workflow for rp2 port.

Signed-off-by: Damien George <damien@micropython.org>

.github/workflows/ports_rp2.yml

+name: rp2 port
+
+on:
+  push:
+  pull_request:
+    paths:
+      - '.github/workflows/*.yml'
+      - 'tools/**'
+      - 'py/**'
+      - 'extmod/**'
+      - 'lib/**'
+      - 'drivers/**'
+      - 'ports/rp2/**'
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v2
+    - name: Install packages
+      run: source tools/ci.sh && ci_rp2_setup
+    - name: Build
+      run: source tools/ci.sh && ci_rp2_build

tools/ci.sh

@@ -176,6 +176,20 @@ function ci_qemu_arm_build {
     make ${MAKEOPTS} -C ports/qemu-arm -f Makefile.test test
 }
 
+########################################################################################
+# ports/rp2
+
+function ci_rp2_setup {
+    ci_gcc_arm_setup
+}
+
+function ci_rp2_build {
+    make ${MAKEOPTS} -C mpy-cross
+    git submodule update --init lib/pico-sdk
+    git -C lib/pico-sdk submodule update --init lib/tinyusb
+    make ${MAKEOPTS} -C ports/rp2
+}
+
 ########################################################################################
 # ports/samd