CI: Add workflow for documentation generation

.github/workflows/docs.yml

@@ -0,0 +1,96 @@
+name: Generate and Preview Rust Docs
+
+on:
+  pull_request:
+    branches:
+      - main  # Only generate docs for PRs targeting main
+  push:
+    branches:
+      - main
+  workflow_dispatch:
+
+permissions:
+  contents: read
+
+jobs:
+  generate-docs:
+    runs-on: ubuntu-24.04
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+        with:
+          path: zephyr-lang-rust
+
+      - name: Set up Python
+        uses: actions/setup-python@v5
+        with:
+          python-version: 3.11
+
+      - name: Setup Zephyr project
+        uses: zephyrproject-rtos/action-zephyr-setup@v1
+        with:
+          app-path: zephyr-lang-rust
+          manifest-file-name: ci-manifest.yml
+          toolchains: arm-zephyr-eabi:riscv64-zephyr-elf
+
+      - name: Install Rust Targets
+        shell: bash
+        run: |
+          rustup target add thumbv7em-none-eabi
+          rustup target add thumbv7m-none-eabi
+
+      - name: Build Rust documentation
+        working-directory: zephyr-lang-rust
+        run: |
+          # Note that the above build doesn't set Zephyrbase, so we'll need to do that here.
+          west build -t rustdoc -b nrf52840dk/nrf52840 docgen
+          mkdir rustdocs
+          mv build/rust/target/thumbv7em-none-eabi/doc rustdocs/nostd
+          cp docs/top-index.html rustdocs/index.html
+
+      - name: Build build documentation
+        working-directory: zephyr-lang-rust
+        run: |
+          cd zephyr-build
+          cargo doc
+          mv target/doc ../rustdocs/std
+
+      - name: Upload docs artifact
+        uses: actions/upload-artifact@v4
+        with:
+          name: rustdocs
+          path: zephyr-lang-rust/rustdocs
+
+  doc-publish:
+    name: Publish Rust Documentation
+    needs: generate-docs
+    runs-on: ubuntu-24.04
+    if: |
+      github.event_name == 'pull_request' &&
+      github.repository == 'zephyrproject-rtos/zephyr-lang-rust'
+
+    steps:
+      # - name: Show github context
+      #   env:
+      #     GITHUB_CONTEXT: ${{ toJson(github) }}
+      #   run: |
+      #     echo "$GITHUB_CONTEXT" | jq .
+
+      - name: Download documentation artifact
+        uses: actions/download-artifact@v4
+        with:
+          name: rustdocs
+
+      # - name: Show our tree
+      #   run: |
+      #     find . -ls
+
+      - name: Publish to S3
+        env:
+          AWS_ACCESS_KEY_ID: ${{ vars.AWS_BUILDS_ZEPHYR_LANG_RUST_PR_ACCESS_KEY_ID }}
+          AWS_SECRET_ACCESS_KEY: ${{ secrets.AWS_BUILDS_ZEPHYR_LANG_RUST_PR_SECRET_ACCESS_KEY }}
+          AWS_REGION: us-east-1
+        run: |
+          PR_NUM=${{ github.event.number || 'not-a-pr' }}
+          aws s3 sync  --only-show-errors . s3://builds.zephyrproject.org/zephyr-lang-rust/pr/$PR_NUM/

CMakeLists.txt

@@ -143,6 +143,11 @@ WRAPPER_FILE = \"${WRAPPER_FILE}\"
 ${config_paths}
 ")
 
+  # The block of environment variables below could theoretically be captured in a variable, but this
+  # seems "challenging" in CMake (to be polite), as many of these contain spaces, and the quoting
+  # rules in CMake are inconsistent, at best.
+  # TODO: Figure out how to factor these out.
+
   # The library is built by invoking Cargo.
   add_custom_command(
     OUTPUT ${DUMMY_FILE}
@@ -183,6 +188,45 @@ ${config_paths}
         kobj_types_h_target
   )
 
+  # Command to generate the rust docs.  As mentioned above, the whole environment is duplicated, so
+  # it is important to keep this in sync with the above.
+  add_custom_command(
+    OUTPUT generate_rust_docs
+    COMMAND
+      ${CMAKE_COMMAND} -E
+      env BUILD_DIR=${CMAKE_CURRENT_BINARY_DIR}
+      ZEPHYR_BASE=${ZEPHYR_BASE}
+      DOTCONFIG=${DOTCONFIG}
+      ZEPHYR_DTS=${ZEPHYR_DTS}
+      INCLUDE_DIRS="${include_dirs}"
+      INCLUDE_DEFINES="${include_defines}"
+      WRAPPER_FILE="${WRAPPER_FILE}"
+      cargo doc
+      ${rust_build_type_arg}
+
+      # Override the features according to the shield given. For a general case,
+      # this will need to come from a variable or argument.
+      # TODO: This needs to be passed in.
+      # --no-default-features
+      # --features ${SHIELD_FEATURE}
+
+      # Set a replacement so that packages can just use `zephyr-sys` as a package
+      # name to find it.
+      ${command_paths}
+      --target ${RUST_TARGET}
+      --target-dir ${CARGO_TARGET_DIR}
+    COMMENT "Building Rust documentation"
+    WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}
+  )
+
+  add_custom_target(rustdoc
+    DEPENDS generate_rust_docs
+        # The variables, defined at the top level, don't seem to be accessible here.
+        syscall_list_h_target
+        driver_validation_h_target
+        kobj_types_h_target
+  )
+
   # Linking with the <rt_library> (`$<TARGET_PROPERTY:linker,rt_library>`).
   # -lgcc / -lcompiler_rt depending on toolchain, linker, and runtime library configuration.
   # In general this shouldn't be needed, as the runtime libary is generally linked late, but

docs/top-index.html

@@ -0,0 +1,14 @@
+<!DOCTYPE html>
+<html lang="en">
+<head>
+    <meta charset="UTF-8">
+    <title>Documentation Index</title>
+</head>
+<body>
+    <h1>Documentation Index</h1>
+    <ul>
+        <li><a href="nostd/zephyr/index.html">zephyr crate Documentation</a></li>
+        <li><a href="std/zephyr_build/index.html">zephyr_build support Documentation</a></li>
+    </ul>
+</body>
+</html>