docs: Begin documenting ISL

This commit mostly just adds the framework required to scrape
documentation out of the ISL sources and headers.  The method chosen
here is a combination of doxygen and breathe (a sphinx extension for
doxygen integration).  I'll freely admit that doxygen is pretty terrible
but it seems like the best option we have available to us today.

Acked-by: Emma Anholt <emma@anholt.net>
Acked-by: Daniel Stone <daniels@collabora.com>
Acked-by: Erik Faye-Lund <erik.faye-lund@collabora.com>.
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/11366>

.gitlab-ci.yml

@@ -97,8 +97,9 @@ stages:
     - .fdo.ci-fairy
     - .ci-run-policy
   script:
-  - apk --no-cache add graphviz
-  - pip3 install "sphinx<4.0" sphinx_rtd_theme
+  - apk --no-cache add graphviz doxygen
+  - pip3 install "sphinx<4.0" breathe mako sphinx_rtd_theme
+  - docs/doxygen-wrapper.py --out-dir=docs/doxygen_xml
   - sphinx-build -W -b html docs public
 
 pages:

docs/conf.py

@@ -38,7 +38,7 @@ sys.path.append(os.path.abspath('_exts'))
 # Add any Sphinx extension module names here, as strings. They can be
 # extensions coming with Sphinx (named 'sphinx.ext.*') or your custom
 # ones.
-extensions = ['sphinx.ext.graphviz', 'formatting', 'redirects']
+extensions = ['sphinx.ext.graphviz', 'breathe', 'formatting', 'redirects']
 
 # Add any paths that contain templates here, relative to this directory.
 templates_path = ['_templates']
@@ -212,3 +212,11 @@ texinfo_documents = [
 # -- Options for Graphviz -------------------------------------------------
 
 graphviz_output_format = 'svg'
+
+# -- Options for breathe --------------------------------------------------
+breathe_projects = {
+    'mesa' : 'doxygen_xml',
+}
+breathe_default_project = 'mesa'
+breathe_show_define_initializer = True
+breathe_show_enumvalue_initializer = True

docs/doxygen-wrapper.py

@@ -0,0 +1,92 @@
+#!/usr/bin/env python3
+#
+# Copyright © 2021 Intel Corporation
+#
+# Permission is hereby granted, free of charge, to any person obtaining a
+# copy of this software and associated documentation files (the
+# "Software"), to deal in the Software without restriction, including
+# without limitation the rights to use, copy, modify, merge, publish,
+# distribute, sub license, and/or sell copies of the Software, and to
+# permit persons to whom the Software is furnished to do so, subject to
+# the following conditions:
+#
+# The above copyright notice and this permission notice (including the
+# next paragraph) shall be included in all copies or substantial portions
+# of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+# OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.
+# IN NO EVENT SHALL VMWARE AND/OR ITS SUPPLIERS BE LIABLE FOR
+# ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+# TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+# SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+import argparse
+from mako.template import Template
+import os
+import subprocess
+import tempfile
+
+INPUT_PATHS = [
+    'src/intel/isl',
+]
+
+TEMPLATE_DOXYFILE = Template("""
+# Doxyfile 1.9.1
+DOXYFILE_ENCODING = UTF-8
+PROJECT_NAME = "Mesa"
+
+INPUT = ${' '.join(input_files)}
+XML_OUTPUT = ${output_xml}
+
+# Only generate XML
+GENERATE_HTML = NO
+GENERATE_LATEX = NO
+GENERATE_XML = YES
+
+# Add aliases for easily writing reStructuredText in comments
+ALIASES  = "rst=\\verbatim embed:rst:leading-asterisk"
+ALIASES += "endrst=\endverbatim"
+
+ENABLE_PREPROCESSING = YES
+MACRO_EXPANSION = YES
+EXPAND_ONLY_PREDEF = YES
+
+# Defines required to keep doxygen from tripping on our attribute macros
+PREDEFINED  = PACKED=
+PREDEFINED += ATTRIBUTE_CONST=
+""")
+
+def run_doxygen(output_path, input_paths=[]):
+    doxyfile = tempfile.NamedTemporaryFile(mode='w', delete=False)
+    try:
+        doxyfile.write(TEMPLATE_DOXYFILE.render(
+            input_files=[ os.path.abspath(i) for i in input_paths ],
+            output_xml=os.path.abspath(output_path),
+        ))
+        doxyfile.close()
+
+        subprocess.run(['doxygen', doxyfile.name])
+
+    finally:
+        doxyfile.close()
+        os.unlink(doxyfile.name)
+
+if __name__ == '__main__':
+    parser = argparse.ArgumentParser()
+    parser.add_argument('--out-dir',
+                        help='Output XML directory.',
+                        required=True)
+    args = parser.parse_args()
+
+    this_dir = os.path.dirname(os.path.abspath(__file__))
+    mesa_dir = os.path.join(this_dir, '..')
+    def fixpath(p):
+        if os.path.isabs(p):
+            return p
+        return os.path.join(mesa_dir, p)
+
+    input_paths = [ fixpath(p) for p in INPUT_PATHS ]
+
+    run_doxygen(args.out_dir, input_paths)

docs/index.rst

@@ -111,6 +111,7 @@ Linux, FreeBSD, and other operating systems.
    release-calendar
    dispatch
    gallium/index
+   isl/index
    android
    macos
    Linux Kernel Drivers <https://www.kernel.org/doc/html/latest/gpu/>

docs/isl/index.rst

@@ -0,0 +1,12 @@
+Intel Surface Layout (ISL)
+==========================
+
+The Intel Surface Layout library (**ISL**) is a subproject in Mesa for doing
+surface layout calculations for Intel graphics drivers.  It was originally
+written by Chad Versace and is now maintained by Jason Ekstrand and Nanley
+Chery.
+
+The core representation of a surface in ISL is :cpp:struct:`isl_surf`.
+
+.. doxygenstruct:: isl_surf
+   :members: