docs: kdoc: move kernel-doc to tools/docs

kernel-doc is the last documentation-related tool still living outside of
the tools/docs directory; the time has come to move it over.

[mchehab: fixed kdoc lib location]

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Message-ID: <311d17e403524349940a8b12de6b5e91e554b1f4.1768823489.git.mchehab+huawei@kernel.org>

3 files changed, 362 insertions, 2 deletions

diff --git a/tools/docs/find-unused-docs.sh b/tools/docs/find-unused-docs.sh
index ca4e607ec3f7..53514c759dc1 100755
--- a/tools/docs/find-unused-docs.sh
+++ b/tools/docs/find-unused-docs.sh
@@ -54,7 +54,7 @@ for file in `find $1 -name '*.c'`; do
 	if [[ ${FILES_INCLUDED[$file]+_} ]]; then
 	continue;
 	fi
-	str=$(PYTHONDONTWRITEBYTECODE=1 scripts/kernel-doc -export "$file" 2>/dev/null)
+	str=$(PYTHONDONTWRITEBYTECODE=1 tools/docs/kernel-doc -export "$file" 2>/dev/null)
 	if [[ -n "$str" ]]; then
 	echo "$file"
 	fi
diff --git a/tools/docs/kernel-doc b/tools/docs/kernel-doc
new file mode 100755
index 000000000000..a19a92566780
--- /dev/null
+++ b/tools/docs/kernel-doc
@@ -0,0 +1,360 @@
+#!/usr/bin/env python3
+# SPDX-License-Identifier: GPL-2.0
+# Copyright(c) 2025: Mauro Carvalho Chehab <mchehab@kernel.org>.
+#
+# pylint: disable=C0103,R0912,R0914,R0915
+#
+# NOTE: While kernel-doc requires at least version 3.6 to run, the
+#       command line should work with Python 3.2+ (tested with 3.4).
+#       The rationale is that it shall fail gracefully during Kernel
+#       compilation with older Kernel versions. Due to that:
+#       - encoding line is needed here;
+#       - f-strings cannot be used in this file.
+#       - libraries that require newer versions can only be included
+#         after the Python version has been checked.
+#
+# Converted from the kernel-doc script originally written in Perl
+# under GPLv2, copyrighted since 1998 by the following authors:
+#
+#    Aditya Srivastava <yashsri421@gmail.com>
+#    Akira Yokosawa <akiyks@gmail.com>
+#    Alexander A. Klimov <grandmaster@al2klimov.de>
+#    Alexander Lobakin <aleksander.lobakin@intel.com>
+#    André Almeida <andrealmeid@igalia.com>
+#    Andy Shevchenko <andriy.shevchenko@linux.intel.com>
+#    Anna-Maria Behnsen <anna-maria@linutronix.de>
+#    Armin Kuster <akuster@mvista.com>
+#    Bart Van Assche <bart.vanassche@sandisk.com>
+#    Ben Hutchings <ben@decadent.org.uk>
+#    Borislav Petkov <bbpetkov@yahoo.de>
+#    Chen-Yu Tsai <wenst@chromium.org>
+#    Coco Li <lixiaoyan@google.com>
+#    Conchúr Navid <conchur@web.de>
+#    Daniel Santos <daniel.santos@pobox.com>
+#    Danilo Cesar Lemes de Paula <danilo.cesar@collabora.co.uk>
+#    Dan Luedtke <mail@danrl.de>
+#    Donald Hunter <donald.hunter@gmail.com>
+#    Gabriel Krisman Bertazi <krisman@collabora.co.uk>
+#    Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+#    Harvey Harrison <harvey.harrison@gmail.com>
+#    Horia Geanta <horia.geanta@freescale.com>
+#    Ilya Dryomov <idryomov@gmail.com>
+#    Jakub Kicinski <kuba@kernel.org>
+#    Jani Nikula <jani.nikula@intel.com>
+#    Jason Baron <jbaron@redhat.com>
+#    Jason Gunthorpe <jgg@nvidia.com>
+#    Jérémy Bobbio <lunar@debian.org>
+#    Johannes Berg <johannes.berg@intel.com>
+#    Johannes Weiner <hannes@cmpxchg.org>
+#    Jonathan Cameron <Jonathan.Cameron@huawei.com>
+#    Jonathan Corbet <corbet@lwn.net>
+#    Jonathan Neuschäfer <j.neuschaefer@gmx.net>
+#    Kamil Rytarowski <n54@gmx.com>
+#    Kees Cook <kees@kernel.org>
+#    Laurent Pinchart <laurent.pinchart@ideasonboard.com>
+#    Levin, Alexander (Sasha Levin) <alexander.levin@verizon.com>
+#    Linus Torvalds <torvalds@linux-foundation.org>
+#    Lucas De Marchi <lucas.demarchi@profusion.mobi>
+#    Mark Rutland <mark.rutland@arm.com>
+#    Markus Heiser <markus.heiser@darmarit.de>
+#    Martin Waitz <tali@admingilde.org>
+#    Masahiro Yamada <masahiroy@kernel.org>
+#    Matthew Wilcox <willy@infradead.org>
+#    Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
+#    Michal Wajdeczko <michal.wajdeczko@intel.com>
+#    Michael Zucchi
+#    Mike Rapoport <rppt@linux.ibm.com>
+#    Niklas Söderlund <niklas.soderlund@corigine.com>
+#    Nishanth Menon <nm@ti.com>
+#    Paolo Bonzini <pbonzini@redhat.com>
+#    Pavan Kumar Linga <pavan.kumar.linga@intel.com>
+#    Pavel Pisa <pisa@cmp.felk.cvut.cz>
+#    Peter Maydell <peter.maydell@linaro.org>
+#    Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
+#    Randy Dunlap <rdunlap@infradead.org>
+#    Richard Kennedy <richard@rsk.demon.co.uk>
+#    Rich Walker <rw@shadow.org.uk>
+#    Rolf Eike Beer <eike-kernel@sf-tec.de>
+#    Sakari Ailus <sakari.ailus@linux.intel.com>
+#    Silvio Fricke <silvio.fricke@gmail.com>
+#    Simon Huggins
+#    Tim Waugh <twaugh@redhat.com>
+#    Tomasz Warniełło <tomasz.warniello@gmail.com>
+#    Utkarsh Tripathi <utripathi2002@gmail.com>
+#    valdis.kletnieks@vt.edu <valdis.kletnieks@vt.edu>
+#    Vegard Nossum <vegard.nossum@oracle.com>
+#    Will Deacon <will.deacon@arm.com>
+#    Yacine Belkadi <yacine.belkadi.1@gmail.com>
+#    Yujie Liu <yujie.liu@intel.com>
+
+"""
+Print formatted kernel documentation to stdout.
+
+Read C language source or header FILEs, extract embedded
+documentation comments, and print formatted documentation
+to standard output.
+
+The documentation comments are identified by the ``/**``
+opening comment mark.
+
+See Documentation/doc-guide/kernel-doc.rst for the
+documentation comment syntax.
+"""
+
+import argparse
+import logging
+import os
+import sys
+
+# Import Python modules
+
+LIB_DIR = "../lib/python"
+SRC_DIR = os.path.dirname(os.path.realpath(__file__))
+
+sys.path.insert(0, os.path.join(SRC_DIR, LIB_DIR))
+
+WERROR_RETURN_CODE = 3
+
+DESC = """
+Read C language source or header FILEs, extract embedded documentation comments,
+and print formatted documentation to standard output.
+
+The documentation comments are identified by the "/**" opening comment mark.
+
+See Documentation/doc-guide/kernel-doc.rst for the documentation comment syntax.
+"""
+
+EXPORT_FILE_DESC = """
+Specify an additional FILE in which to look for EXPORT_SYMBOL information.
+
+May be used multiple times.
+"""
+
+EXPORT_DESC = """
+Only output documentation for symbols that have been
+exported using EXPORT_SYMBOL() and related macros in any input
+FILE or -export-file FILE.
+"""
+
+INTERNAL_DESC = """
+Only output documentation for symbols that have NOT been
+exported using EXPORT_SYMBOL() and related macros in any input
+FILE or -export-file FILE.
+"""
+
+FUNCTION_DESC = """
+Only output documentation for the given function or DOC: section
+title. All other functions and DOC: sections are ignored.
+
+May be used multiple times.
+"""
+
+NOSYMBOL_DESC = """
+Exclude the specified symbol from the output documentation.
+
+May be used multiple times.
+"""
+
+FILES_DESC = """
+Header and C source files to be parsed.
+"""
+
+WARN_CONTENTS_BEFORE_SECTIONS_DESC = """
+Warn if there are contents before sections (deprecated).
+
+This option is kept just for backward-compatibility, but it does nothing,
+neither here nor at the original Perl script.
+"""
+
+
+class MsgFormatter(logging.Formatter):
+    """Helper class to format warnings in a similar way to kernel-doc.pl."""
+
+    def format(self, record):
+        record.levelname = record.levelname.capitalize()
+        return logging.Formatter.format(self, record)
+
+def main():
+    """
+    Main program.
+
+    By default, the return value is:
+
+    - 0: success or Python version is not compatible with
+      kernel-doc.  If -Werror is not used, it will also
+      return 0 if there are issues at kernel-doc markups;
+
+    - 1: an abnormal condition happened;
+
+    - 2: argparse issued an error;
+
+    - 3: -Werror is used, and one or more unfiltered parse warnings happened.
+    """
+
+    parser = argparse.ArgumentParser(formatter_class=argparse.RawTextHelpFormatter,
+                                     description=DESC)
+
+    #
+    # Normal arguments
+    #
+    parser.add_argument("-v", "-verbose", "--verbose", action="store_true",
+                        help="Verbose output, more warnings and other information.")
+
+    parser.add_argument("-d", "-debug", "--debug", action="store_true",
+                        help="Enable debug messages")
+
+    parser.add_argument("-M", "-modulename", "--modulename",
+                        default="Kernel API",
+                        help="Allow setting a module name at the output.")
+
+    parser.add_argument("-l", "-enable-lineno", "--enable_lineno",
+                        action="store_true",
+                        help="Enable line number output (only in ReST mode)")
+
+    #
+    # Arguments to control the warning behavior
+    #
+    parser.add_argument("-Wreturn", "--wreturn", action="store_true",
+                        help="Warns about the lack of a return markup on functions.")
+
+    parser.add_argument("-Wshort-desc", "-Wshort-description", "--wshort-desc",
+                        action="store_true",
+                        help="Warns if initial short description is missing")
+
+    parser.add_argument("-Wcontents-before-sections",
+                        "--wcontents-before-sections", action="store_true",
+                        help=WARN_CONTENTS_BEFORE_SECTIONS_DESC)
+
+    parser.add_argument("-Wall", "--wall", action="store_true",
+                        help="Enable all types of warnings")
+
+    parser.add_argument("-Werror", "--werror", action="store_true",
+                        help="Treat warnings as errors.")
+
+    parser.add_argument("-export-file", "--export-file", action='append',
+                        help=EXPORT_FILE_DESC)
+
+    #
+    # Output format mutually-exclusive group
+    #
+    out_group = parser.add_argument_group("Output format selection (mutually exclusive)")
+
+    out_fmt = out_group.add_mutually_exclusive_group()
+
+    out_fmt.add_argument("-m", "-man", "--man", action="store_true",
+                         help="Output troff manual page format.")
+    out_fmt.add_argument("-r", "-rst", "--rst", action="store_true",
+                         help="Output reStructuredText format (default).")
+    out_fmt.add_argument("-N", "-none", "--none", action="store_true",
+                         help="Do not output documentation, only warnings.")
+
+    #
+    # Output selection mutually-exclusive group
+    #
+    sel_group = parser.add_argument_group("Output selection (mutually exclusive)")
+    sel_mut = sel_group.add_mutually_exclusive_group()
+
+    sel_mut.add_argument("-e", "-export", "--export", action='store_true',
+                         help=EXPORT_DESC)
+
+    sel_mut.add_argument("-i", "-internal", "--internal", action='store_true',
+                         help=INTERNAL_DESC)
+
+    sel_mut.add_argument("-s", "-function", "--symbol", action='append',
+                         help=FUNCTION_DESC)
+
+    #
+    # Those are valid for all 3 types of filter
+    #
+    parser.add_argument("-n", "-nosymbol", "--nosymbol", action='append',
+                        help=NOSYMBOL_DESC)
+
+    parser.add_argument("-D", "-no-doc-sections", "--no-doc-sections",
+                        action='store_true', help="Don't output DOC sections")
+
+    parser.add_argument("files", metavar="FILE",
+                        nargs="+", help=FILES_DESC)
+
+    args = parser.parse_args()
+
+    if args.wall:
+        args.wreturn = True
+        args.wshort_desc = True
+        args.wcontents_before_sections = True
+
+    logger = logging.getLogger()
+
+    if not args.debug:
+        logger.setLevel(logging.INFO)
+    else:
+        logger.setLevel(logging.DEBUG)
+
+    formatter = MsgFormatter('%(levelname)s: %(message)s')
+
+    handler = logging.StreamHandler()
+    handler.setFormatter(formatter)
+
+    logger.addHandler(handler)
+
+    python_ver = sys.version_info[:2]
+    if python_ver < (3,6):
+        #
+        # Depending on the Kernel configuration, kernel-doc --none is called at
+        # build time. As we don't want to break compilation due to the
+        # usage of an old Python version, return 0 here.
+        #
+        if args.none:
+            logger.error("Python 3.6 or later is required by kernel-doc. Skipping checks")
+            sys.exit(0)
+
+        sys.exit("Python 3.6 or later is required by kernel-doc. Aborting.")
+
+    if python_ver < (3,7):
+        logger.warning("Python 3.7 or later is required for correct results")
+
+    #
+    # Import kernel-doc libraries only after checking the Python version
+    #
+    from kdoc.kdoc_files import KernelFiles             # pylint: disable=C0415
+    from kdoc.kdoc_output import RestFormat, ManFormat  # pylint: disable=C0415
+
+    if args.man:
+        out_style = ManFormat(modulename=args.modulename)
+    elif args.none:
+        out_style = None
+    else:
+        out_style = RestFormat()
+
+    kfiles = KernelFiles(verbose=args.verbose,
+                         out_style=out_style, werror=args.werror,
+                         wreturn=args.wreturn, wshort_desc=args.wshort_desc,
+                         wcontents_before_sections=args.wcontents_before_sections)
+
+    kfiles.parse(args.files, export_file=args.export_file)
+
+    for t in kfiles.msg(enable_lineno=args.enable_lineno, export=args.export,
+                        internal=args.internal, symbol=args.symbol,
+                        nosymbol=args.nosymbol, export_file=args.export_file,
+                        no_doc_sections=args.no_doc_sections):
+        msg = t[1]
+        if msg:
+            print(msg)
+
+    error_count = kfiles.errors
+    if not error_count:
+        sys.exit(0)
+
+    if args.werror:
+        print("%s warnings as errors" % error_count)    # pylint: disable=C0209
+        sys.exit(WERROR_RETURN_CODE)
+
+    if args.verbose:
+        print("%s errors" % error_count)                # pylint: disable=C0209
+
+    sys.exit(0)
+
+#
+# Call main method
+#
+if __name__ == "__main__":
+    main()
diff --git a/tools/docs/sphinx-build-wrapper b/tools/docs/sphinx-build-wrapper
index 7a5fcef25429..cb2a5005e633 100755
--- a/tools/docs/sphinx-build-wrapper
+++ b/tools/docs/sphinx-build-wrapper
@@ -246,7 +246,7 @@ class SphinxBuilder:
         #
         self.sphinxbuild = os.environ.get("SPHINXBUILD", "sphinx-build")
         self.kerneldoc = self.get_path(os.environ.get("KERNELDOC",
-                                                      "scripts/kernel-doc.py"))
+                                                      "tools/docs/kernel-doc"))
         self.builddir = self.get_path(builddir, use_cwd=True, abs_path=True)
 
         #