doc: Replace DocBook with sphinx-based docs

The Linux kernel moved to sphinx-based documentation and got rid of the
DocBook based documentation quite a while ago. Hence, the DocBook
documentation for U-Boot should be converted as well.

To achieve this, import the necessary files from Linux v4.17, and
convert the current DocBook documentation (three files altogether) to
sphinx/reStructuredText.

For now, all old DocBook documentation was merged into a single
handbook, tentatively named "U-Boot Hacker Manual".

For some source files, the documentation style was changed to comply
with kernel-doc; no functional changes were applied.

Signed-off-by: Mario Six <mario.six@gdsys.cc>
diff --git a/Documentation/sphinx/parse-headers.pl b/Documentation/sphinx/parse-headers.pl
new file mode 100755
index 0000000..d410f47
--- /dev/null
+++ b/Documentation/sphinx/parse-headers.pl
@@ -0,0 +1,401 @@
+#!/usr/bin/perl
+use strict;
+use Text::Tabs;
+use Getopt::Long;
+use Pod::Usage;
+
+my $debug;
+my $help;
+my $man;
+
+GetOptions(
+	"debug" => \$debug,
+	'usage|?' => \$help,
+	'help' => \$man
+) or pod2usage(2);
+
+pod2usage(1) if $help;
+pod2usage(-exitstatus => 0, -verbose => 2) if $man;
+pod2usage(2) if (scalar @ARGV < 2 || scalar @ARGV > 3);
+
+my ($file_in, $file_out, $file_exceptions) = @ARGV;
+
+my $data;
+my %ioctls;
+my %defines;
+my %typedefs;
+my %enums;
+my %enum_symbols;
+my %structs;
+
+require Data::Dumper if ($debug);
+
+#
+# read the file and get identifiers
+#
+
+my $is_enum = 0;
+my $is_comment = 0;
+open IN, $file_in or die "Can't open $file_in";
+while (<IN>) {
+	$data .= $_;
+
+	my $ln = $_;
+	if (!$is_comment) {
+		$ln =~ s,/\*.*(\*/),,g;
+
+		$is_comment = 1 if ($ln =~ s,/\*.*,,);
+	} else {
+		if ($ln =~ s,^(.*\*/),,) {
+			$is_comment = 0;
+		} else {
+			next;
+		}
+	}
+
+	if ($is_enum && $ln =~ m/^\s*([_\w][\w\d_]+)\s*[\,=]?/) {
+		my $s = $1;
+		my $n = $1;
+		$n =~ tr/A-Z/a-z/;
+		$n =~ tr/_/-/;
+
+		$enum_symbols{$s} =  "\\ :ref:`$s <$n>`\\ ";
+
+		$is_enum = 0 if ($is_enum && m/\}/);
+		next;
+	}
+	$is_enum = 0 if ($is_enum && m/\}/);
+
+	if ($ln =~ m/^\s*#\s*define\s+([_\w][\w\d_]+)\s+_IO/) {
+		my $s = $1;
+		my $n = $1;
+		$n =~ tr/A-Z/a-z/;
+
+		$ioctls{$s} = "\\ :ref:`$s <$n>`\\ ";
+		next;
+	}
+
+	if ($ln =~ m/^\s*#\s*define\s+([_\w][\w\d_]+)\s+/) {
+		my $s = $1;
+		my $n = $1;
+		$n =~ tr/A-Z/a-z/;
+		$n =~ tr/_/-/;
+
+		$defines{$s} = "\\ :ref:`$s <$n>`\\ ";
+		next;
+	}
+
+	if ($ln =~ m/^\s*typedef\s+([_\w][\w\d_]+)\s+(.*)\s+([_\w][\w\d_]+);/) {
+		my $s = $2;
+		my $n = $3;
+
+		$typedefs{$n} = "\\ :c:type:`$n <$s>`\\ ";
+		next;
+	}
+	if ($ln =~ m/^\s*enum\s+([_\w][\w\d_]+)\s+\{/
+	    || $ln =~ m/^\s*enum\s+([_\w][\w\d_]+)$/
+	    || $ln =~ m/^\s*typedef\s*enum\s+([_\w][\w\d_]+)\s+\{/
+	    || $ln =~ m/^\s*typedef\s*enum\s+([_\w][\w\d_]+)$/) {
+		my $s = $1;
+
+		$enums{$s} =  "enum :c:type:`$s`\\ ";
+
+		$is_enum = $1;
+		next;
+	}
+	if ($ln =~ m/^\s*struct\s+([_\w][\w\d_]+)\s+\{/
+	    || $ln =~ m/^\s*struct\s+([[_\w][\w\d_]+)$/
+	    || $ln =~ m/^\s*typedef\s*struct\s+([_\w][\w\d_]+)\s+\{/
+	    || $ln =~ m/^\s*typedef\s*struct\s+([[_\w][\w\d_]+)$/
+	    ) {
+		my $s = $1;
+
+		$structs{$s} = "struct :c:type:`$s`\\ ";
+		next;
+	}
+}
+close IN;
+
+#
+# Handle multi-line typedefs
+#
+
+my @matches = ($data =~ m/typedef\s+struct\s+\S+?\s*\{[^\}]+\}\s*(\S+)\s*\;/g,
+	       $data =~ m/typedef\s+enum\s+\S+?\s*\{[^\}]+\}\s*(\S+)\s*\;/g,);
+foreach my $m (@matches) {
+	my $s = $m;
+
+	$typedefs{$s} = "\\ :c:type:`$s`\\ ";
+	next;
+}
+
+#
+# Handle exceptions, if any
+#
+
+my %def_reftype = (
+	"ioctl"   => ":ref",
+	"define"  => ":ref",
+	"symbol"  => ":ref",
+	"typedef" => ":c:type",
+	"enum"    => ":c:type",
+	"struct"  => ":c:type",
+);
+
+if ($file_exceptions) {
+	open IN, $file_exceptions or die "Can't read $file_exceptions";
+	while (<IN>) {
+		next if (m/^\s*$/ || m/^\s*#/);
+
+		# Parsers to ignore a symbol
+
+		if (m/^ignore\s+ioctl\s+(\S+)/) {
+			delete $ioctls{$1} if (exists($ioctls{$1}));
+			next;
+		}
+		if (m/^ignore\s+define\s+(\S+)/) {
+			delete $defines{$1} if (exists($defines{$1}));
+			next;
+		}
+		if (m/^ignore\s+typedef\s+(\S+)/) {
+			delete $typedefs{$1} if (exists($typedefs{$1}));
+			next;
+		}
+		if (m/^ignore\s+enum\s+(\S+)/) {
+			delete $enums{$1} if (exists($enums{$1}));
+			next;
+		}
+		if (m/^ignore\s+struct\s+(\S+)/) {
+			delete $structs{$1} if (exists($structs{$1}));
+			next;
+		}
+		if (m/^ignore\s+symbol\s+(\S+)/) {
+			delete $enum_symbols{$1} if (exists($enum_symbols{$1}));
+			next;
+		}
+
+		# Parsers to replace a symbol
+		my ($type, $old, $new, $reftype);
+
+		if (m/^replace\s+(\S+)\s+(\S+)\s+(\S+)/) {
+			$type = $1;
+			$old = $2;
+			$new = $3;
+		} else {
+			die "Can't parse $file_exceptions: $_";
+		}
+
+		if ($new =~ m/^\:c\:(data|func|macro|type)\:\`(.+)\`/) {
+			$reftype = ":c:$1";
+			$new = $2;
+		} elsif ($new =~ m/\:ref\:\`(.+)\`/) {
+			$reftype = ":ref";
+			$new = $1;
+		} else {
+			$reftype = $def_reftype{$type};
+		}
+		$new = "$reftype:`$old <$new>`";
+
+		if ($type eq "ioctl") {
+			$ioctls{$old} = $new if (exists($ioctls{$old}));
+			next;
+		}
+		if ($type eq "define") {
+			$defines{$old} = $new if (exists($defines{$old}));
+			next;
+		}
+		if ($type eq "symbol") {
+			$enum_symbols{$old} = $new if (exists($enum_symbols{$old}));
+			next;
+		}
+		if ($type eq "typedef") {
+			$typedefs{$old} = $new if (exists($typedefs{$old}));
+			next;
+		}
+		if ($type eq "enum") {
+			$enums{$old} = $new if (exists($enums{$old}));
+			next;
+		}
+		if ($type eq "struct") {
+			$structs{$old} = $new if (exists($structs{$old}));
+			next;
+		}
+
+		die "Can't parse $file_exceptions: $_";
+	}
+}
+
+if ($debug) {
+	print Data::Dumper->Dump([\%ioctls], [qw(*ioctls)]) if (%ioctls);
+	print Data::Dumper->Dump([\%typedefs], [qw(*typedefs)]) if (%typedefs);
+	print Data::Dumper->Dump([\%enums], [qw(*enums)]) if (%enums);
+	print Data::Dumper->Dump([\%structs], [qw(*structs)]) if (%structs);
+	print Data::Dumper->Dump([\%defines], [qw(*defines)]) if (%defines);
+	print Data::Dumper->Dump([\%enum_symbols], [qw(*enum_symbols)]) if (%enum_symbols);
+}
+
+#
+# Align block
+#
+$data = expand($data);
+$data = "    " . $data;
+$data =~ s/\n/\n    /g;
+$data =~ s/\n\s+$/\n/g;
+$data =~ s/\n\s+\n/\n\n/g;
+
+#
+# Add escape codes for special characters
+#
+$data =~ s,([\_\`\*\<\>\&\\\\:\/\|\%\$\#\{\}\~\^]),\\$1,g;
+
+$data =~ s,DEPRECATED,**DEPRECATED**,g;
+
+#
+# Add references
+#
+
+my $start_delim = "[ \n\t\(\=\*\@]";
+my $end_delim = "(\\s|,|\\\\=|\\\\:|\\;|\\\)|\\}|\\{)";
+
+foreach my $r (keys %ioctls) {
+	my $s = $ioctls{$r};
+
+	$r =~ s,([\_\`\*\<\>\&\\\\:\/]),\\\\$1,g;
+
+	print "$r -> $s\n" if ($debug);
+
+	$data =~ s/($start_delim)($r)$end_delim/$1$s$3/g;
+}
+
+foreach my $r (keys %defines) {
+	my $s = $defines{$r};
+
+	$r =~ s,([\_\`\*\<\>\&\\\\:\/]),\\\\$1,g;
+
+	print "$r -> $s\n" if ($debug);
+
+	$data =~ s/($start_delim)($r)$end_delim/$1$s$3/g;
+}
+
+foreach my $r (keys %enum_symbols) {
+	my $s = $enum_symbols{$r};
+
+	$r =~ s,([\_\`\*\<\>\&\\\\:\/]),\\\\$1,g;
+
+	print "$r -> $s\n" if ($debug);
+
+	$data =~ s/($start_delim)($r)$end_delim/$1$s$3/g;
+}
+
+foreach my $r (keys %enums) {
+	my $s = $enums{$r};
+
+	$r =~ s,([\_\`\*\<\>\&\\\\:\/]),\\\\$1,g;
+
+	print "$r -> $s\n" if ($debug);
+
+	$data =~ s/enum\s+($r)$end_delim/$s$2/g;
+}
+
+foreach my $r (keys %structs) {
+	my $s = $structs{$r};
+
+	$r =~ s,([\_\`\*\<\>\&\\\\:\/]),\\\\$1,g;
+
+	print "$r -> $s\n" if ($debug);
+
+	$data =~ s/struct\s+($r)$end_delim/$s$2/g;
+}
+
+foreach my $r (keys %typedefs) {
+	my $s = $typedefs{$r};
+
+	$r =~ s,([\_\`\*\<\>\&\\\\:\/]),\\\\$1,g;
+
+	print "$r -> $s\n" if ($debug);
+	$data =~ s/($start_delim)($r)$end_delim/$1$s$3/g;
+}
+
+$data =~ s/\\ ([\n\s])/\1/g;
+
+#
+# Generate output file
+#
+
+my $title = $file_in;
+$title =~ s,.*/,,;
+
+open OUT, "> $file_out" or die "Can't open $file_out";
+print OUT ".. -*- coding: utf-8; mode: rst -*-\n\n";
+print OUT "$title\n";
+print OUT "=" x length($title);
+print OUT "\n\n.. parsed-literal::\n\n";
+print OUT $data;
+close OUT;
+
+__END__
+
+=head1 NAME
+
+parse_headers.pl - parse a C file, in order to identify functions, structs,
+enums and defines and create cross-references to a Sphinx book.
+
+=head1 SYNOPSIS
+
+B<parse_headers.pl> [<options>] <C_FILE> <OUT_FILE> [<EXCEPTIONS_FILE>]
+
+Where <options> can be: --debug, --help or --man.
+
+=head1 OPTIONS
+
+=over 8
+
+=item B<--debug>
+
+Put the script in verbose mode, useful for debugging.
+
+=item B<--usage>
+
+Prints a brief help message and exits.
+
+=item B<--help>
+
+Prints a more detailed help message and exits.
+
+=back
+
+=head1 DESCRIPTION
+
+Convert a C header or source file (C_FILE), into a ReStructured Text
+included via ..parsed-literal block with cross-references for the
+documentation files that describe the API. It accepts an optional
+EXCEPTIONS_FILE with describes what elements will be either ignored or
+be pointed to a non-default reference.
+
+The output is written at the (OUT_FILE).
+
+It is capable of identifying defines, functions, structs, typedefs,
+enums and enum symbols and create cross-references for all of them.
+It is also capable of distinguish #define used for specifying a Linux
+ioctl.
+
+The EXCEPTIONS_FILE contain two rules to allow ignoring a symbol or
+to replace the default references by a custom one.
+
+Please read Documentation/doc-guide/parse-headers.rst at the Kernel's
+tree for more details.
+
+=head1 BUGS
+
+Report bugs to Mauro Carvalho Chehab <mchehab@kernel.org>
+
+=head1 COPYRIGHT
+
+Copyright (c) 2016 by Mauro Carvalho Chehab <mchehab+samsung@kernel.org>.
+
+License GPLv2: GNU GPL version 2 <http://gnu.org/licenses/gpl.html>.
+
+This is free software: you are free to change and redistribute it.
+There is NO WARRANTY, to the extent permitted by law.
+
+=cut