1===========================
2Including uAPI header files
3===========================
4
5Sometimes, it is useful to include header files and C example codes in
6order to describe the userspace API and to generate cross-references
7between the code and the documentation. Adding cross-references for
8userspace API files has an additional vantage: Sphinx will generate warnings
9if a symbol is not found at the documentation. That helps to keep the
10uAPI documentation in sync with the Kernel changes.
11The :ref:`parse_headers.pl <parse_headers>` provide a way to generate such
12cross-references. It has to be called via Makefile, while building the
13documentation. Please see ``Documentation/userspace-api/media/Makefile`` for an example
14about how to use it inside the Kernel tree.
15
16.. _parse_headers:
17
18parse_headers.pl
19^^^^^^^^^^^^^^^^
20
21NAME
22****
23
24
25parse_headers.pl - parse a C file, in order to identify functions, structs,
26enums and defines and create cross-references to a Sphinx book.
27
28
29SYNOPSIS
30********
31
32
33\ **parse_headers.pl**\  [<options>] <C_FILE> <OUT_FILE> [<EXCEPTIONS_FILE>]
34
35Where <options> can be: --debug, --help or --usage.
36
37
38OPTIONS
39*******
40
41
42
43\ **--debug**\
44
45 Put the script in verbose mode, useful for debugging.
46
47
48
49\ **--usage**\
50
51 Prints a brief help message and exits.
52
53
54
55\ **--help**\
56
57 Prints a more detailed help message and exits.
58
59
60DESCRIPTION
61***********
62
63
64Convert a C header or source file (C_FILE), into a reStructuredText
65included via ..parsed-literal block with cross-references for the
66documentation files that describe the API. It accepts an optional
67EXCEPTIONS_FILE with describes what elements will be either ignored or
68be pointed to a non-default reference.
69
70The output is written at the (OUT_FILE).
71
72It is capable of identifying defines, functions, structs, typedefs,
73enums and enum symbols and create cross-references for all of them.
74It is also capable of distinguish #define used for specifying a Linux
75ioctl.
76
77The EXCEPTIONS_FILE contain two types of statements: \ **ignore**\  or \ **replace**\ .
78
79The syntax for the ignore tag is:
80
81
82ignore \ **type**\  \ **name**\
83
84The \ **ignore**\  means that it won't generate cross references for a
85\ **name**\  symbol of type \ **type**\ .
86
87The syntax for the replace tag is:
88
89
90replace \ **type**\  \ **name**\  \ **new_value**\
91
92The \ **replace**\  means that it will generate cross references for a
93\ **name**\  symbol of type \ **type**\ , but, instead of using the default
94replacement rule, it will use \ **new_value**\ .
95
96For both statements, \ **type**\  can be either one of the following:
97
98
99\ **ioctl**\
100
101 The ignore or replace statement will apply to ioctl definitions like:
102
103 #define	VIDIOC_DBG_S_REGISTER 	 _IOW('V', 79, struct v4l2_dbg_register)
104
105
106
107\ **define**\
108
109 The ignore or replace statement will apply to any other #define found
110 at C_FILE.
111
112
113
114\ **typedef**\
115
116 The ignore or replace statement will apply to typedef statements at C_FILE.
117
118
119
120\ **struct**\
121
122 The ignore or replace statement will apply to the name of struct statements
123 at C_FILE.
124
125
126
127\ **enum**\
128
129 The ignore or replace statement will apply to the name of enum statements
130 at C_FILE.
131
132
133
134\ **symbol**\
135
136 The ignore or replace statement will apply to the name of enum value
137 at C_FILE.
138
139 For replace statements, \ **new_value**\  will automatically use :c:type:
140 references for \ **typedef**\ , \ **enum**\  and \ **struct**\  types. It will use :ref:
141 for \ **ioctl**\ , \ **define**\  and \ **symbol**\  types. The type of reference can
142 also be explicitly defined at the replace statement.
143
144
145
146EXAMPLES
147********
148
149
150ignore define _VIDEODEV2_H
151
152
153Ignore a #define _VIDEODEV2_H at the C_FILE.
154
155ignore symbol PRIVATE
156
157
158On a struct like:
159
160enum foo { BAR1, BAR2, PRIVATE };
161
162It won't generate cross-references for \ **PRIVATE**\ .
163
164replace symbol BAR1 :c:type:\`foo\`
165replace symbol BAR2 :c:type:\`foo\`
166
167
168On a struct like:
169
170enum foo { BAR1, BAR2, PRIVATE };
171
172It will make the BAR1 and BAR2 enum symbols to cross reference the foo
173symbol at the C domain.
174
175
176BUGS
177****
178
179
180Report bugs to Mauro Carvalho Chehab <mchehab@kernel.org>
181
182
183COPYRIGHT
184*********
185
186
187Copyright (c) 2016 by Mauro Carvalho Chehab <mchehab+samsung@kernel.org>.
188
189License GPLv2: GNU GPL version 2 <https://gnu.org/licenses/gpl.html>.
190
191This is free software: you are free to change and redistribute it.
192There is NO WARRANTY, to the extent permitted by law.
193