tools lib traceevent: Man pages for parse event APIs

Create man pages for libtraceevent APIs:

  tep_parse_event(),
  tep_parse_format()
Signed-off-by: Tzvetomir Stoyanov <tstoyanov@vmware.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: linux-trace-devel@vger.kernel.org
Link: http://lore.kernel.org/linux-trace-devel/20190503091119.23399-24-tstoyanov@vmware.com
Link: http://lkml.kernel.org/r/20190510200109.847820380@goodmis.orgSigned-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/lib/traceevent/Documentation/libtraceevent-parse_event.txt

+libtraceevent(3)
+================
+
+NAME
+----
+tep_parse_event, tep_parse_format - Parse the event format information
+
+SYNOPSIS
+--------
+[verse]
+--
+*#include <event-parse.h>*
+
+enum tep_errno *tep_parse_event*(struct tep_handle pass:[*]_tep_, const char pass:[*]_buf_, unsigned long _size_, const char pass:[*]_sys_);
+enum tep_errno *tep_parse_format*(struct tep_handle pass:[*]_tep_, struct tep_event pass:[*]pass:[*]_eventp_, const char pass:[*]_buf_, unsigned long _size_, const char pass:[*]_sys_);
+--
+
+DESCRIPTION
+-----------
+The _tep_parse_event()_ function parses the event format and creates an event
+structure to quickly parse raw data for a given event. The _tep_ argument is
+the trace event parser context. The created event structure is stored in the
+_tep_ context. The _buf_ argument is a buffer with _size_, where the event
+format data is. The event format data can be taken from
+tracefs/events/.../.../format files. The _sys_ argument is the system of
+the event.
+
+The _tep_parse_format()_ function does the same as _tep_parse_event()_. The only
+difference is in the extra _eventp_ argument, where the newly created event
+structure is returned.
+
+RETURN VALUE
+------------
+Both _tep_parse_event()_ and _tep_parse_format()_ functions return 0 on success,
+or TEP_ERRNO__... in case of an error.
+
+EXAMPLE
+-------
+[source,c]
+--
+#include <event-parse.h>
+...
+struct tep_handle *tep = tep_alloc();
+...
+char *buf;
+int size;
+struct tep_event *event = NULL;
+buf = read_file("/sys/kernel/tracing/events/ftrace/print/format", &size);
+if (tep_parse_event(tep, buf, size, "ftrace") != 0) {
+	/* Failed to parse the ftrace print format */
+}
+
+if (tep_parse_format(tep, &event, buf, size, "ftrace") != 0) {
+	/* Failed to parse the ftrace print format */
+}
+...
+--
+
+FILES
+-----
+[verse]
+--
+*event-parse.h*
+	Header file to include in order to have access to the library APIs.
+*-ltraceevent*
+	Linker switch to add when building a program that uses the library.
+--
+
+SEE ALSO
+--------
+_libtraceevent(3)_, _trace-cmd(1)_
+
+AUTHOR
+------
+[verse]
+--
+*Steven Rostedt* <rostedt@goodmis.org>, author of *libtraceevent*.
+*Tzvetomir Stoyanov* <tz.stoyanov@gmail.com>, author of this man page.
+--
+REPORTING BUGS
+--------------
+Report bugs to  <linux-trace-devel@vger.kernel.org>
+
+LICENSE
+-------
+libtraceevent is Free Software licensed under the GNU LGPL 2.1
+
+RESOURCES
+---------
+https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git