tools lib traceevent: Man page for list events APIs

Create man page for libtraceevent APIs:

  tep_list_events()
  tep_list_events_copy()

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/20190503091119.23399-16-tstoyanov@vmware.com
Link: http://lkml.kernel.org/r/20190510200108.367633707@goodmis.org
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

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

@@ -0,0 +1,122 @@
+libtraceevent(3)
+================
+
+NAME
+----
+tep_list_events, tep_list_events_copy -
+Get list of events, sorted by given criteria.
+
+SYNOPSIS
+--------
+[verse]
+--
+*#include <event-parse.h>*
+
+enum *tep_event_sort_type* {
+	_TEP_EVENT_SORT_ID_,
+	_TEP_EVENT_SORT_NAME_,
+	_TEP_EVENT_SORT_SYSTEM_,
+};
+
+struct tep_event pass:[*]pass:[*]*tep_list_events*(struct tep_handle pass:[*]_tep_, enum tep_event_sort_type _sort_type_);
+struct tep_event pass:[*]pass:[*]*tep_list_events_copy*(struct tep_handle pass:[*]_tep_, enum tep_event_sort_type _sort_type_);
+--
+
+DESCRIPTION
+-----------
+The _tep_list_events()_ function returns an array of pointers to the events,
+sorted by the _sort_type_ criteria. The last element of the array is NULL.
+The returned memory must not be freed, it is managed by the library.
+The function is not thread safe. The _tep_ argument is trace event parser
+context. The _sort_type_ argument is the required sort criteria:
+[verse]
+--
+	_TEP_EVENT_SORT_ID_	- sort by the event ID.
+	_TEP_EVENT_SORT_NAME_	- sort by the event (name, system, id) triplet.
+	_TEP_EVENT_SORT_SYSTEM_	- sort by the event (system, name, id) triplet.
+--
+
+The _tep_list_events_copy()_ is a thread safe version of _tep_list_events()_.
+It has the same behavior, but the returned array is allocated internally and
+must be freed by the caller. Note that the content of the array must not be
+freed (see the EXAMPLE below).
+
+RETURN VALUE
+------------
+The _tep_list_events()_ function returns an array of pointers to events.
+In case of an error, NULL is returned. The returned array must not be freed,
+it is managed by the library.
+
+The _tep_list_events_copy()_ function returns an array of pointers to events.
+In case of an error, NULL is returned. The returned array must be freed by
+the caller.
+
+EXAMPLE
+-------
+[source,c]
+--
+#include <event-parse.h>
+...
+struct tep_handle *tep = tep_alloc();
+...
+int i;
+struct tep_event_format **events;
+
+i=0;
+events = tep_list_events(tep, TEP_EVENT_SORT_ID);
+if (events == NULL) {
+	/* Failed to get the events, sorted by ID */
+} else {
+	while(events[i]) {
+		/* walk through the list of the events, sorted by ID */
+		i++;
+	}
+}
+
+i=0;
+events = tep_list_events_copy(tep, TEP_EVENT_SORT_NAME);
+if (events == NULL) {
+	/* Failed to get the events, sorted by name */
+} else {
+	while(events[i]) {
+		/* walk through the list of the events, sorted by name */
+		i++;
+	}
+	free(events);
+}
+
+...
+--
+
+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