tools lib traceevent: Man pages for event find APIs

Create man pages for libtraceevent APIs:

  tep_find_event()
  tep_find_event_by_name()
  tep_find_event_by_record()
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/20190503091119.23399-15-tstoyanov@vmware.com
Link: http://lkml.kernel.org/r/20190510200108.197407057@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-event_find.txt

+libtraceevent(3)
+================
+
+NAME
+----
+tep_find_event,tep_find_event_by_name,tep_find_event_by_record -
+Find events by given key.
+
+SYNOPSIS
+--------
+[verse]
+--
+*#include <event-parse.h>*
+
+struct tep_event pass:[*]*tep_find_event*(struct tep_handle pass:[*]_tep_, int _id_);
+struct tep_event pass:[*]*tep_find_event_by_name*(struct tep_handle pass:[*]_tep_, const char pass:[*]_sys_, const char pass:[*]_name_);
+struct tep_event pass:[*]*tep_find_event_by_record*(struct tep_handle pass:[*]_tep_, struct tep_record pass:[*]_record_);
+--
+
+DESCRIPTION
+-----------
+This set of functions can be used to search for an event, based on a given
+criteria. All functions require a pointer to a _tep_, trace event parser
+context.
+
+The _tep_find_event()_ function searches for an event by given event _id_. The
+event ID is assigned dynamically and can be viewed in event's format file,
+"ID" field.
+
+The tep_find_event_by_name()_ function searches for an event by given
+event _name_, under the system _sys_. If the _sys_ is NULL (not specified),
+the first event with _name_ is returned.
+
+The tep_find_event_by_record()_ function searches for an event from a given
+_record_.
+
+RETURN VALUE
+------------
+All these functions return a pointer to the found event, or NULL if there is no
+such event.
+
+EXAMPLE
+-------
+[source,c]
+--
+#include <event-parse.h>
+...
+struct tep_handle *tep = tep_alloc();
+...
+struct tep_event *event;
+
+event = tep_find_event(tep, 1857);
+if (event == NULL) {
+	/* There is no event with ID 1857 */
+}
+
+event = tep_find_event_by_name(tep, "kvm", "kvm_exit");
+if (event == NULL) {
+	/* There is no kvm_exit event, from kvm system */
+}
+
+void event_from_record(struct tep_record *record)
+{
+ struct tep_event *event = tep_find_event_by_record(tep, record);
+	if (event == NULL) {
+		/* There is no event from given record */
+	}
+}
+...
+--
+
+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