+ int (*add) (struct perf_event *event, int flags);
+ void (*del) (struct perf_event *event, int flags);
+
+ /*
+ * Starts/Stops a counter present on the PMU. The PMI handler
+ * should stop the counter when perf_event_overflow() returns
+ * !0. ->start() will be used to continue.
+ */
+ void (*start) (struct perf_event *event, int flags);
+ void (*stop) (struct perf_event *event, int flags);
+
+ /*
+ * Updates the counter value of the event.
+ */
+ void (*read) (struct perf_event *event);
+