[profile] Add profile_custom() for profiling with arbitrary time units

Provide profile_custom() as a trivial wrapper around profile_update()
to allow for the use of the profiling infrastructure by code using
timers other than the default profile_timestamp() provider.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/include/ipxe/profile.h

@@ -186,4 +186,18 @@ profile_exclude ( struct profiler *profiler ) {
 		profile_excluded += profile_elapsed ( profiler );
 }
 
+/**
+ * Record profiling sample in custom units
+ *
+ * @v profiler		Profiler
+ * @v sample		Profiling sample
+ */
+static inline __attribute__ (( always_inline )) void
+profile_custom ( struct profiler *profiler, unsigned long sample ) {
+
+	/* If profiling is active then update stats */
+	if ( PROFILING )
+		profile_update ( profiler, sample );
+}
+
 #endif /* _IPXE_PROFILE_H */