Add bootstage accumulation

This adds a new type of boot timer, which records the time taken by
an operation, rather than marking the instant when it occurred. This
is useful to track the amount of time spent in a repeating activity
during boot.

To use this, call bootstage_start() at the start of the activity, then
bootstage_accum() at the end, to add this segment of time to the total.
You can call them (start first, then accum) as many times as you like.

BUG=chromium-os:22938
TEST=build and boot on Kaen

Change-Id: I3f1b536dc140c91a4a780188f6974dc37780f4f0
Reviewed-on: https://gerrit.chromium.org/gerrit/13370
Commit-Ready: Simon Glass <sjg@chromium.org>
Reviewed-by: Simon Glass <sjg@chromium.org>
Tested-by: Simon Glass <sjg@chromium.org>

1 files changed, 33 insertions, 1 deletions

diff --git a/include/bootstage.h b/include/bootstage.h
index bed488f76f..5ae5d1d712 100644
--- a/include/bootstage.h
+++ b/include/bootstage.h
@@ -58,11 +58,43 @@ enum bootstage_id {
 
 #ifdef CONFIG_BOOTSTAGE
 
-/*
+/**
  * Mark a time stamp for the current boot stage.
+ *
+ * @param id	Bootstage id to record this timestamp against
+ * @param name	Textual name to display for this id in the report (maybe NULL)
+ * @return recorded timestamp in microseconds
  */
 uint32_t bootstage_mark(enum bootstage_id id, const char *name);
 
+/**
+ * Mark the start of a bootstage activity. The end will be marked later with
+ * bootstage_accum() and at that point we accumulate the time taken. Calling
+ * this function turns the given id into a accumulator rather than and
+ * absolute mark in time. Accumulators record the total amount of time spent
+ * in an activty during boot.
+ *
+ * @param id	Bootstage id to record this timestamp against
+ * @param name	Textual name to display for this id in the report (maybe NULL)
+ * @return start timestamp in microseconds
+ */
+uint32_t bootstage_start(enum bootstage_id id, const char *name);
+
+/**
+ * Mark the start of a bootstage activity. The end will be marked later with
+ * bootstage_accum() and at that point we accumulate the time taken. Calling
+ * this function turns the given id into a accumulator rather than and
+ * absolute mark in time. Accumulators record the total amount of time spent
+ * in an activty during boot.
+ *
+ * @param id	Bootstage id to record this timestamp against
+ * @param name	Textual name to display for this id in the report (maybe NULL)
+ * @return time spent in this iteration of the activity (i.e. the time now
+ *		less the start time recorded in the last bootstage_start() call
+ *		with this id.
+ */
+uint32_t bootstage_accum(enum bootstage_id id);
+
 /* Print a report about boot time */
 void bootstage_report(void);