bootstage: Add time accumulation feature

Sometimes we want to add up the amount of time spent in a particular
activity when it is happening in a number of discrete chunks.

Add bootstage_start() to mark the start of an acitivity and
bootstage_accum() to accumulate the time since the last start. Calling
these function in pairs results in the accumulated time being collected.

Signed-off-by: Simon Glass <sjg@chromium.org>

common/bootstage.c

@@ -90,6 +90,25 @@ ulong bootstage_mark_name(enum bootstage_id id, const char *name)
 	return bootstage_add_record(id, name, flags, timer_get_boot_us());
 }
 
+uint32_t bootstage_start(enum bootstage_id id, const char *name)
+{
+	struct bootstage_record *rec = &record[id];
+
+	rec->start_us = timer_get_boot_us();
+	rec->name = name;
+	return rec->start_us;
+}
+
+uint32_t bootstage_accum(enum bootstage_id id)
+{
+	struct bootstage_record *rec = &record[id];
+	uint32_t duration;
+
+	duration = (uint32_t)timer_get_boot_us() - rec->start_us;
+	rec->time_us += duration;
+	return duration;
+}
+
 static void print_time(unsigned long us_time)
 {
 	char str[15], *s;
@@ -108,8 +127,13 @@ static void print_time(unsigned long us_time)
 static uint32_t print_time_record(enum bootstage_id id,
 			struct bootstage_record *rec, uint32_t prev)
 {
-	print_time(rec->time_us);
+	if (prev == -1U) {
-	print_time(rec->time_us - prev);
+		printf("%11s", "");
+		print_time(rec->time_us);
+	} else {
+		print_time(rec->time_us);
+		print_time(rec->time_us - prev);
+	}
 	if (rec->name)
 		printf("  %s\n", rec->name);
 	else if (id >= BOOTSTAGE_ID_USER)
@@ -144,13 +168,19 @@ void bootstage_report(void)
 	qsort(record, ARRAY_SIZE(record), sizeof(*rec), h_compare_record);
 
 	for (id = 0; id < BOOTSTAGE_ID_COUNT; id++, rec++) {
-		if (rec->time_us != 0)
+		if (rec->time_us != 0 && !rec->start_us)
 			prev = print_time_record(rec->id, rec, prev);
 	}
 	if (next_id > BOOTSTAGE_ID_COUNT)
 		printf("(Overflowed internal boot id table by %d entries\n"
 			"- please increase CONFIG_BOOTSTAGE_USER_COUNT\n",
 		       next_id - BOOTSTAGE_ID_COUNT);
+
+	puts("\nAccumulated time:\n");
+	for (id = 0, rec = record; id < BOOTSTAGE_ID_COUNT; id++, rec++) {
+		if (rec->start_us)
+			prev = print_time_record(id, rec, -1);
+	}
 }
 
 ulong __timer_get_boot_us(void)

include/bootstage.h

@@ -247,6 +247,33 @@ ulong bootstage_error(enum bootstage_id id);
 
 ulong bootstage_mark_name(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 end of a bootstage activity
+ *
+ * After previously marking the start of an activity with bootstage_start(),
+ * call this function to mark the end. You can call these functions in pairs
+ * as many times as you like.
+ *
+ * @param id	Bootstage id to record this timestamp against
+ * @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);