timestamp: Add function to get time since boot
Add a function to retrieve the elapsed time since boot. For that purpose
use the base time in the timestamp table among with the current
timestamp at call time of the function. So more precise the returned
time is the elapsed time since the timestamp was initialized scaled
in microseconds. This was chosen to get a reliable value even on
platforms where the TSC might not be reset on software reset or warm
start.
Change-Id: Ib93ad89078645c0ebe256048cb48f9622c90451f
Signed-off-by: Werner Zeh <werner.zeh@siemens.com>
Reviewed-on: https://review.coreboot.org/21516
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
diff --git a/src/lib/timestamp.c b/src/lib/timestamp.c
index 30f7c13..2e14fdd 100644
--- a/src/lib/timestamp.c
+++ b/src/lib/timestamp.c
@@ -2,6 +2,7 @@
* This file is part of the coreboot project.
*
* Copyright (C) 2011 The ChromiumOS Authors. All rights reserved.
+ * Copyright 2017 Siemens AG.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
@@ -327,6 +328,19 @@
}
}
+/*
+ * Get the time in microseconds since boot (or more precise: since timestamp
+ * table was initialized).
+ */
+uint32_t get_us_since_boot(void)
+{
+ struct timestamp_table *ts = timestamp_table_get();
+
+ if (ts == NULL || ts->tick_freq_mhz == 0)
+ return 0;
+ return (timestamp_get() - ts->base_time) / ts->tick_freq_mhz;
+}
+
ROMSTAGE_CBMEM_INIT_HOOK(timestamp_sync_cache_to_cbmem)
RAMSTAGE_CBMEM_INIT_HOOK(timestamp_sync_cache_to_cbmem)