timestamp: Apply factor to recorded stamps
If we dont have a constant TSC rate, timestamp table
has odd leaps and may appear to run backwards. Add
functionality to apply a factor such that all stamps
are in the same timebase.
Change-Id: Idab9c2c00e117c4d247db8cc9a2897640fa01edd
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: https://review.coreboot.org/19330
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
diff --git a/src/lib/timestamp.c b/src/lib/timestamp.c
index 816f28f..30f7c13 100644
--- a/src/lib/timestamp.c
+++ b/src/lib/timestamp.c
@@ -299,6 +299,34 @@
ts_cache->cache_state = TIMESTAMP_CACHE_NOT_NEEDED;
}
+void timestamp_rescale_table(uint16_t N, uint16_t M)
+{
+ uint32_t i;
+ struct timestamp_table *ts_table;
+
+ if (!timestamp_should_run())
+ return;
+
+ if (N == 0 || M == 0)
+ return;
+
+ ts_table = timestamp_table_get();
+
+ /* No timestamp table found */
+ if (ts_table == NULL) {
+ printk(BIOS_ERR, "ERROR: No timestamp table found\n");
+ return;
+ }
+
+ ts_table->base_time /= M;
+ ts_table->base_time *= N;
+ for (i = 0; i < ts_table->num_entries; i++) {
+ struct timestamp_entry *tse = &ts_table->entries[i];
+ tse->entry_stamp /= M;
+ tse->entry_stamp *= N;
+ }
+}
+
ROMSTAGE_CBMEM_INIT_HOOK(timestamp_sync_cache_to_cbmem)
RAMSTAGE_CBMEM_INIT_HOOK(timestamp_sync_cache_to_cbmem)