timer: Provide an early timer

In some cases the timer must be accessible before driver model is active.
Examples include when using CONFIG_TRACE to trace U-Boot's execution before
driver model is set up. Enable this option to use an early timer. These
functions must be supported by your timer driver: timer_early_get_count()
and timer_early_get_rate().

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

1 files changed, 21 insertions, 7 deletions

diff --git a/lib/time.c b/lib/time.c
index e9f6861..f37150f 100644
--- a/lib/time.c
+++ b/lib/time.c
@@ -43,11 +43,17 @@ extern unsigned long __weak timer_read_counter(void);
 #ifdef CONFIG_TIMER
 ulong notrace get_tbclk(void)
 {
-	int ret;
+	if (!gd->timer) {
+#ifdef CONFIG_TIMER_EARLY
+		return timer_early_get_rate();
+#else
+		int ret;
 
-	ret = dm_timer_init();
-	if (ret)
-		return ret;
+		ret = dm_timer_init();
+		if (ret)
+			return ret;
+#endif
+	}
 
 	return timer_get_rate(gd->timer);
 }
@@ -57,9 +63,17 @@ uint64_t notrace get_ticks(void)
 	u64 count;
 	int ret;
 
-	ret = dm_timer_init();
-	if (ret)
-		return ret;
+	if (!gd->timer) {
+#ifdef CONFIG_TIMER_EARLY
+		return timer_early_get_count();
+#else
+		int ret;
+
+		ret = dm_timer_init();
+		if (ret)
+			return ret;
+#endif
+	}
 
 	ret = timer_get_count(gd->timer, &count);
 	if (ret)