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, 0 deletions

diff --git a/include/timer.h b/include/timer.h
index f14725cc28..dcc803c392 100644
--- a/include/timer.h
+++ b/include/timer.h
@@ -67,4 +67,25 @@ struct timer_dev_priv {
 	unsigned long clock_rate;
 };
 
+/**
+ * timer_early_get_count() - Implement timer_get_count() before driver model
+ *
+ * If CONFIG_TIMER_EARLY is enabled, this function wil be called to return
+ * the current timer value before the proper driver model timer is ready.
+ * It should be implemented by one of the timer values. This is mostly useful
+ * for tracing.
+ */
+u64 timer_early_get_count(void);
+
+/**
+ * timer_early_get_rate() - Get the timer rate before driver model
+ *
+ * If CONFIG_TIMER_EARLY is enabled, this function wil be called to return
+ * the current timer rate in Hz before the proper driver model timer is ready.
+ * It should be implemented by one of the timer values. This is mostly useful
+ * for tracing. This corresponds to the clock_rate value in struct
+ * timer_dev_priv.
+ */
+unsigned long timer_early_get_rate(void);
+
 #endif	/* _TIMER_H_ */