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>
diff --git a/drivers/timer/Kconfig b/drivers/timer/Kconfig
index ff65a73..cb18f12 100644
--- a/drivers/timer/Kconfig
+++ b/drivers/timer/Kconfig
@@ -9,6 +9,16 @@
will be used. The timer is usually a 32 bits free-running up
counter. There may be no real tick, and no timer interrupt.
+config TIMER_EARLY
+ bool "Allow timer to be used early in U-Boot"
+ depends on TIMER
+ help
+ 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().
+
config ALTERA_TIMER
bool "Altera timer support"
depends on TIMER
diff --git a/include/timer.h b/include/timer.h
index f14725c..dcc803c 100644
--- a/include/timer.h
+++ b/include/timer.h
@@ -67,4 +67,25 @@
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_ */
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 @@
#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 @@
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)