[PATCH 01/22] time: move the CONFIG_SYS_TIMER_RATE handling to the compiler

[Michael Walle]

CONFIG_SYS_TIMER_RATE might be a dynamic value, i.e. a function call
instead of a static value, thus it has to be evaluated at runtime. If it
is a static value, the compiler should be able to optimize the unused
branches out.

This will be needed for kirkwoods dynamic CONFIG_SYS_TCLK setting.

Cc: Pali Rohár <pali at kernel.org>
Signed-off-by: Michael Walle <michael at walle.cc>
---
 lib/time.c | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/lib/time.c b/lib/time.c
index 96074b84af..bbf191f673 100644
--- a/lib/time.c
+++ b/lib/time.c
@@ -47,12 +47,15 @@ ulong timer_get_boot_us(void)
 {
 	ulong count = timer_read_counter();
 
-#if CONFIG_SYS_TIMER_RATE == 1000000
-	return count;
-#elif CONFIG_SYS_TIMER_RATE > 1000000
-	return lldiv(count, CONFIG_SYS_TIMER_RATE / 1000000);
-#elif defined(CONFIG_SYS_TIMER_RATE)
-	return (unsigned long long)count * 1000000 / CONFIG_SYS_TIMER_RATE;
+#ifdef CONFIG_SYS_TIMER_RATE
+	const ulong timer_rate = CONFIG_SYS_TIMER_RATE;
+
+	if (timer_rate == 1000000)
+		return count;
+	else if (timer_rate > 1000000)
+		return lldiv(count, timer_rate / 1000000);
+	else
+		return (unsigned long long)count * 1000000 / timer_rate;
 #else
 	/* Assume the counter is in microseconds */
 	return count;
-- 
2.30.2