dm: timer: Support 64-bit counter

There are timers with a 64-bit counter value but current timer
uclass driver assumes a 32-bit one. Modify timer_get_count()
to ask timer driver to always return a 64-bit counter value,
and provide an inline helper function timer_conv_64() to handle
the 32-bit/64-bit conversion automatically.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Acked-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/lib/time.c b/lib/time.c
index b001745..f37a662 100644
--- a/lib/time.c
+++ b/lib/time.c
@@ -69,9 +69,9 @@
 	return timer_get_rate(gd->timer);
 }
 
-unsigned long notrace timer_read_counter(void)
+uint64_t notrace get_ticks(void)
 {
-	unsigned long count;
+	u64 count;
 	int ret;
 
 	ret = dm_timer_init();
@@ -84,7 +84,8 @@
 
 	return count;
 }
-#endif /* CONFIG_TIMER */
+
+#else /* !CONFIG_TIMER */
 
 uint64_t __weak notrace get_ticks(void)
 {
@@ -97,6 +98,8 @@
 	return ((uint64_t)gd->timebase_h << 32) | gd->timebase_l;
 }
 
+#endif /* CONFIG_TIMER */
+
 /* Returns time in milliseconds */
 static uint64_t notrace tick_to_time(uint64_t tick)
 {