clocksource: improve sh_cmt clocksource overflow handling
This patch improves the sh_cmt clocksource handling.
Currently the counter value is ignored in the case of
overflow. With this patch the overflow flag is read
before and after reading the counter, removing any
counter value and overflow flag mismatch issues.
Signed-off-by: Magnus Damm <damm@igel.co.jp>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
diff --git a/drivers/clocksource/sh_cmt.c b/drivers/clocksource/sh_cmt.c
index c247564..d607ac2 100644
--- a/drivers/clocksource/sh_cmt.c
+++ b/drivers/clocksource/sh_cmt.c
@@ -111,16 +111,21 @@
int *has_wrapped)
{
unsigned long v1, v2, v3;
+ int o1, o2;
+
+ o1 = sh_cmt_read(p, CMCSR) & p->overflow_bit;
/* Make sure the timer value is stable. Stolen from acpi_pm.c */
do {
+ o2 = o1;
v1 = sh_cmt_read(p, CMCNT);
v2 = sh_cmt_read(p, CMCNT);
v3 = sh_cmt_read(p, CMCNT);
- } while (unlikely((v1 > v2 && v1 < v3) || (v2 > v3 && v2 < v1)
- || (v3 > v1 && v3 < v2)));
+ o1 = sh_cmt_read(p, CMCSR) & p->overflow_bit;
+ } while (unlikely((o1 != o2) || (v1 > v2 && v1 < v3)
+ || (v2 > v3 && v2 < v1) || (v3 > v1 && v3 < v2)));
- *has_wrapped = sh_cmt_read(p, CMCSR) & p->overflow_bit;
+ *has_wrapped = o1;
return v2;
}
@@ -394,7 +399,7 @@
raw = sh_cmt_get_counter(p, &has_wrapped);
if (unlikely(has_wrapped))
- raw = p->match_value;
+ raw += p->match_value;
spin_unlock_irqrestore(&p->lock, flags);
return value + raw;