ARM virtual counter supports event stream. It can only trigger an event
when the trigger bit of CNTVCT_EL0 changes from 0 to 1 (or from 1 to 0),
so the actual period of event stream is 2 ^ (cntkctl_evnti + 1). For
example, when the trigger bit is 0, then it triggers an event for every
two cycles.
Signed-off-by: Keqian Zhu <zhukeqian1@xxxxxxxxxx>
---
drivers/clocksource/arm_arch_timer.c | 17 ++++++++++++++---
1 file changed, 14 insertions(+), 3 deletions(-)
diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c
index ecf7b7db2d05..06d99a4b1b9b 100644
--- a/drivers/clocksource/arm_arch_timer.c
+++ b/drivers/clocksource/arm_arch_timer.c
@@ -799,10 +799,20 @@ static void __arch_timer_setup(unsigned type,
static void arch_timer_evtstrm_enable(int divider)
{
u32 cntkctl = arch_timer_get_cntkctl();
+ int cntkctl_evnti;
+
+ /*
+ * Note that it can only trigger an event when the trigger bit
+ * of CNTVCT_EL0 changes from 1 to 0 (or from 0 to 1), so the
+ * actual period of event stream is 2 ^ (cntkctl_evnti + 1).
+ */
+ cntkctl_evnti = divider - 1;
+ cntkctl_evnti = min(cntkctl_evnti, 15);
+ cntkctl_evnti = max(cntkctl_evnti, 0);
cntkctl &= ~ARCH_TIMER_EVT_TRIGGER_MASK;
/* Set the divider and enable virtual event stream */
- cntkctl |= (divider << ARCH_TIMER_EVT_TRIGGER_SHIFT)
+ cntkctl |= (cntkctl_evnti << ARCH_TIMER_EVT_TRIGGER_SHIFT)
| ARCH_TIMER_VIRT_EVT_EN;
arch_timer_set_cntkctl(cntkctl);
arch_timer_set_evtstrm_feature();
@@ -816,10 +826,11 @@ static void arch_timer_configure_evtstream(void)
/* Find the closest power of two to the divisor */
evt_stream_div = arch_timer_rate / ARCH_TIMER_EVT_STREAM_FREQ;
pos = fls(evt_stream_div);
- if (pos > 1 && !(evt_stream_div & (1 << (pos - 2))))
+ if ((pos == 1) || (pos > 1 && !(evt_stream_div & (1 << (pos - 2)))))
pos--;
+
/* enable event stream */
- arch_timer_evtstrm_enable(min(pos, 15));
+ arch_timer_evtstrm_enable(pos);
}
static void arch_counter_set_user_access(void)
--
2.19.1
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