ARM virtual counter supports event stream, it can only trigger an event when the trigger bit (the value of CNTKCTL_EL1.EVNTI) of CNTVCT_EL0 changes, so the actual period of event stream is 2^(cntkctl_evnti + 1). For example, when the trigger bit is 0, then virtual counter trigger an event for every two cycles.
Signed-off-by: Keqian Zhu <zhukeqi...@huawei.com> --- 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..bc019dd0975b 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, 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