From 086ede32afc9c70de3d75c4fb91c63db790cbd5c Mon Sep 17 00:00:00 2001 From: Peter Maydell Date: Mon, 9 Jul 2018 14:51:34 +0100 Subject: ptimer: Add TRIGGER_ONLY_ON_DECREMENT policy option The CMSDK timer behaviour is that an interrupt is triggered when the counter counts down from 1 to 0; however one is not triggered if the counter is manually set to 0 by a guest write to the counter register. Currently ptimer can't handle this; add a policy option to allow a ptimer user to request this behaviour. Signed-off-by: Peter Maydell Reviewed-by: Richard Henderson Tested-by: Guenter Roeck Message-id: 20180703171044.9503-2-peter.maydell@linaro.org --- hw/core/ptimer.c | 22 +++++++++++++++++++++- 1 file changed, 21 insertions(+), 1 deletion(-) (limited to 'hw') diff --git a/hw/core/ptimer.c b/hw/core/ptimer.c index 7221c68..170fd34 100644 --- a/hw/core/ptimer.c +++ b/hw/core/ptimer.c @@ -45,8 +45,20 @@ static void ptimer_reload(ptimer_state *s, int delta_adjust) uint32_t period_frac = s->period_frac; uint64_t period = s->period; uint64_t delta = s->delta; + bool suppress_trigger = false; - if (delta == 0 && !(s->policy_mask & PTIMER_POLICY_NO_IMMEDIATE_TRIGGER)) { + /* + * Note that if delta_adjust is 0 then we must be here because of + * a count register write or timer start, not because of timer expiry. + * In that case the policy might require us to suppress the timer trigger + * that we would otherwise generate for a zero delta. + */ + if (delta_adjust == 0 && + (s->policy_mask & PTIMER_POLICY_TRIGGER_ONLY_ON_DECREMENT)) { + suppress_trigger = true; + } + if (delta == 0 && !(s->policy_mask & PTIMER_POLICY_NO_IMMEDIATE_TRIGGER) + && !suppress_trigger) { ptimer_trigger(s); } @@ -353,6 +365,14 @@ ptimer_state *ptimer_init(QEMUBH *bh, uint8_t policy_mask) s->bh = bh; s->timer = timer_new_ns(QEMU_CLOCK_VIRTUAL, ptimer_tick, s); s->policy_mask = policy_mask; + + /* + * These two policies are incompatible -- trigger-on-decrement implies + * a timer trigger when the count becomes 0, but no-immediate-trigger + * implies a trigger when the count stops being 0. + */ + assert(!((policy_mask & PTIMER_POLICY_TRIGGER_ONLY_ON_DECREMENT) && + (policy_mask & PTIMER_POLICY_NO_IMMEDIATE_TRIGGER))); return s; } -- cgit v1.1