[Qemu-devel] [PATCH v4 1/3] hpet: inverse polarity when pin above ISA_NUM_IRQS

[Liu Ping Fan <qemulist@gmail.com>]

According to hpet spec, hpet irq is high active. But according to
ICH spec, there is inversion before the input of ioapic. So the OS
will expect low active on this IRQ line.(And this is observed on
bare metal).

We fold the emulation of this inversion inside the hpet logic.

Signed-off-by: Liu Ping Fan <pingfank@linux.vnet.ibm.com>
---
 hw/timer/hpet.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/hw/timer/hpet.c b/hw/timer/hpet.c
index 648b383..1139448 100644
--- a/hw/timer/hpet.c
+++ b/hw/timer/hpet.c
@@ -198,13 +198,23 @@ static void update_irq(struct HPETTimer *timer, int set)
     if (!set || !timer_enabled(timer) || !hpet_enabled(timer->state)) {
         s->isr &= ~mask;
         if (!timer_fsb_route(timer)) {
-            qemu_irq_lower(s->irqs[route]);
+            /* fold the ICH PIRQ# pin's internal inversion logic into hpet */
+            if (route >= ISA_NUM_IRQS) {
+                qemu_irq_raise(s->irqs[route]);
+            } else {
+                qemu_irq_lower(s->irqs[route]);
+            }
         }
     } else if (timer_fsb_route(timer)) {
         stl_le_phys(timer->fsb >> 32, timer->fsb & 0xffffffff);
     } else if (timer->config & HPET_TN_TYPE_LEVEL) {
         s->isr |= mask;
-        qemu_irq_raise(s->irqs[route]);
+        /* fold the ICH PIRQ# pin's internal inversion logic into hpet */
+        if (route >= ISA_NUM_IRQS) {
+            qemu_irq_lower(s->irqs[route]);
+        } else {
+            qemu_irq_raise(s->irqs[route]);
+        }
     } else {
         s->isr &= ~mask;
         qemu_irq_pulse(s->irqs[route]);
-- 
1.8.1.4