hpet: Fix emulation of HPET_TN_SETVAL (Jan Kiszka)

While Intel's spec is not that clear here, latest changes to Linux' HPET
code (commit c23e253e67c9d8a91a0ffa33c1f571a17f0a2403, "x86: hpet: stop
HPET_COUNTER when programming periodic mode") strongly suggest that
HPET_TN_SETVAL rather means: Set _both_ the comparator value and
register.

With this patch applied, I'm again able to boot 2.6.30-rc kernels as
they no longer panic like this (which was due to the comparator
register remaining 0):

ENABLING IO-APIC IRQs
..TIMER: vector=0x30 apic1=0 pin1=2 apic2=-1 pin2=-1
..MP-BIOS bug: 8254 timer not connected to IO-APIC
...trying to set up timer (IRQ0) through the 8259A ...
..... (found apic 0 pin 2) ...
....... failed.
...trying to set up timer as Virtual Wire IRQ...
..... failed.
...trying to set up timer as ExtINT IRQ...
..... failed :(.
Kernel panic - not syncing: IO-APIC + timer doesn't work! [...]

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>


git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@7168 c046a42c-6fe2-441c-8c8c-71466251a162

hw/hpet.c

@@ -411,7 +411,7 @@ static void hpet_ram_writel(void *opaque, target_phys_addr_t addr,
                            (timer->config & HPET_TN_SETVAL))
                     timer->cmp = (timer->cmp & 0xffffffff00000000ULL)
                                   | new_val;
-                else {
+                if (timer_is_periodic(timer)) {
                     /*
                      * FIXME: Clamp period to reasonable min value?
                      * Clamp period to reasonable max value