On 5/27/26 2:55 PM, Igor Mammedov wrote:
> On Tue, 26 May 2026 16:24:59 +0200
> Eric Auger <[email protected]> wrote:
>
>> On 3/3/26 10:25 AM, Igor Mammedov wrote:
>>> it will be used by arm/virt board, to pick WDAT compatible watchdog impl.
>>> and act as switch over to WDAT ACPI table vesus default GTDT ACPI table.
>>>
>>> Signed-off-by: Igor Mammedov <[email protected]>
>>> ---
>>> include/hw/watchdog/sbsa_gwdt.h | 1 +
>>> hw/watchdog/sbsa_gwdt.c | 8 ++++++++
>>> 2 files changed, 9 insertions(+)
>>>
>>> diff --git a/include/hw/watchdog/sbsa_gwdt.h
>>> b/include/hw/watchdog/sbsa_gwdt.h
>>> index 307a4f291a..dc77e6be60 100644
>>> --- a/include/hw/watchdog/sbsa_gwdt.h
>>> +++ b/include/hw/watchdog/sbsa_gwdt.h
>>> @@ -73,6 +73,7 @@ typedef struct SBSA_GWDTState {
>>> uint32_t woru;
>>> uint32_t wcvl;
>>> uint32_t wcvu;
>>> + bool wdat;
>>> } SBSA_GWDTState;
>>>
>>> #endif /* WDT_SBSA_GWDT_H */
>>> diff --git a/hw/watchdog/sbsa_gwdt.c b/hw/watchdog/sbsa_gwdt.c
>>> index c4dd8005b7..40d80f7f2b 100644
>>> --- a/hw/watchdog/sbsa_gwdt.c
>>> +++ b/hw/watchdog/sbsa_gwdt.c
>>> @@ -265,6 +265,13 @@ static void wdt_sbsa_gwdt_realize(DeviceState *dev,
>>> Error **errp)
>>>
>>> sysbus_init_irq(sbd, &s->irq);
>>>
>>> + /*
>>> + * WDAT supports only upto 1KHz resolution,
>>> + */
>>> + if (s->wdat) {
>>> + s->freq = 1000;
>> where is it specified in the spec?
>
> next patch has link to WDAT spec and
> comment around relevant field:
>
> + /*
> + * WDAT spec suports only 1KHz or more coarse watchdog timer,
coarser?
By the way, in above comment, you can directly quote the spec:
"The clock interval that the WDT uses must be greater than or equal to 1
millisecond."
Besides:
Reviewed-by: Eric Auger <[email protected]>
Thanks
Eric
> + * Set resolution to minimum supported 1ms.
> + * Before starting watchdog Windows set countdown value to 5min.
> + */
> + g_assert(freq <= 1000);
> + build_append_int_noprefix(table_data, 1, 4);/* Timer Period, ms */
>
> it's the hack to make gwdt usable for wdat and is applied only when
> wdat is enabled, if not the gwdt is instantiated with native 1G and
> provides corresponding fdt.
>
>>
>> Thanks
>>
>> Eric
>>
>>> + }
>>> +
>>> s->timer = timer_new_ns(QEMU_CLOCK_VIRTUAL,
>>> sbsa_gwdt_timer_sysinterrupt,
>>> dev);
>>> }
>>> @@ -276,6 +283,7 @@ static const Property wdt_sbsa_gwdt_props[] = {
>>> */
>>> DEFINE_PROP_UINT64("clock-frequency", struct SBSA_GWDTState, freq,
>>> 1000000000),
>>> + DEFINE_PROP_BOOL("wdat", struct SBSA_GWDTState, wdat, false),
>>> };
>>>
>>> static void wdt_sbsa_gwdt_class_init(ObjectClass *klass, const void *data)
>>>
>>
>
