On 02/20/2012 01:25 AM, Zhang, Yang Z wrote:
> When time base is 32kHz, the update cycle takes 1984us at the end
> of every second. And the update cycle begins 244us later after UIP
> is set. So the UIP is set in 2228us at end of every second.
I think we can keep UIP set only for 244us, since our update cycle is
instantaneous. Otherwise looks good, thanks!
Paolo
> Signed-off-by: Yang Zhang <yang.z.zhang@xxxxxxxxx>
>
> ---
> hw/mc146818rtc.c | 26 ++++++++++++++++++++++++++
> 1 files changed, 26 insertions(+), 0 deletions(-)
>
> diff --git a/hw/mc146818rtc.c b/hw/mc146818rtc.c
> index 2445c6b..d4be8e9 100644
> --- a/hw/mc146818rtc.c
> +++ b/hw/mc146818rtc.c
> @@ -601,6 +601,29 @@ static void rtc_calibrate_time(RTCState *s)
> s->current_tm = *ret;
> }
>
> +static int update_in_progress(RTCState *s)
> +{
> + struct timeval tv_now;
> + int64_t host_usec, offset_usec, guest_usec;
> +
> + if (s->cmos_data[RTC_REG_B] & REG_B_SET) {
> + return 0;
> + }
> +
> + gettimeofday(&tv_now, NULL);
> + host_usec = tv_now.tv_sec * USEC_PER_SEC + tv_now.tv_usec;
> + offset_usec = s->offset_sec * USEC_PER_SEC + s->offset_usec;
> + guest_usec = host_usec + offset_usec;
> +
> + /* UIP bit will be set at last 2228us of every second.
> + * Only consider oscillator in 32.768kHz*/
> + if ((guest_usec % USEC_PER_SEC) >= (USEC_PER_SEC - 2228)) {
> + return 1;
> + }
--
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