* [Qemu-devel] [PATCH v5 3/7] RTC: Add UIP(update in progress) check logic
@ 2012-05-09 7:22 Zhang, Yang Z
0 siblings, 0 replies; only message in thread
From: Zhang, Yang Z @ 2012-05-09 7:22 UTC (permalink / raw)
To: 'qemu-devel@nongnu.org'
Cc: 'Paolo Bonzini', 'aliguori@us.ibm.com'
The UIP(update in progress) is set when RTC is updating. And the update cycle begins 244us later after UIP is set. And it is cleared when update end.
Signed-off-by: Yang Zhang <yang.z.zhang@Intel.com>
---
hw/mc146818rtc.c | 18 ++++++++++++++++++
1 files changed, 18 insertions(+), 0 deletions(-)
diff --git a/hw/mc146818rtc.c b/hw/mc146818rtc.c
index 2d10013..b70422a 100644
--- a/hw/mc146818rtc.c
+++ b/hw/mc146818rtc.c
@@ -380,6 +380,21 @@ static void rtc_calibrate_time(RTCState *s)
s->current_tm = *ret;
}
+static int update_in_progress(RTCState *s)
+{
+ int64_t guest_usec;
+
+ if (s->cmos_data[RTC_REG_B] & REG_B_SET) {
+ return 0;
+ }
+ guest_usec = get_guest_rtc_us(s);
+ /* UIP bit will be set at last 244us of every second. */
+ if ((guest_usec % USEC_PER_SEC) >= (USEC_PER_SEC - 244)) {
+ return 1;
+ }
+ return 0;
+}
+
static uint32_t cmos_ioport_read(void *opaque, uint32_t addr)
{
RTCState *s = opaque;
@@ -405,6 +420,9 @@ static uint32_t cmos_ioport_read(void *opaque, uint32_t addr)
break;
case RTC_REG_A:
ret = s->cmos_data[s->cmos_index];
+ if (update_in_progress(s)) {
+ ret |= REG_A_UIP;
+ }
break;
case RTC_REG_C:
ret = s->cmos_data[s->cmos_index];
--
1.7.1
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2012-05-09 7:22 [Qemu-devel] [PATCH v5 3/7] RTC: Add UIP(update in progress) check logic Zhang, Yang Z
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