[PATCH RFC 4/4] rtc: Have event RTC_CHANGE identify the RTC by QOM path

[Markus Armbruster <armbru@redhat.com>]

Event RTC_CHANGE is "emitted when the guest changes the RTC time" (and
the RTC supports the event).  What if there's more than one RTC?
Which one changed?  New @qom-path identifies it.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
---
RFC because it's compile-tested only.  Worthwhile?  Let me know what you
think.

 qapi/misc.json       | 4 +++-
 hw/ppc/spapr_rtc.c   | 4 +++-
 hw/rtc/mc146818rtc.c | 3 ++-
 hw/rtc/pl031.c       | 3 ++-
 4 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/qapi/misc.json b/qapi/misc.json
index 0ab235e41f..b83cc39029 100644
--- a/qapi/misc.json
+++ b/qapi/misc.json
@@ -536,6 +536,8 @@
 # @offset: offset in seconds between base RTC clock (as specified
 #          by -rtc base), and new RTC clock value
 #
+# @qom-path: path to the RTC object in the QOM tree
+#
 # Note: This event is rate-limited.
 #       It is not guaranteed that the RTC in the system implements
 #       this event, or even that the system has an RTC at all.
@@ -550,4 +552,4 @@
 #
 ##
 { 'event': 'RTC_CHANGE',
-  'data': { 'offset': 'int' } }
+  'data': { 'offset': 'int', 'qom-path': 'str' } }
diff --git a/hw/ppc/spapr_rtc.c b/hw/ppc/spapr_rtc.c
index 79677cf550..d55b4b0c50 100644
--- a/hw/ppc/spapr_rtc.c
+++ b/hw/ppc/spapr_rtc.c
@@ -97,6 +97,7 @@ static void rtas_set_time_of_day(PowerPCCPU *cpu, SpaprMachineState *spapr,
                                  uint32_t nret, target_ulong rets)
 {
     SpaprRtcState *rtc = &spapr->rtc;
+    g_autofree const char *qom_path = NULL;
     struct tm tm;
     time_t new_s;
     int64_t host_ns;
@@ -120,7 +121,8 @@ static void rtas_set_time_of_day(PowerPCCPU *cpu, SpaprMachineState *spapr,
     }
 
     /* Generate a monitor event for the change */
-    qapi_event_send_rtc_change(qemu_timedate_diff(&tm));
+    qom_path = object_get_canonical_path(OBJECT(rtc));
+    qapi_event_send_rtc_change(qemu_timedate_diff(&tm), qom_path);
 
     host_ns = qemu_clock_get_ns(rtc_clock);
 
diff --git a/hw/rtc/mc146818rtc.c b/hw/rtc/mc146818rtc.c
index 57c514e15c..ac9a60c90e 100644
--- a/hw/rtc/mc146818rtc.c
+++ b/hw/rtc/mc146818rtc.c
@@ -611,12 +611,13 @@ static void rtc_get_time(RTCState *s, struct tm *tm)
 static void rtc_set_time(RTCState *s)
 {
     struct tm tm;
+    g_autofree const char *qom_path = object_get_canonical_path(OBJECT(s));
 
     rtc_get_time(s, &tm);
     s->base_rtc = mktimegm(&tm);
     s->last_update = qemu_clock_get_ns(rtc_clock);
 
-    qapi_event_send_rtc_change(qemu_timedate_diff(&tm));
+    qapi_event_send_rtc_change(qemu_timedate_diff(&tm), qom_path);
 }
 
 static void rtc_set_cmos(RTCState *s, const struct tm *tm)
diff --git a/hw/rtc/pl031.c b/hw/rtc/pl031.c
index 60167c778f..b01d0e75d1 100644
--- a/hw/rtc/pl031.c
+++ b/hw/rtc/pl031.c
@@ -138,12 +138,13 @@ static void pl031_write(void * opaque, hwaddr offset,
 
     switch (offset) {
     case RTC_LR: {
+        g_autofree const char *qom_path = object_get_canonical_path(opaque);
         struct tm tm;
 
         s->tick_offset += value - pl031_get_count(s);
 
         qemu_get_timedate(&tm, s->tick_offset);
-        qapi_event_send_rtc_change(qemu_timedate_diff(&tm));
+        qapi_event_send_rtc_change(qemu_timedate_diff(&tm), qom_path);
 
         pl031_set_alarm(s);
         break;
-- 
2.35.1