Enable host-clock-based RTC

Switch RTC emulations to the new host_clock instead of vm_clock by
default. This has the advantage that the emulated RTC will follow
automatically the host time while it might be tuned via NTP. vm_clock
can still be selected by passing '-rtc clock=vm' on the command line.

Note that some RTC emulations (at least M48T59) already use the host
time unconditionally while others (namely MC146818) do not. This patch
introduces the required infrastructure for selecting the base clock but
only converts MC146818 for now.

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

1 files changed, 18 insertions, 20 deletions

diff --git a/hw/mc146818rtc.c b/hw/mc146818rtc.c
index 9d6a62751f..bec5687e42 100644
--- a/hw/mc146818rtc.c
+++ b/hw/mc146818rtc.c
@@ -108,8 +108,8 @@ static void rtc_coalesced_timer_update(RTCState *s)
     } else {
         /* divide each RTC interval to 2 - 8 smaller intervals */
         int c = MIN(s->irq_coalesced, 7) + 1; 
-        int64_t next_clock = qemu_get_clock(vm_clock) +
-		muldiv64(s->period / c, get_ticks_per_sec(), 32768);
+        int64_t next_clock = qemu_get_clock(rtc_clock) +
+            muldiv64(s->period / c, get_ticks_per_sec(), 32768);
         qemu_mod_timer(s->coalesced_timer, next_clock);
     }
 }
@@ -161,7 +161,8 @@ static void rtc_timer_update(RTCState *s, int64_t current_time)
         /* compute 32 khz clock */
         cur_clock = muldiv64(current_time, 32768, get_ticks_per_sec());
         next_irq_clock = (cur_clock & ~(period - 1)) + period;
-        s->next_periodic_time = muldiv64(next_irq_clock, get_ticks_per_sec(), 32768) + 1;
+        s->next_periodic_time =
+            muldiv64(next_irq_clock, get_ticks_per_sec(), 32768) + 1;
         qemu_mod_timer(s->periodic_timer, s->next_periodic_time);
     } else {
 #ifdef TARGET_I386
@@ -232,7 +233,7 @@ static void cmos_ioport_write(void *opaque, uint32_t addr, uint32_t data)
             /* UIP bit is read only */
             s->cmos_data[RTC_REG_A] = (data & ~REG_A_UIP) |
                 (s->cmos_data[RTC_REG_A] & REG_A_UIP);
-            rtc_timer_update(s, qemu_get_clock(vm_clock));
+            rtc_timer_update(s, qemu_get_clock(rtc_clock));
             break;
         case RTC_REG_B:
             if (data & REG_B_SET) {
@@ -246,7 +247,7 @@ static void cmos_ioport_write(void *opaque, uint32_t addr, uint32_t data)
                 }
             }
             s->cmos_data[RTC_REG_B] = data;
-            rtc_timer_update(s, qemu_get_clock(vm_clock));
+            rtc_timer_update(s, qemu_get_clock(rtc_clock));
             break;
         case RTC_REG_C:
         case RTC_REG_D:
@@ -605,18 +606,17 @@ static int rtc_initfn(ISADevice *dev)
 
     rtc_set_date_from_host(s);
 
-    s->periodic_timer = qemu_new_timer(vm_clock,
-                                       rtc_periodic_timer, s);
+    s->periodic_timer = qemu_new_timer(rtc_clock, rtc_periodic_timer, s);
 #ifdef TARGET_I386
     if (rtc_td_hack)
-        s->coalesced_timer = qemu_new_timer(vm_clock, rtc_coalesced_timer, s);
+        s->coalesced_timer =
+            qemu_new_timer(rtc_clock, rtc_coalesced_timer, s);
 #endif
-    s->second_timer = qemu_new_timer(vm_clock,
-                                     rtc_update_second, s);
-    s->second_timer2 = qemu_new_timer(vm_clock,
-                                      rtc_update_second2, s);
+    s->second_timer = qemu_new_timer(rtc_clock, rtc_update_second, s);
+    s->second_timer2 = qemu_new_timer(rtc_clock, rtc_update_second2, s);
 
-    s->next_second_time = qemu_get_clock(vm_clock) + (get_ticks_per_sec() * 99) / 100;
+    s->next_second_time =
+        qemu_get_clock(rtc_clock) + (get_ticks_per_sec() * 99) / 100;
     qemu_mod_timer(s->second_timer2, s->next_second_time);
 
     register_ioport_write(base, 2, 1, cmos_ioport_write, s);
@@ -747,14 +747,12 @@ RTCState *rtc_mm_init(target_phys_addr_t base, int it_shift, qemu_irq irq,
     s->base_year = base_year;
     rtc_set_date_from_host(s);
 
-    s->periodic_timer = qemu_new_timer(vm_clock,
-                                       rtc_periodic_timer, s);
-    s->second_timer = qemu_new_timer(vm_clock,
-                                     rtc_update_second, s);
-    s->second_timer2 = qemu_new_timer(vm_clock,
-                                      rtc_update_second2, s);
+    s->periodic_timer = qemu_new_timer(rtc_clock, rtc_periodic_timer, s);
+    s->second_timer = qemu_new_timer(rtc_clock, rtc_update_second, s);
+    s->second_timer2 = qemu_new_timer(rtc_clock, rtc_update_second2, s);
 
-    s->next_second_time = qemu_get_clock(vm_clock) + (get_ticks_per_sec() * 99) / 100;
+    s->next_second_time =
+        qemu_get_clock(rtc_clock) + (get_ticks_per_sec() * 99) / 100;
     qemu_mod_timer(s->second_timer2, s->next_second_time);
 
     io_memory = cpu_register_io_memory(rtc_mm_read, rtc_mm_write, s);