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authorPaolo Bonzini <pbonzini@redhat.com>2012-10-01 14:22:07 +0200
committerAnthony Liguori <aliguori@us.ibm.com>2012-10-05 08:02:30 -0500
commite67edb943f0c812530aaae2491da56f9542f928b (patch)
tree882a919b6e3490b4050d6c914d2a4c22bf0ea1e8
parentb6db4aca20e9af4f62c9c9e08b9b9672a6ed3390 (diff)
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rtc: map CMOS index 0x37 to 0x32 on read and writes
QEMU's attempt to implement the century byte cover two possible places for the byte. A common one on modern chipsets is 0x32, but QEMU also stores the value in 0x37 (apparently for IBM PS/2 compatibility---it's only been 25 years). To simplify the implementation of the century byte, store it only at 0x32 but remap transparently 0x37 to 0x32 when reading and writing from CMOS. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
-rw-r--r--hw/mc146818rtc.c15
-rw-r--r--hw/mc146818rtc_regs.h4
2 files changed, 13 insertions, 6 deletions
diff --git a/hw/mc146818rtc.c b/hw/mc146818rtc.c
index d63554f..a7d20d5 100644
--- a/hw/mc146818rtc.c
+++ b/hw/mc146818rtc.c
@@ -399,6 +399,10 @@ static void cmos_ioport_write(void *opaque, uint32_t addr, uint32_t data)
s->cmos_data[s->cmos_index] = data;
check_update_timer(s);
break;
+ case RTC_IBM_PS2_CENTURY_BYTE:
+ s->cmos_index = RTC_CENTURY;
+ /* fall through */
+ case RTC_CENTURY:
case RTC_SECONDS:
case RTC_MINUTES:
case RTC_HOURS:
@@ -598,6 +602,10 @@ static uint32_t cmos_ioport_read(void *opaque, uint32_t addr)
return 0xff;
} else {
switch(s->cmos_index) {
+ case RTC_IBM_PS2_CENTURY_BYTE:
+ s->cmos_index = RTC_CENTURY;
+ /* fall through */
+ case RTC_CENTURY:
case RTC_SECONDS:
case RTC_MINUTES:
case RTC_HOURS:
@@ -661,10 +669,6 @@ void rtc_set_memory(ISADevice *dev, int addr, int val)
s->cmos_data[addr] = val;
}
-/* PC cmos mappings */
-#define REG_IBM_CENTURY_BYTE 0x32
-#define REG_IBM_PS2_CENTURY_BYTE 0x37
-
static void rtc_set_date_from_host(ISADevice *dev)
{
RTCState *s = DO_UPCAST(RTCState, dev, dev);
@@ -681,8 +685,7 @@ static void rtc_set_date_from_host(ISADevice *dev)
rtc_set_cmos(s, &tm);
val = rtc_to_bcd(s, (tm.tm_year / 100) + 19);
- rtc_set_memory(dev, REG_IBM_CENTURY_BYTE, val);
- rtc_set_memory(dev, REG_IBM_PS2_CENTURY_BYTE, val);
+ rtc_set_memory(dev, RTC_CENTURY, val);
}
static int rtc_post_load(void *opaque, int version_id)
diff --git a/hw/mc146818rtc_regs.h b/hw/mc146818rtc_regs.h
index fc10076..ccdee42 100644
--- a/hw/mc146818rtc_regs.h
+++ b/hw/mc146818rtc_regs.h
@@ -44,6 +44,10 @@
#define RTC_REG_C 12
#define RTC_REG_D 13
+/* PC cmos mappings */
+#define RTC_CENTURY 0x32
+#define RTC_IBM_PS2_CENTURY_BYTE 0x37
+
#define REG_A_UIP 0x80
#define REG_B_SET 0x80