From e67edb943f0c812530aaae2491da56f9542f928b Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Mon, 1 Oct 2012 14:22:07 +0200 Subject: [PATCH] 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 Signed-off-by: Anthony Liguori --- hw/mc146818rtc.c | 15 +++++++++------ hw/mc146818rtc_regs.h | 4 ++++ 2 files changed, 13 insertions(+), 6 deletions(-) diff --git a/hw/mc146818rtc.c b/hw/mc146818rtc.c index d63554f896..a7d20d5c25 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 fc10076ece..ccdee42b3c 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 -- GitLab