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Kernel: Fix BIOS date/time on hardware

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It turns out some BIOS vendors don't support non-BCD date/time mode, but
we were relying on it being available. We no longer do this, but instead
check whether the BIOS claims to provide BCD or regular binary values for
its date/time data.
This commit is contained in:
Conrad Pankoff 2019-09-28 21:52:56 +10:00 • committed by Andreas Kling
parent b03a0534e0
commit 07ca753124
1 changed files with 27 additions and 10 deletions
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37
Kernel/RTC.cpp
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@ -8,11 +8,6 @@ static time_t s_boot_time;
void initialize()
{
u8 cmos_mode = CMOS::read(0x0b);
cmos_mode |= 2; // 24 hour mode
cmos_mode |= 4; // No BCD mode
CMOS::write(0x0b, cmos_mode);
s_boot_time = now();
}
@ -87,17 +82,39 @@ static unsigned days_in_years_since_epoch(unsigned year)
return days;
}
u8 bcd_to_binary(u8 bcd)
{
return (bcd & 0x0F) + ((bcd >> 4) * 10);
}
void read_registers(unsigned& year, unsigned& month, unsigned& day, unsigned& hour, unsigned& minute, unsigned& second)
{
while (update_in_progress())
;
year = (CMOS::read(0x32) * 100) + CMOS::read(0x09);
month = CMOS::read(0x08);
day = CMOS::read(0x07);
hour = CMOS::read(0x04);
minute = CMOS::read(0x02);
u8 status_b = CMOS::read(0x0b);
second = CMOS::read(0x00);
minute = CMOS::read(0x02);
hour = CMOS::read(0x04);
day = CMOS::read(0x07);
month = CMOS::read(0x08);
year = CMOS::read(0x09);
if (!(status_b & 0x04)) {
second = bcd_to_binary(second);
minute = bcd_to_binary(minute);
hour = bcd_to_binary(hour & 0x70);
day = bcd_to_binary(day);
month = bcd_to_binary(month);
year = bcd_to_binary(year);
}
if (!(status_b & 0x02) && (hour & 0x80)) {
hour = ((hour & 0x7F) + 12) % 24;
}
year += 2000;
}
time_t now()