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atrtc: reads Century field from FADT table

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The ACPI spec describes the FADT->Century field as:

    The RTC CMOS RAM index to the century of data value (hundred and
    thousand year decimals).  If this field contains a zero, then the
    RTC centenary feature is not supported.  If this field has a non-zero
    value, then this field contains an index into RTC RAM space that
    OSPM can use to program the centenary field.

Use this field to decide whether to program the CENTURY register
of the CMOS RTC device.

Reviewed by:	akumar3@isilon.com, dab, vangyzen
MFC after:	1 week
Sponsored by:	Dell EMC Isilon
Differential Revision:	https://reviews.freebsd.org/D33667

MFC after:	1 week
Sponsored by:	Dell EMC Isilon

(cherry picked from commit e1ef6c0ef2)
This commit is contained in:
Austin Zhang 2022-01-13 11:13:25 -06:00 committed by Eric van Gyzen
parent 487cee4ddc
commit b8319d9f78
1 changed files with 31 additions and 6 deletions
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37
sys/x86/isa/atrtc.c
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@ -79,6 +79,7 @@ MTX_SYSINIT(atrtc_time_lock_init, &atrtc_time_lock, "atrtc_time", MTX_DEF);
int atrtcclock_disable = 0;
static int rtc_century = 0;
static int rtc_reg = -1;
static u_char rtc_statusa = RTCSA_DIVIDER | RTCSA_NOPROF;
static u_char rtc_statusb = RTCSB_24HR;
@ -420,6 +421,31 @@ atrtc_acpi_disabled(void)
#endif
}
static int
rtc_acpi_century_get(void)
{
#ifdef DEV_ACPI
ACPI_TABLE_FADT *fadt;
vm_paddr_t physaddr;
int century;
physaddr = acpi_find_table(ACPI_SIG_FADT);
if (physaddr == 0)
return (0);
fadt = acpi_map_table(physaddr, ACPI_SIG_FADT);
if (fadt == NULL)
return (0);
century = fadt->Century;
acpi_unmap_table(fadt);
return (century);
#else
return (0);
#endif
}
static int
atrtc_probe(device_t dev)
{
@ -435,6 +461,7 @@ atrtc_probe(device_t dev)
device_set_desc(dev, "AT realtime clock");
return (BUS_PROBE_LOW_PRIORITY);
}
rtc_century = rtc_acpi_century_get();
return (result);
}
@ -548,9 +575,8 @@ atrtc_settime(device_t dev __unused, struct timespec *ts)
rtcout_locked(RTC_DAY, bct.day);
rtcout_locked(RTC_MONTH, bct.mon);
rtcout_locked(RTC_YEAR, bct.year & 0xff);
#ifdef USE_RTC_CENTURY
rtcout_locked(RTC_CENTURY, bct.year >> 8);
#endif
if (rtc_century)
rtcout_locked(rtc_century, bct.year >> 8);
/*
* Re-enable RTC updates and interrupts.
@ -592,9 +618,8 @@ atrtc_gettime(device_t dev, struct timespec *ts)
bct.day = rtcin_locked(RTC_DAY);
bct.mon = rtcin_locked(RTC_MONTH);
bct.year = rtcin_locked(RTC_YEAR);
#ifdef USE_RTC_CENTURY
bct.year |= rtcin_locked(RTC_CENTURY) << 8;
#endif
if (rtc_century)
bct.year |= rtcin_locked(rtc_century) << 8;
mtx_unlock_spin(&atrtc_lock);
mtx_unlock(&atrtc_time_lock);
/* dow is unused in timespec conversion and we have no nsec info. */