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atrtc: expose power loss as sysctl

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Exposing the a power loss of the rtc as an sysctl makes it easier to
detect an empty cmos battery.

Reviewed by:		manu
MFC after:		1 week
Sponsored by:		Beckhoff Automation GmbH & Co. KG
Differential Revision:	https://reviews.freebsd.org/D38325
This commit is contained in:
Corvin Köhne 2022-12-08 08:28:42 +01:00
parent 99187c3a44
commit 55f1ca209d
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GPG Key ID: D854DA56315E026A
1 changed files with 6 additions and 0 deletions
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6
sys/x86/isa/atrtc.c
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@ -62,6 +62,11 @@ __FBSDID("$FreeBSD$");
#include <machine/md_var.h>
#endif
/* tunable to detect a power loss of the rtc */
static bool atrtc_power_lost = false;
SYSCTL_BOOL(_machdep, OID_AUTO, atrtc_power_lost, CTLFLAG_RD, &atrtc_power_lost,
false, "RTC lost power on last power cycle (probably caused by an emtpy cmos battery)");
/*
* atrtc_lock protects low-level access to individual hardware registers.
* atrtc_time_lock protects the entire sequence of accessing multiple registers
@ -600,6 +605,7 @@ atrtc_gettime(device_t dev, struct timespec *ts)
/* Look if we have a RTC present and the time is valid */
if (!(rtcin(RTC_STATUSD) & RTCSD_PWR)) {
atrtc_power_lost = true;
device_printf(dev, "WARNING: Battery failure indication\n");
return (EINVAL);
}