Copyright (c) 2004 Jason L. Wright (jason@thought.net)
Copyright (c) 2005 Marius Strobl <marius@FreeBSD.org>
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from: OpenBSD: clock.4,v 1.3 2004/09/24 07:04:15 miod Exp
$FreeBSD: releng/11.0/share/man/man4/man4.sparc64/eeprom.4 267938 2014-06-26 21:46:14Z bapt $
.Dd February 15, 2006 .Dt EEPROM 4 sparc64 .Os .Sh NAME .Nm eeprom .Nd "non-volatile RAM / real time clock" .Sh SYNOPSIS .Cd "device genclock" .Cd "device mk48txx" .Cd "device eeprom" .Sh DESCRIPTION The .Nm driver is a front-end for the machine-independent .Tn Mostek MK48Txx driver. The .Tn Mostek MK48Txx driver provides access to the real time clock and the watchdog part of the supported chips to .Fx by interfacing them with the generic clock code and .Xr watchdog 4 respectively.
p .Tn Mostek MK48Txx chips providing real time clock functionality are found on the .Tn EBus , .Tn FireHose and .Tn SBus busses of .Tn UltraSPARC systems. On systems where the hostid is stored in the NVRAM part of the .Tn Mostek MK48Txx chip the .Nm driver prints out the hostid on attach.
p On .Tn Sun Enterprise 250 and 450 systems additionally the watchdog functionality of the .Tn Mostek MK48Txx chips is available. The .Nm driver automatically registers the watchdog part with .Xr watchdog 4 on these systems. Thus it can be used with .Xr watchdog 8 and .Xr watchdogd 8 . The timeout interval supported by the .Tn Mostek MK48Txx watchdog is 1/16 second to 128 seconds. In the .Tn Sun Enterprise machines a system reset is triggered when the .Tn Mostek MK48Txx watchdog times out regardless of what the .Tn Open Firmware environment variable .Va watchdog-reboot? is set to. .Sh DIAGNOSTICS The following driver specific error message may be reported: l -diag t "mk48txx_attach: battery low" The device signals that its battery is low and should be replaced. The .Nm driver refused to attach the device in this case as the time in the real time clock is probably invalid. This gives the generic clock code the chance to use another device as the system real time clock that otherwise would not have been chosen. .El .Sh SEE ALSO .Xr ebus 4 , .Xr fhc 4 , .Xr rtc 4 , .Xr sbus 4 , .Xr watchdog 4 , .Xr watchdog 8 , .Xr watchdogd 8 .Sh HISTORY The .Nm driver first appeared in .Fx 5.0 . .Sh AUTHORS .An -nosplit The .Nm driver was written by .An Thomas Moestl Aq Mt tmm@FreeBSD.org based on the .Nx sparc64 clock code written by .An Paul Kranenburg .