131 lines
3.6 KiB
Groff
131 lines
3.6 KiB
Groff
.\"-
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.\" Copyright (c) 2004 Jason L. Wright (jason@thought.net)
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.\" Copyright (c) 2005 Marius Strobl <marius@FreeBSD.org>
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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.\" WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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.\" DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
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.\" INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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.\" (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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.\" SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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.\" STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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.\" ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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.\" POSSIBILITY OF SUCH DAMAGE.
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.\"
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.\" from: OpenBSD: clock.4,v 1.3 2004/09/24 07:04:15 miod Exp
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.\" $FreeBSD$
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.\"
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.Dd February 15, 2006
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.Dt EEPROM 4 sparc64
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.Os
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.Sh NAME
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.Nm eeprom
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.Nd "non-volatile RAM / real time clock"
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.Sh SYNOPSIS
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.Cd "device genclock"
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.Cd "device mk48txx"
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.Cd "device eeprom"
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.Sh DESCRIPTION
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The
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.Nm
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driver is a front-end for the machine-independent
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.Tn Mostek
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MK48Txx driver.
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The
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.Tn Mostek
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MK48Txx driver provides access to the real time clock and the watchdog part
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of the supported chips to
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.Fx
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by interfacing them with the generic clock code and
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.Xr watchdog 4
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respectively.
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.Pp
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.Tn Mostek
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MK48Txx chips providing real time clock functionality are found on the
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.Tn EBus ,
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.Tn FireHose
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and
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.Tn SBus
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busses of
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.Tn UltraSPARC
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systems.
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On systems where the hostid is stored in the NVRAM part of the
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.Tn Mostek
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MK48Txx chip the
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.Nm
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driver prints out the hostid on attach.
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.Pp
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On
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.Tn Sun Enterprise
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250 and 450 systems additionally the watchdog functionality of the
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.Tn Mostek
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MK48Txx chips is available.
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The
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.Nm
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driver automatically registers the watchdog part with
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.Xr watchdog 4
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on these systems.
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Thus it can be used with
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.Xr watchdog 8
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and
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.Xr watchdogd 8 .
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The timeout interval supported by the
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.Tn Mostek
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MK48Txx watchdog is 1/16 second to 128 seconds.
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In the
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.Tn Sun Enterprise
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machines a system reset is triggered when the
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.Tn Mostek
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MK48Txx watchdog times out regardless of what the
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.Tn Open Firmware
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environment variable
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.Va watchdog-reboot?
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is set to.
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.Sh DIAGNOSTICS
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The following driver specific error message may be reported:
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.Bl -diag
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.It "mk48txx_attach: battery low"
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The device signals that its battery is low and should be replaced.
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The
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.Nm
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driver refused to attach the device in this case as the time in the real time
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clock is probably invalid.
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This gives the generic clock code the chance to use another device as the
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system real time clock that otherwise would not have been chosen.
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.El
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.Sh SEE ALSO
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.Xr ebus 4 ,
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.Xr fhc 4 ,
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.Xr rtc 4 ,
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.Xr sbus 4 ,
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.Xr watchdog 4 ,
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.Xr watchdog 8 ,
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.Xr watchdogd 8
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.Sh HISTORY
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The
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.Nm
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driver first appeared in
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.Fx 5.0 .
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.Sh AUTHORS
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.An -nosplit
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The
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.Nm
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driver was written by
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.An Thomas Moestl Aq Mt tmm@FreeBSD.org
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based on the
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.Nx
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sparc64 clock code written by
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.An Paul Kranenburg .
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