226 lines
6.1 KiB
Groff
226 lines
6.1 KiB
Groff
.\" $NetBSD: mk48txx.4,v 1.16 2009/04/10 17:14:07 joerg Exp $
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.\"
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.\" Copyright (c) 2000, 2002 The NetBSD Foundation, Inc.
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.\" All rights reserved.
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.\"
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.\" This code is derived from software contributed to The NetBSD Foundation
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.\" by Paul Kranenburg.
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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 NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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.\" ARISING IN 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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.\" $FreeBSD$
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.\"
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.Dd December 25, 2009
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.Dt MK48TXX 4
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.Os
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.Sh NAME
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.Nm mk48txx
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.Nd
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.Tn Mostek
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time-of-day clock driver
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.Sh SYNOPSIS
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.In sys/eventhandler.h
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.In sys/lock.h
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.In sys/mutex.h
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.In dev/mk48txx/mk48txxvar.h
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.Pp
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To compile this driver into the kernel,
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place the following line in your
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kernel configuration file:
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.Bd -ragged -offset indent
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.Cd "device mk48txx"
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.Ed
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.Sh DESCRIPTION
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The
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.Nm
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driver is a back-end for several models of
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.Tn Mostek
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time-of-day clock chips.
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It provides access methods to retrieve and set date and time for use with the
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.Dq Li clock
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KOBJ interface.
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.Pp
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To tie an instance of this device to the system, use the
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.Fn mk48txx_attach
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function and the mk48txx_softc structure defined as follows:
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.Pp
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.Ft "int"
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.Fn mk48txx_attach "device_t dev"
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.Bd -literal
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typedef uint8_t (*mk48txx_nvrd_t)(device_t dev, int off);
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typedef void (*mk48txx_nvwr_t)(device_t dev, int off, uint8_t v);
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.Ed
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.Bd -literal
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struct mk48txx_softc {
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struct resource sc_res;
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struct mtx sc_mtx;
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eventhandler_tag sc_wet;
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const char *sc_model;
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bus_size_t sc_nvramsz;
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bus_size_t sc_clkoffset;
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u_int sc_year0;
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u_int sc_flag;
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mk48txx_nvrd_t sc_nvrd;
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mk48txx_nvwr_t sc_nvwr;
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};
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.Ed
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.Bl -tag -width indent
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.It Fa sc_res
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The bus resource used for accessing the chip's non-volatile memory
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.Pq including the clock registers ,
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which must be supplied by the front-end when using the default access methods
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.Pq see below .
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Otherwise this member is optional.
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.It Fa sc_mtx
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The hardware mutex used when accessing the chip's non-volatile memory
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.Pq including the clock registers ,
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which must be initialized with
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.Dv MTX_DEF
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by the front-end.
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.It Fa sc_wet
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The event handler tag for the watchdog functionality,
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which is registered by the
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.Fn mk48txx_attach
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function if supported by the chip and specified as part of the
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machine-dependent features
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.Pq see below .
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.It Fa sc_model
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The chip model which this instance should serve.
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This member must be set to one of
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.Dq mk48t02 ,
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.Dq mk48t08 ,
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.Dq mk48t18 ,
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or
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.Dq mk48t59
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by the front-end.
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.It Fa sc_nvramsz
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The size of the non-volatile RAM in the
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.Tn Mostek
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chip,
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which is set by the
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.Fn mk48txx_attach
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function.
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.It Fa sc_clkoffset
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The offset into the control registers of the
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.Tn Mostek
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chip,
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which is set by the
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.Fn mk48txx_attach
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function.
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.It Fa sc_year0
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The year offset to be used with the
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.Sq year
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counter of the clock,
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which must be set by the front-end.
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This value is generally dependent on the system configuration in which
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the clock device is mounted.
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For instance, on
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.Tn Sun Microsystems
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machines the convention is to have clock's two-digit year represent
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the year since 1968.
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.It Fa sc_flag
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This flag is used to specify machine-dependent features.
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The following flags are supported:
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.Bl -tag -width ".Dv MK48TXX_WDOG_ENABLE_WDS"
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.It Dv MK48TXX_NO_CENT_ADJUST
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If the resulting date retrieved with the
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.Dq Li clock_gettime() method
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would be earlier than January 1, 1970,
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the driver will assume that the chip's year counter actually represents a
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year in the 21st century.
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This behavior can be overridden by setting this flag,
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which causes the
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.Nm
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driver to respect the clock's century bit instead.
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.It Dv MK48TXX_WDOG_REGISTER
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When this flag is set,
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the
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.Nm
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driver will register as a watchdog via the interface defined in
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.Xr watchdog 9
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if supported by the specific chip model.
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.It Dv MK48TXX_WDOG_ENABLE_WDS
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When this flag is set,
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the
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.Nm
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driver will set the watchdog steering
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.Pq WDS
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bit when enabling the watchdog functionality of the chip.
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enabled
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.Pq see the chip documentation for further information regarding the WDS bit .
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.El
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.It Fa sc_nvread
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.It Fa sc_nvwrite
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These members specify the access methods for reading respectively writing
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clock device registers.
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The default,
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when
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.Dv NULL
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is passed as an access method,
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is to access the chip memory
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.Pq and clock registers
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as if they were direct-mapped using the specified bus resource.
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.Pp
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Otherwise, the driver will call the respective function supplied by the
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front-end to perform the access,
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passing it the offset
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.Va off
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of the chip memory
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.Pq or clock register
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location to be read from or written to, respectively.
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.El
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.Sh HARDWARE
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The following models are supported:
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.Pp
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.Bl -tag -width indent -offset indent -compact
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.It Tn Mostek MK48T02
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.It Tn Mostek MK48T08
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.It Tn Mostek MK48T18
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.It Tn Mostek MK48T59
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.El
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.Sh SEE ALSO
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.Xr intro 4 ,
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.Xr watchdog 9
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.Sh HISTORY
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The
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.Nm mk48txx
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driver appeared in
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.Nx 1.5 .
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The first
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.Fx
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version to include it was
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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 for
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.Nx
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by
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.An Paul Kranenburg Aq Mt pk@NetBSD.org .
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It was ported to
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.Fx
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by
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.An Thomas Moestl Aq Mt tmm@FreeBSD.org
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and later on improved by
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.An Marius Strobl Aq Mt marius@FreeBSD.org .
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