287 lines
7.6 KiB
Groff
287 lines
7.6 KiB
Groff
.\" Copyright (c) 2004 Joerg Wunsch
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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 AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR 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, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd May 16, 2004
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.Dt SMBMSG 8
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.Os
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.Sh NAME
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.Nm smbmsg
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.Nd "send or receive messages over an SMBus"
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.Sh SYNOPSIS
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.Nm
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.Op Fl f Ar dev
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.Fl p
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.Pp
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.Nm
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.Op Fl f Ar dev
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.Fl s Ar slave
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.Op Fl F Ar fmt
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.Op Fl c Ar cmd
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.Op Fl w
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.Op Fl i Ar incnt
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.Op Fl o Ar outcnt
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.Op Ar outdata ...
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.Sh DESCRIPTION
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The
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.Nm
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command can be used to send or receive messages over an
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SMBus, see
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.Xr smbus 4 .
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.Pp
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The
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.Nm
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command has two different modi of operation.
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The first form shown in the synopsis can be used to
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.Dq probe
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the devices on the SMBus.
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This is done by sending each valid device address one
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receive byte, and one quick read message, respectively.
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Devices that respond to these requests will by displayed
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by their device address, followed by the strings
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.Ql r ,
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.Ql w ,
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or
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.Ql rw ,
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for devices that are readable, writeable, or both, readable
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and writeable, respectively.
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The only valid additional option for this modus of operation (besides
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the
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.Fl p
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option that choses the modus) is
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.Fl f Ar dev .
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See below for a description.
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.Pp
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Note that probing the bus is risky, since individual devices could
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perform unwanted actions upon receiving one of the mentioned messages.
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For example, if a particular SMBus device considers
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.Em any
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write operation issued to it as a request to power off the system,
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the probing would trigger this action.
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.Pp
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The second form shown in the synopsis can be used to send or receive
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arbitrary messages to or from individual devices.
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This might be useful to explore individual devices on the SMBus, or
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maybe even to write short shell scripts performing maintenance
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operations on the bus.
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.Pp
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Any data values on the command-line are integer values in the
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range 0 through 255 for byte values, or 0 through 65535 for
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word values.
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They can be specified using standard
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.Ql C
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notation (prefix 0 for octal interpretation, or 0x for
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hexadecimal interpretation).
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.Pp
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Since the low-order bit of the device address of SMBus devices
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selects between read and write operations, only even-numbered
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slave addresses can exist on the bus.
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.Pp
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The options are as follows:
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.Bl -tag -width ".Fl o Ar outcnt"
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.It Fl F Ar fmt
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Specify the
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.Xr printf 3
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format to be used for displaying input data.
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This option is ignored in messages that do not read any input
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from the SMBus device.
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The format defaults to
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.Ql 0x%02x
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for byte input operations, and to
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.Ql 0x%04x
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for word input operations.
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For multi-byte input (block read), the same format is used for
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each individual byte read from the SMBus.
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.It Fl c Ar cmd
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This is the value of the
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.Em command
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byte to be issued as part of the SMBus message.
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.It Fl f Ar dev
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This specifies that
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.Ar dev
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should be used as the connection to the SMBus, rather than the
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default of
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.Pa /dev/smb0 .
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.It Fl i Ar incnt
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An SMBus message should be generated to read
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.Ar incnt
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bytes from the device.
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.It Fl o Ar outcnt
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An SMBus message should be generated to write
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.Ar outcnt
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bytes to the device.
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The data values to write are expected to follow all of the options
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(and their arguments) on the command-line, where the number of data
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bytes must match the
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.Ar outcnt
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value.
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.It Fl p
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This selects the
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.Em probe bus
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modus of operation.
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.It Fl s Ar slave
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The
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.Ar slave
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parameter specifies which SMBus device to connect to.
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This option also selects the
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.Em transfer messages from/to device
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modus of operation, where a slave address is mandatory.
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.It Fl w
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This option specifies that IO operations are word operations,
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rather than byte operations.
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Either
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.Ar incnt ,
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or
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.Ar outcnt
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(or both) must be equal 2 in this case.
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Note that the SMBus byte order is defined to be little-endian
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(low byte first, high byte follows).
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.El
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.Pp
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Not all argument combinations make sense in order to form valid SMBus
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messages.
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If no
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.Fl c Ar cmd
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option has been provided, the following messages can be
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issued:
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.Pp
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.Bd -unfilled -offset indent
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.TS
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l r r.
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\fBmessage incnt outcnt\fR
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quick read 0 \&-
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quick write \&- 0
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receive byte 1 \&-
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send byte \&- 1
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.TE
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.Ed
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.Pp
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Note in particular that specifying 0 as a count value
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has a different meaning than omitting the respective
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option entirely.
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.Pp
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If a command value has been given using the
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.Fl c Ar cmd
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option, the following messages can be generated:
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.Pp
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.Bd -unfilled -offset indent
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.TS
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l l r r.
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\fBmessage \&-w incnt outcnt\fR
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read byte no 1 \&-
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write byte no \&- 1
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read word yes 2 \&-
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write word yes \&- 2
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process call yes 2 2
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block read no \*(Ge 2 \&-
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block write no \&- \*(Ge 2
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.TE
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.Ed
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.Sh FILES
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.Bl -tag -width ".Pa /dev/smb0" -compact
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.It Pa /dev/smb0
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The default device to connect to, unless
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.Fl f Ar dev
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has been provided.
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.El
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.Sh EXAMPLES
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Typical usage examples of the
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.Nm
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command include:
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.Pp
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.Dl "smbmsg -f /dev/smb1 -p"
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.Pp
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Probe all devices on the SMBus attached to
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.Pa /dev/smb1 .
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.Pp
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.Dl "smbmsg -s 0x70 -i 1"
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.Pp
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Issue a
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.Em receive byte
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message to the device at address 0x70, and display
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the received byte using the default format.
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.Pp
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.Dl "smbmsg -s 0x70 -c 0xff -i 1 -F %d"
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.Pp
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Issue a
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.Em read byte
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message to the device at slave address 0x70, using
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255 (0xff) as the command-byte to send to the device,
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and display the result using the custom format %d.
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.Pp
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.Dl "smbmsg -s 0xa0 -c 0 -o 1 0x80"
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.Pp
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Send a
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.Em write byte
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message to the slave device at address 0xa0, using
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0 as the command-byte value, and 0x80 as the byte to
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send (after the command).
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Assuming this might be a Philips PCF8583 real-time clock,
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this would stop the clock.
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.Pp
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.Dl "smbmsg -s 0xa0 -c 1 -i 6 -F %02x"
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.Pp
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Send a
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.Em block read
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command to device at address 0xa0, and read 6 bytes from
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it, using hexadecimal display.
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Again, assuming a PCF8583 RTC, this would display the
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fractions of second, seconds, minutes, hours, year/date,
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and weekday/month values.
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Since this RTC uses BCD notation, the actual values displayed
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were decimal then.
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.Pp
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.Dl "smbmsg -s 0xa0 -c 2 -o 5 0x00 0x07 0x22 0x16 0x05"
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.Pp
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Send a
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.Em block write
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command to device at address 0xa0.
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For the PCF8583 RTC, this would set the clock to Sunday (2004%4)-05-16
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22:07:00.
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.Sh DIAGNOSTICS
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Exit status is 0 on success, or according to
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.Xr sysexits 3
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in case of failure.
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Diagnostic messages issued are supposed to be self-explanatory.
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.Sh SEE ALSO
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.Xr printf 3 ,
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.Xr sysexits 3 ,
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.Xr smb 4 ,
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.Xr smbus 4
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.Rs
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.%T "The SMBus specification"
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.%O http://www.smbus.org/specs/
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.Re
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.Sh HISTORY
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The
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.Nm
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command first appeared in
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.Fx 5.3 .
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.Sh AUTHORS
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The
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.Nm
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utility and this manual page were written by
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.An J\(:org Wunsch .
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