1.\" Copyright (c) 1998, Nicolas Souchu 2.\" All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 13.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 14.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 15.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 16.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 17.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 18.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 19.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 20.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 21.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 22.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 23.\" SUCH DAMAGE. 24.\" 25.\" 26.Dd August 10, 1998 27.Dt SMBBUS 4 28.Os FreeBSD 29.Sh NAME 30.Nm smbus 31.Nd 32System Management Bus 33.Sh SYNOPSIS 34.Cd "controller smbus" 35.Pp 36.Cd "device iicsmb0 at iicbus?" 37.Cd "device bktr0" 38.Sh DESCRIPTION 39The 40.Em smbus 41system provides a uniform, modular and architecture-independent 42system for the implementation of drivers to control various SMB devices 43and to utilize different SMB controllers (I2C, PIIX4, Brooktree848, vm86...). 44.Sh System Management Bus 45The 46.Em System Management Bus 47is a two-wire interface through which simple power-related chips can communicate 48with rest of the system. It uses I2C as its backbone (see 49.Xr iicbus 4 ). 50 51A system using SMB passes messages to and from devices instead of tripping 52individual control lines. 53 54With the SMBus, a device can provide manufacturer information, tell the 55system what its model/part number is, save its state for a suspend event, 56report different types of errors, accept control parameters, and return its 57status. 58 59The SMBus may share the same host device and physical bus as ACCESS bus 60components provided that an appropriate electrical bridge is provided 61between the internal SMB devices and external ACCESS bus devices. 62.Sh SEE ALSO 63.Xr iicbus 4 , 64.Xr iicsmb 4 , 65.Xr bktr 4 , 66.Xr smb 4 67.Sh HISTORY 68The 69.Nm 70manual page first appeared in 71.Fx 3.0 . 72.Sh AUTHOR 73This 74manual page was written by 75.An Nicolas Souchu . 76