1.\" $NetBSD: acpismbus.4,v 1.2 2010/02/06 21:57:08 wiz Exp $ 2.\" 3.\" Copyright (c) 2009 The NetBSD Foundation, Inc. 4.\" All rights reserved. 5.\" 6.\" This code is derived from software contributed to The NetBSD Foundation 7.\" by Paul Goyette 8.\" 9.\" Redistribution and use in source and binary forms, with or without 10.\" modification, are permitted provided that the following conditions 11.\" are met: 12.\" 1. Redistributions of source code must retain the above copyright 13.\" notice, this list of conditions and the following disclaimer. 14.\" 2. Redistributions in binary form must reproduce the above copyright 15.\" notice, this list of conditions and the following disclaimer in the 16.\" documentation and/or other materials provided with the distribution. 17.\" 18.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 19.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 20.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 21.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 22.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 23.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 24.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 25.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 26.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 27.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 28.\" POSSIBILITY OF SUCH DAMAGE. 29.\" 30.Dd February 6, 2010 31.Dt ACPISMBUS 4 32.Os 33.Sh NAME 34.Nm acpismbus 35.Nd ACPI SMBus Control Method Interface 36.Sh SYNOPSIS 37.Cd "acpismbus* at acpi?" 38.Cd "iic* at acpismbus?" 39.Sh DESCRIPTION 40The 41.Nm 42driver supports instances of the ACPI SMBus Control Method Interface. 43This enables i2c access to bus segments which might not otherwise be 44accessible due to missing "native" driver support. 45The SMBus Process Call protocol is not supported. 46All other SMBus protocols are supported to the extent that the underlying 47controller supports them. 48.Sh SEE ALSO 49.Xr acpi 4 , 50.Xr iic 4 51.Sh HISTORY 52The 53.Nm 54driver 55appeared in 56.Nx 6.0 . 57.Sh BUGS 58Although 59.Nm 60SMBus Alerts can be associated with individual devices, this 61capability is ignored. 62When an 63.Nm 64SMBus Alert is generated, all devices on the i2c bus segment which have 65registered an interrupt routine are notified. 66.Pp 67The SMBus CMI protocol defines a method to provide a list of devices on an 68i2c bus segment and their addresses. 69The 70.Nm 71driver makes no attempt to retrieve or process this device list. 72.Pp 73There is currently no way to determine if the i2c controller managed by 74an instance of the ACPI SMBus CMI can also be accessed using a native 75device driver. 76Therefore, the 77.Nm 78driver should not be enabled by default. 79If both a native driver and the 80.Nm 81driver attempt to access the same i2c bus segment, the results are 82undefined. 83