ACPISMBUS(4)						   BSD Kernel Interfaces Manual 					      ACPISMBUS(4)

NAME

     acpismbus -- ACPI SMBus Control Method Interface

SYNOPSIS

     acpismbus* at acpi?
     iic* at acpismbus?

DESCRIPTION

     The acpismbus driver supports instances of the ACPI SMBus Control Method Interface.  This enables i2c access to bus segments which might not
     otherwise be accessible due to missing "native" driver support.  The SMBus Process Call protocol is not supported.  All other SMBus protocols
     are supported to the extent that the underlying controller supports them.

SEE ALSO

     acpi(4), iic(4)

HISTORY

     The acpismbus driver appeared in NetBSD 6.0.

BUGS

     Although acpismbus SMBus Alerts can be associated with individual devices, this capability is ignored.  When an acpismbus SMBus Alert is gen-
     erated, all devices on the i2c bus segment which have registered an interrupt routine are notified.

     The SMBus CMI protocol defines a method to provide a list of devices on an i2c bus segment and their addresses.  The acpismbus driver makes
     no attempt to retrieve or process this device list.

     There is currently no way to determine if the i2c controller managed by an instance of the ACPI SMBus CMI can also be accessed using a native
     device driver.  Therefore, the acpismbus driver should not be enabled by default.	If both a native driver and the acpismbus driver attempt
     to access the same i2c bus segment, the results are undefined.

BSD
								 February 6, 2010							       BSD