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 oth‐
erwise 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 ALSOacpi(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
generated, 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