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 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.