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ACPISMBUS(4)               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
     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.

NetBSD 6.1.5                   February 6, 2010                   NetBSD 6.1.5