acpi: Add helper for deactivating memory region
Sometimes memory resource may be overlapping with SystemMemory Operation Region by design, for example if the memory region is used as a mailbox for communication with a firmware in the system. One occasion of such mailboxes is USB Type-C Connector System Software Interface (UCSI). With regions like that, it is important that the driver is able to map the memory with the requirements it has. For example, the driver should be allowed to map the memory as non-cached memory. However, if the operation region has been accessed before the driver has mapped the memory, the memory has been marked as write-back by the time the driver is loaded. That means the driver will fail to map the memory if it expects non-cached memory. To work around the problem, introducing helper that the drivers can use to temporarily deactivate (unmap) SystemMemory Operation Regions that overlap with their IO memory. Fixes: 8243edf4 ("usb: typec: ucsi: Add ACPI driver") Cc: stable@vger.kernel.org Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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