Commit [8b6d04] Maximize Restore History

resource: shared I/O region support

SuperIO devices share regions and use lock/unlock operations to chip
select. We therefore need to be able to request a resource and wait for
it to be freed by whichever other SuperIO device currently hogs it.
Right now you have to poll which is horrible.

Add a MUXED field to IO port resources. If the MUXED field is set on the
resource and on the request (via request_muxed_region) then we block
until the previous owner of the muxed resource releases their region.

This allows us to implement proper resource sharing and locking for
superio chips using code of the form

enable_my_superio_dev() {
request_muxed_region(0x44, 0x02, "superio:watchdog");
outb() ..sequence to enable chip
}

disable_my_superio_dev() {
outb() .. sequence of disable chip
release_region(0x44, 0x02);
}

Signed-off-by: Giel van Schijndel <me@mortis.eu>
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

Alan Cox Alan Cox 2010-03-29

Jesse Barnes Jesse Barnes 2010-05-11

changed include/linux/ioport.h
changed kernel/resource.c
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