aic79xx.c:

aic79xx.c:
aic79xx.seq:
	Convert the COMPLETE_DMA_SCB list to an "stailq".  This allows us to
	safely keep the SCB that is currently being DMA'ed back the host on
	the head of the list while processing completions off of the bus.  The
	newly completed SCBs are appended to the tail of the queue.   In the
	past, we just dequeued the SCB that was in flight from the list, but
	this could result in a lost completion should the host perform certain
	types of error recovery that must cancel all in-flight SCB DMA operations.

	Switch from using a 16bit completion entry, holding just the tag and the
	completion valid bit, to a 64bit completion entry that also contains a
	"status packet valid" indicator.  This solves two problems:
	  o The SCB DMA engine on at least Rev B. silicon does not properly deal
	    with a PCI disconnect that occurs at a non-64bit aligned offset in the
	    chips "source buffer".  When the transfer is resumed, the DMA engine
	    continues at the correct offset, but may wrap to the head of the buffer
	    causing duplicate completions to be reported to the host.  By using a
	    completion buffer in host memory that is 64bit aligned and using 64bit
	    completion entries, such disconnects should only occur at aligned addresses.
	    This assumes that the host bridge will only disconnect on cache-line
	    boundaries and that cache-lines are multpiles of 64bits.

	  o By embedding the status information in the completion entry we can avoid
	    an extra memory reference to the HSCB for commands that complete without
	    error.

	Use the comparison of a "host freeze count" and a "sequencer freeze count"
	to allow the host to process most SCBs that complete with non-zero status
	without having to clear critical sections.  Instead the host can just pause the
	sequencer, performs any necessary cleanup in the waiting for selection list,
	increments its freeze count on the controller, and unpauses.  This is only
	possible because the sequencer defers completions of SCBs with bad status
	until after all pending selections have completed.  The sequencer then avoids
	referencing any data structures the host may touch during completion of the
	SCB until the freeze counts match.

aic79xx.c:
	Change the strategy for allocating our sentinal HSCB for the QINFIFO.  In
	the past, this allocation was tacked onto the QOUTFIFO allocation.  Now that
	the qoutfifo has grown to accomodate larger completion entries, the old
	approach will result in a 64byte allocation that costs an extra page of
	coherent memory.  We now do this extra allocation via ahd_alloc_scbs()
	where the "unused space" can be used to allocate "normal" HSCBs.

	In our packetized busfree handler, use the ENSELO bit to differentiate
	between packetized and non-packetized unexpected busfree events that
	occur just after selection, but before the sequencer has had the oportunity
	to service the selection.

	When cleaning out the waiting for selection list, use the SCSI mode
	instead of the command channel mode.  The SCB pointer in the command
	channel mode may be referenced by the SCB dma engine even while the
	sequencer is paused, whereas the SCSI mode SCB pointer is only accessed
	by the sequencer.

	Print the "complete on qfreeze" sequencer SCB completion list in
	ahd_dump_card_state().  This list holds all SCB completions that are deferred
	until a pending select-out qfreeze event has taken effect.

aic79xx.h:
	Add definitions and structures to handle the new SCB completion scheme.

	Add a controller flag that indicates if the controller is in HostRAID
	mode.

aic79xx.reg:
	Remove macros used for toggling from one data fifo mode to the other.
	They have not been in use for some time.

	Add scratch ram fields for our new qfreeze count scheme, converting
	the complete dma list into an "stailq", and providing for the "complete
	on qfreeze" SCB completion list.  Some other fields were moved to retain
	proper field alignment (alignment >= field size in bytes).

aic79xx.seq:
	Add code to our idle loop to:
	  o Process deferred completions once a qfreeze event has taken full
	    effect.
	  o Thaw the queue once the sequencer and host qfreeze counts match.

	Generate 64bit completion entries passing the SCB_SGPTR field as the
	"good status" indicator.  The first bit in this field is only set if
	we have a valid status packet to send to the host.

	Convert the COMPLETE_DMA_SCB list to an "stailq".

	When using "setjmp" to register an idle loop handler, do not combine
	the "ret" with the block move to pop the stack address in the same
	instruction.  At least on the A, this results in a return to the setjmp
	caller, not to the new address at the top of the stack.  Since we want
	the latter (we want the newly registered handler to only be invoked from
	the idle loop), we must use a separate ret instruction.

	Add a few missing critical sections.

	Close a race condition that can occur on Rev A. silicon.  If both FIFOs
	happen to be allocated before the sequencer has a chance to service the
	FIFO that was allocated first, we must take special care to service the
	FIFO that is not active on the SCSI bus first.  This guarantees that a
	FIFO will be freed to handle any snapshot requests for the FIFO that is
	still on the bus.  Chosing the incorrect FIFO will result in deadlock.

	Update comments.

aic79xx_inline.h
	Correct the offset calculation for the syncing of our qoutfifo.

	Update ahd_check_cmdcmpltqueues() for the larger completion entries.

aic79xx_pci.c:
	Attach to HostRAID controllers by default.

Obtained-from: FreeBSD