The list structures and related logic used in the NCR5380 driver mean that
a command cannot be queued twice (i.e. can't appear on more than one queue
and can't appear on the same queue more than once).

The abort handler must forget the command so that the mid-layer can re-use
it. E.g. the ML may send it back to the LLD via via scsi_eh_get_sense().

Fix this and also fix two error paths, so that commands get forgotten iff
completed.

Fixes: 8b00c3d5 ("ncr5380: Implement new eh_abort_handler")
Tested-by: NMichael Schmitz <schmitzmic@gmail.com>
Cc: <stable@vger.kernel.org> # 4.5
Signed-off-by: NFinn Thain <fthain@telegraphics.com.au>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Calling NCR5380_select() from the abort handler causes various problems.
Firstly, it means potentially re-entering NCR5380_select(). Secondly, it
means that the lock is released, which permits the EH handlers to be
re-entered. The combination results in crashes. Don't do it.

Fixes: 8b00c3d5 ("ncr5380: Implement new eh_abort_handler")
Reported-and-tested-by: NMichael Schmitz <schmitzmic@gmail.com>
Cc: <stable@vger.kernel.org> # 4.5
Signed-off-by: NFinn Thain <fthain@telegraphics.com.au>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

The calls to NCR5380_transfer_pio() for DATA IN and DATA OUT phases will
modify cmd->SCp.this_residual, cmd->SCp.ptr and cmd->SCp.buffer. That
works as long as EH does not intervene, which became possible in
atari_NCR5380.c when I changed the locking to bring it closer to
NCR5380.c.

If error recovery aborts the command, the scsi_cmnd in question and its
buffer will be returned to the mid-layer. So the transfer has to cease,
but it can't be stopped by the initiator because the target controls the
bus phase.

The problem does not arise if the lock is not released. That was fine for
atari_scsi, because it implements DMA. For the other drivers, we have to
release the lock and re-enable interrupts for long PIO data transfers.

The solution is to split the transfer into small chunks. In between chunks
the main loop releases the lock and re-enables interrupts. Thus interrupts
can be serviced and eh_bus_reset_handler can intervene if need be.

This fixes an oops in NCR5380_transfer_pio() that can happen when the EH
abort handler is invoked during DATA IN or DATA OUT phase.

Fixes: 11d2f63b ("ncr5380: Change instance->host_lock to hostdata->lock")
Reported-and-tested-by: NMichael Schmitz <schmitzmic@gmail.com>
Cc: <stable@vger.kernel.org> # 4.5
Signed-off-by: NFinn Thain <fthain@telegraphics.com.au>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Commands subject to exception handling are to be returned to the scsi
mid-layer. Make sure that the various command pointers and command lists
in the low-level driver are correctly cleansed of affected commands.

This fixes some bugs that I accidentally introduced in v4.5-rc1 including
the removal of INIT_LIST_HEAD for the 'autosense' and 'disconnected'
command lists, and the possible NULL pointer dereference in
NCR5380_bus_reset() that was reported by Dan Carpenter.

hostdata->sensing may also point to an affected command so this pointer
also has to be cleared. The abort handler calls complete_cmd() to take
care of this; let's have the bus reset handler do the same.

The issue queue may also contain an affected command. If so, remove it.
This also follows the abort handler logic.
Reported-by: NDan Carpenter <dan.carpenter@oracle.com>
Fixes: 62717f53 ("ncr5380: Implement new eh_bus_reset_handler")
Tested-by: NMichael Schmitz <schmitzmic@gmail.com>
Cc: <stable@vger.kernel.org> # 4.5
Signed-off-by: NFinn Thain <fthain@telegraphics.com.au>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Signed-off-by: NFinn Thain <fthain@telegraphics.com.au>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Tested-by: NOndrej Zary <linux@rainbow-software.org>
Tested-by: NMichael Schmitz <schmitzmic@gmail.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

In the past, NCR5380.c was overlooked by those working on atari_NCR5380.c
and this caused needless divergence. All of the changes in this patch were
taken from atari_NCR5380.c.

This removes some unimportant discrepancies between the two core driver
forks so that 'diff' can be used to reveal the important ones, to
facilitate reunification.
Signed-off-by: NFinn Thain <fthain@telegraphics.com.au>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Tested-by: NOndrej Zary <linux@rainbow-software.org>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Hanging indentation was a poor choice for the text inside comments. It
has been used in the wrong places and done badly elsewhere. There is
little consistency within any file. One fork of the core driver uses
tabs for this indentation while the other uses spaces. Better to use
flush-left alignment throughout.

This patch is the result of the following substitution. It replaces tabs
and spaces at the start of a comment line with a single space.

perl -i -pe 's,^(\t*[/ ]\*)[ \t]+,$1 ,' drivers/scsi/{atari_,}NCR5380.c

This removes some unimportant discrepancies between the two core driver
forks so that the important ones become obvious, to facilitate
reunification.
Signed-off-by: NFinn Thain <fthain@telegraphics.com.au>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Tested-by: NOndrej Zary <linux@rainbow-software.org>
Tested-by: NMichael Schmitz <schmitzmic@gmail.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

This patch is the result of the following substitution. It removes any
tabs and spaces at the end of a line.

perl -i -pe 's,[\t ]+$,,' drivers/scsi/{atari_,}NCR5380.c

This removes some unimportant discrepancies between the two core driver
forks so that the important ones become obvious, to facilitate
reunification.
Signed-off-by: NFinn Thain <fthain@telegraphics.com.au>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Tested-by: NOndrej Zary <linux@rainbow-software.org>
Tested-by: NMichael Schmitz <schmitzmic@gmail.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

The CVS revision log is not nearly as useful as the history/history.git
repo, so remove it. Roman's commentary at the top of his driver repeats
the same information elsewhere in the file so remove it. Also remove
some other redundant or obsolete comments.

Both the driver and the datasheets confusingly refer to a DMA access
for a SCSI WRITE command as a "DMA write". Similarly a SCSI READ command
is called a "DMA read". This is the opposite of the usual convention.
Thankfully, the chip documentation and driver code also use "DMA send" and
"DMA receive", so adopt this terminology.

This removes some unimportant discrepancies between the two core driver
forks so that 'diff' can be used to reveal the important ones, to
facilitate reunification.
Signed-off-by: NFinn Thain <fthain@telegraphics.com.au>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Tested-by: NOndrej Zary <linux@rainbow-software.org>
Tested-by: NMichael Schmitz <schmitzmic@gmail.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Because of the rudimentary design of the chip, it is necessary to poll the
SCSI bus signals during PIO and this tends to hog the CPU. The driver will
accept new commands while others execute, and this causes a soft lockup
because the workqueue item will not terminate until the issue queue is
emptied.

When exercising dmx3191d using sequential IO from dd, the driver is sent
512 KiB WRITE commands and 128 KiB READs. For a PIO transfer, the rate is
is only about 300 KiB/s, so these are long-running commands. And although
PDMA may run at several MiB/s, interrupts are disabled for the duration
of the transfer.

Fix the unresponsiveness and soft lockup issues by calling cond_resched()
after each command is completed and by limiting max_sectors for drivers
that don't implement real DMA.
Signed-off-by: NFinn Thain <fthain@telegraphics.com.au>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Tested-by: NOndrej Zary <linux@rainbow-software.org>
Tested-by: NMichael Schmitz <schmitzmic@gmail.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Keep the two core driver forks in sync.
Signed-off-by: NFinn Thain <fthain@telegraphics.com.au>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Tested-by: NOndrej Zary <linux@rainbow-software.org>
Tested-by: NMichael Schmitz <schmitzmic@gmail.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Remove the HOSTNO macro that is peculiar to atari_NCR5380.c and
contributes to the problem of divergence of the NCR5380 core drivers.
Keep NCR5380.c in sync.
Signed-off-by: NFinn Thain <fthain@telegraphics.com.au>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Tested-by: NOndrej Zary <linux@rainbow-software.org>
Tested-by: NMichael Schmitz <schmitzmic@gmail.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

NCR5380.c lacks a sane eh_bus_reset_handler. The atari_NCR5380.c code is
much better but it should not throw out the issue queue (that would be
a host reset) and it neglects to set the result code for commands that it
throws out. Fix these bugs and keep the two core drivers in sync.
Signed-off-by: NFinn Thain <fthain@telegraphics.com.au>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Tested-by: NOndrej Zary <linux@rainbow-software.org>
Tested-by: NMichael Schmitz <schmitzmic@gmail.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

During arbitration and selection, the relevant command is invisible to
exception handlers and can be found only in a pointer on the stack of a
different thread.

When eh_abort_handler can't find a given command, it can't decide whether
that command was completed already or is still in arbitration or selection
phase. But it must return either SUCCESS (e.g. command completed earlier)
or FAILED (could not abort the nexus, try bus reset).

The solution is to make sure all commands belonging to the LLD are always
visible to exception handlers. Add another scsi_cmnd pointer to the
hostdata struct to track the command in arbitration or selection phase.

Replace 'retain_dma_irq' with the new 'selecting' pointer, to bring
atari_NCR5380.c into line with NCR5380.c.
Signed-off-by: NFinn Thain <fthain@telegraphics.com.au>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Tested-by: NOndrej Zary <linux@rainbow-software.org>
Tested-by: NMichael Schmitz <schmitzmic@gmail.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Introduce a new eh_abort_handler implementation. This one attempts to
follow all of the rules relating to EH handlers. There is still a known
bug: during selection, a command becomes invisible to the EH handlers
because it only appears in a pointer on the stack of a different thread.
This bug is addressed in a subsequent patch.
Signed-off-by: NFinn Thain <fthain@telegraphics.com.au>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Tested-by: NOndrej Zary <linux@rainbow-software.org>
Tested-by: NMichael Schmitz <schmitzmic@gmail.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

NCR5380_information_transfer() may re-queue a command for autosense,
after calling scsi_eh_prep_cmnd(). This creates several possibilities:

1. Reselection may intervene before the re-queued command gets processed.
   If the reconnected command then undergoes autosense, this causes the
   scsi_eh_save data from the previous command to be overwritten.

2. After NCR5380_information_transfer() calls scsi_eh_prep_cmnd(),
   a new REQUEST SENSE command may arrive. This would be queued ahead
   of any command already undergoing autosense, which means the
   scsi_eh_save data might be restored to the wrong command.

3. After NCR5380_information_transfer() calls scsi_eh_prep_cmnd(),
   eh_abort_handler() may abort the command. But the scsi_eh_save data is
   not discarded, which means the scsi_eh_save data might be incorrectly
   restored to the next REQUEST SENSE command issued.

This patch adds a new autosense list so that commands that are re-queued
because of a CHECK CONDITION result can be kept apart from the REQUEST
SENSE commands that arrive via queuecommand.

This patch also adds a function dedicated to dequeueing and preparing the
next command for processing. By refactoring the main loop in this way,
scsi_eh_save takes place when an autosense command is dequeued rather
than when re-queued.
Signed-off-by: NFinn Thain <fthain@telegraphics.com.au>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Tested-by: NOndrej Zary <linux@rainbow-software.org>
Tested-by: NMichael Schmitz <schmitzmic@gmail.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Implement a 'complete_cmd' function to complete commands. This is needed
by the following patch; the new function provides a site for the logic
needed to correctly handle REQUEST SENSE commands.
Signed-off-by: NFinn Thain <fthain@telegraphics.com.au>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Tested-by: NOndrej Zary <linux@rainbow-software.org>
Tested-by: NMichael Schmitz <schmitzmic@gmail.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

The NCR5380 drivers have a home-spun linked list implementation for
scsi_cmnd structs that uses cmd->host_scribble as a 'next' pointer. Adopt
the standard list_head data structure and list operations instead. Remove
the eh_abort_handler rather than convert it. Doing the conversion would
only be churn because the existing EH handlers don't work and get replaced
in a subsequent patch.
Signed-off-by: NFinn Thain <fthain@telegraphics.com.au>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Tested-by: NOndrej Zary <linux@rainbow-software.org>
Tested-by: NMichael Schmitz <schmitzmic@gmail.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Printing command pointers can be useful when debugging queues. Other than
that, the LIST and REMOVE macros are just clutter. These macros are
redundant now that NDEBUG_QUEUES causes pointers to be printed, so remove
them.
Signed-off-by: NFinn Thain <fthain@telegraphics.com.au>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Tested-by: NOndrej Zary <linux@rainbow-software.org>
Tested-by: NMichael Schmitz <schmitzmic@gmail.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Print the command pointers in the log messages for debugging queue data
structures. The LIST and REMOVE macros can then be removed.
Signed-off-by: NFinn Thain <fthain@telegraphics.com.au>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Tested-by: NOndrej Zary <linux@rainbow-software.org>
Tested-by: NMichael Schmitz <schmitzmic@gmail.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Make use of the shost_priv() helper. Remove HOSTDATA and SETUP_HOSTDATA
macros because they harm readability.
Signed-off-by: NFinn Thain <fthain@telegraphics.com.au>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Tested-by: NOndrej Zary <linux@rainbow-software.org>
Tested-by: NMichael Schmitz <schmitzmic@gmail.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Replace all H_NO and some HOSTNO macros (both peculiar to atari_NCR5380.c)
with a new dsprintk macro that's more useful and more consistent. The new
macro avoids a lot of boilerplate in new code in subsequent patches. Keep
NCR5380.c in sync. Remaining HOSTNO macros are removed as side-effects
of subsequent patches.
Signed-off-by: NFinn Thain <fthain@telegraphics.com.au>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Tested-by: NOndrej Zary <linux@rainbow-software.org>
Tested-by: NMichael Schmitz <schmitzmic@gmail.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Some NCR5380 hosts offer a .show_info method to access the contents of
the various command list data structures from a procfs file. When NDEBUG
is set, the same information is sent to the console during EH.

The two core drivers, atari_NCR5380.c and NCR5380.c differ here. Because
it is just for debugging, the easiest way to fix the discrepancy is
simply remove this code.

The only remaining users of NCR5380_show_info() and NCR5380_write_info()
are drivers that define PSEUDO_DMA. The others have no use for the
.show_info method, so don't initialize it.
Signed-off-by: NFinn Thain <fthain@telegraphics.com.au>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Tested-by: NOndrej Zary <linux@rainbow-software.org>
Tested-by: NMichael Schmitz <schmitzmic@gmail.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

NCR5380.c presently uses the instance->host_lock spin lock. Convert this
to a new spin lock that protects the NCR5380_hostdata struct.

atari_NCR5380.c previously used local_irq_save/restore() rather than a
spin lock. Convert this to hostdata->lock in irq mode. For SMP platforms,
the interrupt handler now also acquires the spin lock.

This brings all locking in the two core drivers into agreement.

Adding this locking also means that a bunch of volatile qualifiers can be
removed from the members of the NCR5380_hostdata struct. This is done in
a subsequent patch.

Proper locking will allow the abort handler to locate a command being
aborted. This is presently impossible if the abort handler is invoked when
the command has been moved from a queue to a pointer on the stack. (If
eh_abort_handler can't determine whether a command has been completed
or is still being processed then it can't decide whether to return
success or failure.)

The hostdata spin lock is now held when calling NCR5380_select() and
NCR5380_information_transfer(). Where possible, the lock is dropped for
polling and PIO transfers.

Clean up the now-redundant SELECT_ENABLE_REG writes, that used to provide
limited mutual exclusion between information_transfer() and reselect().

Accessing hostdata->connected without data races means taking the lock;
cleanup these accesses.

The new spin lock falls away for m68k and other UP builds, so this should
have little impact there. In the SMP case the new lock should be
uncontested even when the SCSI bus is contested.
Signed-off-by: NFinn Thain <fthain@telegraphics.com.au>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Tested-by: NOndrej Zary <linux@rainbow-software.org>
Tested-by: NMichael Schmitz <schmitzmic@gmail.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Remove FLAG_DTC3181E. It was used to suppress a final Arbitration Lost
(SEL asserted) test that isn't actually needed. The test was suppressed
because it causes problems for DTC436 and DTC536 chips. It takes place
after the host wins arbitration, so SEL has been asserted. These chips
can't seem to tell whether it was the host or another bus device that
did so.

This questionable final test appears in a flow chart in an early NCR5380
datasheet. It was removed from later documents like the DP5380 datasheet.

By the time this final test takes place, the driver has already tested
the Arbitration Lost bit several times. The first test happens 3 us after
BUS FREE (or longer due to register access delays). The protocol requires
that a device stop signalling within 1.8 us after BUS FREE unless it won
arbitration, in which case it must assert SEL, which is detected 1.2 us
later by the first Arbitration Lost test.
Signed-off-by: NFinn Thain <fthain@telegraphics.com.au>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Tested-by: NOndrej Zary <linux@rainbow-software.org>
Tested-by: NMichael Schmitz <schmitzmic@gmail.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

NDEBUG_NO_DATAOUT should not disable DATA IN phases too. Fix this.
(This bug has long been fixed in atari_NCR5380.c.)
Signed-off-by: NFinn Thain <fthain@telegraphics.com.au>
Tested-by: NOndrej Zary <linux@rainbow-software.org>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Remove unused includes (stat.h, signal.h, proc_fs.h) and move includes
needed by the core drivers into the common header (delay.h etc).
Signed-off-by: NFinn Thain <fthain@telegraphics.com.au>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Tested-by: NOndrej Zary <linux@rainbow-software.org>
Tested-by: NMichael Schmitz <schmitzmic@gmail.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Fix the array bounds check when transferring an extended message from the
target.
Signed-off-by: NFinn Thain <fthain@telegraphics.com.au>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Tested-by: NOndrej Zary <linux@rainbow-software.org>
Tested-by: NMichael Schmitz <schmitzmic@gmail.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Bring the two NCR5380_reselect() implementations into agreement.

Replace infinite loops in atari_NCR5380.c with timeouts, as per NCR5380.c.

Remove 'abort' flag in NCR5380.c as per atari_NCR5380.c -- if reselection
fails, there may be no MESSAGE IN phase so don't attempt data transfer.

During selection, don't interfere with the chip registers after a
reselection interrupt intervenes.

Clean up some trivial issues with code style, comments and printk.
Signed-off-by: NFinn Thain <fthain@telegraphics.com.au>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Tested-by: NOndrej Zary <linux@rainbow-software.org>
Tested-by: NMichael Schmitz <schmitzmic@gmail.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

The workarounds for chip errata appear twice, in slightly different
forms. One is used when defined(REAL_DMA) || defined(REAL_DMA_POLL), the
other when defined(PSEUDO_DMA). In the PDMA case, the workarounds have
been made conditional on FLAG_NO_DMA_FIXUPS. Do the same for the DMA case,
to eliminate the READ_OVERRUNS macro.
Signed-off-by: NFinn Thain <fthain@telegraphics.com.au>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Tested-by: NOndrej Zary <linux@rainbow-software.org>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

The flags DMA_WORKS_RIGHT, FLAG_NCR53C400 and FLAG_HAS_LAST_BYTE_SENT
all mean the same thing, i.e. the chip is not a 538[01]. (More recent
devices such as the 53C80 have a 'Last Byte Sent' bit in the Target
Command Register as well as other fixes for End-of-DMA errata.)

These flags have no additional meanings since previous cleanup patches
eliminated the NCR53C400 macro, moved g_NCR5380-specific code out of the
core driver and standardized interrupt handling.

Use the FLAG_NO_DMA_FIXUP flag to suppress End-of-DMA errata workarounds,
for those cards and drivers that make use of the TCR_LAST_BYTE_SENT bit.
Remove the old flags.
Signed-off-by: NFinn Thain <fthain@telegraphics.com.au>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Tested-by: NOndrej Zary <linux@rainbow-software.org>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

SCSI bus protocol sometimes requires monitoring two related conditions
simultaneously. Enhance NCR5380_poll_politely() for this purpose, and
put it to use in the arbitration algorithm. It will also find use in
pseudo DMA.
Signed-off-by: NFinn Thain <fthain@telegraphics.com.au>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Tested-by: NOndrej Zary <linux@rainbow-software.org>
Tested-by: NMichael Schmitz <schmitzmic@gmail.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Because interrupt handling is crucial to the core driver(s), all wrapper
drivers need to agree on this code. This patch removes discrepancies.

NCR5380_intr() in NCR5380.c has the following pointless loop that differs
from the code in atari_NCR5380.c.

	done = 1;
	do {
		/* ... */
	} while (!done);

The 'done' flag gets cleared when a reconnected command is to be processed
from the work queue. But in NCR5380.c, the flag is also used to cause the
interrupt conditions to be re-examined. Perhaps this was because
NCR5380_reselect() was expected to cause another interrupt, or perhaps
the remaining present interrupt conditions need to be handled after the
NCR5380_reselect() call?

Actually, both possibilities are bogus, as is the loop itself. It seems
have been overlooked in the hit-and-miss removal of scsi host instance
list iteration many years ago; see history/history.git commit 491447e1fcff
("[PATCH] next NCR5380 updates") and commit 69e1a9482e57 ("[PATCH] fix up
NCR5380 private data"). See also my earlier patch, "Always retry
arbitration and selection".

The datasheet says, "IRQ can be reset simply by reading the Reset
Parity/Interrupt Register". So don't treat the chip IRQ like a
level-triggered interrupt. Of the conditions that set the IRQ flag,
some are level-triggered and some are edge-triggered, which means IRQ
itself must be edge-triggered.

Some interrupt conditions are latched and some are not. Before clearing
the chip IRQ flag, clear all state that may cause it to be raised. That
means clearing the DMA Mode and Busy Monitor bits in the Mode Register
and clearing the host ID in the Select Enable register.

Also clean up some printk's and some comments. Keep atari_NCR5380.c and
NCR5380.c in agreement.
Signed-off-by: NFinn Thain <fthain@telegraphics.com.au>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Tested-by: NOndrej Zary <linux@rainbow-software.org>
Tested-by: NMichael Schmitz <schmitzmic@gmail.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Configuring core drivers using macros like this one prevents re-unifying
the core driver forks, and prevents implementing the core driver as a
library or a platform driver.

The UNSAFE macro in particular is a poor workaround for the problem of
interrupt latency. Releasing the locks complicates things because then we
would have to handle the possibility of EH handler invocation during a
PDMA transfer.

The comments say that instead of using this macro, "you're going to be
better off twiddling with transfersize". I agree. Remove this stuff.
Signed-off-by: NFinn Thain <fthain@telegraphics.com.au>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Tested-by: NOndrej Zary <linux@rainbow-software.org>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Each host instance now has it's own work queue so the main() work item can
sleep when necessary. That means we can use a simple work item rather than
a delayed work item. This brings NCR5380.c closer to atari_NCR5380.c.
Signed-off-by: NFinn Thain <fthain@telegraphics.com.au>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Tested-by: NOndrej Zary <linux@rainbow-software.org>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

When there is a queued command and no connected command, NCR5380_select()
is called and arbitration begins. The chip waits for BUS FREE once the
MR_ARBITRATE bit in the mode register is enabled. That means there is
no need to wait for BUS FREE after disconnecting.

There is presently no polling for BUS FREE after sending an ABORT or
other message that might lead to disconnection. It only happens after
COMMAND COMPLETE or DISCONNECT messages, which seems inconsistent.
Remove the polling for !BSY in the COMMAND COMPLETE and DISCONNECT
cases.

BTW, the comments say "avoid nasty timeouts" and perhaps BUS FREE polling
was somehow helpful back in Linux v0.99.14u, when it was introduced.
The relevant timeout is presently 1 second (for bus arbitration).
Signed-off-by: NFinn Thain <fthain@telegraphics.com.au>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Tested-by: NOndrej Zary <linux@rainbow-software.org>
Tested-by: NMichael Schmitz <schmitzmic@gmail.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Allow target selection to fail with a timeout instead of waiting in
infinite loops. This gets rid of the unused NCR_TIMEOUT macro, it is more
defensive and has proved helpful in debugging.
Signed-off-by: NFinn Thain <fthain@telegraphics.com.au>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Tested-by: NOndrej Zary <linux@rainbow-software.org>
Tested-by: NMichael Schmitz <schmitzmic@gmail.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Use timeouts in do_abort() in atari_NCR5380.c instead of infinite loops.
Also fix the kernel-doc comment. Keep the two core driver forks in sync.
Signed-off-by: NFinn Thain <fthain@telegraphics.com.au>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Tested-by: NOndrej Zary <linux@rainbow-software.org>
Tested-by: NMichael Schmitz <schmitzmic@gmail.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

NCR5380_poll_politely() returns either 0 (success) or -ETIMEDOUT. However,
in do_abort(), the return value is incorrectly taken to be the status
register value. This means that the bus is put into DATA OUT phase instead
of MESSAGE OUT. Fix this.
Signed-off-by: NFinn Thain <fthain@telegraphics.com.au>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Tested-by: NOndrej Zary <linux@rainbow-software.org>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

NCR5380_poll_politely() never returns -1. That means do_abort() can fail
to handle a timeout after waiting for the target to negate REQ. Fix this
and cleanup other NCR5380_poll_politely() call sites.
Signed-off-by: NFinn Thain <fthain@telegraphics.com.au>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Tested-by: NOndrej Zary <linux@rainbow-software.org>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>