When an IRQ arrives during PDMA transfer, pread() and pwrite() return
without waiting for the 53C80 registers to be ready and this ends up
messing up the chip state. This was observed with SONY CDU-55S which is
slow enough to disconnect during 4096-byte reads.

IRQ during PDMA is not an error so don't return -1. Instead, store the
remaining byte count for use by NCR5380_dma_residual().

[Poll for the BASR_END_DMA_TRANSFER condition rather than remove the
error message -- F.T.]
Signed-off-by: NOndrej Zary <linux@rainbow-software.org>
Signed-off-by: NFinn Thain <fthain@telegraphics.com.au>
Tested-by: NOndrej Zary <linux@rainbow-software.org>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

generic_NCR5380_dma_xfer_len() incorrectly uses cmd->transfersize which
causes rescan-scsi-bus and CD-ROM access to hang the system.  Use
cmd->SCp.this_residual instead, like other NCR5380 drivers.
Signed-off-by: NOndrej Zary <linux@rainbow-software.org>
Signed-off-by: NFinn Thain <fthain@telegraphics.com.au>
Tested-by: NOndrej Zary <linux@rainbow-software.org>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

When the kernel is running in secure boot mode, we lock down the kernel to
prevent userspace from modifying the running kernel image.  Whilst this
includes prohibiting access to things like /dev/mem, it must also prevent
access by means of configuring driver modules in such a way as to cause a
device to access or modify the kernel image.

To this end, annotate module_param* statements that refer to hardware
configuration and indicate for future reference what type of parameter they
specify.  The parameter parser in the core sees this information and can
skip such parameters with an error message if the kernel is locked down.
The module initialisation then runs as normal, but just sees whatever the
default values for those parameters is.

Note that we do still need to do the module initialisation because some
drivers have viable defaults set in case parameters aren't specified and
some drivers support automatic configuration (e.g. PNP or PCI) in addition
to manually coded parameters.

This patch annotates drivers in drivers/scsi/.
Suggested-by: NAlan Cox <gnomes@lxorguk.ukuu.org.uk>
Signed-off-by: NDavid Howells <dhowells@redhat.com>
cc: "Juergen E. Fischer" <fischer@norbit.de>
cc: "James E.J. Bottomley" <jejb@linux.vnet.ibm.com>
cc: "Martin K. Petersen" <martin.petersen@oracle.com>
cc: Dario Ballabio <ballabio_dario@emc.com>
cc: Finn Thain <fthain@telegraphics.com.au>
cc: Michael Schmitz <schmitzmic@gmail.com>
cc: Achim Leubner <achim_leubner@adaptec.com>
cc: linux-scsi@vger.kernel.org

The NCR5380 wrapper drivers don't export symbols or declarations and
don't actually need separate header files. Most of these header files
were removed already; only sun3_scsi.h and g_NCR5380.h remain.

Move the remaining definitions to the corresponding .c files to improve
readability and proximity. The #defines which influence the #included
core driver are no longer mixed up with unrelated #defines and #includes.
Signed-off-by: NFinn Thain <fthain@telegraphics.com.au>
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>

Automatically probe the board irq when no irq parameter is provided, to
simulate PnP. The old default behaviour was to disable the irq.

Update driver documentation accordingly and add some printk messages to
make this behaviour visible.
Signed-off-by: NFinn Thain <fthain@telegraphics.com.au>
Tested-by: NOndrej Zary <linux@rainbow-software.org>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

When IRQ_AUTO is used, the interrupt for HP C2502 cards gets disabled.
Fix this by programming the card for a suitable free irq. The code for
the free irq search comes from ALSA.

Also allow IRQ 9 to work (it aliases to IRQ 2 on the card), as per
Ondrej Zary's patch.
Suggested-by: NOndrej Zary <linux@rainbow-software.org>
Signed-off-by: NFinn Thain <fthain@telegraphics.com.au>
Tested-by: NOndrej Zary <linux@rainbow-software.org>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Use standard probe_irq_on() and probe_irq_off() functions instead of own
implementation.  This prevents warning messages like this in the kernel
log: genirq: Flags mismatch irq 1. 00000000 (NCR-probe) vs. 00000080
(i8042)

Move the IRQ trigger code from NCR5380 to g_NCR5380 where it is used.

Also clear interrupt flag before and after the probe.
Signed-off-by: NOndrej Zary <linux@rainbow-software.org>
Signed-off-by: NFinn Thain <fthain@telegraphics.com.au>
Tested-by: NOndrej Zary <linux@rainbow-software.org>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Write and read back mode register to check that a chip is really there.
If no card is present, reads result in 0xff.
Signed-off-by: NOndrej Zary <linux@rainbow-software.org>
Signed-off-by: NFinn Thain <fthain@telegraphics.com.au>
Tested-by: NOndrej Zary <linux@rainbow-software.org>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

When a SW-configurable card is specified but not found, the driver
releases wrong region, causing the following message in kernel log:
Trying to free nonexistent resource <0000000000000000-000000000000000f>

Fix it by assigning base earlier.
Signed-off-by: NOndrej Zary <linux@rainbow-software.org>
Fixes: a8cfbcae ("scsi: g_NCR5380: Stop using scsi_module.c")
Signed-off-by: NFinn Thain <fthain@telegraphics.com.au>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Apply prototypes to get consistent function signatures for the DMA
functions implemented in the board-specific drivers. To avoid using
macros to alter actual parameters, some of those functions are reworked
slightly.

This is a step toward the goal of passing the board-specific routines
to the core driver using an ops struct (as in a platform driver or
library module).

This also helps fix some inconsistent types: where the core driver uses
ints (cmd->SCp.this_residual and hostdata->dma_len) for keeping track of
transfers, certain board-specific routines used unsigned long.

While we are fixing these function signatures, pass the hostdata pointer
to DMA routines instead of a Scsi_Host pointer, for shorter and faster
code.
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>
Acked-by: NRussell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

The various 5380 drivers inconsistently store register pointers
either in the Scsi_Host struct "legacy crap" area or in special,
board-specific members of the NCR5380_hostdata struct. Uniform
use of the latter struct makes for simpler and faster code (see
the following patches) and helps to reduce use of the
NCR5380_implementation_fields 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>
Tested-by: NMichael Schmitz <schmitzmic@gmail.com>
Acked-by: NRussell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Merge the port-mapped IO and memory-mapped IO support (with the help of
ioport_map) into the g_NCR5380 module and delete g_NCR5380_mmio.
Signed-off-by: NOndrej Zary <linux@rainbow-software.org>
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>

Convert g_NCR5380 to use scsi_add_host instead of scsi_module.c Use
pnp_driver and isa_driver to manage cards.

In order to support multiple cards, new module parameter format is
introduced. The old parameters are kept for compatibility.
Signed-off-by: NOndrej Zary <linux@rainbow-software.org>
Acked-by: NFinn Thain <fthain@telegraphics.com.au>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Remove compile-time card type definition GENERIC_NCR5380_OVERRIDE.  Then
remove all code iterating the overrides[] array and reduce it to struct
card.
Signed-off-by: NOndrej Zary <linux@rainbow-software.org>
Acked-by: NFinn Thain <fthain@telegraphics.com.au>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Remove deprecated __setup for parsing command line parameters.
g_NCR5380.* parameters could be used instead.

This might break existing setups with g_NCR5380 built-in (if there are
any). But it has to go in order to remove the overrides[] array.
Signed-off-by: NOndrej Zary <linux@rainbow-software.org>
Acked-by: NFinn Thain <fthain@telegraphics.com.au>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Update kernel parameter documentation for atari_scsi, mac_scsi and
g_NCR5380 drivers. Remove duplication.
Signed-off-by: NFinn Thain <fthain@telegraphics.com.au>
Reviewed-by: NHannes Reinecke <hare@suse.com>
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: NMichael Schmitz <schmitzmic@gmail.com>
Tested-by: NOndrej Zary <linux@rainbow-software.org>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Adopt the DMA implementation from atari_NCR5380.c. This means that
atari_scsi and sun3_scsi can make use of the NCR5380.c core driver
and the atari_NCR5380.c driver fork can be made redundant.
Signed-off-by: NFinn Thain <fthain@telegraphics.com.au>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Tested-by: NMichael Schmitz <schmitzmic@gmail.com>
Tested-by: NOndrej Zary <linux@rainbow-software.org>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Those wrapper drivers which use DMA define the REAL_DMA macro and
those which use pseudo DMA define PSEUDO_DMA. These macros need to be
removed for a number of reasons, not least of which is to have drivers
share more code.

Redefine the PDMA send and receive hooks as DMA setup hooks, so that the
DMA code can be shared by all 5380 wrapper drivers. This will help to
reunify the forked core driver.
Signed-off-by: NFinn Thain <fthain@telegraphics.com.au>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Tested-by: NMichael Schmitz <schmitzmic@gmail.com>
Tested-by: NOndrej Zary <linux@rainbow-software.org>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

For those wrapper drivers which only implement Programmed IO, have
NCR5380_dma_xfer_len() evaluate to zero. That allows PDMA to be easily
disabled at run-time and so the PSEUDO_DMA macro is no longer needed.

Also remove the spin counters used for debugging pseudo DMA drivers.
Signed-off-by: NFinn Thain <fthain@telegraphics.com.au>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Tested-by: NMichael Schmitz <schmitzmic@gmail.com>
Tested-by: NOndrej Zary <linux@rainbow-software.org>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

The only chip that needs the workarounds enabled is an early NMOS
device. That means that the common case is to disable them.

Unfortunately the sense of the flag is such that it has to be set
for the common case.

Rename the flag so that zero can be used to mean "no errata workarounds
needed". This simplifies the code.
Signed-off-by: NFinn Thain <fthain@telegraphics.com.au>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Tested-by: NMichael Schmitz <schmitzmic@gmail.com>
Tested-by: NOndrej Zary <linux@rainbow-software.org>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Drivers that define PSEUDO_DMA also define NCR5380_dma_xfer_len.
The core driver must call NCR5380_dma_xfer_len which means
FLAG_NO_PSEUDO_DMA can be eradicated from the core driver.

dmx3191d doesn't define PSEUDO_DMA and has no use for FLAG_NO_PSEUDO_DMA,
so remove it there also.
Signed-off-by: NFinn Thain <fthain@telegraphics.com.au>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Tested-by: NMichael Schmitz <schmitzmic@gmail.com>
Tested-by: NOndrej Zary <linux@rainbow-software.org>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

This change brings a number of improvements: fewer macros, better test
coverage, simpler code and sane Kconfig options. The downside is a small
chance of incompatibility (which seems unavoidable).

CONFIG_SCSI_GENERIC_NCR53C400 exists to enable or inhibit pseudo DMA
transfers when the driver is used with 53C400-compatible cards. Thanks to
Ondrej Zary's patches, PDMA now works which means it can be enabled
unconditionally.

Due to bad design, CONFIG_SCSI_GENERIC_NCR53C400 ties together unrelated
functionality as it sets both PSEUDO_DMA and BIOSPARAM macros. This patch
effectively enables PSEUDO_DMA and disables BIOSPARAM.

The defconfigs and the Kconfig default leave CONFIG_SCSI_GENERIC_NCR53C400
undefined. Red Hat 9 and CentOS 2.1 were the same. This leaves both
PSEUDO_DMA and BIOSPARAM disabled. The effect of this patch should be
better performance from enabling PSEUDO_DMA.

On the other hand, Debian 4 and SLES 10 had CONFIG_SCSI_GENERIC_NCR53C400
enabled, so both PSEUDO_DMA and BIOSPARAM were enabled. This patch might
affect configurations like this by disabling BIOSPARAM. My best guess is
that this could be a problem only in the vanishingly rare case that
1) the CHS values stored in the boot device partition table are wrong and
2) a 5380 card is in use (because PDMA on 53C400 used to be broken).
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>

HP C2502 cards (based on 53C400A chips) use different magic numbers for
software-based I/O address configuration than other cards.
The configuration is also extended to allow setting the IRQ.

Move the configuration to a new function magic_configure() and move
magic the magic numbers into an array. Add new magic numbers for these
HP cards and hp_c2502 module parameter to use them, e.g.:
modprobe g_NCR5380 ncr_irq=7 ncr_addr=0x280 hp_c2502=1

Tested with HP C2502 and DTCT-436P.
Signed-off-by: NOndrej Zary <linux@rainbow-software.org>
Signed-off-by: NFinn Thain <fthain@telegraphics.com.au>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

The check for 53C80 registers accessibility was commented out because
it was broken (inverted). Fix and enable it.
Signed-off-by: NOndrej Zary <linux@rainbow-software.org>
Signed-off-by: NFinn Thain <fthain@telegraphics.com.au>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Add I/O register mapping for DTC chips and enable PDMA mode.

These chips have 16-bit wide HOST BUFFER register and it must be read
by 16-bit accesses (we lose data otherwise).

Large PIO transfers crash at least the DTCT-436P chip (all reads result
in 0xFF) so this patch actually makes it work.

The chip also crashes when we bang on the C400 host status register too
heavily after PDMA write - a small udelay is needed.

Tested on DTCT-436P and verified that it does not break 53C400A.
Signed-off-by: NOndrej Zary <linux@rainbow-software.org>
Signed-off-by: NFinn Thain <fthain@telegraphics.com.au>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Add I/O register mapping for NCR53C400A and enable PDMA mode to
improve performance and fix non-working IRQ.

Tested with HP C2502 (and user-space enabler).
Signed-off-by: NOndrej Zary <linux@rainbow-software.org>
Signed-off-by: NFinn Thain <fthain@telegraphics.com.au>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Convert compile-time C400_ register mapping to runtime mapping.
This removes the weird negative register offsets and allows adding
additional mappings.

While at it, convert read/write loops into insb/outsb.
Signed-off-by: NOndrej Zary <linux@rainbow-software.org>
Signed-off-by: NFinn Thain <fthain@telegraphics.com.au>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Pseudo-DMA (PDMA) has been broken for ages, resulting in hangs on
53C400-based cards.

According to 53C400 datasheet, PDMA transfer length must be a multiple
of 128. Check if that's true and use PIO if it's not.

This makes PDMA work on 53C400 (Canon FG2-5202).
Signed-off-by: NOndrej Zary <linux@rainbow-software.org>
Signed-off-by: NFinn Thain <fthain@telegraphics.com.au>
Reviewed-by: NHannes Reinecke <hare@suse.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>

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>

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>

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>

Add missing .module initializer. Use distinct .proc_name values for the
g_NCR5380 and g_NCR5380_mmio modules. Remove pointless CAN_QUEUE and
CMD_PER_LUN override macros. Cleanup whitespace and code style.
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 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>

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>

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>

The atari_NCR5380.c and NCR5380.c core drivers differ in their handling of
target disconnection. This is partly because atari_NCR5380.c had all of
the polling and sleeping removed to become entirely interrupt-driven, and
it is partly because of damage done to NCR5380.c after atari_NCR5380.c was
forked. See commit 37cd23b44929 ("Linux 2.1.105") in history/history.git.

The polling changes that were made in v2.1.105 are questionable at best:
if REQ is not already asserted when NCR5380_transfer_pio() is invoked, and
if the expected phase is DATA IN or DATA OUT, the function will schedule
main() to execute after USLEEP_SLEEP jiffies and then return. The problems
here are the expected REQ timing and the sleep interval*. Avoid this issue
by using NCR5380_poll_politely() instead of scheduling main().

The atari_NCR5380.c core driver requires the use of the chip interrupt and
always permits target disconnection. It sets the cmd->device->disconnect
flag when a device disconnects, but never tests this flag.

The NCR5380.c core driver permits disconnection only when
instance->irq != NO_IRQ. It sets the cmd->device->disconnect flag when
a device disconnects and it tests this flag in a couple of places:

1. During NCR5380_information_transfer(), following COMMAND OUT phase,
   if !cmd->device->disconnect, the initiator will take a guess as to
   whether or not the target will then choose to go to MESSAGE IN phase
   and disconnect. If the driver guesses "yes", it will schedule main()
   to execute after USLEEP_SLEEP jiffies and then return there.

   Unfortunately the driver may guess "yes" even after it has denied
   the target the disconnection privilege. When the target does not
   disconnect, the sleep can be beneficial, assuming the sleep interval
   is appropriate (mostly it is not*).

   And even if the driver guesses "yes" correctly, and the target would
   then disconnect, the driver still has to go through the MESSAGE IN
   phase in order to get to BUS FREE phase. The main loop can do nothing
   useful until BUS FREE, and sleeping just delays the phase transition.

2. If !cmd->device->disconnect and REQ is not already asserted when
   NCR5380_information_transfer() is invoked, the function polls for REQ
   for USLEEP_POLL jiffies. If REQ is not asserted, it then schedules
   main() to execute after USLEEP_SLEEP jiffies and returns.

   The idea is apparently to yeild the CPU while waiting for REQ.
   This is conditional upon !cmd->device->disconnect, but there seems
   to be no rhyme or reason for that. For example, the flag may be
   unset because disconnection privilege was denied because the driver
   has no IRQ. Or the flag may be unset because the device has never
   needed to disconnect before. Or if the flag is set, disconnection
   may have no relevance to the present bus phase.

Another deficiency of the existing algorithm is as follows. When the
driver has no IRQ, it prevents disconnection, and generally polls and
sleeps more than it would normally. Now, if the driver is going to poll
anyway, why not allow the target to disconnect? That way the driver can do
something useful with the bus instead of polling unproductively!

Avoid this pointless latency, complexity and guesswork by using
NCR5380_poll_politely() instead of scheduling main().

* For g_NCR5380, the time intervals for USLEEP_SLEEP and USLEEP_POLL are
  200 ms and 10 ms, respectively. They are 20 ms and 200 ms respectively
  for the other NCR5380 drivers. There doesn't seem to be any reason for
  this discrepancy. The timing seems to have no relation to the type of
  adapter. Bizarrely, the timing in g_NCR5380 seems to relate only to one
  particular type of target device. This patch attempts to solve the
  problem for all NCR5380 drivers and all target devices.
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>

Follow the example of the atari_NCR5380.c core driver and adopt the
NCR5380_dma_xfer_len() hook. Implement NCR5380_dma_xfer_len() for dtc.c
and g_NCR5380.c to take care of the limitations of these cards. Keep the
default for drivers using PSEUDO_DMA.

Eliminate the unused macro LIMIT_TRANSFERSIZE.
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>

Allocate a work queue that will permit busy waiting and sleeping. This
means NCR5380_init() can potentially fail, so add this error path.
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>