LIBATA_MAX_PRD is the maximum number of DMA scatter/gather elements
permitted by the HBA's DMA engine. It's properly set to
q->max_hw_segments via the sg_tablesize parameter.

libata shouldn't call blk_queue_max_phys_segments. Now LIBATA_MAX_PRD
is equal to SCSI_MAX_PHYS_SEGMENTS by default (both is 128), so
everything is fine. But if they are changed, some code (like the scsi
mid layer, sg chaining, etc) might not work properly.

(Addition from Jens) The basic issue is that the physical segment
setting is purely a driver issue. And since SCSI is managing the sglist,
libata has no business changing the setting. All libata should care
about is the hw segment setting.
Signed-off-by: NFUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

After commands which can change device configuration, EH is scheduled
to revalidate and reconfigure the device.  Host link was incorrectly
used unconditionally when scheduling EH action.  This resulted in
bogus revalidation request and mismatched configuration between device
and driver.  Fix it.

This bug was reported by Igor Durdanovic.
Signed-off-by: NTejun Heo <htejun@gmail.com>
Cc: Igor Durdanovic <idurdanovic@comcast.net>
Signed-off-by: NJeff Garzik <jeff@garzik.org>

Some controller variants snoop the ATAPI length value for Packet
transfers to do state machine and FIFO management. Thus we want to
set it properly, even for cases where it is otherwise meaningless.
Signed-off-by: NAlan Cox <alan@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NJeff Garzik <jeff@garzik.org>

AN serves multiple purposes.  For ATAPI, it's used for media change
notification.  For PMP, for downstream PHY status change notification.
Implement sata_async_notification() which demultiplexes AN.

To avoid unnecessary port events, ATAPI AN is not enabled if PMP is
attached but SNTF is not available.
Signed-off-by: NTejun Heo <htejun@gmail.com>
Cc: Kriten Carlson Accardi <kristen.c.accardi@intel.com>
Signed-off-by: NJeff Garzik <jeff@garzik.org>

Some pseudo devices fail PM commands unnecessarily aborting system
suspend.  Implement ATA_HORKAGE_SKIP_PM which makes libata skip PM
commands for these devices.
Signed-off-by: NTejun Heo <htejun@gmail.com>
Signed-off-by: NJeff Garzik <jeff@garzik.org>

Controllers which support PMP have various restrictions on which
combinations of commands are allowed to what number of devices
concurrently.  This patch implements ops->qc_defer() which determines
whether a qc can be issued at the moment or should be deferred.

If the function returns ATA_DEFER_LINK, the qc will be deferred until
a qc completes on the link.  If ATA_DEFER_PORT, until a qc completes
on any link.  The defer conditions are advisory and in general
ATA_DEFER_LINK can be considered as lower priority deferring than
ATA_DEFER_PORT.

ops->qc_defer() replaces fixed ata_scmd_need_defer().  For standard
NCQ/non-NCQ exclusion, ata_std_qc_defer() is implemented.  ahci and
sata_sil24 are converted to use ata_std_qc_defer().

ops->qc_defer() is heavier than the original mechanism because full qc
is prepped before determining to defer it, but various information is
needed to determine defer conditinos and fully translating a qc is the
only way to supply such information in generic manner.

IMHO, this shouldn't cause any noticeable performance issues as

* for most cases deferring occurs rarely (except for NCQ-aware
  cmd-switching PMP)
* translation itself isn't that expensive
* once deferred the command won't be repeated until another command
  completes which usually is a very long time cpu-wise.
Signed-off-by: NTejun Heo <htejun@gmail.com>
Signed-off-by: NJeff Garzik <jeff@garzik.org>

Update AN support in preparation of PMP support.

* s/ata_id_has_AN/ata_id_has_atapi_AN/
* add AN enabled reporting during configuration
* add err_mask to AN configuration failure reporting
* update LOCKING comment for ata_scsi_media_change_notify()
* check whether ATA dev is attached to SCSI dev ata_scsi_media_change_notify()
* set ATA_FLAG_AN in ahci and sata_sil24
Signed-off-by: NTejun Heo <htejun@gmail.com>
Cc: Kriten Carlson Accardi <kristen.c.accardi@intel.com>
Signed-off-by: NJeff Garzik <jeff@garzik.org>

Signed-off-by: NJeff Garzik <jeff@garzik.org>

Clear ARRE, we don't do auto-reallocation on reads, just on writes.

Also, hardcode the size of the array using RW_RECOVERY_MPAGE_LEN,
following the style of the surrounding code.
Signed-off-by: NJeff Garzik <jeff@garzik.org>

* SAT specifies that FORMAT UNIT should be translated into a series
  of READ and WRITE commands that zero the ATA device.  That is far too
  cumbersome to bother with.

  Since we don't actually format the device, the old behavior of
  always returning success was inaccurate.  Change FORMAT UNIT from
  returning success immediately (old behavior) to always returning
  an error (new behavior).

* Add some comments around SYNCHRONIZE CACHE

* Shuffle scsi command code around a bit, so that things are close
  to alphabetic order.
Signed-off-by: NJeff Garzik <jgarzik@redhat.com>

A few pedantic apps care about missing or lame "mandatory" SCSI
commands, so

REQUEST SENSE -- as we autosense, R.S. just returns zeroes

SEND DIAGNOSTIC -- our default (no-op) self-test succeeds, all
		   other requests for testing fail.
Signed-off-by: NJeff Garzik <jeff@garzik.org>

Signed-off-by: NJeff Garzik <jeff@garzik.org>

  simple search-and-replace of direct scsi_cmnd access to
  use the data buffer accessors.
Signed-off-by: NBoaz Harrosh <bharrosh@panasas.com>
Signed-off-by: NJeff Garzik <jeff@garzik.org>

     This is a minimal patch needed to remove use of !use_sg
     but it is not a complete clean up of the !use_sg paths.
     Libata-core still has the qc->flags & ATA_QCFLAG_SG
     and !qc->n_elem code paths. Perhaps an ata maintainer
     would have a go at it.

     - TODO: further cleanup of qc->flags & ATA_QCFLAG_SG
       and !qc->n_elem code paths in libata-core
     - TODO: Use scsi_dma_{map,unmap} where applicable.
Signed-off-by: NJeff Garzik <jeff@garzik.org>

When we get an SDB FIS with the 'N' bit set, we should send
an event to user space to indicate that there has been a
media change.  This will be done via the scsi device.
Signed-off-by: NKristen Carlson Accardi <kristen.c.accardi@intel.com>
Signed-off-by: NJeff Garzik <jeff@garzik.org>

Add support for issuing ATA_16 passthru commands to ATAPI devices
managed by libata.  It requires the previous CDB length fix patch.

A boot/module parameter, "atapi_passthru16=0" can be used to globally
disable this feature, if ever desired.

tj: restructured __ata_scsi_queuecmd() according to Jeff's suggestion.
Signed-off-by: NMark Lord <liml@rtr.ca>
Signed-off-by: NTejun Heo <htejun@gmail.com>
Signed-off-by: NJeff Garzik <jeff@garzik.org>

Update hotplug to handle PMP links.  When PMP is attached, the PMP
number corresponds to C of SCSI H:C:I:L.  While at it, change argument
to ata_find_dev() to @devno from @id to avoid confusion with SCSI
device ID.
Signed-off-by: NTejun Heo <htejun@gmail.com>
Signed-off-by: NJeff Garzik <jeff@garzik.org>

Multiple links and different number of devices per link should be
considered to iterate over links and devices.  This patch implements
and uses link and device iterators - ata_port_for_each_link() and
ata_link_for_each_dev() - and ata_link_max_devices().

This change makes a lot of functions iterate over only possible
devices instead of from dev 0 to dev ATA_MAX_DEVICES.  All such
changes have been examined and nothing should be broken.

While at it, add a separating comment before device helpers to
distinguish them better from link helpers and others.
Signed-off-by: NTejun Heo <htejun@gmail.com>
Signed-off-by: NJeff Garzik <jeff@garzik.org>

Introduce ata_link.  It abstracts PHY and sits between ata_port and
ata_device.  This new level of abstraction is necessary to support
SATA Port Multiplier, which basically adds a bunch of links (PHYs) to
a ATA host port.  Fields related to command execution, spd_limit and
EH are per-link and thus moved to ata_link.

This patch only defines the host link.  Multiple link handling will be
added later.  Also, a lot of ap->link derefences are added but many of
them will be removed as each part is converted to deal directly with
ata_link instead of ata_port.

This patch introduces no behavior change.
Signed-off-by: NTejun Heo <htejun@gmail.com>
Cc: James Bottomley <James.Bottomley@SteelEye.com>
Signed-off-by: NJeff Garzik <jeff@garzik.org>

Some of the code has been gradually transitioned to using the proper
struct request_queue, but there's lots left. So do a full sweet of
the kernel and get rid of this typedef and replace its uses with
the proper type.
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

SCSI scan may fail due to memory allocation failure even if EH is not
in progress.  Due to use of GFP_ATOMIC in SCSI scan path, allocation
failure isn't too rare especially while probing multiple devices at
once which is the case when a bunch of devices are connected to PMP.

This patch moves SCSI scan failure detetion logic from
ata_scsi_hotplug() to ata_scsi_scan_host() and implement synchronous
scan behavior.  The synchronous path sleeps briefly and repeats SCSI
scan if some devices aren't attached properly.  It contains robust
retry loop to minimize the chance of device misdetection during boot
and falls back to async retry if everything fails.
Signed-off-by: NTejun Heo <htejun@gmail.com>
Signed-off-by: NJeff Garzik <jeff@garzik.org>

Add ata_dumb_qc_prep and supporting logic so that a driver can just
specify it needs to be helped in this area. 64K entries are split
as with drivers/ide.
Signed-off-by: NAlan Cox <alan@redhat.com>
Signed-off-by: NJeff Garzik <jeff@garzik.org>

In atapi_xlat(), prepare qc better before calling
ata_check_atapi_dma() such that ata_check_atapi_dma() can use info
from qc.  While at it, reformat weird looking if/else block in the
function.
Signed-off-by: NTejun Heo <htejun@gmail.com>
Signed-off-by: NJeff Garzik <jeff@garzik.org>

INIT_DEV_PARAMS and SET_MULTI_MODE change the device parameters cached
by libata.  Re-read IDENTIFY DEVICE info and update the cached device
paramters when seeing these commands.
Signed-off-by: NAlbert Lee <albertcc@tw.ibm.com>
Signed-off-by: NJeff Garzik <jeff@garzik.org>

 Always enforce correct DEV bit since we know which drive the command
is targeted. SAT demands to ignore the DEV bit, too.
Signed-off-by: NAlbert Lee <albertcc@tw.ibm.com>
Signed-off-by: NJeff Garzik <jeff@garzik.org>

 Map the ATA passthru UDMA protocols to ATA_PROT_DMA.
Signed-off-by: NAlbert Lee <albertcc@tw.ibm.com>
Signed-off-by: NJeff Garzik <jeff@garzik.org>

  support the pass through of PIO multi commands.
Signed-off-by: NAlbert Lee <albertcc@tw.ibm.com>
Signed-off-by: NJeff Garzik <jeff@garzik.org>

 Update the ATA passthru protocol numbers according to the new spec.
Signed-off-by: NAlbert Lee <albertcc@tw.ibm.com>
Signed-off-by: NJeff Garzik <jeff@garzik.org>

The code for parsing 6-byte SCSI command LBAs
missed the top 5 bits (the MSB).
Signed-off-by: NJeff Garzik <jeff@garzik.org>

With STANDBYDOWN tracking added, libata.spindown_compat isn't
necessary anymore.  If userspace shutdown(8) issues STANDBYNOW, libata
warns.  If userspace shutdown(8) doesn't issue STANDBYNOW, libata does
the right thing.  Userspace can tell whether kernel supports spindown
by testing whether sysfs node manage_start_stop exists as before.
Signed-off-by: NTejun Heo <htejun@gmail.com>
Signed-off-by: NJeff Garzik <jeff@garzik.org>

Our assumption that most distros issue STANDBYNOW seems wrong.  The
upstream sysvinit and thus many distros including gentoo and opensuse
don't take any action for libata disks on spindown.  We can skip
compat handling for these distros so that they don't need to update
anything to take advantage of kernel-side shutdown.
Signed-off-by: NTejun Heo <htejun@gmail.com>
Signed-off-by: NJeff Garzik <jeff@garzik.org>

Unlocking ap->lock and ssleeping don't work because SCSI commands can
be issued from completion path without context.  Reimplement delayed
completion by allowing translation functions to override
qc->scsidone(), storing the original completion function to
scmd->scsi_done() and overriding qc->scsidone() with a function which
schedules delayed invocation of scmd->scsi_done().

This isn't pretty at all but all the ugly parts are thankfully
contained in the stop translation path where the compat feature is
implemented.
Signed-off-by: NTejun Heo <htejun@gmail.com>
Signed-off-by: NJeff Garzik <jeff@garzik.org>

Now that libata uses sd->manage_start_stop, libata spins down disk on
shutdown.  In an attempt to compensate libata's previous shortcoming,
some distros sync and spin down disks attached via libata in their
shutdown(8).  Some disks spin back up just to spin down again on
STANDBYNOW1 if the command is issued when the disk is spun down, so
this double spinning down causes problem.

This patch implements module parameter libata.spindown_compat which,
when set to one (default value), prevents libata from spinning down
disks on shutdown thus avoiding double spinning down.  Note that
libata spins down disks for suspend to mem and disk, so with
libata.spindown_compat set to one, disks should be properly spun down
in all cases without modifying shutdown(8).

shutdown(8) should be fixed eventually.  Some drive do spin up on
SYNCHRONZE_CACHE even when their cache is clean.  Those disks
currently spin up briefly when sd tries to shutdown the device and
then the machine powers off immediately, which can't be good for the
head.  We can't skip SYNCHRONIZE_CACHE during shudown as it can be
dangerous data integrity-wise.

So, this spindown_compat parameter is already scheduled for removal by
the end of the next year and here's what shutdown(8) should do.

  * Check whether /sys/modules/libata/parameters/spindown_compat
    exists.  If it does, write 0 to it.

  * For each libata harddisk {
	* Check whether /sys/class/scsi_disk/h:c:i:l/manage_start_stop
	  exists.  Iff it doesn't, synchronize cache and spin the disk
	  down as before.
  }

The above procedure will make shutdown(8) work properly with kernels
before this change, ones with this workaround and later ones without
it.

To accelerate shutdown(8) updates, if the compat mode is in use, this
patch prints BIG FAT warning for five seconds during shutdown (the
optimal interval to annoy the user just the right amount discovered by
hours of tireless usability testing).
Signed-off-by: NTejun Heo <htejun@gmail.com>
Signed-off-by: NJeff Garzik <jeff@garzik.org>

Reimplement suspend/resume support using sdev->manage_start_stop.

* Device suspend/resume is now SCSI layer's responsibility and the
  code is simplified a lot.

* DPM is dropped.  This also simplifies code a lot.  Suspend/resume
  status is port-wide now.

* ata_scsi_device_suspend/resume() and ata_dev_ready() removed.

* Resume now has to wait for disk to spin up before proceeding.  I
  couldn't find easy way out as libata is in EH waiting for the
  disk to be ready and sd is waiting for EH to complete to issue
  START_STOP.

* sdev->manage_start_stop is set to 1 in ata_scsi_slave_config().
  This fixes spindown on shutdown and suspend-to-disk.
Signed-off-by: NTejun Heo <htejun@gmail.com>
Signed-off-by: NJeff Garzik <jeff@garzik.org>

Reorganize ata_host_alloc() and its subroutines into the following
three functions.

* ata_host_alloc() : allocates host and its ports.  shost is not
  registered automatically.

* ata_scsi_add_hosts() : allocates and adds shosts associated with an
  ATA host.  Used by ata_host_register().

* ata_host_register() : takes a fully initialized ata_host structure
  and registers it to libata layer and probes it.

Only ata_host_alloc() and ata_host_register() are exported.
ata_device_add() is rewritten using the above functions.  This patch
does not introduce any observable behavior change.  Things worth
mentioning.

* print_id is assigned at registration time and LLDs are allowed to
  overallocate ports and reduce host->n_ports during initialization.
  ata_host_register() will throw away unused ports automatically.

* All SCSI host initialization stuff now resides in
  ata_scsi_add_hosts() in libata-scsi.c, where it should be.

* ipr is now the only user of ata_host_init().  Either kill it by
  converting ipr to use ata_host_alloc() and friends or rename and
  move it to libata-scsi.c
Signed-off-by: NTejun Heo <htejun@gmail.com>
Signed-off-by: NJeff Garzik <jeff@garzik.org>

The READ/WRITE LONG commands are theoretically obsolete,
but the majority of drives in existance still implement them.

The WRITE_LONG and WRITE_LONG_ONCE commands are of particular
interest for fault injection testing -- eg. creating "media errors"
at specific locations on a disk.

The fussy bit is that these commands require a non-standard
sector size, usually 520 bytes instead of 512.

This patch adds support to libata for READ/WRITE LONG commands
issued via SG_IO/ATA_16.
Signed-off-by: NMark Lord <mlord@pobox.com>
Signed-off-by: NJeff Garzik <jeff@garzik.org>

Resending, with s/printk/DPRINTK/ as pointed out by Alan.

Fix libata to perform CDB len validation per device
rather than per host.  This way, validation still works
when we have a mix of 12-byte and 16-byte devices on
a common host interface.
Signed-off-by: NMark Lord <mlord@pobox.com>
Signed-off-by: NJeff Garzik <jeff@garzik.org>

Preserve the LBA bit in the DevSel/Head register for HDIO_DRIVE_TASK.
Signed-off-by: NMark Lord <mlord@pobox.com>
Signed-off-by: NJeff Garzik <jeff@garzik.org>

Conditionalize all PM related stuff in libata core layer using
CONFIG_PM.
Signed-off-by: NTejun Heo <htejun@gmail.com>
Signed-off-by: NJeff Garzik <jeff@garzik.org>

ata_port has two different id fields - id and port_no.  id is
system-wide 1-based unique id for the port while port_no is 0-based
host-wide port number.  The former is primarily used to identify the
ATA port to the user in printk messages while the latter is used in
various places in libata core and LLDs to index the port inside the
host.

The two fields feel quite similar and sometimes ap->id is used in
place of ap->port_no, which is very difficult to spot.  This patch
renames ap->id to ap->print_id to reduce the possibility of such bugs.

Some printk messages are adjusted such that id string (ata%u[.%u])
isn't printed twice and/or to use ata_*_printk() instead of hardcoded
id format.
Signed-off-by: NTejun Heo <htejun@gmail.com>
Signed-off-by: NJeff Garzik <jeff@garzik.org>