Implement ATA part of hotplug.  To avoid probing broken devices over
and over again, disabled devices are not automatically detached.  They
are detached only if probing is requested for the device or the
associated port is offline.  Also, to avoid infinite probing loop,
Each device is probed only once per EH run.

As SATA PHY status is fragile, devices are detached only after it has
used up its recovery chances unless explicitly requested by LLDD or
user (LLDD may request direct detach if, for example, it supports cold
presence detection).
Signed-off-by: Tejun Heo <htejun@gmail.com>

Implement ata_eh_detach_dev().  This function is responsible for
detaching an ATA device and offlining the associated SCSI device
atomically so that the detached device is not accessed after ATA
detach is complete.
Signed-off-by: Tejun Heo <htejun@gmail.com>

In some cases, hardreset must be followed by SRST.

* some controllers can't classify with hardreset
* some controllers can't wait for !BSY after hardreset (LLDD should
  explicitly request followup softreset by returning -EAGAIN)
* (later) PM needs SRST w/ PMP==15 to operate after hardreset

To handle above cases, this patch implements follow-up softreset.
After a hardreset, ata_eh_reset() checks whether any of above
conditions are met and do a follow-up softreset if necessary.
Signed-off-by: Tejun Heo <htejun@gmail.com>

With hotplug, every reset might be a probing reset and thus something
similar to probe_init() is needed.  prereset() method is called before
a series of resets to a port and is the counterpart of postreset().
prereset() can tell EH to use different type of reset or skip reset by
modifying ehc->i.action.

This patch also implements ata_std_prereset().  Most controllers
should be able to use this function directly or with some wrapping.
After hotplug, different controllers need different actions to resume
the PHY and detect the newly attached device.  Controllers can be
categorized as follows.

* Controllers which can wait for the first D2H FIS after hotplug.
  Note that if the waiting is implemented by polling TF status, there
  needs to be a way to set BSY on PHY status change.  It can be
  implemented by hardware or with the help of the driver.

* Controllers which can wait for the first D2H FIS after sending
  COMRESET.  These controllers need to issue COMRESET to wait for the
  first FIS.  Note that the received D2H FIS could be the first D2H
  FIS after POR (power-on-reset) or D2H FIS in response to the
  COMRESET.  Some controllers use COMRESET as TF status
  synchronization point and clear TF automatically (sata_sil).

* Controllers which cannot wait for the first D2H FIS reliably.
  Blindly issuing SRST to spinning-up device often results in command
  issue failure or timeout, causing extended delay.  For these
  controllers, ata_std_prereset() explicitly waits ATA_SPINUP_WAIT
  (currently 8s) to give newly attached device time to spin up, then
  issues reset.  Note that failing to getting ready in ATA_SPINUP_WAIT
  is not critical.  libata will retry.  So, the timeout needs to be
  long enough to spin up most devices.

LLDDs can tell ata_std_prereset() which of above action is needed with
ATA_FLAG_HRST_TO_RESUME and ATA_FLAG_SKIP_D2H_BSY flags.  These flags
are PHY-specific property and will be moved to ata_link later.

While at it, this patch unifies function typedef's such that they all
have named arguments.
Signed-off-by: Tejun Heo <htejun@gmail.com>

Implement ata_eh_wait().  On return from this function, it's
guaranteed that the EH which was pending or in progress when the
function was called is complete - including the tailing part of SCSI
EH.  This will be used by hotplug and others to synchronize with EH.
Signed-off-by: Tejun Heo <htejun@gmail.com>

Set ata_device->pio_mode to XFER_PIO_0 after a successful reset.  This
is to keep EH resets consistent with probe resets as updated by the
commit b6079ca4.  Note that, with
soon-to-follow hotplug update, EH resets will include probe resets.
Signed-off-by: Tejun Heo <htejun@gmail.com>

libata implemented a feature to schedule EH without an associated EH
by manipulating shost->host_eh_scheduled in ata_scsi_schedule_eh()
directly.  Move this function to scsi_error.c and rename it to
scsi_schedule_eh().  It is now an exported API for SCSI transports and
exported via new header file drivers/scsi/scsi_transport_api.h

This patch also de-export scsi_eh_wakeup() which was exported
specifically for ata_scsi_schedule_eh().
Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

LLDDs rely on libata that certain EH actions are automatically taken
on some errors.  If the port is frozen or one or more qc's have failed
with HSM violation or timeout, softreset is enforced (LLDD can ask for
storonger EH action at will).  If any other error condition exists,
libata EH always revalidates.

This behavior existed in earlier revisions of new EH but lost during
development process.  This patch restores it.
Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

Update EH to handle NCQ.  ata_eh_autopsy() is updated to call
ata_eh_analyze_ncq_error() which reads log page 10h on NCQ device
error and updates eh_context accordingly.  ata_eh_report() is updated
to report SActive.
Signed-off-by: Tejun Heo <htejun@gmail.com>

Implement new EH.  The exported interface is ata_do_eh() which is to
be called from ->error_handler and performs the following steps to
recover the failed port.

ata_eh_autopsy() : analyze SError/TF, determine the cause of failure
		   and required recovery actions and record it in
		   ap->eh_context
ata_eh_report()	 : report the failure to user
ata_eh_recover() : perform recovery actions described in ap->eh_context
ata_eh_finish()	 : finish failed qcs

LLDDs can customize error handling by modifying eh_context before
calling ata_do_eh() or, if necessary, doing so inbetween each major
steps by calling each step explicitly.
Signed-off-by: Tejun Heo <htejun@gmail.com>

struct ata_eh_info serves as the communication channel between
execution path and EH.  Execution path describes detected error
condition in ap->eh_info and EH recovers the port using it.  To avoid
missing error conditions detected during EH, EH makes its own copy of
eh_info and clears it on entry allowing error info to accumulate
during EH.

Most EH states including EH's copy of eh_info are stored in
ap->eh_context (struct ata_eh_context) which is owned by EH and thus
doesn't require any synchronization to access and alter.  This
standardized context makes it easy to integrate various parts of EH
and extend EH to handle multiple links (for PM).
Signed-off-by: Tejun Heo <htejun@gmail.com>

This patch implements ata_ering and uses it to define dev->ering.

ata_ering is a ring buffer which records libata errors - whether a
command was for normar IO request, err_mask and timestamp.  Errors are
recorded per-device in dev->ering.  This will be used by EH to
determine recovery actions.
Signed-off-by: Tejun Heo <htejun@gmail.com>

Update ata_scsi_error() for new EH.  ata_scsi_error() is responsible
for claiming timed out qcs and invoking ->error_handler in safe and
synchronized manner.  As the state of the controller is unknown if a
qc has timed out, the port is frozen in such cases.

Note that ata_scsi_timed_out() isn't used for new EH.  This is because
a timed out qc cannot be claimed by EH without freezing the port and
freezing the port in ata_scsi_timed_out() results in unnecessary
abortion of other active qcs.  ata_scsi_timed_out() can be removed
once all drivers are converted to new EH.

While at it, add 'TODO: kill' comments to old EH functions.
Signed-off-by: Tejun Heo <htejun@gmail.com>

Freezing is performed atomic w.r.t. host_set->lock and once frozen
LLDD is not allowed to access the port or any qc on it.  Also, libata
makes sure that no new qc gets issued to a frozen port.

A frozen port is thawed after a reset operation completes
successfully, so reset methods must do its job while the port is
frozen.  During initialization all ports get frozen before requesting
IRQ, so reset methods are always invoked on a frozen port.

Optional ->freeze and ->thaw operations notify LLDD that the port is
being frozen and thawed, respectively.  LLDD can disable/enable
hardware interrupt in these callbacks if the controller's IRQ mask can
be changed dynamically.  If the controller doesn't allow such
operation, LLDD can check for frozen state in the interrupt handler
and ack/clear interrupts unconditionally while frozen.
Signed-off-by: Tejun Heo <htejun@gmail.com>

ata_port_schedule_eh() directly schedules EH for @ap without
associated qc.  Once EH scheduled, no further qc is allowed and EH
kicks in as soon as all currently active qc's are drained.

ata_port_abort() schedules all currently active commands for EH by
qc_completing them with ATA_QCFLAG_FAILED set.  If ata_port_abort()
doesn't find any qc to abort, it directly schedule EH using
ata_port_schedule_eh().

These two functions provide ways to invoke EH for conditions which
aren't directly related to any specfic qc.
Signed-off-by: Tejun Heo <htejun@gmail.com>

There are several ways a qc can get schedule for EH in new EH.  This
patch implements one of them - completing a qc with ATA_QCFLAG_FAILED
set or with non-zero qc->err_mask.  ALL such qc's are examined by EH.

New EH schedules a qc for EH from completion iff ->error_handler is
implemented, qc is marked as failed or qc->err_mask is non-zero and
the command is not an internal command (internal cmd is handled via
->post_internal_cmd).  The EH scheduling itself is performed by asking
SCSI midlayer to schedule EH for the specified scmd.

For drivers implementing old-EH, nothing changes.  As this change
makes ata_qc_complete() rather large, it's not inlined anymore and
__ata_qc_complete() is exported to other parts of libata for later
use.
Signed-off-by: Tejun Heo <htejun@gmail.com>

Use ATA printk helpers.
Signed-off-by: Tejun Heo <htejun@gmail.com>

irq-pio minor fix:
- remove the redundant hsm_task_state = HSM_ST_IDLE
- add devno to printk() as done in upstream
Signed-off-by: Albert Lee <albertcc@tw.ibm.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

A lot of EH codes are about to be added to libata.  Separate out
libata-eh.c.  ata_scsi_timed_out(), ata_scsi_error(),
ata_qc_timeout(), ata_eng_timeout(), ata_eh_qc_complete() and
ata_eh_qc_retry() are moved.  No code is changed by this patch.
Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>