Expose pm qos flags to user space so that user has a chance to disable
ZPODD feature, if he/she has a broken platform or devices or simply does
not like this feature.

This flag is exposed to user space only for ZPODD devices.

Due to this flag, it is possible the ODD is ZP ready but we didn't power
it off. So the zp_ready flag will need to be cleared whenever we found
the ODD is not in ZP ready state. Previously, once zp_ready is set, the
ODD will always be powered off and the flag will be cleared in
post_poweron. But this is no longer the case now.
Signed-off-by: NAaron Lu <aaron.lu@intel.com>
Signed-off-by: NJeff Garzik <jgarzik@redhat.com>

When ata port is runtime suspended, it will check if the ODD attched to
it is a zero power(ZP) capable ODD and if the ZP capable ODD is in zero
power ready state. And if this is not the case, the highest acpi state
will be limited to ACPI_STATE_D3_HOT to avoid powering off the ODD. And
if the ODD can be powered off, runtime wake capability needs to be
enabled and powered_off flag will be set to let resume code knows that
the ODD was in powered off state.

And on resume, before it is powered on, if it was powered off during
suspend, runtime wake capability needs to be disabled. After it is
recovered, the ODD is considered functional, post power on processing
like eject tray if the ODD is drawer type is done, and several ZPODD
related fields will also be reset.
Signed-off-by: NAaron Lu <aaron.lu@intel.com>
Acked-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NJeff Garzik <jgarzik@redhat.com>

Per the Mount Fuji spec, the ODD is considered zero power ready when:
  - For slot type ODD, no media inside;
  - For tray type ODD, no media inside and tray closed.

The information can be retrieved by either the returned information of
command GET_EVENT_STATUS_NOTIFICATION(the command is used to poll for
media event) or sense code.

The information provided by the media status byte is not accurate, it
is possible that after a new disc is just inserted, the status byte
still returns media not present. So this information can not be used as
the deciding factor, we use sense code to decide if zpready status is
true.

When we first sensed the ODD in the zero power ready state, the
zp_sampled will be set and timestamp will be recoreded. And after ODD
stayed in this state for some pre-defined period, the ODD is considered
as power off ready and the zp_ready flag will be set. The zp_ready flag
serves as the deciding factor other code will use to see if power off is
OK for the ODD.

The Mount Fuji spec suggests a delay should be used here, to avoid the
case user ejects the ODD and then instantly inserts a new one again, so
that we can avoid a power transition. And some ODDs may be slow to place
its head to the home position after disc is ejected, so a delay here is
generally a good idea. And the delay time can be changed via the module
param zpodd_poweroff_delay.

The zero power ready status check is performed in the ata port's runtime
suspend code path, when port is not frozen yet, as we need to issue some
IOs to the ODD.
Signed-off-by: NAaron Lu <aaron.lu@intel.com>
Signed-off-by: NJeff Garzik <jgarzik@redhat.com>

Since the ata acpi notification code introduced in commit
3bd46600 is solely for ZPODD, and we
now have a dedicated place for it, move these code there.

And the ata_acpi_add_pm_notifier code is changed a little bit in that it
is now invoked when scsi device is not bound with ACPI yet, so the way
to get the acpi handle is different with the previous version. And the
ata_acpi_add/remove_pm_notifier is also simplified a little bit in that
it doesn't check if the acpi_device for the handle exists or not as the
odd_can_poweroff function already checked that.
Signed-off-by: NAaron Lu <aaron.lu@intel.com>
Acked-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NJeff Garzik <jgarzik@redhat.com>

The ODD can be enabled for ZPODD if the following three conditions are
satisfied:
1 The ODD supports device attention;
2 The platform can runtime power off the ODD through ACPI;
3 The ODD is either slot type or drawer type.
For such ODDs, zpodd_init is called and a new structure is allocated for
it to store ZPODD related stuffs.

And the zpodd_dev_enabled function is used to test if ZPODD is currently
enabled for this ODD.

A new config CONFIG_SATA_ZPODD is added to selectively build ZPODD code.
Signed-off-by: NAaron Lu <aaron.lu@intel.com>
Acked-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NJeff Garzik <jgarzik@redhat.com>