thunderbolt: Enable plug events

Thunderbolt switches have a plug events capability. This patch adds the
tb_plug_events_active method and uses it to activate plug events during
switch allocation.

Signed-off-by: Andreas Noever <andreas.noever@gmail.com>
thunderbolt: Scan for downstream switches

Add utility methods tb_port_state and tb_wait_for_port. Add
tb_scan_switch which recursively checks for downstream switches.

Signed-off-by: Andreas Noever <andreas.noever@gmail.com>
thunderbolt: Handle hotplug events

We receive a plug event callback whenever a thunderbolt device is added
or removed. This patch fills in the tb_handle_hotplug method and starts
reacting to these events by adding/removing switches from the hierarchy.

Signed-off-by: Andreas Noever <andreas.noever@gmail.com>
thunderbolt: Add path setup code.

A thunderbolt path is a unidirectional channel between two thunderbolt
ports. Two such paths are needed to establish a pci tunnel.

This patch introduces struct tb_path as well as a set of tb_path_*
methods which are used to activate & deactivate paths.

Signed-off-by: Andreas Noever <andreas.noever@gmail.com>
thunderbolt: Add support for simple pci tunnels

A pci downstream and pci upstream port can be connected through a
tunnel. To establish the tunnel we have to setup two unidirectional
paths between the two ports.

Right now we only support paths with two hops (i.e. no chaining) and at
most one pci device per thunderbolt device.

Signed-off-by: Andreas Noever <andreas.noever@gmail.com>
PCI: Add pci_fixup_suspend_late quirk pass

Add pci_fixup_suspend_late as a new pci_fixup_pass. The pass is called
from suspend_noirq and poweroff_noirq. Using the same pass for suspend
and hibernate is consistent with resume_early which is called by
resume_noirq and restore_noirq.

The new quirk pass is required for Thunderbolt support on Apple
hardware.

Signed-off-by: Andreas Noever <andreas.noever@gmail.com>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
PCI: Suspend/resume quirks for Apple thunderbolt

Add two quirks to support thunderbolt suspend/resume on Apple systems.
We need to perform two different actions during suspend and resume:

The whole controller has to be powered down before suspend. If this is
not done then the native host interface device will be gone after resume
if a thunderbolt device was plugged in before suspending. The controller
represents itself as multiple PCI devices/bridges. To power it down we
hook into the upstream bridge of the controller and call the magic ACPI
methods.  Power will be restored automatically during resume (by the
firmware presumably).

During resume we have to wait for the native host interface to
reestablish all pci tunnels. Since there is no parent-child relationship
between the NHI and the bridges we have to explicitly wait for them
using device_pm_wait_for_dev. We do this in the resume_noirq phase of
the downstream bridges of the controller (which lead into the
thunderbolt tunnels).

Signed-off-by: Andreas Noever <andreas.noever@gmail.com>
thunderbolt: Read switch uid from EEPROM

Add eeprom access code and read the uid during switch initialization.
The UID will be used to check device identity after suspend.

Signed-off-by: Andreas Noever <andreas.noever@gmail.com>
thunderbolt: Add suspend/hibernate support

We use _noirq since we have to restore the pci tunnels before the pci
core wakes the tunneled devices.

Signed-off-by: Andreas Noever <andreas.noever@gmail.com>
ACPI: Support _OSI("Darwin") correctly

Apple hardware queries _OSI("Darwin") in order to determine whether the
system is running OS X, and changes firmware behaviour based on the answer.
The most obvious difference in behaviour is that Thunderbolt hardware is
forcibly powered down unless the system is running OS X. The obvious solution
would be to simply add Darwin to the list of supported _OSI strings, but this
causes problems.

Recent Apple hardware includes two separate methods for checking _OSI
strings. The first will check whether Darwin is supported, and if so will
exit. The second will check whether Darwin is supported, but will then
continue to check for further operating systems. If a further operating
system is found then later firmware code will assume that the OS is not OS X.
This results in the unfortunate situation where the Thunderbolt controller is
available at boot time but remains powered down after suspend.

The easiest way to handle this is to special-case it in the Linux-specific
OSI handling code. If we see Darwin, we should answer true and then disable
all other _OSI vendor strings.

Signed-off-by: Matthew Garrett <matthew.garrett@nebula.com>
ACPI: Don't call PCI OSC on Apple hardware when claiming to be Darwin

The Apple PCI _OSC method has the following code:

if (LEqual (0x01, OSDW ()))
  if (LAnd (LEqual (Arg0, GUID), NEXP)
    (do stuff)
  else
    (fail)
NEXP is a value in high memory and is presumably under the control of
the firmware. No methods set it. The methods that are called in the "do
stuff" path are dummies. Unless there's some additional firmware call in
early boot, there's no way for this call to succeed - and even if it
does, it doesn't do anything.

The easiest way to handle this is simply to ignore it. We know which
flags would be set, so just set them by hand if the platform is running
in Darwin mode.

Signed-off-by: Matthew Garrett <matthew.garrett@nebula.com>
ACPI: Don't assume the existence of an SBS charger

Apple hardware continues to expose an ACPI AC charger even when using
SBS to report battery state. The charger status byte returns all 0s in
this case.  Since the spec requires that bit 4 be 1 at all times, assume
that there's not really a charger if it's set to zero.

Signed-off-by: Matthew Garrett <matthew.garrett@nebula.com>
ACPI: Disable smart battery manager on Apple

Touching the smart battery manager at all on Apple hardware appears to
make it unhappy - unplugging the AC adapter triggers accesses that hang
the controller for several minutes. Quirk it out via DMI in order to
avoid this.  Compensate by changing battery presence if we fail to
communicate with the battery.

Signed-off-by: Matthew Garrett <matthew.garrett@nebula.com>