When a device is hotplugged, Presence Detect and Link Up events often do
not occur simultaneously, but with a lag of a few milliseconds.  Only
the first event received is relevant, the other one can be disregarded.

Moreover, Stefan Roese reports that on certain platforms, Link State and
Presence Detect may flap for up to 100 ms before stabilizing, suggesting
that such events should be disregarded for at least this long:
https://lkml.kernel.org/r/20180130084121.18653-1-sr@denx.de

On slot enablement, pciehp_check_link_status() waits for 100 ms per
PCIe r4.0, sec 6.7.3.3, then probes the hotplugged device's vendor
register for up to 1 second.

If this succeeds, the link is definitely up, so ignore any Presence
Detect or Link State events that occurred up to this point.

pciehp_check_link_status() then checks the Link Training bit in the
Link Status register.  This is the final opportunity to detect
inaccessibility of the device and abort slot enablement.  Any link
or presence change that occurs afterwards will cause the slot to be
disabled again immediately after attempting to enable it.

The astute reviewer may appreciate that achieving this behavior would be
more complicated had pciehp not just been converted to enable/disable
the slot exclusively from the IRQ thread:  When the slot is enabled via
sysfs, each link or presence flap would otherwise cause the IRQ thread
to run and it would have to sense that those events are belonging to a
concurrent slot enablement operation and disregard them.  It would be
much more difficult than this mere 3 line change.
Signed-off-by: NLukas Wunner <lukas@wunner.de>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Cc: Stefan Roese <sr@denx.de>

No callers of pciehp_enable/disable_slot() outside of pciehp_ctrl.c
remain, so declare the functions static.  For now this requires forward
declarations.  Those can be eliminated by reshuffling functions once the
ongoing effort to refactor the driver has settled.
Signed-off-by: NLukas Wunner <lukas@wunner.de>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>

Previously slot enablement and disablement could happen concurrently.
But now it's under the exclusive control of the IRQ thread, rendering
the locking obsolete.  Drop it.
Signed-off-by: NLukas Wunner <lukas@wunner.de>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>

Besides the IRQ thread, there are several other places in the driver
which enable or disable the slot:

- pciehp_probe() enables the slot if it's occupied and the pciehp_force
  module parameter is used.

- pciehp_resume() enables or disables the slot after system sleep.

- pciehp_queue_pushbutton_work() enables or disables the slot after the
  5 second delay following an Attention Button press.

- pciehp_sysfs_enable_slot() and pciehp_sysfs_disable_slot() enable or
  disable the slot on sysfs write.

This requires locking and complicates pciehp's state machine.

A simplification can be achieved by enabling and disabling the slot
exclusively from the IRQ thread.

Amend the functions listed above to request slot enable/disablement from
the IRQ thread by either synthesizing a Presence Detect Changed event or,
in the case of a disable user request (via sysfs or an Attention Button
press), submitting a newly introduced force disable request.  The latter
is needed because the slot shall be forced off despite being occupied.
For this force disable request, avoid colliding with Slot Status register
bits by using a bit number greater than 16.

For synchronous execution of requests (on sysfs write), wait for the
request to finish and retrieve the result.  There can only ever be one
sysfs write in flight due to the locking in kernfs_fop_write(), hence
there is no risk of returning the result of a different sysfs request to
user space.

The POWERON_STATE and POWEROFF_STATE is now no longer entered by the
above-listed functions, but solely by the IRQ thread when it begins a
power transition.  Afterwards, it moves to STATIC_STATE.  The same
applies to canceling the Attention Button work, it likewise becomes an
IRQ thread only operation.

An immediate consequence is that the POWERON_STATE and POWEROFF_STATE is
never observed by the IRQ thread itself, only by functions called in a
different context, such as pciehp_sysfs_enable_slot().  So remove
handling of these states from pciehp_handle_button_press() and
pciehp_handle_link_change() which are exclusively called from the IRQ
thread.
Signed-off-by: NLukas Wunner <lukas@wunner.de>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>

handle_button_press_event() currently determines whether the slot has
been turned on or off by looking at the Power Controller Control bit in
the Slot Control register.  This assumes that an attention button
implies presence of a power controller even though that's not mandated
by the spec.  Moreover the Power Controller Control bit is unreliable
when a power fault occurs (PCIe r4.0, sec 6.7.1.8).  This issue has
existed since the driver was introduced in 2004.

Fix by replacing STATIC_STATE with ON_STATE and OFF_STATE and tracking
whether the slot has been turned on or off.  This is also a required
ingredient to make pciehp resilient to missed events, which is the
object of an upcoming commit.
Signed-off-by: NLukas Wunner <lukas@wunner.de>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>

The PCI hotplug core has just been refactored to separate slot
initialization for in-kernel use from publication to user space.

Take advantage of it in pciehp by publishing to user space last on
probe.  This will allow enable/disablement of the slot exclusively from
the IRQ thread because the IRQ is requested after initialization for
in-kernel use (thereby getting its unique name needed by the IRQ thread)
but before user space is able to submit enable/disable requests.

On teardown, the order is the same in reverse:  The user space interface
is removed prior to freeing the IRQ and destroying the slot.
Signed-off-by: NLukas Wunner <lukas@wunner.de>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>

When a hotplug driver calls pci_hp_register(), all steps necessary for
registration are carried out in one go, including creation of a kobject
and addition to sysfs.  That's a problem for pciehp once it's converted
to enable/disable the slot exclusively from the IRQ thread:  The thread
needs to be spawned after creation of the kobject (because it uses the
kobject's name), but before addition to sysfs (because it will handle
enable/disable requests submitted via sysfs).

pci_hp_deregister() does offer a ->release callback that's invoked
after deletion from sysfs and before destruction of the kobject.  But
because pci_hp_register() doesn't offer a counterpart, hotplug drivers'
->probe and ->remove code becomes asymmetric, which is error prone
as recently discovered use-after-free bugs in pciehp's ->remove hook
have shown.

In a sense, this appears to be a case of the midlayer antipattern:

   "The core thesis of the "midlayer mistake" is that midlayers are
    bad and should not exist.  That common functionality which it is
    so tempting to put in a midlayer should instead be provided as
    library routines which can [be] used, augmented, or ignored by
    each bottom level driver independently.  Thus every subsystem
    that supports multiple implementations (or drivers) should
    provide a very thin top layer which calls directly into the
    bottom layer drivers, and a rich library of support code that
    eases the implementation of those drivers.  This library is
    available to, but not forced upon, those drivers."
        --  Neil Brown (2009), https://lwn.net/Articles/336262/

The presence of midlayer traits in the PCI hotplug core might be ascribed
to its age:  When it was introduced in February 2002, the blessings of a
library approach might not have been well known:
https://git.kernel.org/tglx/history/c/a8a2069f432c

For comparison, the driver core does offer split functions for creating
a kobject (device_initialize()) and addition to sysfs (device_add()) as
an alternative to carrying out everything at once (device_register()).
This was introduced in October 2002:
https://git.kernel.org/tglx/history/c/8b290eb19962

The odd ->release callback in the PCI hotplug core was added in 2003:
https://git.kernel.org/tglx/history/c/69f8d663b595

Clearly, a library approach would not force every hotplug driver to
implement a ->release callback, but rather allow the driver to remove
the sysfs files, release its data structures and finally destroy the
kobject.  Alternatively, a driver may choose to remove everything with
pci_hp_deregister(), then release its data structures.

To this end, offer drivers pci_hp_initialize() and pci_hp_add() as a
split-up version of pci_hp_register().  Likewise, offer pci_hp_del()
and pci_hp_destroy() as a split-up version of pci_hp_deregister().

Eliminate the ->release callback and move its code into each driver's
teardown routine.

Declare pci_hp_deregister() void, in keeping with the usual kernel
pattern that enablement can fail, but disablement cannot.  It only
returned an error if the caller passed in a NULL pointer or a slot which
has never or is no longer registered or is sharing its name with another
slot.  Those would be bugs, so WARN about them.  Few hotplug drivers
actually checked the return value and those that did only printed a
useless error message to dmesg.  Remove that.

For most drivers the conversion was straightforward since it doesn't
matter whether the code in the ->release callback is executed before or
after destruction of the kobject.  But in the case of ibmphp, it was
unclear to me whether setting slot_cur->ctrl and slot_cur->bus_on to
NULL needs to happen before the kobject is destroyed, so I erred on
the side of caution and ensured that the order stays the same.  Another
nontrivial case is pnv_php, I've found the list and kref logic difficult
to understand, however my impression was that it is safe to delete the
list element and drop the references until after the kobject is
destroyed.
Signed-off-by: NLukas Wunner <lukas@wunner.de>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Acked-by: Andy Shevchenko <andy.shevchenko@gmail.com>  # drivers/platform/x86
Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
Cc: Len Brown <lenb@kernel.org>
Cc: Scott Murray <scott@spiteful.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Gavin Shan <gwshan@linux.vnet.ibm.com>
Cc: Sebastian Ott <sebott@linux.vnet.ibm.com>
Cc: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Cc: Corentin Chary <corentin.chary@gmail.com>
Cc: Darren Hart <dvhart@infradead.org>
Cc: Andy Shevchenko <andy@infradead.org>

Previously the slot workqueue was used to handle events and enable or
disable the slot.  That's no longer the case as those tasks are done
synchronously in the IRQ thread.  The slot workqueue is thus merely used
to handle a button press after the 5 second delay and only one such work
item may be in flight at any given time.  A separate workqueue isn't
necessary for this simple task, so use the system workqueue instead.
Signed-off-by: NLukas Wunner <lukas@wunner.de>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>

Up until now, pciehp's IRQ handler schedules a work item for each event,
which in turn schedules a work item to enable or disable the slot.  This
double indirection was necessary because sleeping wasn't allowed in the
IRQ handler.

However it is now that pciehp has been converted to threaded IRQ handling
and polling, so handle events synchronously in pciehp_ist() and remove
the work item infrastructure (with the exception of work items to handle
a button press after the 5 second delay).

For link or presence change events, move the register read to determine
the current link or presence state behind acquisition of the slot lock
to prevent it from becoming stale while the lock is contended.
Signed-off-by: NLukas Wunner <lukas@wunner.de>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>

If the attention button is pressed to power on the slot AND the user
powers on the slot via sysfs before 5 seconds have elapsed AND powering
on the slot fails because either the slot is unoccupied OR the latch is
open, we neglect turning off the green LED so it keeps on blinking.

That's because the error path of pciehp_sysfs_enable_slot() doesn't call
pciehp_green_led_off(), unlike pciehp_power_thread() which does.
The bug has been present since 2004 when the driver was introduced.

Fix by deduplicating common code in pciehp_sysfs_enable_slot() and
pciehp_power_thread() into a wrapper function pciehp_enable_slot() and
renaming the existing function to __pciehp_enable_slot().  Same for
pciehp_disable_slot().  This will also simplify the upcoming rework of
pciehp's event handling.
Signed-off-by: NLukas Wunner <lukas@wunner.de>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>

We've just converted pciehp to threaded IRQ handling, but still cannot
sleep in pciehp_ist() because the function is also called in poll mode,
which runs in softirq context (from a timer).

Convert poll mode to a kthread so that pciehp_ist() always runs in task
context.
Signed-off-by: NLukas Wunner <lukas@wunner.de>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>

pciehp's IRQ handler queues up a work item for each event signaled by
the hardware.  A more modern alternative is to let a long running
kthread service the events.  The IRQ handler's sole job is then to check
whether the IRQ originated from the device in question, acknowledge its
receipt to the hardware to quiesce the interrupt and wake up the kthread.

One benefit is reduced latency to handle the IRQ, which is a necessity
for realtime environments.  Another benefit is that we can make pciehp
simpler and more robust by handling events synchronously in process
context, rather than asynchronously by queueing up work items.  pciehp's
usage of work items is a historic artifact, it predates the introduction
of threaded IRQ handlers by two years.  (The former was introduced in
2007 with commit 5d386e1a ("pciehp: Event handling rework"), the
latter in 2009 with commit 3aa551c9 ("genirq: add threaded interrupt
handler support").)

Convert pciehp to threaded IRQ handling by retrieving the pending events
in pciehp_isr(), saving them for later consumption by the thread handler
pciehp_ist() and clearing them in the Slot Status register.

By clearing the Slot Status (and thereby acknowledging the events) in
pciehp_isr(), we can avoid requesting the IRQ with IRQF_ONESHOT, which
would have the unpleasant side effect of starving devices sharing the
IRQ until pciehp_ist() has finished.

pciehp_isr() does not count how many times each event occurred, but
merely records the fact *that* an event occurred.  If the same event
occurs a second time before pciehp_ist() is woken, that second event
will not be recorded separately, which is problematic according to
commit fad214b0 ("PCI: pciehp: Process all hotplug events before
looking for new ones") because we may miss removal of a card in-between
two back-to-back insertions.  We're about to make pciehp_ist() resilient
to missed events.  The present commit regresses the driver's behavior
temporarily in order to separate the changes into reviewable chunks.
This doesn't affect regular slow-motion hotplug, only plug-unplug-plug
operations that happen in a timespan shorter than wakeup of the IRQ
thread.
Signed-off-by: NLukas Wunner <lukas@wunner.de>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Mayurkumar Patel <mayurkumar.patel@intel.com>
Cc: Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>

Document the driver's data structures to lower the barrier to entry for
contributors.
Signed-off-by: NLukas Wunner <lukas@wunner.de>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>

Since commit 0f4bd801 ("PCI: hotplug: Drop checking of PCI_BRIDGE_
CONTROL in *_unconfigure_device()"), pciehp_unconfigure_device() can no
longer fail, so declare it and its sole caller remove_board() void, in
keeping with the usual kernel pattern that enablement can fail, but
disablement cannot.  No functional change intended.
Signed-off-by: NLukas Wunner <lukas@wunner.de>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Cc: Mika Westerberg <mika.westerberg@linux.intel.com>

pciehp_disable_slot() checks if the ctrl attribute of the slot is NULL
and bails out if so.  However the function is not called prior to the
attribute being set in pcie_init_slot(), and pcie_init_slot() is not
called if ctrl is NULL.  So the check is unnecessary.  Drop it.

It has been present ever since the driver was introduced in 2004, but it
was already unnecessary back then:
https://git.kernel.org/tglx/history/c/c16b4b14d980Signed-off-by: NLukas Wunner <lukas@wunner.de>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>

Commit b440bde7 ("PCI: Add pci_ignore_hotplug() to ignore hotplug
events for a device") iterates over the devices on a hotplug port's
subordinate bus in pciehp's IRQ handler without acquiring pci_bus_sem.
It is thus possible for a user to cause a crash by concurrently
manipulating the device list, e.g. by disabling slot power via sysfs
on a different CPU or by initiating a remove/rescan via sysfs.

This can't be fixed by acquiring pci_bus_sem because it may sleep.
The simplest fix is to avoid the list iteration altogether and just
check the ignore_hotplug flag on the port itself.  This works because
pci_ignore_hotplug() sets the flag both on the device as well as on its
parent bridge.

We do lose the ability to print the name of the device blocking hotplug
in the debug message, but that's probably bearable.

Fixes: b440bde7 ("PCI: Add pci_ignore_hotplug() to ignore hotplug events for a device")
Signed-off-by: NLukas Wunner <lukas@wunner.de>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Cc: stable@vger.kernel.org

When pciehp is unbound (e.g. on unplug of a Thunderbolt device), the
hotplug_slot struct is deregistered and thus freed before freeing the
IRQ.  The IRQ handler and the work items it schedules print the slot
name referenced from the freed structure in various informational and
debug log messages, each time resulting in a quadruple dereference of
freed pointers (hotplug_slot -> pci_slot -> kobject -> name).

At best the slot name is logged as "(null)", at worst kernel memory is
exposed in logs or the driver crashes:

  pciehp 0000:10:00.0:pcie204: Slot((null)): Card not present

An attacker may provoke the bug by unplugging multiple devices on a
Thunderbolt daisy chain at once.  Unplugging can also be simulated by
powering down slots via sysfs.  The bug is particularly easy to trigger
in poll mode.

It has been present since the driver's introduction in 2004:
https://git.kernel.org/tglx/history/c/c16b4b14d980

Fix by rearranging teardown such that the IRQ is freed first.  Run the
work items queued by the IRQ handler to completion before freeing the
hotplug_slot struct by draining the work queue from the ->release_slot
callback which is invoked by pci_hp_deregister().
Signed-off-by: NLukas Wunner <lukas@wunner.de>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Cc: stable@vger.kernel.org # v2.6.4

If addition of sysfs files fails on registration of a hotplug slot, the
struct pci_slot as well as the entry in the slot_list is leaked.  The
issue has been present since the hotplug core was introduced in 2002:
https://git.kernel.org/tglx/history/c/a8a2069f432c

Perhaps the idea was that even though sysfs addition fails, the slot
should still be usable.  But that's not how drivers use the interface,
they abort probe if a non-zero value is returned.
Signed-off-by: NLukas Wunner <lukas@wunner.de>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Cc: stable@vger.kernel.org # v2.4.15+
Cc: Greg Kroah-Hartman <greg@kroah.com>

Ten years ago, commit 58319b80 ("PCI: Hotplug core: remove 'name'")
dropped the name element from struct hotplug_slot but neglected to update
the skeleton driver.

That same year, commit f46753c5 ("PCI: introduce pci_slot") raised the
number of arguments to pci_hp_register() from one to four.

Fourteen years ago, historic commit 7ab60fc1b8e7 ("PCI Hotplug skeleton:
final cleanups") removed all usages of the retval variable from
pcihp_skel_init() but not the variable itself, provoking a compiler
warning: https://git.kernel.org/tglx/history/c/7ab60fc1b8e7

It seems fair to assume the driver hasn't been used as a template for a new
driver in a while.  Per Bjorn's and Christoph's preference, delete it.
Signed-off-by: NLukas Wunner <lukas@wunner.de>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Cc: Christoph Hellwig <hch@lst.de>

The shpchp driver registers for all PCI bridge devices.  Its probe method
should fail if either (1) the bridge doesn't have an SHPC or (2) the OS
isn't allowed to use it (the platform firmware may be operating the SHPC
itself).

Separate these two tests into:

  - A new shpc_capable() that looks for the SHPC hardware and is applicable
    on all systems (ACPI and non-ACPI), and

  - A simplified acpi_get_hp_hw_control_from_firmware() that we call only
    when we already know an SHPC exists and there may be ACPI methods to
    either request permission to use it (_OSC) or transfer control to the
    OS (OSHP).

acpi_get_hp_hw_control_from_firmware() is implemented when CONFIG_ACPI=y,
but does nothing if the current platform doesn't support ACPI.
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Reviewed-by: NMika Westerberg <mika.westerberg@linux.intel.com>

An SHPC can be operated either by platform firmware or by the OS.  The OS
uses a host bridge ACPI _OSC method to negotiate for control of SHPC.  If
firmware wants to prevent an OS from operating an SHPC, it must supply an
_OSC method that declines to grant SHPC ownership to the OS.

If acpi_pci_find_root() returns NULL, it means there's no ACPI host bridge
device (PNP0A03 or PNP0A08) and hence no _OSC method, so the OS is always
allowed to manage the SHPC.

Fix a NULL pointer dereference when CONFIG_ACPI=y but the current
hardware/firmware platform doesn't support ACPI.  In that case,
acpi_get_hp_hw_control_from_firmware() is implemented but
acpi_pci_find_root() returns NULL.

Fixes: 90cc0c3c ("PCI: shpchp: Add shpchp_is_native()")
Link: https://lkml.kernel.org/r/20180621164715.28160-1-marc.zyngier@arm.comReported-by: NMarc Zyngier <marc.zyngier@arm.com>
Tested-by: NMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Reviewed-by: NMika Westerberg <mika.westerberg@linux.intel.com>

Remove unnecessary parentheses.
Signed-off-by: NMika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Reviewed-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

Following PCIehp mark the unplugged PCI devices disconnected.  This makes
sure PCI core code leaves the now missing hardware registers alone.
Signed-off-by: NMika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Reviewed-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: NAndy Shevchenko <andriy.shevchenko@linux.intel.com>

When acpiphp re-enumerates a PCI hierarchy because of an ACPI Notify()
event, we should skip bridges managed by native hotplug (pciehp or shpchp).
We don't want to scan below a native hotplug bridge until the hotplug
controller generates a hot-add event.

A typical scenario is a Root Port leading to a Thunderbolt host router that
remains powered off until something is connected to it.  See [1] for the
lspci details.

  1. Before something is connected, only the Root Port exists.  It has
     PCI_EXP_SLTCAP_HPC set and pciehp is responsible for hotplug:

       00:1b.0 Root Port (HotPlug+)

  2. When a USB-C or Thunderbolt device is connected, the Switch in the
     Thunderbolt host router is powered up, the Root Port signals a hotplug
     add event and pciehp enumerates the Switch:

       01:00.0 Switch Upstream Port   to [bus 02-39]
       02:00.0 Switch Downstream Port to [bus 03]    (HotPlug-, to NHI)
       02:01.0 Switch Downstream Port to [bus 04-38] (HotPlug+, to Thunderbolt connector)
       02:02.0 Switch Downstream Port to [bus 39]    (HotPlug-, to xHCI)

     The 02:00.0 and 02:02.0 Ports lead to Endpoints that are not powered
     up yet.  The Ports have PCI_EXP_SLTCAP_HPC cleared, so pciehp doesn't
     handle hotplug for them and we assign minimal resources to them.

     The 02:01.0 Port has PCI_EXP_SLTCAP_HPC set, so pciehp handles native
     hotplug events for it.

  3. The BIOS powers up the xHCI controller.  If a Thunderbolt device was
     connected (not just a USB-C device), it also powers up the NHI.  Then
     it sends an ACPI Notify() to the Root Port, and acpiphp enumerates the
     new device(s):

       03:00.0 Thunderbolt Host Controller (NHI) Endpoint
       39:00.0 xHCI Endpoint

  4. If a Thunderbolt device was connected, the host router firmware uses
     the NHI to set up Thunderbolt tunnels and triggers a native hotplug
     event (via 02:01.0 in this example).  Then pciehp enumerates the new
     Thunderbolt devices:

       04:00.0 Switch Upstream Port   to [bus 05-38]
       05:01.0 Switch Downstream Port to [bus 06-09] (HotPlug-)
       05:04.0 Switch Downstream Port to [bus 0a-38] (HotPlug+)

     In this example, 05:01.0 leads to another Switch and some NICs.  This
     subtree is static, so 05:01.0 doesn't support hotplug and has
     PCI_EXP_SLTCAP_HPC cleared.

In step 3, acpiphp previously enumerated everything below the Root Port,
including things below the 02:01.0 Port.  We don't want that because pciehp
expects to manage hotplug below that Port, and firmware on the host router
may be in the middle of configuring its Link so it may not be ready yet.

To make this work better with the native PCIe (pciehp) and standard PCI
(shpchp) hotplug drivers, we let them handle all slot management and
resource allocation for hotplug bridges and restrict ACPI hotplug to
non-hotplug bridges.

[1] https://bugzilla.kernel.org/show_bug.cgi?id=199581#c5
Link: https://lkml.kernel.org/r/20180529160155.1738-1-mika.westerberg@linux.intel.comSigned-off-by: NMika Westerberg <mika.westerberg@linux.intel.com>
[bhelgaas: changelog, use hotplug_is_native() instead of
dev->is_hotplug_bridge]
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Reviewed-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: NAndy Shevchenko <andriy.shevchenko@linux.intel.com>

In the same way we do for pciehp, add shpchp_is_native(), which returns
true if the bridge should be handled by the native SHPC driver.  Then
convert the driver to use this function.
Signed-off-by: NMika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>

The fix for an AMD POGO erratum related to SHPC incorrectly identified the
device.  The workaround should be applied only for AMD POGO devices, but it
was instead applied to:

  - all AMD bridges, and
  - all devices from any vendor with device ID 0x7458

Fixes: 53044f35 ("[PATCH] PCI Hotplug: shpchp: AMD POGO errata fix")
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Reviewed-by: NMika Westerberg <mika.westerberg@linux.intel.com>
Reviewed-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

Use dev_printk() for messages related to requesting control of SHPC hotplug
via the OSHP method.
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Reviewed-by: NMika Westerberg <mika.westerberg@linux.intel.com>
Reviewed-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

get_hp_hw_control_from_firmware() is a trivial wrapper around
acpi_get_hp_hw_control_from_firmware(), probably intended to be generic in
case other firmware needed similar OS/platform negotiation.

Remove get_hp_hw_control_from_firmware() and call
acpi_get_hp_hw_control_from_firmware() directly.  Add a stub for
acpi_get_hp_hw_control_from_firmware() for the non-ACPI case.
Signed-off-by: NMika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Reviewed-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

acpi_get_hp_hw_control_from_firmware() no longer uses the flags parameter,
so remove it.
Signed-off-by: NMika Westerberg <mika.westerberg@linux.intel.com>
[bhelgaas: split to separate patch]
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Reviewed-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

If _OSC exists, we evaluated it when adding the ACPI host bridge, and we
requested SHPC control if the SHPC driver is present.  Use the result of
that _OSC evaluation instead of evaluating it again.
Signed-off-by: NMika Westerberg <mika.westerberg@linux.intel.com>
[bhelgaas: split to separate patch]
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>

We need to be able coordinate between SHPC and acpiphp to determine which
driver handles hotplug of a given bridge.  Because acpiphp is already bool,
convert SHPC to be bool as well.
Suggested-by: NBjorn Helgaas <bhelgaas@google.com>
Signed-off-by: NMika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Reviewed-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

After a suspend/resume cycle the Presence Detect or Data Link Layer Status
Changed bits might be set.  If we don't clear them those events will not
fire anymore and nothing happens for instance when a device is now
hot-unplugged.

Fix this by clearing those bits in a newly introduced function
pcie_reenable_notification().  This should be fine because immediately
after, we check if the adapter is still present by reading directly from
the status register.
Signed-off-by: NMika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Reviewed-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: NAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: stable@vger.kernel.org

The device node iterators perform an of_node_get() on each iteration, so a
jump out of the loop requires an of_node_put().

The semantic patch that fixes this problem is as follows
(http://coccinelle.lip6.fr):

// <smpl>
@@
expression root,e;
local idexpression child;
iterator name for_each_child_of_node;
@@

 for_each_child_of_node(root, child) {
   ... when != of_node_put(child)
       when != e = child
+  of_node_put(child);
?  break;
   ...
}
... when != child
// </smpl>
Signed-off-by: NJulia Lawall <Julia.Lawall@lip6.fr>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>

Clients such as hotplug and Downstream Port Containment (DPC) both need to
wait until a link becomes active or inactive.

Add a generic pcie_wait_link_active() interface and use it instead of
duplicating the code.
Signed-off-by: NOza Pawandeep <poza@codeaurora.org>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Reviewed-by: NKeith Busch <keith.busch@intel.com>

Several PCIe hotplug controllers have errata that mean they do not set the
Command Completed bit unless writes to the Slot Command register change
"Control" bits.  Command Completed is never set for writes that only change
software notification "Enable" bits.  This results in timeouts like this:

  pciehp 0000:00:1c.0:pcie004: Timeout on hotplug command 0x1038 (issued 65284 msec ago)

When this erratum is present, avoid these timeouts by marking commands
"completed" immediately unless they change the "Control" bits.

Here's the text of the Intel erratum CF118.  We assume this applies to all
Intel parts:

  CF118        PCIe Slot Status Register Command Completed bit not always
               updated on any configuration write to the Slot Control
               Register

  Problem:     For PCIe root ports (devices 0 - 10) supporting hot-plug,
               the Slot Status Register (offset AAh) Command Completed
               (bit[4]) status is updated under the following condition:
               IOH will set Command Completed bit after delivering the new
               commands written in the Slot Controller register (offset
               A8h) to VPP. The IOH detects new commands written in Slot
               Control register by checking the change of value for Power
               Controller Control (bit[10]), Power Indicator Control
               (bits[9:8]), Attention Indicator Control (bits[7:6]), or
               Electromechanical Interlock Control (bit[11]) fields. Any
               other configuration writes to the Slot Control register
               without changing the values of these fields will not cause
               Command Completed bit to be set.

               The PCIe Base Specification Revision 2.0 or later describes
               the “Slot Control Register” in section 7.8.10, as follows
               (Reference section 7.8.10, Slot Control Register, Offset
               18h). In hot-plug capable Downstream Ports, a write to the
               Slot Control register must cause a hot-plug command to be
               generated (see Section 6.7.3.2 for details on hot-plug
               commands). A write to the Slot Control register in a
               Downstream Port that is not hotplug capable must not cause a
               hot-plug command to be executed.

               The PCIe Spec intended that every write to the Slot Control
               Register is a command and expected a command complete status
               to abstract the VPP implementation specific nuances from the
               OS software. IOH PCIe Slot Control Register implementation
               is not fully conforming to the PCIe Specification in this
               respect.

  Implication: Software checking on the Command Completed status after
               writing to the Slot Control register may time out.

  Workaround:  Software can read the Slot Control register and compare the
               existing and new values to determine if it should check the
               Command Completed status after writing to the Slot Control
               register.

Per Sinan, the Qualcomm QDF2400 controller also does not set the Command
Completed bit unless writes to the Slot Command register change "Control"
bits.

Link: http://www.intel.com/content/www/us/en/processors/xeon/xeon-e7-v2-spec-update.html
Link: https://lkml.kernel.org/r/8770820b-85a0-172b-7230-3a44524e6c9f@molgen.mpg.de
Reported-by: Paul Menzel <pmenzel+linux-pci@molgen.mpg.de>	# Lenovo X60
Tested-by: Paul Menzel <pmenzel+linux-pci@molgen.mpg.de>	# Lenovo X60
Signed-off-by: Sinan Kaya <okaya@codeaurora.org>		# Qcom quirk
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Reviewed-by: NMika Westerberg <mika.westerberg@linux.intel.com>

The "rc" variable is only initialized on the error path.  The caller
doesn't check the return but, if "rc" is non-zero, then this function is
basically a no-op.

Fixes: 3749c51a ("PCI: Make current and maximum bus speeds part of the PCI core")
Signed-off-by: NDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>

Mike Lothian reported that plugging in a USB-C device does not work
properly in his Dell Alienware system.  This system has an Intel Alpine
Ridge Thunderbolt controller providing USB-C functionality.  In these
systems the USB controller (xHCI) is hotplugged whenever a device is
connected to the port using ACPI-based hotplug.

The ACPI description of the root port in question is as follows:

  Device (RP01)
  {
      Name (_ADR, 0x001C0000)

      Device (PXSX)
      {
          Name (_ADR, 0x02)

          Method (_RMV, 0, NotSerialized)
          {
              // ...
          }
      }

Here _ADR 0x02 means device 0, function 2 on the bus under root port (RP01)
but that seems to be incorrect because device 0 is the upstream port of the
Alpine Ridge PCIe switch and it has no functions other than 0 (the bridge
itself).  When we get ACPI Notify() to the root port resulting from
connecting a USB-C device, Linux tries to read PCI_VENDOR_ID from device 0,
function 2 which of course always returns 0xffffffff because there is no
such function and we never find the device.

In Windows this works fine.

Now, since we get ACPI Notify() to the root port and not to the PXSX device
we should actually start our scan from there as well and not from the
non-existent PXSX device.  Fix this by checking presence of the slot itself
(function 0) if we fail to do that otherwise.

While there use pci_bus_read_dev_vendor_id() in get_slot_status(), which is
the recommended way to read Device and Vendor IDs of devices on PCI buses.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=198557Reported-by: NMike Lothian <mike@fireburn.co.uk>
Signed-off-by: NMika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Reviewed-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: stable@vger.kernel.org

In pnv_php_unregister_one(), pnv_php_put_slot() might kfree
php_slot structure. But there is pci_hp_deregister() after
that with php_slot reference.

This patch moves pnv_php_put_slot() to the end of function.
Signed-off-by: NSimon Guo <wei.guo.simon@gmail.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

pcieport_if.h contained the interfaces to register port service driver,
e.g., pcie_port_service_register().  portdrv.h contained internal data
structures of the port driver.

I don't think it's worth keeping those files separate, since both headers
and their users are all inside the PCI core.

Merge pcieport_if.h directly in drivers/pci/pcie/portdrv.h and update the
users to include that instead.
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>

Check io_node for NULL before dereferencing it.
Signed-off-by: NShawn Lin <shawn.lin@rock-chips.com>
Signed-off-by: NBjorn Helgaas <helgaas@kernel.org>