driver core: component: fix spellos

Correct spelling mistakes reported by codespell.

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: dri-devel@lists.freedesktop.org
Link: https://lore.kernel.org/r/20240107055750.22441-1-rdunlap@infradead.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers: base: component: fix memory leak with using debugfs_lookup()

When calling debugfs_lookup() the result must have dput() called on it,
otherwise the memory will leak over time. To make things simpler, just
call debugfs_lookup_and_remove() instead which handles all of the logic
at once.

Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Link: https://lore.kernel.org/r/20230202141621.2296458-1-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

component: Add common helper for compare/release functions

The component requires the compare/release functions, there are so many
copies in current kernel. Just define four common helpers for them.

Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Signed-off-by: Yong Wu <yong.wu@mediatek.com>
Link: https://lore.kernel.org/r/20220214060819.7334-2-yong.wu@mediatek.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

component: Replace most references to 'master' with 'aggregate device'

Remove most references to 'master' in the code and replace them with
some form of 'aggregate device'. This better reflects the reality of
what this code does, i.e. an aggregate device that represents a
device like a GPU card once some set of devices that make up the
aggregate device probe and register with the component framework.

Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Rob Clark <robdclark@gmail.com>
Cc: Russell King <rmk+kernel@arm.linux.org.uk>
Cc: Saravana Kannan <saravanak@google.com>
Signed-off-by: Stephen Boyd <swboyd@chromium.org>
Link: https://lore.kernel.org/r/20220127200141.1295328-2-swboyd@chromium.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

component: do not leave master devres group open after bind

In current code, the devres group for aggregate master is left open
after call to component_master_add_*(). This leads to problems when the
master does further managed allocations on its own. When any
participating driver calls component_del(), this leads to immediate
release of resources.

This came up when investigating a page fault occurring with i915 DRM
driver unbind with 5.15-rc1 kernel. The following sequence occurs:

i915_pci_remove()
-> intel_display_driver_unregister()
-> i915_audio_component_cleanup()
-> component_del()
-> component.c:take_down_master()
-> hdac_component_master_unbind() [via master->ops->unbind()]
-> devres_release_group(master->parent, NULL)

With older kernels this has not caused issues, but with audio driver
moving to use managed interfaces for more of its allocations, this no
longer works. Devres log shows following to occur:

component_master_add_with_match()
[ 126.886032] snd_hda_intel 0000:00:1f.3: DEVRES ADD 00000000323ccdc5 devm_component_match_release (24 bytes)
[ 126.886045] snd_hda_intel 0000:00:1f.3: DEVRES ADD 00000000865cdb29 grp< (0 bytes)
[ 126.886049] snd_hda_intel 0000:00:1f.3: DEVRES ADD 000000001b480725 grp< (0 bytes)

audio driver completes its PCI probe()
[ 126.892238] snd_hda_intel 0000:00:1f.3: DEVRES ADD 000000001b480725 pcim_iomap_release (48 bytes)

component_del() called() at DRM/i915 unbind()
[ 137.579422] i915 0000:00:02.0: DEVRES REL 00000000ef44c293 grp< (0 bytes)
[ 137.579445] snd_hda_intel 0000:00:1f.3: DEVRES REL 00000000865cdb29 grp< (0 bytes)
[ 137.579458] snd_hda_intel 0000:00:1f.3: DEVRES REL 000000001b480725 pcim_iomap_release (48 bytes)

So the "devres_release_group(master->parent, NULL)" ends up freeing the
pcim_iomap allocation. Upon next runtime resume, the audio driver will
cause a page fault as the iomap alloc was released without the driver
knowing about it.

Fix this issue by using the "struct master" pointer as identifier for
the devres group, and by closing the devres group after
the master->ops->bind() call is done. This allows devres allocations
done by the driver acting as master to be isolated from the binding state
of the aggregate driver. This modifies the logic originally introduced in
commit 9e1ccb4a7700 ("drivers/base: fix devres handling for master device")

Fixes: 9e1ccb4a7700 ("drivers/base: fix devres handling for master device")
Cc: stable@vger.kernel.org
Acked-by: Imre Deak <imre.deak@intel.com>
Acked-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Signed-off-by: Kai Vehmanen <kai.vehmanen@linux.intel.com>
BugLink: https://gitlab.freedesktop.org/drm/intel/-/issues/4136
Link: https://lore.kernel.org/r/20211013161345.3755341-1-kai.vehmanen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/base/component.c: remove superfluous header files from component.c

component.c hasn't use any macro or function declared in linux/kref.h.
Thus, these files can be removed from component.c safely without
affecting the compilation of the drivers/base/ module

Signed-off-by: Mianhan Liu <liumh1@shanghaitech.edu.cn>
Link: https://lore.kernel.org/r/20210928193849.28717-1-liumh1@shanghaitech.edu.cn
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

component: Rename 'dev' to 'parent'

Let's rename this struct member to 'parent' to better reflect the
reality that it's the parent device of this psuedo-device. In the next
patch we'll put a 'struct device' inside of this struct so moving this
away simplifies that patch by reducing the number of places that 'dev'
is modified.

Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Rob Clark <robdclark@gmail.com>
Cc: Russell King <rmk+kernel@arm.linux.org.uk>
Cc: Saravana Kannan <saravanak@google.com>
Signed-off-by: Stephen Boyd <swboyd@chromium.org>
Link: https://lore.kernel.org/r/20210520002519.3538432-3-swboyd@chromium.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

component: Drop 'dev' argument to component_match_realloc()

This argument isn't used. Drop it.

Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Rob Clark <robdclark@gmail.com>
Cc: Russell King <rmk+kernel@arm.linux.org.uk>
Cc: Saravana Kannan <saravanak@google.com>
Signed-off-by: Stephen Boyd <swboyd@chromium.org>
Link: https://lore.kernel.org/r/20210520002519.3538432-2-swboyd@chromium.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

driver core: component: remove dentry pointer in "struct master"

There is no need to keep around a pointer to a dentry when all it is
used for is to remove the debugfs file when tearing things down. As the
name is simple, have debugfs look up the dentry when removing things,
keeping the logic much simpler.

Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: linux-kernel@vger.kernel.org
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Link: https://lore.kernel.org/r/20210216142400.3759099-1-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

component: Silence bind error on -EPROBE_DEFER

If a component fails to bind due to -EPROBE_DEFER we should not log an
error as this is not a real failure.

Fixes messages like:
vc4-drm soc:gpu: failed to bind 3f902000.hdmi (ops vc4_hdmi_ops): -517
vc4-drm soc:gpu: master bind failed: -517

Signed-off-by: James Hilliard <james.hilliard1@gmail.com>
Link: https://lore.kernel.org/r/20200411190241.89404-1-james.hilliard1@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

component: allow missing unbind callback

The component framework reuses the devres managed functions. There is no
need to specify an unbind() callback if the driver only wants to release
the devres managed resources. The bind/unbind is like the probe/remove
pair. The bind/probe is necessary and the unbind/remove is optional.

Signed-off-by: Marco Felsch <m.felsch@pengutronix.de>
Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de>
Link: https://lore.kernel.org/r/20200227104547.30085-1-m.felsch@pengutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

component: do not dereference opaque pointer in debugfs

The match data does not have to be a struct device pointer, and indeed
very often is not. Attempt to treat it as such easily results in a
crash.

For the components that are not registered, we don't know which device
is missing. Once it it is there, we can use the struct component to get
the device and whether it's bound or not.

Fixes: 59e73854b5fd ('component: add debugfs support')
Signed-off-by: Lubomir Rintel <lkundrak@v3.sk>
Cc: stable <stable@vger.kernel.org>
Cc: Arnaud Pouliquen <arnaud.pouliquen@st.com>
Link: https://lore.kernel.org/r/20191118115431.63626-1-lkundrak@v3.sk
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/component: remove modular code

drivers/base/Makefile always adds component.o to obj-y, like this:

obj-y := component.o core.o bus.o dd.o syscore.o \

Hence it is never compiled as a module. Remove useless modular code.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Link: https://lore.kernel.org/r/20191218144307.19243-1-masahiroy@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/component: kerneldoc polish

Polish the kerneldoc a bit with suggestions from Randy.

v2: Randy found another typo: s/compent/component/

Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Ramalingam C <ramalingam.c@intel.com>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

components: multiple components for a device

Component framework is extended to support multiple components for
a struct device. These will be matched with different masters based on
its sub component value.

We are introducing this, as I915 needs two different components
with different subcomponent value, which will be matched to two
different component masters(Audio and HDCP) based on the subcomponent
values.

v2: Add documenation.

v3: Rebase on top of updated documenation.

v4: Review from Rafael:
- Remove redundant "This" from kerneldoc (also in the previous patch)
- Streamline the logic in find_component() a bit.

Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch> (v1 code)
Signed-off-by: Ramalingam C <ramalingam.c@intel.com> (v1 commit message)
Cc: Ramalingam C <ramalingam.c@intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Russell King <rmk+kernel@arm.linux.org.uk>
Cc: Rafael J. Wysocki <rafael@kernel.org>
Cc: Jaroslav Kysela <perex@perex.cz>
Cc: Takashi Iwai <tiwai@suse.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20190207232759.14553-2-daniel.vetter@ffwll.ch

component: Add documentation

While typing these I think doing an s/component_master/aggregate/
would be useful:
- it's shorter :-)
- I think component/aggregate is much more meaningful naming than
component/puppetmaster or something like that. At least to my
English ear "aggregate" emphasizes much more the "assemble a pile of
things into something bigger" aspect, and there's not really much
of a control hierarchy between aggregate and constituing components.

But that's way more than a quick doc typing exercise ...

Thanks to Ram for commenting on an initial draft of these docs.

v2: Review from Rafael:
- git add Documenation/driver-api/component.rst
- lots of polish to the wording + spelling fixes.

v3: Review from Russell:
- s/framework/helper
- clarify the documentation for component_match_add functions.

v4: Remove a few superflous "This".

Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: "C, Ramalingam" <ramalingam.c@intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Russell King <rmk+kernel@arm.linux.org.uk>
Cc: Rafael J. Wysocki <rafael@kernel.org>
Cc: Jaroslav Kysela <perex@perex.cz>
Cc: Takashi Iwai <tiwai@suse.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190207232759.14553-1-daniel.vetter@ffwll.ch

component: convert to DEFINE_SHOW_ATTRIBUTE

Use DEFINE_SHOW_ATTRIBUTE macro to simplify the code.

Signed-off-by: Yangtao Li <tiny.windzz@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

component: fix loop condition to call unbind() if bind() fails

During component_bind_all(), if bind() fails for any
particular component associated with a master, unbind()
should be called for all previous components in that
master's match array, whose bind() might have completed
successfully. As per the current logic, if bind() fails
for the component at position 'n' in the master's match
array, it would start calling unbind() from component in
'n'th position itself and work backwards, and will always
skip calling unbind() for component in 0th position in the
master's match array.
Fix this by updating the loop condition, and the logic to
refer to the components in master's match array, so that
unbind() is called for all components starting from 'n-1'st
position in the array, until (and including) component in
0th position.

Signed-off-by: Banajit Goswami <bgoswami@codeaurora.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

component: add debugfs support

Currently there is no information in any vfs about which devices
a master component consists of, what makes debugging hard if
one of the component devices fails to register.

Add 'device_component' directory to debugfs. Create a new file for each
component master, when it has been added. Remove it on a master
deletion. Show a list of devices required by the given master and their
status (registered or not). This provides an easy way to check, which
device has failed to register if the given master device is not
available in the system.

Signed-off-by: Maciej Purski <m.purski@samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

driver core: Remove redundant license text

Now that the SPDX tag is in all driver core files, that identifies the
license in a specific and legally-defined manner. So the extra GPL text
wording can be removed as it is no longer needed at all.

This is done on a quest to remove the 700+ different ways that files in
the kernel describe the GPL license text. And there's unneeded stuff
like the address (sometimes incorrect) for the FSF which is never
needed.

No copyright headers or other non-license-description text was removed.

Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: "Luis R. Rodriguez" <mcgrof@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

driver core: add SPDX identifiers to all driver core files

It's good to have SPDX identifiers in all files to make it easier to
audit the kernel tree for correct licenses.

Update the driver core files files with the correct SPDX license
identifier based on the license text in the file itself. The SPDX
identifier is a legally binding shorthand, which can be used instead of
the full boiler plate text.

This work is based on a script and data from Thomas Gleixner, Philippe
Ombredanne, and Kate Stewart.

Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: "Luis R. Rodriguez" <mcgrof@kernel.org>
Cc: William Breathitt Gray <vilhelm.gray@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Kate Stewart <kstewart@linuxfoundation.org>
Cc: Philippe Ombredanne <pombredanne@nexb.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

component: remove device from master match list on failed add

Calling component_add() may result in the completion of a set of
devices, which will try to bring up a master. In bringing the master
up, we populate its match array with the current set of children.

If binding any of the devices fails, component_add() itself will fail,
free the struct component entry, and return to the caller. The
now-freed entry is never removed from the master's match array, and
will later be used in a futile attempt to bind to freed memory.

Bring component_add's behaviour on failure to bring up a master into
line with component_del by removing the (to-be-freed) component from
the master's match array.

The specific case which broke was:
- rockchip_drm_drv adds a component master
- dwhdmi_rockchip adds a child component in probe (master incomplete)
- rockchip_drm_vop adds two children in probe, which completes the
set
- inside component_add, we try to bring up the master, having
populated the master's match array, and fail with EPROBE_DEFER from
dwhdmi_rockchip; we delete the putative component
- rockchip_drm_vop's probe fails and returns EPROBE_DEFER
- we later re-probe rockchip_drm_vop and add the component; the
master is complete, so we attempt to bring it up again
- walking the match array, we find the previous child, whose master
pointer doesn't match (as it has been freed in the meantime)
- rockchip_drm_vop probe fails, and will never be attempted again

Fixes: ffc30b74fd6d01588bd3fdebc3b1acc0857e6fc8
Signed-off-by: Daniel Stone <daniels@collabora.com>
Cc: Russell King <rmk+kernel@arm.linux.org.uk>
Cc: Thierry Reding <treding@nvidia.com>
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

component: remove impossible condition

We will be evaluating this condition only if match->num == match->alloc
and that means we have already dereferenced match which implies match
can not be NULL at this point.
Moreover we have done a NULL check on match just before this.

Signed-off-by: Sudip Mukherjee <sudip@vectorindia.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

component: Detach components when deleting master struct

component_master_add_with_match calls find_components which, if any
components already exist, it attaches to the master struct. However, if
we later encounter an error the master struct is deleted, leaving
components with a dangling pointer to it.

If the error was a temporary one, e.g. for probe deferral, then when
the master device is re-probed, it will fail to find the required
components as they appear to already be attached to a master.

Fix this by nulling components pointers to the master struct when it is
deleted. This code is factored out into a separate function so it can be
shared with component_master_del.

Signed-off-by: Jon Medhurst <tixy@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

component: fix crash on x86_64 with hda audio drivers

Maarten reports that the addition of releasing match data to the
component helper results in a general protection fault on x86_64.

This is caused by the devm resources being freed in reverse order
to their allocation, which caused a use-after-free of the match
array.

Switch the match array to be a more conventional kmalloc/kfree()
affair, explicitly freeing it along with the parent match data
structure.

Reported-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Fixes: ce657b1cddf1 ("component: add support for releasing match data")
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

component: add support for releasing match data

The component helper treats the void match data pointer as an opaque
object which needs no further management. When device nodes being
passed, this is not true: the caller should pass its refcount to the
component helper, and there should be a way to drop the refcount when
the matching information is destroyed.

This patch provides a per-match release method in addition to the match
method to solve this issue. Rather than using component_match_add(),
users should use component_match_add_release() which takes an additional
function pointer for releasing this reference.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

component: track components via array rather than list

Since we now have an array which defines each component, maintain the
components to be bound in the array rather than a separate list. We
also need duplicate tracking so we can eliminate multiple bind calls
for the same component: we preserve the list-based component order in
that the first match which adds the component determines its position.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

component: move check for unbound master into try_to_bring_up_masters()

Clean up the code a little; we don't need to check that the master is
unbound for every invocation of try_to_bring_up_master(), so let's move
it to where it's really needed - try_to_bring_up_masters(), where we may
encounter already bound masters.

Reviewed-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

component: remove old add_components method

Now that drivers create an array of component matches at probe time, we
can retire the old methods. This involves removing the add_components
master method, and removing component_master_add_child() from public
view. We also remove component_add_master() as that interface is no
longer useful.

Acked-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

component: fix bug with legacy API

Sachin Kamat reports that "component: add support for component match
array" broke Exynos DRM due to a NULL pointer deref. Fix this.

Reported-by: Sachin Kamat <sachin.kamat@samsung.com>
Tested-by: Sachin Kamat <sachin.kamat@samsung.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

component: add support for component match array

Add support for generating a set of component matches at master probe
time, and submitting them to the component layer. This allows the
component layer to perform the matches internally without needing to
call into the master driver, and allows for further restructuring of
the component helper.

Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

component: ignore multiple additions of the same component

Permit masters to call component_master_add_child() and match the same
child multiple times. This may happen if there's multiple connections
to a single component device from other devices. In such scenarios,
we should not return a failure, but instead ignore the attempt.

Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

component: fix missed cleanup in case of devres failure

In try_to_bring_up_master(), we tear down the master's component list
for each error case, except for devres group failure. Fix this
oversight by making the code less prone to such mistakes.

Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

drivers/base: fix devres handling for master device

We weren't handling the devres issues for the master device failing a
bind, or being unbound properly. Add a devres group to contain these,
and release the resources at the appropriate points.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/base: provide an infrastructure for componentised subsystems

Subsystems such as ALSA, DRM and others require a single card-level
device structure to represent a subsystem. However, firmware tends to
describe the individual devices and the connections between them.

Therefore, we need a way to gather up the individual component devices
together, and indicate when we have all the component devices.

We do this in DT by providing a "superdevice" node which specifies
the components, eg:

imx-drm {
compatible = "fsl,drm";
crtcs = <&ipu1>;
connectors = <&hdmi>;
};

The superdevice is declared into the component support, along with the
subcomponents. The superdevice receives callbacks to locate the
subcomponents, and identify when all components are present. At this
point, we bind the superdevice, which causes the appropriate subsystem
to be initialised in the conventional way.

When any of the components or superdevice are removed from the system,
we unbind the superdevice, thereby taking the subsystem down.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>