Instead of manually creating the bit masks,
use the `BIT()` macro to do it.
Signed-off-by: NBarnabás Pőcze <pobrn@protonmail.com>
Link: https://lore.kernel.org/r/20210904175450.156801-12-pobrn@protonmail.comReviewed-by: NHans de Goede <hdegoede@redhat.com>
Signed-off-by: NHans de Goede <hdegoede@redhat.com>

The `find_guid_context()` is only called from one place,
and `wblock` and `wdriver` cannot be NULL there.
So remove the currently redundant checks.
Signed-off-by: NBarnabás Pőcze <pobrn@protonmail.com>
Link: https://lore.kernel.org/r/20210904175450.156801-11-pobrn@protonmail.comReviewed-by: NHans de Goede <hdegoede@redhat.com>
Signed-off-by: NHans de Goede <hdegoede@redhat.com>

Remove an empty line after the last statement
in `acpi_wmi_notify_handler()` which serves
no purpose.
Signed-off-by: NBarnabás Pőcze <pobrn@protonmail.com>
Link: https://lore.kernel.org/r/20210904175450.156801-10-pobrn@protonmail.comReviewed-by: NHans de Goede <hdegoede@redhat.com>
Signed-off-by: NHans de Goede <hdegoede@redhat.com>

Void pointers are implictly cast to arbitrary pointer types,
so remove superfluous casts.
Signed-off-by: NBarnabás Pőcze <pobrn@protonmail.com>
Link: https://lore.kernel.org/r/20210904175450.156801-9-pobrn@protonmail.comReviewed-by: NHans de Goede <hdegoede@redhat.com>
Signed-off-by: NHans de Goede <hdegoede@redhat.com>

The GUID block is available for `wmi_create_device()`
through `wblock->gblock`. Use that consistently in
the function instead of using a mix of `gblock` and
`wblock->gblock`.
Signed-off-by: NBarnabás Pőcze <pobrn@protonmail.com>
Link: https://lore.kernel.org/r/20210904175450.156801-8-pobrn@protonmail.comReviewed-by: NHans de Goede <hdegoede@redhat.com>
Signed-off-by: NHans de Goede <hdegoede@redhat.com>

The `status` variable was assigned at the end, and then
immediately returned. Remove it altogether, and return
the previously assigned value directly.
Signed-off-by: NBarnabás Pőcze <pobrn@protonmail.com>
Link: https://lore.kernel.org/r/20210904175450.156801-7-pobrn@protonmail.comReviewed-by: NHans de Goede <hdegoede@redhat.com>
Signed-off-by: NHans de Goede <hdegoede@redhat.com>

Some pointers are initialized when they are defined,
but they are almost immediately reassigned in the
following lines. Remove these superfluous assignments.
Signed-off-by: NBarnabás Pőcze <pobrn@protonmail.com>
Link: https://lore.kernel.org/r/20210904175450.156801-6-pobrn@protonmail.comReviewed-by: NHans de Goede <hdegoede@redhat.com>
Signed-off-by: NHans de Goede <hdegoede@redhat.com>

The empty initializer `{ }` is enough to properly initialize
the terminating acpi_device_id entry in the device table,
so use that.
Signed-off-by: NBarnabás Pőcze <pobrn@protonmail.com>
Link: https://lore.kernel.org/r/20210904175450.156801-5-pobrn@protonmail.comReviewed-by: NHans de Goede <hdegoede@redhat.com>
Signed-off-by: NHans de Goede <hdegoede@redhat.com>

Remove commas that are after terminating entries in arrays.
Signed-off-by: NBarnabás Pőcze <pobrn@protonmail.com>
Link: https://lore.kernel.org/r/20210904175450.156801-4-pobrn@protonmail.comReviewed-by: NHans de Goede <hdegoede@redhat.com>
Signed-off-by: NHans de Goede <hdegoede@redhat.com>

Fix the following two checkpatch warnings:

 * "space required before the open parenthesis '('"
 * "that open brace { should be on the previous line"
Signed-off-by: NBarnabás Pőcze <pobrn@protonmail.com>
Link: https://lore.kernel.org/r/20210904175450.156801-3-pobrn@protonmail.comReviewed-by: NHans de Goede <hdegoede@redhat.com>
Signed-off-by: NHans de Goede <hdegoede@redhat.com>

The kernel doc erroneously specified `wmi_uninstall_notify_handler()`
for the `wmi_remove_notify_handler()` function. Fix that.
Signed-off-by: NBarnabás Pőcze <pobrn@protonmail.com>
Link: https://lore.kernel.org/r/20210904175450.156801-2-pobrn@protonmail.comReviewed-by: NHans de Goede <hdegoede@redhat.com>
Signed-off-by: NHans de Goede <hdegoede@redhat.com>

The driver core ignores the return value of this callback because there
is only little it can do when a device disappears.

This is the final bit of a long lasting cleanup quest where several
buses were converted to also return void from their remove callback.
Additionally some resource leaks were fixed that were caused by drivers
returning an error code in the expectation that the driver won't go
away.

With struct bus_type::remove returning void it's prevented that newly
implemented buses return an ignored error code and so don't anticipate
wrong expectations for driver authors.

Reviewed-by: Tom Rix <trix@redhat.com> (For fpga)
Reviewed-by: NMathieu Poirier <mathieu.poirier@linaro.org>
Reviewed-by: Cornelia Huck <cohuck@redhat.com> (For drivers/s390 and drivers/vfio)
Acked-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk> (For ARM, Amba and related parts)
Acked-by: NMark Brown <broonie@kernel.org>
Acked-by: Chen-Yu Tsai <wens@csie.org> (for sunxi-rsb)
Acked-by: NPali Rohár <pali@kernel.org>
Acked-by: Mauro Carvalho Chehab <mchehab@kernel.org> (for media)
Acked-by: Hans de Goede <hdegoede@redhat.com> (For drivers/platform)
Acked-by: NAlexandre Belloni <alexandre.belloni@bootlin.com>
Acked-By: NVinod Koul <vkoul@kernel.org>
Acked-by: Juergen Gross <jgross@suse.com> (For xen)
Acked-by: Lee Jones <lee.jones@linaro.org> (For mfd)
Acked-by: Johannes Thumshirn <jth@kernel.org> (For mcb)
Acked-by: NJohan Hovold <johan@kernel.org>
Acked-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org> (For slimbus)
Acked-by: Kirti Wankhede <kwankhede@nvidia.com> (For vfio)
Acked-by: NMaximilian Luz <luzmaximilian@gmail.com>
Acked-by: Heikki Krogerus <heikki.krogerus@linux.intel.com> (For ulpi and typec)
Acked-by: Samuel Iglesias Gonsálvez <siglesias@igalia.com> (For ipack)
Acked-by: Geoff Levand <geoff@infradead.org> (For ps3)
Acked-by: Yehezkel Bernat <YehezkelShB@gmail.com> (For thunderbolt)
Acked-by: Alexander Shishkin <alexander.shishkin@linux.intel.com> (For intel_th)
Acked-by: Dominik Brodowski <linux@dominikbrodowski.net> (For pcmcia)
Acked-by: Rafael J. Wysocki <rafael@kernel.org> (For ACPI)
Acked-by: Bjorn Andersson <bjorn.andersson@linaro.org> (rpmsg and apr)
Acked-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com> (For intel-ish-hid)
Acked-by: Dan Williams <dan.j.williams@intel.com> (For CXL, DAX, and NVDIMM)
Acked-by: William Breathitt Gray <vilhelm.gray@gmail.com> (For isa)
Acked-by: Stefan Richter <stefanr@s5r6.in-berlin.de> (For firewire)
Acked-by: Benjamin Tissoires <benjamin.tissoires@redhat.com> (For hid)
Acked-by: Thorsten Scherer <t.scherer@eckelmann.de> (For siox)
Acked-by: Sven Van Asbroeck <TheSven73@gmail.com> (For anybuss)
Acked-by: Ulf Hansson <ulf.hansson@linaro.org> (For MMC)
Acked-by: Wolfram Sang <wsa@kernel.org> # for I2C
Acked-by: NSudeep Holla <sudeep.holla@arm.com>
Acked-by: NGeert Uytterhoeven <geert@linux-m68k.org>
Acked-by: NDmitry Torokhov <dmitry.torokhov@gmail.com>
Acked-by: NFinn Thain <fthain@linux-m68k.org>
Signed-off-by: NUwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20210713193522.1770306-6-u.kleine-koenig@pengutronix.deSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The driver core ignores the return value of struct bus_type::remove()
(and so wmi_dev_remove()) because there is only little that can be done.

To simplify the quest to make this function return void, let struct
wmi_driver::remove() return void, too. All implementers of this callback
return 0 already and this way it should be obvious to driver authors
that returning an error code is a bad idea.
Signed-off-by: NUwe Kleine-König <u.kleine-koenig@pengutronix.de>
Reviewed-by: NPali Rohár <pali@kernel.org>
Link: https://lore.kernel.org/r/20210301160404.1677064-1-u.kleine-koenig@pengutronix.deSigned-off-by: NHans de Goede <hdegoede@redhat.com>

A few x86 platform drivers use ACPI_DEBUG_PRINT() or ACPI_EXCEPTION()
for printing messages, but that is questionable, because those macros
belong to ACPICA and they should not be used elsewhere.  In addition,
ACPI_DEBUG_PRINT() requires special enabling to allow it to actually
print the message, which is a nuisance, and the _COMPONENT symbol
generally needed for that is not defined in any of the files in
question.

For this reason, replace the ACPI_DEBUG_PRINT() in lg-laptop.c with
pr_debug() and the one in xo15-ebook.c with acpi_handle_debug()
(with the additional benefit that the source object can be identified
more easily after this change).

Also drop the ACPI_MODULE_NAME() definitions that are only used by
the ACPICA message printing macros from those files and from wmi.c
and surfacepro3_button.c (while at it).
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Link: https://lore.kernel.org/r/2074665.VPHYfYaQb6@kreacher
[hdegoede@redhat.com: Drop acer-wmi.c chunk, a similar patch was already merged]
Signed-off-by: NHans de Goede <hdegoede@redhat.com>

A break is not needed if it is preceded by a return
Signed-off-by: NTom Rix <trix@redhat.com>
Link: https://lore.kernel.org/r/20201019133212.12671-1-trix@redhat.comSigned-off-by: NHans de Goede <hdegoede@redhat.com>

This reverts commit 7b11e898.

Consider the following hardware setting.

|-PNP0C14:00
|  |-- device #1
|-PNP0C14:01
|  |-- device #2

When unloading wmi driver module, device #2 will be first unregistered.
But device_destroy() using MKDEV(0, 0) will locate PNP0C14:00 first
and unregister it. This is incorrect. Should use device_unregister() to
unregister the real parent device.
Signed-off-by: NYongxin Liu <yongxin.liu@windriver.com>
Link: https://lore.kernel.org/r/20191115052710.46880-1-yongxin.liu@windriver.comSigned-off-by: NHans de Goede <hdegoede@redhat.com>

There are few parameters that are not described properly.
Fill the gap by describing them properly in kernel doc format.
Signed-off-by: NAndy Shevchenko <andriy.shevchenko@linux.intel.com>

There is no need to split lines as they perfectly fit 80 character limit.
Signed-off-by: NAndy Shevchenko <andriy.shevchenko@linux.intel.com>

There are types and helpers that are redefined with old names.
Convert the WMI library to use those types and helpers directly.
Signed-off-by: NAndy Shevchenko <andriy.shevchenko@linux.intel.com>

In order to avoid future header hell, remove the inclusion of
proc_fs.h from acpi_bus.h. All it needs is a forward declaration of a
struct.
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: NAndy Shevchenko <andy.shevchenko@gmail.com>
Link: https://lkml.kernel.org/r/20200321113241.246190285@linutronix.de

The .ioctl and .compat_ioctl file operations have the same prototype so
they can both point to the same function, which works great almost all
the time when all the commands are compatible.

One exception is the s390 architecture, where a compat pointer is only
31 bit wide, and converting it into a 64-bit pointer requires calling
compat_ptr(). Most drivers here will never run in s390, but since we now
have a generic helper for it, it's easy enough to use it consistently.

I double-checked all these drivers to ensure that all ioctl arguments
are used as pointers or are ignored, but are not interpreted as integer
values.
Acked-by: NJason Gunthorpe <jgg@mellanox.com>
Acked-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Acked-by: NMauro Carvalho Chehab <mchehab+samsung@kernel.org>
Acked-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: NDavid Sterba <dsterba@suse.com>
Acked-by: NDarren Hart (VMware) <dvhart@infradead.org>
Acked-by: NJonathan Cameron <Jonathan.Cameron@huawei.com>
Acked-by: NBjorn Andersson <bjorn.andersson@linaro.org>
Acked-by: NDan Williams <dan.j.williams@intel.com>
Signed-off-by: NArnd Bergmann <arnd@arndb.de>

acpi_has_method() is unnecessary within __query_block() and should be
removed to avoid extra work.

wc_status is initialized to AE_ERROR before the acpi_has_method() call.
acpi_has_method() and acpi_execute_simple_method() failing due to the
method not existing will result in the same outcome from __query_block().
Signed-off-by: NKelsey Skunberg <skunberg.kelsey@gmail.com>
Signed-off-by: NAndy Shevchenko <andriy.shevchenko@linux.intel.com>

The struct wmi_device_id has a context pointer field, forward this
pointer as an argument to the probe function in struct wmi_driver.

Update existing users of the same probe function to accept this new
context argument.
Signed-off-by: NMattias Jacobsson <2pi@mok.nu>
Signed-off-by: NAndy Shevchenko <andriy.shevchenko@linux.intel.com>

When using wmi_install_notify_handler() to initialize a WMI handler a
data pointer can be supplied which will be passed on to the notification
handler. No similar feature exist when handling WMI events via struct
wmi_driver.

Add a context field pointer to struct wmi_device_id and add a function
find_guid_context() to retrieve that context pointer.
Signed-off-by: NMattias Jacobsson <2pi@mok.nu>
Signed-off-by: NAndy Shevchenko <andriy.shevchenko@linux.intel.com>

Add a new function to acpi.h / wmi.c that returns _UID of the ACPI WMI
device. For example, it returns "ATK" for the following declaration in
DSDT:
Device (ATKD)
{
    Name (_HID, "PNP0C14" /* Windows Management Instrumentation Device */)
      // _HID: Hardware ID
    Name (_UID, "ATK")  // _UID: Unique ID
    ..

Generally, it is possible that multiple PNP0C14 ACPI devices are present in
the system as mentioned in the commit message of commit bff431e4
("ACPI: WMI: Add ACPI-WMI mapping driver").

Therefore the _UID is returned for a specific ACPI device that declares the
given GUID, to which it is also mapped by other methods of wmi module.
Signed-off-by: NYurii Pavlovskyi <yurii.pavlovskyi@gmail.com>
Signed-off-by: NAndy Shevchenko <andriy.shevchenko@linux.intel.com>

Based on 1 normalized pattern(s):

  this program is free software you can redistribute it and or modify
  it under the terms of the gnu general public license as published by
  the free software foundation either version 2 of the license or at
  your option any later version this program is distributed in the
  hope that it will be useful but without any warranty without even
  the implied warranty of merchantability or fitness for a particular
  purpose see the gnu general public license for more details you
  should have received a copy of the gnu general public license along
  with this program if not write to the free software foundation inc
  59 temple place suite 330 boston ma 02111 1307 usa

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-or-later

has been chosen to replace the boilerplate/reference in 1334 file(s).
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Reviewed-by: NAllison Randal <allison@lohutok.net>
Reviewed-by: NRichard Fontana <rfontana@redhat.com>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190527070033.113240726@linutronix.deSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

In preparation for adding WMI support to MODULE_DEVICE_TABLE() move the
definition of struct wmi_device_id to mod_devicetable.h and inline
guid_string in the struct.

Changing guid_string to an inline char array changes the loop conditions
when looping over an array of struct wmi_device_id. Therefore update
wmi_dev_match()'s loop to check for an empty guid_string instead of a
NULL pointer.
Signed-off-by: NMattias Jacobsson <2pi@mok.nu>
[dvhart: Move UUID_STRING_LEN define to this patch]
Signed-off-by: NDarren Hart (VMware) <dvhart@infradead.org>

In the function wmi_dev_match() the variable id is dereferenced without
first performing a NULL check. The variable can for example be NULL if
a WMI driver is registered without specifying the id_table field in
struct wmi_driver.

Add a NULL check and return that the driver can't handle the device if
the variable is NULL.

Fixes: 844af950 ("platform/x86: wmi: Turn WMI into a bus driver")
Signed-off-by: NMattias Jacobsson <2pi@mok.nu>
Signed-off-by: NDarren Hart (VMware) <dvhart@infradead.org>

The only usage of device_type structure is getting stored as
a reference in the type field of device structure. This type
field is declared const. Therefore, the device_type structure
can never be modified and can be declared as const.
Signed-off-by: NBhumika Goyal <bhumirks@gmail.com>
Signed-off-by: NAndy Shevchenko <andriy.shevchenko@linux.intel.com>

The probe handler_data was being allocated with __get_free_pages()
for no reason I could find. The error path was using kfree(). Since
other things are happily using kmalloc() in the probe path, switch to
kmalloc() entirely. This fixes the error path mismatch and will avoid
issues with CONFIG_HARDENED_USERCOPY_PAGESPAN=y.
Reported-by: NMihai Donțu <mihai.dontu@gmail.com>
Signed-off-by: NKees Cook <keescook@chromium.org>
Acked-by: NMario Limonciello <Mario.limonciello@dell.com>
Cc: stable@vger.kernel.org
Signed-off-by: NDarren Hart (VMware) <dvhart@infradead.org>

%pULL doesn't officially exist but %pUL does.

Miscellanea:

o Add missing newlines to a couple logging messages
Signed-off-by: NJoe Perches <joe@perches.com>
Signed-off-by: NDarren Hart (VMware) <dvhart@infradead.org>

%pULL doesn't officially exist but %pUL does.

Miscellanea:

o Add missing newlines to a couple logging messages
Signed-off-by: NJoe Perches <joe@perches.com>
Signed-off-by: NDarren Hart (VMware) <dvhart@infradead.org>

In all cases list_for_each() followed by list_entry(),
so, replace them by list_for_each_entry() macro.
Signed-off-by: NAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: NDarren Hart (VMware) <dvhart@infradead.org>

kasprintf() does the job of two: kmalloc() and sprintf().
Replace two calls with one.
Reviewed-by: NDarren Hart (VMware) <dvhart@infradead.org>
Signed-off-by: NAndy Shevchenko <andriy.shevchenko@linux.intel.com>

wmi_dev_probe() allocates one byte less than necessary, thus
subsequent sprintf() call writes trailing zero past the end
of the 'buf':

    BUG: KASAN: slab-out-of-bounds in vsnprintf+0xda4/0x1240
    Write of size 1 at addr ffff880423529caf by task kworker/1:1/32

    Call Trace:
     dump_stack+0xb3/0x14d
     print_address_description+0xd7/0x380
     kasan_report+0x166/0x2b0
     vsnprintf+0xda4/0x1240
     sprintf+0x9b/0xd0
     wmi_dev_probe+0x1c3/0x400
     driver_probe_device+0x5d1/0x990
     bus_for_each_drv+0x109/0x190
     __device_attach+0x217/0x360
     bus_probe_device+0x1ad/0x260
     deferred_probe_work_func+0x10f/0x5d0
     process_one_work+0xa8b/0x1dc0
     worker_thread+0x20d/0x17d0
     kthread+0x311/0x3d0
     ret_from_fork+0x3a/0x50

    Allocated by task 32:
     kasan_kmalloc+0xa0/0xd0
     __kmalloc+0x14f/0x3e0
     wmi_dev_probe+0x182/0x400
     driver_probe_device+0x5d1/0x990
     bus_for_each_drv+0x109/0x190
     __device_attach+0x217/0x360
     bus_probe_device+0x1ad/0x260
     deferred_probe_work_func+0x10f/0x5d0
     process_one_work+0xa8b/0x1dc0
     worker_thread+0x20d/0x17d0
     kthread+0x311/0x3d0
     ret_from_fork+0x3a/0x50

Increment allocation size to fix this.

Fixes: 44b6b766 ("platform/x86: wmi: create userspace interface for drivers")
Signed-off-by: NAndrey Ryabinin <aryabinin@virtuozzo.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: NAndy Shevchenko <andriy.shevchenko@linux.intel.com>

Calling acpi_wmi_init() at the subsys_initcall() level causes ordering
issues to appear on some systems and they are difficult to reproduce,
because there is no guaranteed ordering between subsys_initcall()
calls, so they may occur in different orders on different systems.

In particular, commit 86d9f485 (mm/slab: fix kmemcg cache
creation delayed issue) exposed one of these issues where genl_init()
and acpi_wmi_init() are both called at the same initcall level, but
the former must run before the latter so as to avoid a NULL pointer
dereference.

For this reason, move the acpi_wmi_init() invocation to the
initcall_sync level which should still be early enough for things
to work correctly in the WMI land.

Link: https://marc.info/?t=151274596700002&r=1&w=2Reported-by: NJonathan McDowell <noodles@earth.li>
Reported-by: NJoonsoo Kim <iamjoonsoo.kim@lge.com>
Tested-by: NJonathan McDowell <noodles@earth.li>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: NDarren Hart (VMware) <dvhart@infradead.org>

Calling acpi_wmi_init() at the subsys_initcall() level causes ordering
issues to appear on some systems and they are difficult to reproduce,
because there is no guaranteed ordering between subsys_initcall()
calls, so they may occur in different orders on different systems.

In particular, commit 86d9f485 (mm/slab: fix kmemcg cache
creation delayed issue) exposed one of these issues where genl_init()
and acpi_wmi_init() are both called at the same initcall level, but
the former must run before the latter so as to avoid a NULL pointer
dereference.

For this reason, move the acpi_wmi_init() invocation to the
initcall_sync level which should still be early enough for things
to work correctly in the WMI land.

Link: https://marc.info/?t=151274596700002&r=1&w=2Reported-by: NJonathan McDowell <noodles@earth.li>
Reported-by: NJoonsoo Kim <iamjoonsoo.kim@lge.com>
Tested-by: NJonathan McDowell <noodles@earth.li>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: NDarren Hart (VMware) <dvhart@infradead.org>

This failure mode should have also released the mutex.
Signed-off-by: NMario Limonciello <mario.limonciello@dell.com>
Signed-off-by: NDarren Hart (VMware) <dvhart@infradead.org>

For WMI operations that are only Set or Query readable and writable sysfs
attributes created by WMI vendor drivers or the bus driver makes sense.

For other WMI operations that are run on Method, there needs to be a
way to guarantee to userspace that the results from the method call
belong to the data request to the method call.  Sysfs attributes don't
work well in this scenario because two userspace processes may be
competing at reading/writing an attribute and step on each other's
data.

When a WMI vendor driver declares a callback method in the wmi_driver
the WMI bus driver will create a character device that maps to that
function.  This callback method will be responsible for filtering
invalid requests and performing the actual call.

That character device will correspond to this path:
/dev/wmi/$driver

Performing read() on this character device will provide the size
of the buffer that the character device needs to perform calls.
This buffer size can be set by vendor drivers through a new symbol
or when MOF parsing is available by the MOF.

Performing ioctl() on this character device will be interpretd
by the WMI bus driver. It will perform sanity tests for size of
data, test them for a valid instance, copy the data from userspace
and pass iton to the vendor driver to further process and run.

This creates an implicit policy that each driver will only be allowed
a single character device.  If a module matches multiple GUID's,
the wmi_devices will need to be all handled by the same wmi_driver.

The WMI vendor drivers will be responsible for managing inappropriate
access to this character device and proper locking on data used by
it.

When a WMI vendor driver is unloaded the WMI bus driver will clean
up the character device and any memory allocated for the call.
Signed-off-by: NMario Limonciello <mario.limonciello@dell.com>
Reviewed-by: NEdward O'Callaghan <quasisec@google.com>
Signed-off-by: NDarren Hart (VMware) <dvhart@infradead.org>

The only driver using this was dell-wmi, and it really was a hack.
The driver was getting a data attribute from another driver and this
type of action should not be encouraged.

Rather drivers that need to interact with one another should pass
data back and forth via exported functions.
Signed-off-by: NMario Limonciello <mario.limonciello@dell.com>
Reviewed-by: NEdward O'Callaghan <quasisec@google.com>
Reviewed-by: NPali Rohár <pali.rohar@gmail.com>
Signed-off-by: NDarren Hart (VMware) <dvhart@infradead.org>