Move some initialization out of _init and into _probe.
Update signatures and logic to use the wmi bus and device structures.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
[dvhart: drop deprecated sparse_keymap_free, order declarations, add commit msg]
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Mario Limonciello <mario_limonciello@dell.com>
Cc: Pali Rohár <pali.rohar@gmail.com>
Cc: linux-kernel@vger.kernel.org
Cc: platform-driver-x86@vger.kernel.org
Cc: linux-acpi@vger.kernel.org
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Darren Hart (VMware) <dvhart@infradead.org>

Many laptops (and maybe servers?) have embedded WMI Binary MOF metadata.
We do not yet have open-source tools for processing the data, although
one is in the works thanks to Pali:

	https://github.com/pali/bmfdec

There is currently no interface to get the data in the first place. By
exposing it, we facilitate the development of new tools.

This is based on the original work of Andy Lutomirski <luto@kernel.org>,
but contains several modifications in response to various reviews.
Signed-off-by: Darren Hart (VMware) <dvhart@infradead.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Mario Limonciello <mario_limonciello@dell.com>
Cc: Pali Rohár <pali.rohar@gmail.com>
Cc: linux-kernel@vger.kernel.org
Cc: platform-driver-x86@vger.kernel.org
Cc: linux-acpi@vger.kernel.org
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>

The Microsoft WMI documentation requires all data blocks to implement
the Query Control Method (WQxx). If we encounter a data block not
implementing this control method, issue a warning, and ignore the data
block. Remove the "readable" attribute as all data blocks must be
readable (query-able).

Be consistent with the language in the documentation, replace the
"writable" attribute with "setable".

Simplify (flatten) the control flow of wmi_create_device a bit while
we are updating it for the above changes.
Signed-off-by: Darren Hart (VMware) <dvhart@infradead.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Mario Limonciello <mario_limonciello@dell.com>
Cc: Pali Rohár <pali.rohar@gmail.com>
Cc: linux-kernel@vger.kernel.org
Cc: platform-driver-x86@vger.kernel.org
Cc: linux-acpi@vger.kernel.org
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Some subdrivers need to access sibling devices. This gives them a
clean way to do so.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Mario Limonciello <mario_limonciello@dell.com>
Cc: Pali Rohár <pali.rohar@gmail.com>
Cc: linux-kernel@vger.kernel.org
Cc: platform-driver-x86@vger.kernel.org
Cc: linux-acpi@vger.kernel.org
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Darren Hart (VMware) <dvhart@infradead.org>

We already have the PNP glue to instantiate platform devices for the
ACPI devices that WMI drives. WMI should therefore attach to the
platform device, not the ACPI node.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Mario Limonciello <mario_limonciello@dell.com>
Cc: Pali Rohár <pali.rohar@gmail.com>
Cc: linux-kernel@vger.kernel.org
Cc: platform-driver-x86@vger.kernel.org
Cc: linux-acpi@vger.kernel.org
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Darren Hart (VMware) <dvhart@infradead.org>

wmi_query_block is unnecessarily indirect. Add a straightforward
method for wmi bus drivers to use to read block data.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Mario Limonciello <mario_limonciello@dell.com>
Cc: Pali Rohár <pali.rohar@gmail.com>
Cc: linux-kernel@vger.kernel.org
Cc: platform-driver-x86@vger.kernel.org
Cc: linux-acpi@vger.kernel.org
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Darren Hart (VMware) <dvhart@infradead.org>

As a platform driver, acpi_driver.notify will not be available,
so use acpi_install_notify_handler as we will be converting to a
platform driver.

This gives event drivers a simple way to handle events. It
also seems closer to what the Windows docs suggest that Windows
does: it sounds like, in Windows, the mapper is responsible for
called _WED before dispatching to the subdriver.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
[dvhart: merge two development commits and update commit message]
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Mario Limonciello <mario_limonciello@dell.com>
Cc: Pali Rohár <pali.rohar@gmail.com>
Cc: linux-kernel@vger.kernel.org
Cc: platform-driver-x86@vger.kernel.org
Cc: linux-acpi@vger.kernel.org
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Darren Hart (VMware) <dvhart@infradead.org>

At some point, we will want sub-drivers to get references to other
devices on the same WMI bus. This change is needed to avoid races.

This ends up simplifying the setup code and fixing some leaks, too.

This is based on the original work of Andy Lutomirski <luto@kernel.org>,
but includes several modifications, many in response to review from
Michał Kępień <kernel@kempniu.pl>:

  https://www.spinics.net/lists/platform-driver-x86/msg08201.htmlSigned-off-by: Darren Hart (VMware) <dvhart@infradead.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Mario Limonciello <mario_limonciello@dell.com>
Cc: Pali Rohár <pali.rohar@gmail.com>
Cc: linux-kernel@vger.kernel.org
Cc: platform-driver-x86@vger.kernel.org
Cc: linux-acpi@vger.kernel.org
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

The Dell XPS 13 9350 has one RW data object, one RO data object, and one
totally inaccessible data object. Check for the existence of the
accessor methods and report in sysfs.

The docs also permit WQxx getters for single-instance objects to
take no parameters. Probe for that as well to avoid ACPICA warnings
about mismatched signatures.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Mario Limonciello <mario_limonciello@dell.com>
Cc: Pali Rohár <pali.rohar@gmail.com>
Cc: linux-kernel@vger.kernel.org
Cc: platform-driver-x86@vger.kernel.org
Cc: linux-acpi@vger.kernel.org
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Darren Hart (VMware) <dvhart@infradead.org>

Divide the "data", "method" and "event" types. All devices get
"instance_count" and "expensive" attributes, data and method devices get
"object_id" attributes, and event devices get "notify_id" attributes.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Mario Limonciello <mario_limonciello@dell.com>
Cc: Pali Rohár <pali.rohar@gmail.com>
Cc: linux-kernel@vger.kernel.org
Cc: platform-driver-x86@vger.kernel.org
Cc: linux-acpi@vger.kernel.org
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Darren Hart (VMware) <dvhart@infradead.org>

We have two memory leaks. If guid_already_parsed returned true, we leak
the wmi_block. If wmi_create_device failed, we leak the device.

Simplify the logic and fix both of them.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Mario Limonciello <mario_limonciello@dell.com>
Cc: Pali Rohár <pali.rohar@gmail.com>
Cc: linux-kernel@vger.kernel.org
Cc: platform-driver-x86@vger.kernel.org
Cc: linux-acpi@vger.kernel.org
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Darren Hart (VMware) <dvhart@infradead.org>

WMI is logically a bus: the WMI driver binds to an ACPI node (or
more than one), and each instance of the WMI driver enumerates its
children and hopes that drivers will attach to the children that are
useful.

This patch gives WMI a driver model bus type and the ability to
match to drivers. The bus itself is a device in the new "wmi_bus"
class, and all of the individual WMI devices are slotted into the
device hierarchy correctly.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Mario Limonciello <mario_limonciello@dell.com>
Cc: Pali Rohár <pali.rohar@gmail.com>
Cc: linux-kernel@vger.kernel.org
Cc: platform-driver-x86@vger.kernel.org
Cc: linux-acpi@vger.kernel.org
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Darren Hart (VMware) <dvhart@infradead.org>

Currently we free all devices when we detach from any ACPI node.
Instead, keep track of which node WMI devices are attached to and
free them only as needed. While we are at it, match up notifications
with the device they came from correctly.

This will make our behavior more straightforward on systems with
more than one WMI node in the ACPI tables (e.g. the Dell XPS 13
9350).

This also adds a warning when GUIDs are not unique.

NB: The guid_string parameter in guid_already_parsed was a
little-endian binary GUID, not a string.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Mario Limonciello <mario_limonciello@dell.com>
Cc: Pali Rohár <pali.rohar@gmail.com>
Cc: linux-kernel@vger.kernel.org
Cc: platform-driver-x86@vger.kernel.org
Cc: linux-acpi@vger.kernel.org
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Darren Hart (VMware) <dvhart@infradead.org>

Rearrange acpi_wmi_add to use Linux's error handling conventions.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Mario Limonciello <mario_limonciello@dell.com>
Cc: Pali Rohár <pali.rohar@gmail.com>
Cc: linux-kernel@vger.kernel.org
Cc: platform-driver-x86@vger.kernel.org
Cc: linux-acpi@vger.kernel.org
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Darren Hart (VMware) <dvhart@infradead.org>

We will need the device to convert to a bus architecture and bind WMI to
the platform device.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Mario Limonciello <mario_limonciello@dell.com>
Cc: Pali Rohár <pali.rohar@gmail.com>
Cc: linux-kernel@vger.kernel.org
Cc: platform-driver-x86@vger.kernel.org
Cc: linux-acpi@vger.kernel.org
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Darren Hart (VMware) <dvhart@infradead.org>

WMI is just a driver. There is no need to announce when it is loaded.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Mario Limonciello <mario_limonciello@dell.com>
Cc: Pali Rohár <pali.rohar@gmail.com>
Cc: linux-kernel@vger.kernel.org
Cc: platform-driver-x86@vger.kernel.org
Cc: linux-acpi@vger.kernel.org
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Darren Hart (VMware) <dvhart@infradead.org>

According to Mario at Dell, the DELLABC6 device should not be used on a
Linux system. It also conflicts with Intel-HID and its interactions with
Network Manager. Document that we are aware of the device, but that we
are intentionally ignoring it.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
[dvhart: New commit message and minor comment wording fixes]
Cc: Mario Limonciello <mario_limonciello@dell.com>
Cc: "Pali Rohár" <pali.rohar@gmail.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Darren Hart (VMware) <dvhart@infradead.org>

This is based on Mario's explanation and observation of my laptop.
Suggested-by: "Pali Rohár" <pali.rohar@gmail.com>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Mario Limonciello <mario_limonciello@dell.com>
Cc: Matthew Garrett <mjg59@srcf.ucam.org>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Darren Hart (VMware) <dvhart@infradead.org>

The hotkey table is 0xb2, add a comment for clarity.
Suggested-by: Darren Hart <dvhart@infradead.org>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Matthew Garrett <mjg59@srcf.ucam.org>
Reviewed-by: Pali Rohár <pali.rohar@gmail.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Darren Hart (VMware) <dvhart@infradead.org>

To avoid using module-wide data in remaining module code, employ
acpi_driver_data() and dev_get_drvdata() to fetch device-specific data
to work on in each function.  This makes the input local variables in
hotkey-related callbacks and the module-wide struct fujitsu_laptop
redundant, so remove them.  Adjust whitespace to make checkpatch happy.
Signed-off-by: Michał Kępień <kernel@kempniu.pl>
Reviewed-by: Jonathan Woithe <jwoithe@just42.net>
Signed-off-by: Darren Hart (VMware) <dvhart@infradead.org>

In order to perform their duties, all LED callbacks need a pointer to
the struct acpi_device representing the FUJ02E3 ACPI device.  To limit
the use of the module-wide pointer, the same pointer should be extracted
from data that gets passed to LED callbacks as arguments.  However, LED
core does not currently support supplying driver-specific pointers to
struct led_classdev callbacks, so the latter have to be implemented a
bit differently than backlight device callbacks and platform device
attribute callbacks.  As the FUJ02E3 ACPI device is the parent device of
all LED class devices registered by fujitsu-laptop, struct acpi_device
representing the former can be extracted by following the parent link
present inside the struct device belonging to the struct led_classdev
passed as an argument to each LED callback.

To get rid of module-wide structures defining LED class devices,
allocate them dynamically using devm_kzalloc() and initialize them in
acpi_fujitsu_laptop_leds_register().
Signed-off-by: Michał Kępień <kernel@kempniu.pl>
Reviewed-by: Jonathan Woithe <jwoithe@just42.net>
Signed-off-by: Darren Hart (VMware) <dvhart@infradead.org>

Prepare for not using module-wide data in call_fext_func() by explicitly
passing it a pointer to struct acpi_device while still using a
module-wide pointer in each call.

Doing this enables call_fext_func() to fetch the ACPI handle from its
argument, making the acpi_handle field of struct fujitsu_laptop useless,
so remove that field.  While we are at it, the dev field of the same
structure is assigned in acpi_fujitsu_laptop_add() but not used for
anything, so remove it as well.
Signed-off-by: Michał Kępień <kernel@kempniu.pl>
Reviewed-by: Jonathan Woithe <jwoithe@just42.net>
Signed-off-by: Darren Hart (VMware) <dvhart@infradead.org>

fujitsu-laptop registers two ACPI drivers: one for ACPI device FUJ02B1
enabling backlight control and another for ACPI device FUJ02E3 which
handles various other stuff (hotkeys, LEDs, etc.)  In a perfect world,
private data used by each of these drivers would be neatly encapsulated
in a structure specific to a given driver instance.  Sadly, firmware
present on some Fujitsu laptops makes that impossible by exposing
backlight power control (which is what the FUJ02B1 ACPI device should
take care of) through the FUJ02E3 ACPI device.  This means the backlight
driver needs a way to access an ACPI device it is not bound to.  When
the backlight driver is extracted into a separate module, it will not be
able to rely on a module-wide variable any more and such access will
happen through an API exposed by fujitsu-laptop.

For all known firmwares out in the wild, it seems that whenever the
FUJ02B1 ACPI device is present, it is always accompanied by a single
instance of the FUJ02E3 ACPI device.  We could independently grab an
ACPI handle to the FUJ02E3 ACPI device from the backlight driver, but
that would require using a hardcoded absolute path to that ACPI device,
which is subject to change.  It is easier to simply store a module-wide
pointer to the last (most likely only) FUJ02E3 ACPI device found, make
the aforementioned API use it and cover our bases by warning the user if
firmware exposes multiple FUJ02E3 ACPI devices.

Introducing this pointer in advance allows us to get rid of the
acpi_handle field of struct fujitsu_bl and also enables a bit more
step-by-step migration to a device-specific implementation of
call_fext_func().
Signed-off-by: Michał Kępień <kernel@kempniu.pl>
Reviewed-by: Jonathan Woithe <jwoithe@just42.net>
Signed-off-by: Darren Hart (VMware) <dvhart@infradead.org>

Only allocate memory for struct fujitsu_laptop when the FUJ02E3 ACPI
device is present.  Use devm_kzalloc() for allocating memory to simplify
cleanup.
Signed-off-by: Michał Kępień <kernel@kempniu.pl>
Reviewed-by: Jonathan Woithe <jwoithe@just42.net>
Signed-off-by: Darren Hart (VMware) <dvhart@infradead.org>

To prevent using module-wide data in backlight-related code, employ
acpi_driver_data() and bl_get_data() where possible to fetch
device-specific data to work on in each function.  This makes the input
local variable in acpi_fujitsu_bl_notify() and the acpi_handle field of
struct fujitsu_bl redundant, so remove them.
Signed-off-by: Michał Kępień <kernel@kempniu.pl>
Reviewed-by: Jonathan Woithe <jwoithe@just42.net>
Signed-off-by: Darren Hart (VMware) <dvhart@infradead.org>

Only allocate memory for struct fujitsu_bl when the FUJ02B1 ACPI device
is present.  Use devm_kzalloc() for allocating memory to simplify
cleanup.

Due to the fact that the power property of the backlight device created
by the backlight driver is accessed from acpi_fujitsu_laptop_add(),
pointer to the allocated memory will remain stored in a module-wide
variable until the backlight driver is extracted into a separate module.
Signed-off-by: Michał Kępień <kernel@kempniu.pl>
Reviewed-by: Jonathan Woithe <jwoithe@just42.net>
Signed-off-by: Darren Hart (VMware) <dvhart@infradead.org>

In portions of the driver which use device-specific data, rename local
variables from fujitsu_bl and fujitsu_laptop to priv in order to clearly
distinguish these parts from code that uses module-wide data.
Signed-off-by: Michał Kępień <kernel@kempniu.pl>
Reviewed-by: Jonathan Woithe <jwoithe@just42.net>
Signed-off-by: Darren Hart (VMware) <dvhart@infradead.org>

Devices with the intel_cht_int33fe ACPI device use a max17047 fuel-gauge
combined with a bq24272i charger, in order for the fuel-gauge driver to
correctly display charging / discharging status it needs to know which
charger is supplying the battery.

This commit sets the supplied-from device property to the name of the
bq24272i charger for this.
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

The function is currently not used, however it is part of the API and
might be used in the future. Adding the attribute fixes the following
warning when building with clang:

    drivers/platform/x86/intel_pmc_ipc.c:189:18: error: unused function
        'ipc_data_readb' [-Werror,-Wunused-function]
Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

Don't simply throw this to userspace via the sparse_keymap (which does not
have a mapping for scancode 1), as this causes KEY_UNKNOWN to be emitted,
which is a nuisance and of no use at all (it is not the right way to expose
this ACPI event to userspace, anyway, and the original intention of the commit
which added this (cfee5d63) was only to suppress
an unhandled event log message).
Signed-off-by: Hao Wei Tee <angelsl@angelsl.xyz>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

A readonly sysfs property must not have a 'store' function:

drivers/platform/x86/ideapad-laptop.c:438:16: error: 'touchpad_store' defined but not used [-Werror=unused-function]

We can either comment it out or remove the function entirely,
without a good reason one or or another I picked the second option.

Fixes: 7f363145 ("platform/x86: ideapad-laptop: Switch touchpad attribute to be RO")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

The latest Topstar BIOS updates (109_931P) advertise the "TPS0001"
device id by default, preventing the topstar-laptop module from being
loaded automatically.
Signed-off-by: Guillaume Douézan-Grard <gdouezangrard@gmail.com>
Signed-off-by: Darren Hart (VMware) <dvhart@infradead.org>

PEAQ is a new European OEM, I've bought one of their 2-in-1 x86 devices,
which is actually quite a nice device. Under Windows it has Dolby
software for "better" sound and you can select different equalizer
presets using a special button.

This WMI interface for this button is not really nice, as it does not do
notifies (it really does not I triple checked), but since I had already
figured out the entire WMI interface for this I decided to go the full
mile anyway and implement a WMI based input driver for this using
input_polldev since, well, we need to poll.

This commit adds support for this button making it report KEY_SOUND
input events. KEY_SOUND is already used in various places to switch
sound into theatre mode and things like that so it seems appropriate
here.
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Reviewed-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
[dvhart: minor declaration ordering and commit log typo fixes]
Signed-off-by: Darren Hart (VMware) <dvhart@infradead.org>

As per discussion [1] there are only few users of module_param_call() in
kernel which prevent to read module parameters back.

It thinkpad_acpi driver there is even no method do so. Thus, for now,
add just a comment to explain why 0 is used as permissions in
module_param_call().

[1]: https://patchwork.ozlabs.org/patch/713245/

Cc: Richard Weinberger <richard.weinberger@gmail.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Henrique de Moraes Holschuh <hmh@hmh.eng.br>

There is no point to keep string literal split. It even makes slightly
harder to maintain and debug.

Join string literals back to be oneliners.

While here, print negative error without changing a sign as it is a
common pattern in the kernel.

Other than above there were no functional changes intended.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Henrique de Moraes Holschuh <hmh@hmh.eng.br>

Add touchscreen info for the GP-electronic T701 tablet.
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Darren Hart (VMware) <dvhart@infradead.org>

Use memdup_user_nul() helper instead of open-coding to simplify the
code.
Signed-off-by: Geliang Tang <geliangtang@gmail.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

For now let's restrict touchpad attribute to be read only.
We might revisit this in the future though.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

Lenovo Yoga (many variants: Yoga, Yoga2 Pro, Yoga2 13, Yoga3 Pro, Yoga 3
14, etc) has multiple modles that are a hybrid laptop, working in laptop
mode as well as tablet mode.

Currently, there is no easy interface to determine the touchpad status,
which in case of the Yoga family of machines, can also be useful to
assume tablet mode status.

Note: The ideapad-laptop driver does not provide a SW_TABLET_MODE either.

For a detailed discussion  on why we want either of the interfaces,
please see:
https://bugs.launchpad.net/onboard/+bug/1366421/comments/43

This patch adds a sysfs interface for read/write access under:
/sys/bus/platform/devices/VPC2004\:00/touchpad_mode
Signed-off-by: Ritesh Raj Sarraf <rrs@debian.org>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>