History log of /linux-master/drivers/input/rmi4/rmi_f54.c
Revision Date Author Comments
# a9f08ad7 18-Aug-2022 Wolfram Sang <wsa+renesas@sang-engineering.com>

Input: move from strlcpy with unused retval to strscpy

Follow the advice of the below link and prefer 'strscpy' in this
subsystem. Conversion is 1:1 because the return value is not used.
Generated by a coccinelle script.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Link: https://lore.kernel.org/r/20220818210022.6865-1-wsa+renesas@sang-engineering.com
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>


# 40f6d265 24-Apr-2022 ran jianping <ran.jianping@zte.com.cn>

Input: synaptics-rmi4 - remove unnecessary flush_workqueue()

All work currently pending will be done first by calling destroy_workqueue,
so there is unnecessary to flush it explicitly.

Reported-by: Zeal Robot <zealci@zte.com.cn>
Signed-off-by: ran jianping <ran.jianping@zte.com.cn>
Link: https://lore.kernel.org/r/20220422093304.2781183-1-ran.jianping@zte.com.cn
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>


# 7e909891 04-Nov-2020 Lee Jones <lee.jones@linaro.org>

Input: synaptics-rmi4 - fix kerneldoc warnings

Fixes the kerneldoc warnings from building the driver with W=1.

Signed-off-by: Lee Jones <lee.jones@linaro.org>
Link: https://lore.kernel.org/r/20201104162427.2984742-2-lee.jones@linaro.org
[dtor: folded together several Lee's patches; added more descriptions]
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>


# c15f8ba6 16-Jan-2020 Hans Verkuil <hverkuil-cisco@xs4all.nl>

Input: rmi_f54 - read from FIFO in 32 byte blocks

The F54 Report Data is apparently read through a fifo and for
the smbus protocol that means that between reading a block of 32
bytes the rmiaddr shouldn't be incremented. However, changing
that causes other non-fifo reads to fail and so that change was
reverted.

This patch changes just the F54 function and it now reads 32 bytes
at a time from the fifo, using the F54_FIFO_OFFSET to update the
start address that is used when reading from the fifo.

This has only been tested with smbus, not with i2c or spi. But I
suspect that the same is needed there since I think similar
problems will occur there when reading more than 256 bytes.

Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Tested-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Reported-by: Timo Kaufmann <timokau@zoho.com>
Link: https://lore.kernel.org/r/20200115124819.3191024-3-hverkuil-cisco@xs4all.nl
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>


# 71c296f6 22-Nov-2019 Hans Verkuil <hverkuil-cisco@xs4all.nl>

Input: synaptics-rmi4 - fix various V4L2 compliance problems in F54

The v4l2-compliance utility reported several V4L2 API compliance
issues:

- the sequence counter wasn't filled in
- the sequence counter wasn't reset to 0 at the start of streaming
- the returned field value wasn't set to V4L2_FIELD_NONE
- the timestamp wasn't set
- the payload size was undefined if an error was returned
- min_buffers_needed doesn't need to be initialized

Fix these issues.

Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Reviewed-by: Lucas Stach <l.stach@pengutronix.de
Link: https://lore.kernel.org/r/20191119105118.54285-3-hverkuil-cisco@xs4all.nl
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>


# ba60cf9f 15-Nov-2019 Chuhong Yuan <hslester96@gmail.com>

Input: synaptics-rmi4 - destroy F54 poller workqueue when removing

The driver forgets to destroy workqueue in remove() similarly to what is
done when probe() fails. Add a call to destroy_workqueue() to fix it.

Since unregistration will wait for the work to finish, we do not need to
cancel/flush the work instance in remove().

Signed-off-by: Chuhong Yuan <hslester96@gmail.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20191114023405.31477-1-hslester96@gmail.com
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>


# 549766ac 12-Nov-2019 Lucas Stach <l.stach@pengutronix.de>

Input: synaptics-rmi4 - clear IRQ enables for F54

The driver for F54 just polls the status and doesn't even have a IRQ
handler registered. Make sure to disable all F54 IRQs, so we don't crash
the kernel on a nonexistent handler.

Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Link: https://lore.kernel.org/r/20191105114402.6009-1-l.stach@pengutronix.de
Cc: stable@vger.kernel.org
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>


# d843304b 04-Nov-2019 Lucas Stach <l.stach@pengutronix.de>

Input: synaptics-rmi4 - simplify data read in rmi_f54_work

The body of the for loop is only ever run once as the second standard_report
element is never changed from its initial zero init, so the loop condition is
never satisfies after the first run. Equally the start member of the first
element is never changed from 0, so the index offset is always a constant 0.

Remove this needless obfuscation of the code and write it in a straight
forward manner.

Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Link: https://lore.kernel.org/r/20191104114454.10500-3-l.stach@pengutronix.de
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>


# 003f01c7 04-Nov-2019 Lucas Stach <l.stach@pengutronix.de>

Input: synaptics-rmi4 - fix video buffer size

The video buffer used by the queue is a vb2_v4l2_buffer, not a plain
vb2_buffer. Using the wrong type causes the allocation of the buffer
storage to be too small, causing a out of bounds write when
__init_vb2_v4l2_buffer initializes the buffer.

Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Fixes: 3a762dbd5347 ("[media] Input: synaptics-rmi4 - add support for F54 diagnostics")
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20191104114454.10500-1-l.stach@pengutronix.de
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>


# d2912cb1 04-Jun-2019 Thomas Gleixner <tglx@linutronix.de>

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500

Based on 2 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 version 2 as
published by the free software foundation

this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license version 2 as
published by the free software foundation #

extracted by the scancode license scanner the SPDX license identifier

GPL-2.0-only

has been chosen to replace the boilerplate/reference in 4122 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Enrico Weigelt <info@metux.net>
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190604081206.933168790@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>


# 9a952206 26-Apr-2019 Philipp Zabel <p.zabel@pengutronix.de>

Input: synaptics-rmi4 - fix enum_fmt

Do not enumerate all formats, some of which the device may not even
support. Instead, only report the one fixed format of the currently
selected input that will survive try_fmt/s_fmt.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>


# 9f6da5d4 26-Apr-2019 Philipp Zabel <p.zabel@pengutronix.de>

Input: synaptics-rmi4 - fill initial format

The driver doesn't set an initial video format until s_input is called:

$ v4l2-ctl -d /dev/v4l-touch0 --get-input
Video input : 0 (Normalized 16-Bit Image: ok)
$ v4l2-ctl -d /dev/v4l-touch0 --get-fmt-video
Width/Height : 0/0
Pixel Format : ''
[...]
$ v4l2-ctl -d /dev/v4l-touch0 --set-input 0
Video input set to 0 (Normalized 16-Bit Image: Touch, ok)
$ v4l2-ctl -d /dev/v4l-touch0 --get-fmt-video
Width/Height : 71/40
Pixel Format : 'TD16'
[...]

To fix this, initialize the video format to input 0 during probe.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>


# a86854d0 12-Jun-2018 Kees Cook <keescook@chromium.org>

treewide: devm_kzalloc() -> devm_kcalloc()

The devm_kzalloc() function has a 2-factor argument form, devm_kcalloc().
This patch replaces cases of:

devm_kzalloc(handle, a * b, gfp)

with:
devm_kcalloc(handle, a * b, gfp)

as well as handling cases of:

devm_kzalloc(handle, a * b * c, gfp)

with:

devm_kzalloc(handle, array3_size(a, b, c), gfp)

as it's slightly less ugly than:

devm_kcalloc(handle, array_size(a, b), c, gfp)

This does, however, attempt to ignore constant size factors like:

devm_kzalloc(handle, 4 * 1024, gfp)

though any constants defined via macros get caught up in the conversion.

Any factors with a sizeof() of "unsigned char", "char", and "u8" were
dropped, since they're redundant.

Some manual whitespace fixes were needed in this patch, as Coccinelle
really liked to write "=devm_kcalloc..." instead of "= devm_kcalloc...".

The Coccinelle script used for this was:

// Fix redundant parens around sizeof().
@@
expression HANDLE;
type TYPE;
expression THING, E;
@@

(
devm_kzalloc(HANDLE,
- (sizeof(TYPE)) * E
+ sizeof(TYPE) * E
, ...)
|
devm_kzalloc(HANDLE,
- (sizeof(THING)) * E
+ sizeof(THING) * E
, ...)
)

// Drop single-byte sizes and redundant parens.
@@
expression HANDLE;
expression COUNT;
typedef u8;
typedef __u8;
@@

(
devm_kzalloc(HANDLE,
- sizeof(u8) * (COUNT)
+ COUNT
, ...)
|
devm_kzalloc(HANDLE,
- sizeof(__u8) * (COUNT)
+ COUNT
, ...)
|
devm_kzalloc(HANDLE,
- sizeof(char) * (COUNT)
+ COUNT
, ...)
|
devm_kzalloc(HANDLE,
- sizeof(unsigned char) * (COUNT)
+ COUNT
, ...)
|
devm_kzalloc(HANDLE,
- sizeof(u8) * COUNT
+ COUNT
, ...)
|
devm_kzalloc(HANDLE,
- sizeof(__u8) * COUNT
+ COUNT
, ...)
|
devm_kzalloc(HANDLE,
- sizeof(char) * COUNT
+ COUNT
, ...)
|
devm_kzalloc(HANDLE,
- sizeof(unsigned char) * COUNT
+ COUNT
, ...)
)

// 2-factor product with sizeof(type/expression) and identifier or constant.
@@
expression HANDLE;
type TYPE;
expression THING;
identifier COUNT_ID;
constant COUNT_CONST;
@@

(
- devm_kzalloc
+ devm_kcalloc
(HANDLE,
- sizeof(TYPE) * (COUNT_ID)
+ COUNT_ID, sizeof(TYPE)
, ...)
|
- devm_kzalloc
+ devm_kcalloc
(HANDLE,
- sizeof(TYPE) * COUNT_ID
+ COUNT_ID, sizeof(TYPE)
, ...)
|
- devm_kzalloc
+ devm_kcalloc
(HANDLE,
- sizeof(TYPE) * (COUNT_CONST)
+ COUNT_CONST, sizeof(TYPE)
, ...)
|
- devm_kzalloc
+ devm_kcalloc
(HANDLE,
- sizeof(TYPE) * COUNT_CONST
+ COUNT_CONST, sizeof(TYPE)
, ...)
|
- devm_kzalloc
+ devm_kcalloc
(HANDLE,
- sizeof(THING) * (COUNT_ID)
+ COUNT_ID, sizeof(THING)
, ...)
|
- devm_kzalloc
+ devm_kcalloc
(HANDLE,
- sizeof(THING) * COUNT_ID
+ COUNT_ID, sizeof(THING)
, ...)
|
- devm_kzalloc
+ devm_kcalloc
(HANDLE,
- sizeof(THING) * (COUNT_CONST)
+ COUNT_CONST, sizeof(THING)
, ...)
|
- devm_kzalloc
+ devm_kcalloc
(HANDLE,
- sizeof(THING) * COUNT_CONST
+ COUNT_CONST, sizeof(THING)
, ...)
)

// 2-factor product, only identifiers.
@@
expression HANDLE;
identifier SIZE, COUNT;
@@

- devm_kzalloc
+ devm_kcalloc
(HANDLE,
- SIZE * COUNT
+ COUNT, SIZE
, ...)

// 3-factor product with 1 sizeof(type) or sizeof(expression), with
// redundant parens removed.
@@
expression HANDLE;
expression THING;
identifier STRIDE, COUNT;
type TYPE;
@@

(
devm_kzalloc(HANDLE,
- sizeof(TYPE) * (COUNT) * (STRIDE)
+ array3_size(COUNT, STRIDE, sizeof(TYPE))
, ...)
|
devm_kzalloc(HANDLE,
- sizeof(TYPE) * (COUNT) * STRIDE
+ array3_size(COUNT, STRIDE, sizeof(TYPE))
, ...)
|
devm_kzalloc(HANDLE,
- sizeof(TYPE) * COUNT * (STRIDE)
+ array3_size(COUNT, STRIDE, sizeof(TYPE))
, ...)
|
devm_kzalloc(HANDLE,
- sizeof(TYPE) * COUNT * STRIDE
+ array3_size(COUNT, STRIDE, sizeof(TYPE))
, ...)
|
devm_kzalloc(HANDLE,
- sizeof(THING) * (COUNT) * (STRIDE)
+ array3_size(COUNT, STRIDE, sizeof(THING))
, ...)
|
devm_kzalloc(HANDLE,
- sizeof(THING) * (COUNT) * STRIDE
+ array3_size(COUNT, STRIDE, sizeof(THING))
, ...)
|
devm_kzalloc(HANDLE,
- sizeof(THING) * COUNT * (STRIDE)
+ array3_size(COUNT, STRIDE, sizeof(THING))
, ...)
|
devm_kzalloc(HANDLE,
- sizeof(THING) * COUNT * STRIDE
+ array3_size(COUNT, STRIDE, sizeof(THING))
, ...)
)

// 3-factor product with 2 sizeof(variable), with redundant parens removed.
@@
expression HANDLE;
expression THING1, THING2;
identifier COUNT;
type TYPE1, TYPE2;
@@

(
devm_kzalloc(HANDLE,
- sizeof(TYPE1) * sizeof(TYPE2) * COUNT
+ array3_size(COUNT, sizeof(TYPE1), sizeof(TYPE2))
, ...)
|
devm_kzalloc(HANDLE,
- sizeof(TYPE1) * sizeof(THING2) * (COUNT)
+ array3_size(COUNT, sizeof(TYPE1), sizeof(TYPE2))
, ...)
|
devm_kzalloc(HANDLE,
- sizeof(THING1) * sizeof(THING2) * COUNT
+ array3_size(COUNT, sizeof(THING1), sizeof(THING2))
, ...)
|
devm_kzalloc(HANDLE,
- sizeof(THING1) * sizeof(THING2) * (COUNT)
+ array3_size(COUNT, sizeof(THING1), sizeof(THING2))
, ...)
|
devm_kzalloc(HANDLE,
- sizeof(TYPE1) * sizeof(THING2) * COUNT
+ array3_size(COUNT, sizeof(TYPE1), sizeof(THING2))
, ...)
|
devm_kzalloc(HANDLE,
- sizeof(TYPE1) * sizeof(THING2) * (COUNT)
+ array3_size(COUNT, sizeof(TYPE1), sizeof(THING2))
, ...)
)

// 3-factor product, only identifiers, with redundant parens removed.
@@
expression HANDLE;
identifier STRIDE, SIZE, COUNT;
@@

(
devm_kzalloc(HANDLE,
- (COUNT) * STRIDE * SIZE
+ array3_size(COUNT, STRIDE, SIZE)
, ...)
|
devm_kzalloc(HANDLE,
- COUNT * (STRIDE) * SIZE
+ array3_size(COUNT, STRIDE, SIZE)
, ...)
|
devm_kzalloc(HANDLE,
- COUNT * STRIDE * (SIZE)
+ array3_size(COUNT, STRIDE, SIZE)
, ...)
|
devm_kzalloc(HANDLE,
- (COUNT) * (STRIDE) * SIZE
+ array3_size(COUNT, STRIDE, SIZE)
, ...)
|
devm_kzalloc(HANDLE,
- COUNT * (STRIDE) * (SIZE)
+ array3_size(COUNT, STRIDE, SIZE)
, ...)
|
devm_kzalloc(HANDLE,
- (COUNT) * STRIDE * (SIZE)
+ array3_size(COUNT, STRIDE, SIZE)
, ...)
|
devm_kzalloc(HANDLE,
- (COUNT) * (STRIDE) * (SIZE)
+ array3_size(COUNT, STRIDE, SIZE)
, ...)
|
devm_kzalloc(HANDLE,
- COUNT * STRIDE * SIZE
+ array3_size(COUNT, STRIDE, SIZE)
, ...)
)

// Any remaining multi-factor products, first at least 3-factor products,
// when they're not all constants...
@@
expression HANDLE;
expression E1, E2, E3;
constant C1, C2, C3;
@@

(
devm_kzalloc(HANDLE, C1 * C2 * C3, ...)
|
devm_kzalloc(HANDLE,
- (E1) * E2 * E3
+ array3_size(E1, E2, E3)
, ...)
|
devm_kzalloc(HANDLE,
- (E1) * (E2) * E3
+ array3_size(E1, E2, E3)
, ...)
|
devm_kzalloc(HANDLE,
- (E1) * (E2) * (E3)
+ array3_size(E1, E2, E3)
, ...)
|
devm_kzalloc(HANDLE,
- E1 * E2 * E3
+ array3_size(E1, E2, E3)
, ...)
)

// And then all remaining 2 factors products when they're not all constants,
// keeping sizeof() as the second factor argument.
@@
expression HANDLE;
expression THING, E1, E2;
type TYPE;
constant C1, C2, C3;
@@

(
devm_kzalloc(HANDLE, sizeof(THING) * C2, ...)
|
devm_kzalloc(HANDLE, sizeof(TYPE) * C2, ...)
|
devm_kzalloc(HANDLE, C1 * C2 * C3, ...)
|
devm_kzalloc(HANDLE, C1 * C2, ...)
|
- devm_kzalloc
+ devm_kcalloc
(HANDLE,
- sizeof(TYPE) * (E2)
+ E2, sizeof(TYPE)
, ...)
|
- devm_kzalloc
+ devm_kcalloc
(HANDLE,
- sizeof(TYPE) * E2
+ E2, sizeof(TYPE)
, ...)
|
- devm_kzalloc
+ devm_kcalloc
(HANDLE,
- sizeof(THING) * (E2)
+ E2, sizeof(THING)
, ...)
|
- devm_kzalloc
+ devm_kcalloc
(HANDLE,
- sizeof(THING) * E2
+ E2, sizeof(THING)
, ...)
|
- devm_kzalloc
+ devm_kcalloc
(HANDLE,
- (E1) * E2
+ E1, E2
, ...)
|
- devm_kzalloc
+ devm_kcalloc
(HANDLE,
- (E1) * (E2)
+ E1, E2
, ...)
|
- devm_kzalloc
+ devm_kcalloc
(HANDLE,
- E1 * E2
+ E1, E2
, ...)
)

Signed-off-by: Kees Cook <keescook@chromium.org>


# 24d28e4f 05-Jun-2018 Nick Dyer <nick@shmanahar.org>

Input: synaptics-rmi4 - convert irq distribution to irq_domain

Convert the RMI driver to use the standard mechanism for
distributing IRQs to the various functions.

Tested on:
* S7300 (F11, F34, F54)
* S7817 (F12, F34, F54)

Signed-off-by: Nick Dyer <nick@shmanahar.org>
Acked-by: Christopher Heiny <cheiny@synaptics.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>


# 60942e67 04-Oct-2017 Colin Ian King <colin.king@canonical.com>

Input: synaptics-rmi4 - make array rmi_f54_report_type_names static

The array rmi_f54_report_type_names is local to the source and does
not need to be in global scope, so make it static. Also make the array
const char * const.

Cleans up sparse warning:
symbol 'rmi_f54_report_type_names' was not declared. Should it be static?

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>


# 97689352 23-Jun-2017 Andrew Duggan <aduggan@synaptics.com>

Input: synaptics-rmi4 - only read the F54 query registers which are used

The F54 driver is currently only using the first 6 bytes of F54 so there is
no need to read all 27 bytes. Some Dell systems (Dell XP13 9333 and
similar) have an issue with the touchpad or I2C bus when reading reports
larger then 16 bytes. Reads larger then 16 bytes are reported in two HID
reports. Something about the back to back reports seems to cause the next
read to report incorrect data. This results in F30 failing to load and the
click button failing to work.

Previous issues with the I2C controller or touchpad were addressed in:
commit 5b65c2a02966 ("HID: rmi: check sanity of the incoming report")

Fixes: https://bugzilla.kernel.org/show_bug.cgi?id=195949
Signed-off-by: Andrew Duggan <aduggan@synaptics.com>
Reviewed-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Reviewed-by: Nick Dyer <nick@shmanahar.org>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>


# c762cc68 22-Nov-2016 Guenter Roeck <linux@roeck-us.net>

Input: synaptics-rmi4 - propagate correct number of rx and tx electrodes to F54

F54 diagnostics report functions provide data based on the number of
enabled rx and tx electrodes, which is not identical to the number of
electrodes reported with F54:Query0 and F54:Query1. Those values report
the number of supported electrodes, not the number of enabled electrodes.
The number of enabled electrodes can be determined by analyzing F55:Ctrl1
(sensor receiver assignment) and F55:Ctrl2 (sensor transmitter assignment).

Propagate the number of enabled electrodes from F55 to F54 to avoid
corrupted output if not all electrodes are enabled.

Fixes: 3a762dbd5347 ("[media] Input: synaptics-rmi4 - add support for F54 ...")
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Tested-by: Nick Dyer <nick@shmanahar.org>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>


# 792f497b 16-Nov-2016 Dan Carpenter <dan.carpenter@oracle.com>

Input: synaptics-rmi4 - unlock on error

We should unlock before returning on this error path.

Fixes: 3a762dbd5347 ('[media] Input: synaptics-rmi4 - add support for F54 diagnostics')
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>


# f3c4a8f8 15-Sep-2016 Nick Dyer <nick@shmanahar.org>

[media] Input: v4l-touch - add copyright lines

Add copyright lines for Zodiac who paid for the V4L touch work.

Signed-off-by: Nick Dyer <nick@shmanahar.org>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>


# 3a762dbd 18-Jul-2016 Nick Dyer <nick@shmanahar.org>

[media] Input: synaptics-rmi4 - add support for F54 diagnostics

Function 54 implements access to various RMI4 diagnostic features.

This patch adds support for retrieving this data. It registers a V4L2
device to output the data to user space.

Signed-off-by: Nick Dyer <nick@shmanahar.org>
Tested-by: Andrew Duggan <aduggan@synaptics.com>
Tested-by: Chris Healy <cphealy@gmail.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>