When polled input device is opened and closed and there are no other
users of polled device, the workqueue is created and destroyed in
every open / close operation. It is probable that at some point
dynamic allocation of internal parts of the workqueue cause changes to the
workqueue.

When a work is queued to the workqueue the work struct contains pointers
to the workqueue data. If the workqueue has been changed and the work
has never been queued to the new workqueue, work-struct contains pointers
to the non-existing workqueue. This will cause crash at the work
cancellation during device close since cancellation of a work assumes
that the workqueue exists.

To prevent that, work struct is cleaned up at device close. This keeps
work struct clean for the next use.
Signed-off-by: NSamu Onkalo <samu.p.onkalo@nokia.com>
Signed-off-by: NDmitry Torokhov <dtor@mail.ru>

More and more devices choose to reimplement support for sparse keymaps
first introduced by wistron driver. Move it into a library module so it
can be easily used by interested parties.
Reviewed-by: NAnisse Astier <anisse@astier.eu>
Signed-off-by: NDmitry Torokhov <dtor@mail.ru>

If the poll interval is set to 0 via new sysfs entry and device is
opened after that, polling is started with interval 0. This causes
huge CPU load. Same happens if the rate was 0 when the device was
closed and then reopened.
Signed-off-by: NSamu Onkalo <samu.p.onkalo@nokia.com>
Signed-off-by: NDmitry Torokhov <dtor@mail.ru>

It does not make sense to wait poll_interval before performing first
read after opening the device, schedule the read immediately instead.
Signed-off-by: NDmitry Torokhov <dtor@mail.ru>

Sysfs entry for reading and setting of the polling interval. If the
interval is set to 0, polling is stopped. Polling is restarted when
interval is changed to non-zero.

sysfs entries:
poll = current polling interval in msec (RW)
max = max allowed polling interval (RO)
min = min allowed polling interval (RO)

Minimum and maximum limit for interval can be set while setting up the
device.

Interval can be adjusted even if the input device is not currently open.

[dtor@mail.ru: add kernel doc markup for the new fields]
Signed-off-by: NSamu Onkalo <samu.p.onkalo@nokia.com>
Signed-off-by: NDmitry Torokhov <dtor@mail.ru>

Optional open and close methods for preparing and closing
the device.
Signed-off-by: NSamu Onkalo <samu.p.onkalo@nokia.com>
Signed-off-by: NDmitry Torokhov <dtor@mail.ru>

Everyone should be using input_{get|set}_drvdata() by now.
Alias them to dev_{get|set}_drvdata() and remove ->private.
Signed-off-by: NDmitry Torokhov <dtor@mail.ru>

Rounding doesn't matter for the first tick, but we want
succeeding ticks to be aligned on second boundary if poll
interval is large enough.

Also: cancel_rearming_delayed_workqueue is marked as obsolete
in workqueue.h so use cancel_delayed_work_sync.
Signed-off-by: NStephen Hemminger <shemminger@linux-foundation.org>
Acked-by: NArjan van de Ven <arjan@linux.intel.com>
Signed-off-by: NDmitry Torokhov <dtor@mail.ru>

For slow running polling, it saves power to align wakeups on tick boundary.
Signed-off-by: NStephen Hemminger <shemminger@linux-foundation.org>
Signed-off-by: NDmitry Torokhov <dtor@mail.ru>

To work around deficiences in Kconfig that allows to "select"
a symbol without automatically selecting all dependencies for
that symbol move input-polldev from drivers/input/misc to
drivers/input thus removing extra dependency on CONFIG_INPUT_MISC.
Signed-off-by: NDmitry Torokhov <dtor@mail.ru>

This is required to load it as a module, as GPL-compatible
license is necessary to use workqueues.
Signed-off-by: NEric Piel <eric.piel@tremplin-utc.net>
Signed-off-by: NDmitry Torokhov <dtor@mail.ru>

input-polldev provides a skeleton for supporting simple input
devices that need to be periodically scanned or polled to
detect changes in their state.
Signed-off-by: NDmitry Torokhov <dtor@mail.ru>