Input: goodix - fix race on driver unbind

Because there is no way to detect if the touchscreen has pen support,
the driver is allocating and registering the input_pen input_dev on
receiving the first pen event.

But this means that the input_dev gets allocated after the request_irq()
call which means that the devm framework will free it before disabling
the irq, leaving a window where the irq handler may run and reference the
free-ed input_dev.

To fix this move the allocation of the input_pen input_dev to before
the request_irq() call, while still only registering it on the first pen
event so that the driver does not advertise pen capability on touchscreens
without it (most goodix touchscreens do not have pen support).

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20220131143539.109142-4-hdegoede@redhat.com
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

Input: goodix - add pen support

Some Goodix touchscreens have support for a (Goodix) active pen, add
support for this. The info on how to detect when a pen is down and to
detect when the stylus buttons are pressed was lifted from the out
of tree Goodix driver with pen support written by Adya:
https://gitlab.com/AdyaAdya/goodix-touchscreen-linux-driver/

Since there is no way to tell if pen support is present, the registering
of the pen input_dev is delayed till the first pen event is detected.

This has been tested on a Trekstor Surftab duo W1, a Chuwi Hi13 and
a Cyberbook T116 tablet.

BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=202161
BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=204513
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20211207100754.31155-3-hdegoede@redhat.com

Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

Input: goodix - try not to touch the reset-pin on x86/ACPI devices

Unless the controller is not responding at boot or after suspend/resume,
the driver never resets the controller on x86/ACPI platforms. The driver
still requesting the reset pin at probe() though in case it needs it.

Until now the driver has always requested the reset pin with GPIOD_IN
as type. The idea being to put the pin in high-impedance mode to save
power until the driver actually wants to issue a reset.

But this means that just requesting the pin can cause issues, since
requesting it in another mode then GPIOD_ASIS may cause the pinctrl
driver to touch the pin settings. We have already had issues before
due to a bug in the pinctrl-cherryview.c driver which has been fixed in
commit 921daeeca91b ("pinctrl: cherryview: Preserve
CHV_PADCTRL1_INVRXTX_TXDATA flag on GPIOs").

And now it turns out that requesting the reset-pin as GPIOD_IN also stops
the touchscreen from working on the GPD P2 max mini-laptop. The behavior
of putting the pin in high-impedance mode relies on there being some
external pull-up to keep it high and there seems to be no pull-up on the
GPD P2 max, causing things to break.

This commit fixes this by requesting the reset pin as is when using
the x86/ACPI code paths to lookup the GPIOs; and by not dropping it
back into input-mode in case the driver does end up issuing a reset
for error-recovery.

BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=209061
Fixes: a7d4b171660c ("Input: goodix - add support for getting IRQ + reset GPIOs on Cherry Trail devices")
Cc: stable@vger.kernel.org
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20211206091116.44466-2-hdegoede@redhat.com
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

Input: goodix - add support for controllers without flash

Some Goodix touchscreen controllers, such as for example the GT912,
don't have flash-storage for their firmware.

These models require the OS to load the firmware at runtime, as well as
some other special handling. Add support for this to the goodix driver.

This patch was developed and tested on a Glavey TM800A550L tablet.

Note the "goodix,main-clk" and "firmware-name" device-properties used
by the new code are *not* documented in the
Documentation/devicetree/bindings/input/touchscreen/goodix.yaml
device-tree bindings for now.

Not documenting these is intentional. This is done because this code has
only been tested on x86/ACPI so far, where devicetree is not used.
Instead these properties are set through a software-fwnode attached to the
device by the drivers/platform/x86/touchscreen_dmi.c code. This means that
the use of this properties for now is purely a kernel-internal thing and
the name/working of the properties may still be changed for now.

Reviewed-by: Bastien Nocera <hadess@hadess.net>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20210920150643.155872-7-hdegoede@redhat.com
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

Input: goodix - allow specifying the config filename

The config which needs to be send to the controller on some device-models
is model-specific. Allow specifying a model-specific filename through
a device-property, rather then always using a fixed filename.

Note the "goodix,config-name" device-property used by this is
*not* documented in the
Documentation/devicetree/bindings/input/touchscreen/goodix.yaml
device-tree bindings for now.

Not documenting these is intentional. This is done because this code has
only been tested on x86/ACPI so far, where devicetree is not used.
Instead these properties are set through a software-fwnode attached to the
device by the drivers/platform/x86/touchscreen_dmi.c code. This means that
the use of this property for now is purely a kernel-internal thing and
the name/working of the property may still be changed for now.

Reviewed-by: Bastien Nocera <hadess@hadess.net>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20210920150643.155872-6-hdegoede@redhat.com
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

Input: goodix - refactor reset handling

Refactor reset handling a bit, change the main reset handler
into a new goodix_reset_no_int_sync() helper and add a
goodix_reset() wrapper which calls goodix_int_sync()
separately.

Also push the dev_err() call on reset failure into the
goodix_reset_no_int_sync() and goodix_int_sync() functions,
so that we don't need to have separate dev_err() calls in
all their callers.

This is a preparation patch for adding support for controllers
without flash, which need to have their firmware uploaded and
need some other special handling too.

Reviewed-by: Bastien Nocera <hadess@hadess.net>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20210920150643.155872-4-hdegoede@redhat.com
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

Input: goodix - add a goodix.h header file

Add a goodix.h header file, and move the register definitions,
and struct declarations there and add prototypes for various
helper functions.

This is a preparation patch for adding support for controllers
without flash, which need to have their firmware uploaded and
need some other special handling too.

Since MAINTAINERS needs updating because of this change anyways,
also add myself as co-maintainer.

Reviewed-by: Bastien Nocera <hadess@hadess.net>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20210920150643.155872-3-hdegoede@redhat.com
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>