Input: ad7879 - use device core to create driver-specific device attributes

Instead of creating driver-specific device attributes with
devm_device_add_group() have device core do this by setting up dev_groups
pointer in the driver structure.

Acked-by: Michael Hennerich <michael.hennerich@analog.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://lore.kernel.org/r/20230729005133.1095051-6-dmitry.torokhov@gmail.com
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 149

Based on 1 normalized pattern(s):

licensed under the gpl 2 or later

extracted by the scancode license scanner the SPDX license identifier

GPL-2.0-or-later

has been chosen to replace the boilerplate/reference in 82 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Richard Fontana <rfontana@redhat.com>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190524100845.150836982@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Input: ad7879 - return plain error code from ad7879_probe()

With the switch to devm, there is no need for ad7879_probe() to return the
touchscreen structure, we can use plain error code. This also fixes issue
introduced with devm concersion, where we returned 0 on success (which
worked OK since IS_ERR(0) would not trigger, but was not correct
regardless).

Fixes: 381f688eee3d ("Input: ad7879 - use more devm interfaces")
Acked-by: Michael Hennerich <michael.hennerich@analog.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

Input: ad7879 - use more devm interfaces

gpiochip_add now has a managed version, and we can remove sysfs attribute
group via devm_add_action_or_reset (at least until we have devm version of
sysfs_create_group). This allows us to get rid of ad7879_remove().

Reviewed-by: Michael Hennerich <michael.hennerich@analog.com>
Tested-by: Michael Hennerich <michael.hennerich@analog.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

Input: ad7879 - convert to use regmap

Instead of rolling our own infrastructure to provide uniform access to I2C
and SPI buses, let's switch to using regmap.

Reviewed-by: Michael Hennerich <michael.hennerich@analog.com>
Tested-by: Michael Hennerich <michael.hennerich@analog.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

Input: ad7879 - consolidate PM methods

The PM methods are basically the same for SPI and I2C busses, so let's
use the same dev_pm_ops for both of them.

Acked-by: Michael Hennerich <michael.hennerich@analog.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>

Input: ad7879 - add open and close methods

Tested-by: Michael Hennerich <michael.hennerich@analog.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>

Input: ad7879 - split bus logic out

The ad7879 driver is using the old bus method of only supporting one
at a time (I2C or SPI). So refactor it like the other input drivers
that support multiple busses simultaneously.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>