regulator: rpi-panel-attiny: Drop useless header

The RPI panel regulator driver includes the legacy header
<linux/gpio.h> for no reason, this is a driver and <linux/gpio/driver.h>
is already included. Drop the include.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20230808-descriptors-regulator-v1-3-939b5e84dd18@linaro.org
Signed-off-by: Mark Brown <broonie@kernel.org>

regulator: rpi-panel-attiny-regulator: Remove redundant of_match_ptr()

The driver depends on CONFIG_OF, so it is not necessary to use
of_match_ptr() here, and __maybe_unused can also be removed.

Even for drivers that do not depend on CONFIG_OF, it's almost always
better to leave out the of_match_ptr(), since the only thing it can
possibly do is to save a few bytes of .text if a driver can be used both
with and without it.

Signed-off-by: Ruan Jinjie <ruanjinjie@huawei.com>
Link: https://lore.kernel.org/r/20230807134127.2380390-1-ruanjinjie@huawei.com
Signed-off-by: Mark Brown <broonie@kernel.org>

regulator: Switch i2c drivers back to use .probe()

After commit b8a1a4cd5a98 ("i2c: Provide a temporary .probe_new()
call-back type"), all drivers being converted to .probe_new() and then
03c835f498b5 ("i2c: Switch .probe() to not take an id parameter") convert
back to (the new) .probe() to be able to eventually drop .probe_new() from
struct i2c_driver.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de
Link: https://lore.kernel.org/r/20230505220218.1239542-1-u.kleine-koenig@pengutronix.de
Signed-off-by: Mark Brown <broonie@kernel.org

regulator: Set PROBE_PREFER_ASYNCHRONOUS for drivers between 5.4 and 5.10

This follows on the change ("regulator: Set PROBE_PREFER_ASYNCHRONOUS
for drivers that existed in 4.14") but changes regulators didn't exist
in Linux 5.4 but did exist in Linux 5.10.

Signed-off-by: Douglas Anderson <dianders@chromium.org>
Link: https://lore.kernel.org/r/20230316125351.4.I01f21c98901641a009890590ddc1354c0f294e5e@changeid
Signed-off-by: Mark Brown <broonie@kernel.org>

regulator: rpi-panel-attiny-regulator: Convert to i2c's .probe_new()

The probe function doesn't make use of the i2c_device_id * parameter so it
can be trivially converted.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Acked-for-MFD-by: Lee Jones <lee@kernel.org>
Acked-for-Backlight-by: Lee Jones <lee@kernel.org>
Link: https://lore.kernel.org/r/20221118224540.619276-556-uwe@kleine-koenig.org
Signed-off-by: Mark Brown <broonie@kernel.org>

i2c: Make remove callback return void

The value returned by an i2c driver's remove function is mostly ignored.
(Only an error message is printed if the value is non-zero that the
error is ignored.)

So change the prototype of the remove function to return no value. This
way driver authors are not tempted to assume that passing an error to
the upper layer is a good idea. All drivers are adapted accordingly.
There is no intended change of behaviour, all callbacks were prepared to
return 0 before.

Reviewed-by: Peter Senna Tschudin <peter.senna@gmail.com>
Reviewed-by: Jeremy Kerr <jk@codeconstruct.com.au>
Reviewed-by: Benjamin Mugnier <benjamin.mugnier@foss.st.com>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Reviewed-by: Crt Mori <cmo@melexis.com>
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Marek Behún <kabel@kernel.org> # for leds-turris-omnia
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Petr Machata <petrm@nvidia.com> # for mlxsw
Reviewed-by: Maximilian Luz <luzmaximilian@gmail.com> # for surface3_power
Acked-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com> # for bmc150-accel-i2c + kxcjk-1013
Reviewed-by: Hans Verkuil <hverkuil-cisco@xs4all.nl> # for media/* + staging/media/*
Acked-by: Miguel Ojeda <ojeda@kernel.org> # for auxdisplay/ht16k33 + auxdisplay/lcd2s
Reviewed-by: Luca Ceresoli <luca.ceresoli@bootlin.com> # for versaclock5
Reviewed-by: Ajay Gupta <ajayg@nvidia.com> # for ucsi_ccg
Acked-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> # for iio
Acked-by: Peter Rosin <peda@axentia.se> # for i2c-mux-*, max9860
Acked-by: Adrien Grassein <adrien.grassein@gmail.com> # for lontium-lt8912b
Reviewed-by: Jean Delvare <jdelvare@suse.de> # for hwmon, i2c-core and i2c/muxes
Acked-by: Corey Minyard <cminyard@mvista.com> # for IPMI
Reviewed-by: Vladimir Oltean <olteanv@gmail.com>
Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Acked-by: Sebastian Reichel <sebastian.reichel@collabora.com> # for drivers/power
Acked-by: Krzysztof Hałasa <khalasa@piap.pl>
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Wolfram Sang <wsa@kernel.org>

regulator: rpi-panel-attiny: Use backlight helper

backlight_properties.fb_blank is deprecated. The states it represents
are handled by other properties; but instead of accessing those
properties directly, drivers should use the helpers provided by
backlight.h.

Instead of retrieving the backlight brightness in struct
backlight_properties manually, and then checking whether the backlight
should be on at all, use backlight_get_brightness() which does all
this and insulates this from future changes.

Signed-off-by: Stephen Kitt <steve@sk2.org>
Cc: Liam Girdwood <lgirdwood@gmail.com>
Cc: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20220607185304.1128962-1-steve@sk2.org
Signed-off-by: Mark Brown <broonie@kernel.org>

regulator: rpi-panel-attiny: Get rid of duplicate of_node assignment

GPIO library does copy the of_node from the parent device of
the GPIO chip, there is no need to repeat this in the individual
drivers. Remove these assignment all at once.

For the details one may look into the of_gpio_dev_init() implementation.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20220325184508.45670-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>

regulator/rpi-panel-attiny: Use two transactions for I2C read

The I2C to the Atmel is very fussy, and locks up easily on
Pi0-3 particularly on reads.
If running at 100kHz on Pi3, reading the ID register generally
locks up the Atmel, but splitting the register select write and
read into two transactions is reliable.

Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
Signed-off-by: Detlev Casanova <detlev.casanova@collabora.com>
Link: https://lore.kernel.org/r/20220124220129.158891-10-detlev.casanova@collabora.com
Signed-off-by: Mark Brown <broonie@kernel.org>

regulator/rpi-panel-attiny: Use the regmap cache

The I2C to the Atmel is very fussy, and locks up easily on
Pi0-3 particularly on reads.

The LCD power status is controlled solely by this driver, so
rather than reading it back from the Atmel, use the regmap cache
to avoid reading values.

Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
Signed-off-by: Detlev Casanova <detlev.casanova@collabora.com>
Link: https://lore.kernel.org/r/20220124220129.158891-9-detlev.casanova@collabora.com
Signed-off-by: Mark Brown <broonie@kernel.org>

regulator: rpi-panel: Remove get_brightness hook

The driver was implementing a get_brightness function that
tried to read back the PWM setting of the display to report
as the current brightness.
The controller on the display does not support that, therefore
we end up reporting a brightness of 0, and that confuses
systemd's backlight service.

Remove the hook so that the framework returns the current
brightness automatically.

Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
Signed-off-by: Detlev Casanova <detlev.casanova@collabora.com>
Link: https://lore.kernel.org/r/20220124220129.158891-8-detlev.casanova@collabora.com
Signed-off-by: Mark Brown <broonie@kernel.org>

regulator: rpi-panel: Add GPIO control for panel and touch resets

We need independent control of the resets for the panel&bridge,
vs the touch controller.

Expose the reset lines that are on the Atmel's port C via the GPIO
API so that they can be controlled appropriately.

Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
Signed-off-by: Detlev Casanova <detlev.casanova@collabora.com>
Link: https://lore.kernel.org/r/20220124220129.158891-7-detlev.casanova@collabora.com
Signed-off-by: Mark Brown <broonie@kernel.org>

regulator: rpi-panel: Convert to drive lines directly

The Atmel was doing a load of automatic sequencing of
control lines, however it was combining the touch controller's
reset with the bridge/panel control.

Change to control the control signals directly rather than
through the automatic POWERON control.

Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
Signed-off-by: Detlev Casanova <detlev.casanova@collabora.com>
Link: https://lore.kernel.org/r/20220124220129.158891-6-detlev.casanova@collabora.com
Signed-off-by: Mark Brown <broonie@kernel.org>

regulator: rpi-panel: Ensure the backlight is off during probe.

The initial state of the Atmel is not defined, so ensure the
backlight PWM is set to 0 by default.

Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
Signed-off-by: Detlev Casanova <detlev.casanova@collabora.com>
Link: https://lore.kernel.org/r/20220124220129.158891-5-detlev.casanova@collabora.com
Signed-off-by: Mark Brown <broonie@kernel.org>

regulator: rpi-panel: Serialise operations.

The driver was using the regmap lock to serialise the
individual accesses, but we really need to protect the
timings of enabling the regulators, including any communication
with the Atmel.

Use a mutex within the driver to control overall accesses to
the Atmel, instead of the regmap lock.

Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
Signed-off-by: Detlev Casanova <detlev.casanova@collabora.com>
Link: https://lore.kernel.org/r/20220124220129.158891-4-detlev.casanova@collabora.com
Signed-off-by: Mark Brown <broonie@kernel.org>

regulator: rpi-panel: Handle I2C errors/timing to the Atmel

The Atmel is doing some things in the I2C ISR, during which
period it will not respond to further commands. This is
particularly true of the POWERON command.

Increase delays appropriately, and retry should I2C errors be
reported.

Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
Signed-off-by: Detlev Casanova <detlev.casanova@collabora.com>
Link: https://lore.kernel.org/r/20220124220129.158891-3-detlev.casanova@collabora.com
Signed-off-by: Mark Brown <broonie@kernel.org>

regulator: rpi-panel: Register with a unique backlight name

There's no reason why 2 Raspberry Pi DSI displays can't be
attached to a Pi Compute Module, so the backlight names need to
be unique.

Use the parent dev_name. It's not as readable, but is unique.

Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
Signed-off-by: Detlev Casanova <detlev.casanova@collabora.com>
Link: https://lore.kernel.org/r/20220124220129.158891-2-detlev.casanova@collabora.com
Signed-off-by: Mark Brown <broonie@kernel.org>

regulator: rpi-panel: Add regulator/backlight driver for RPi panel

This regulator/backlight driver handles the ATTINY88 present on the
RPi 7" touchscreen panel and exposes the power/backlight interfaces.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Eric Anholt <eric@anholt.net>
Cc: Mark Brown <broonie@kernel.org>
Cc: Sam Ravnborg <sam@ravnborg.org>
To: dri-devel@lists.freedesktop.org
Link: https://lore.kernel.org/r/20200809105938.6388-2-marex@denx.de
Signed-off-by: Mark Brown <broonie@kernel.org>