platform/chrome: 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>
Reviewed-by: Guenter Roeck <groeck@chromium.org>
Signed-off-by: Tzung-Bi Shih <tzungbi@kernel.org>
Link: https://lore.kernel.org/r/20230526214703.2135137-1-u.kleine-koenig@pengutronix.de

platform/chrome: cros_ec: 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>
Reviewed-by: Guenter Roeck <groeck@chromium.org>
Signed-off-by: Tzung-Bi Shih <tzungbi@kernel.org>
Link: https://lore.kernel.org/r/20221118224540.619276-513-uwe@kleine-koenig.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>

platform/chrome: cros_ec_i2c: drop BUG_ON() in cros_ec_pkt_xfer_i2c()

It is overkill to crash the kernel if the given message is oversize.

Drop the BUG_ON() and return -EINVAL instead.

Reviewed-by: Guenter Roeck <groeck@chromium.org>
Signed-off-by: Tzung-Bi Shih <tzungbi@kernel.org>
Link: https://lore.kernel.org/r/20220513044143.1045728-6-tzungbi@kernel.org

platform/chrome: correct cros_ec_prepare_tx() usage

cros_ec_prepare_tx() returns either:
- >= 0 for number of prepared bytes.
- < 0 for -errno.

Correct the comment and make sure all callers check the return code.

Reviewed-by: Guenter Roeck <groeck@chromium.org>
Signed-off-by: Tzung-Bi Shih <tzungbi@kernel.org>
Link: https://lore.kernel.org/r/20220513044143.1045728-3-tzungbi@kernel.org

platform/chrome: cros_ec: Make cros_ec_unregister() return void

Up to now cros_ec_unregister() returns zero unconditionally. Make it
return void instead which makes it easier to see in the callers that
there is no error to handle.

Also the return value of i2c, platform and spi remove callbacks is
ignored anyway.

Reviewed-by: Guenter Roeck <groeck@chromium.org>
Link: https://lore.kernel.org/r/20211020071753.wltjslmimb6wtlp5@pengutronix.de
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Acked-by: Lee Jones <lee.jones@linaro.org>
Link: https://lore.kernel.org/r/20220123175201.34839-5-u.kleine-koenig@pengutronix.de
Signed-off-by: Mark Brown <broonie@kernel.org>

platform/chrome: cros_ec_i2c: Appease the kernel-doc deity

Replace a comment starting with /** by simply /* to avoid having
it interpreted as a kernel-doc comment.

Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Signed-off-by: Benson Leung <bleung@chromium.org>

platform/chrome: cros_ec: Match implementation with headers

The 'cros_ec' core driver is the common interface for the cros_ec
transport drivers to do the shared operations to register, unregister,
suspend, resume and handle_event. The interface is provided by including
the header 'include/linux/platform_data/cros_ec_proto.h', however, instead
of have the implementation of these functions in cros_ec_proto.c, it is in
'cros_ec.c', which is a different kernel module. Apart from being a bad
practice, this can induce confusions allowing the users of the cros_ec
protocol to call these functions.

The register, unregister, suspend, resume and handle_event functions
*should* only be called by the different transport drivers (i2c, spi, lpc,
etc.), so make this a bit less confusing by moving these functions from
the public in-kernel space to a private include in platform/chrome, and
then, the interface for cros_ec module and for the cros_ec_proto module is
clean.

Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Signed-off-by: Benson Leung <bleung@chromium.org>

mfd / platform: cros_ec: Reorganize platform and mfd includes

There is a bit of mess between cros-ec mfd includes and platform
includes. For example, we have a linux/mfd/cros_ec.h include that
exports the interface implemented in platform/chrome/cros_ec_proto.c. Or
we have a linux/mfd/cros_ec_commands.h file that is non related to the
multifunction device (in the sense that is not exporting any function of
the mfd device). This causes crossed includes between mfd and
platform/chrome subsystems and makes the code difficult to read, apart
from creating 'curious' situations where a platform/chrome driver includes
a linux/mfd/cros_ec.h file just to get the exported functions that are
implemented in another platform/chrome driver.

In order to have a better separation on what the cros-ec multifunction
driver does and what the cros-ec core provides move and rework the
affected includes doing:

- Move cros_ec_commands.h to include/linux/platform_data/cros_ec_commands.h
- Get rid of the parts that are implemented in the platform/chrome/cros_ec_proto.c
driver from include/linux/mfd/cros_ec.h to a new file
include/linux/platform_data/cros_ec_proto.h
- Update all the drivers with the new includes, so
- Drivers that only need to know about the protocol include
- linux/platform_data/cros_ec_proto.h
- linux/platform_data/cros_ec_commands.h
- Drivers that need to know about the cros-ec mfd device also include
- linux/mfd/cros_ec.h

Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Mark Brown <broonie@kernel.org>
Acked-by: Wolfram Sang <wsa@the-dreams.de>
Acked-by: Neil Armstrong <narmstrong@baylibre.com>
Acked-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Acked-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Acked-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Acked-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Acked-by: Chanwoo Choi <cw00.choi@samsung.com>
Reviewed-by: Gwendal Grignou <gwendal@chromium.org>
Tested-by: Gwendal Grignou <gwendal@chromium.org>
Series changes: 3
- Fix dereferencing pointer to incomplete type 'struct cros_ec_dev' (lkp)
Signed-off-by: Lee Jones <lee.jones@linaro.org>

mfd / platform: cros_ec: Handle chained ECs as platform devices

An MFD is a device that contains several sub-devices (cells). For instance,
the ChromeOS EC fits in this description as usually contains a charger and
can have other devices with different functions like a Real-Time Clock,
an Audio codec, a Real-Time Clock, ...

If you look at the driver, though, we're doing something odd. We have
two MFD cros-ec drivers where one of them (cros-ec-core) instantiates
another MFD driver as sub-driver (cros-ec-dev), and the latest
instantiates the different sub-devices (Real-Time Clock, Audio codec,
etc).

MFD
------------------------------------------
cros-ec-core
|___ mfd-cellA (cros-ec-dev)
| |__ mfd-cell0
| |__ mfd-cell1
| |__ ...
|
|___ mfd-cellB (cros-ec-dev)
|__ mfd-cell0
|__ mfd-cell1
|__ ...

The problem that was trying to solve is to describe some kind of topology for
the case where we have an EC (cros-ec) chained with another EC
(cros-pd). Apart from that this extends the bounds of what MFD was
designed to do we might be interested on have other kinds of topology that
can't be implemented in that way.

Let's prepare the code to move the cros-ec-core part from MFD to
platform/chrome as this is clearly a platform specific thing non-related
to a MFD device.

platform/chrome | MFD
------------------------------------------
|
cros-ec ________|___ cros-ec-dev
| |__ mfd-cell0
| |__ mfd-cell1
| |__ ...
|
cros-pd ________|___ cros-ec-dev
| |__ mfd-cell0
| |__ mfd-cell1
| |__ ...

Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Gwendal Grignou <gwendal@chromium.org>
Tested-by: Gwendal Grignou <gwendal@chromium.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

platform/chrome: cros_ec_i2c: switch to SPDX identifier

Adopt the SPDX license identifier headers to ease license compliance
management. Also fix the module license mismatch and change the
description for a more descriptive phrase.

Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Reviewed-by: Guenter Roeck <groeck@chromium.org>

mfd / platform: cros_ec: Use devm_mfd_add_devices

Use devm_mfd_add_devices() for adding cros-ec core MFD child devices. This
reduces the need of remove callback from platform/chrome for removing the
MFD child devices.

Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Reviewed-by: Guenter Roeck <groeck@chromium.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

platform/chrome: Move cros-ec transport drivers to drivers/platform.

There are some cros-ec transport drivers (I2C, SPI) living in MFD, while
others (LPC) living in drivers/platform. The transport drivers are more
platform specific. So, move the I2C and SPI transport drivers to the
platform/chrome directory. The patch also removes the MFD_ prefix of
their Kconfig symbols.

Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Reviewed-by: Guenter Roeck <groeck@chromium.org>
Acked-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Benson Leung <bleung@chromium.org>