platform/chrome/wilco_ec: core: Convert to platform remove callback returning void

The .remove() callback for a platform driver returns an int which makes
many driver authors wrongly assume it's possible to do error handling by
returning an error code. However the value returned is ignored (apart
from emitting a warning) and this typically results in resource leaks.

To improve here there is a quest to make the remove callback return
void. In the first step of this quest all drivers are converted to
.remove_new(), which already returns void. Eventually after all drivers
are converted, .remove_new() will be renamed to .remove().

Trivially convert this driver from always returning zero in the remove
callback to the void returning variant.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20230927081040.2198742-11-u.kleine-koenig@pengutronix.de
Signed-off-by: Tzung-Bi Shih <tzungbi@kernel.org>

platform/chrome: cros_ec_lpc_mec: remove cros_ec_lpc_mec_destroy()

It's pointless (and invalid) to destroy a statically allocated mutex in
cros_ec_lpc_mec_destroy().

Let's remove it.

Signed-off-by: Tzung-Bi Shih <tzungbi@kernel.org>
Reviewed-by: Guenter Roeck <groeck@chromium.org>
Reviewed-by: Brian Norris <briannorris@chromium.org>
Link: https://lore.kernel.org/r/20221031050657.3899359-1-tzungbi@kernel.org

platform/chrome: wilco_ec: Add newlines to printks

printk messages all require newlines, or it looks very odd in the log
when messages are not on different lines. Add them.

Cc: Nick Crews <ncrews@chromium.org>
Cc: Daniel Campello <campello@chromium.org>
Cc: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Signed-off-by: Stephen Boyd <swboyd@chromium.org>
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>

platform/chrome: wilco_ec: Fix unregistration order

The unregistration should happen in the opposite order of
the registration, so change it accordingly.

No real issue has been noticed, but it is good practice to
keep the correct unregistration order.

Signed-off-by: Daniel Campello <campello@chromium.org>
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>

platform/chrome: wilco_ec: Add keyboard backlight LED support

The EC is in charge of controlling the keyboard backlight on
the Wilco platform. We expose a standard LED class device
named platform::kbd_backlight.

Since the EC will never change the backlight level of its own accord,
we don't need to implement a brightness_get() method.

Signed-off-by: Nick Crews <ncrews@chromium.org>
Signed-off-by: Daniel Campello <campello@chromium.org>
Reviewed-by: Daniel Campello <campello@chromium.org>
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>

platform/chrome: wilco_ec: Add charging config driver

Add a device to control the charging algorithm used on Wilco devices,
which will be picked up by the drivers/power/supply/wilco-charger.c
driver. See Documentation/ABI/testing/sysfs-class-power-wilco for the
userspace interface and other info.

Signed-off-by: Nick Crews <ncrews@chromium.org>
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>

platform/chrome: wilco_ec: Add telemetry char device interface

The Wilco Embedded Controller is able to send telemetry data
which is useful for enterprise applications. A daemon running on
the OS sends a command to the EC via a write() to a char device,
and can read the response with a read(). The write() request is
verified by the driver to ensure that it is performing only one
of the whitelisted commands, and that no extraneous data is
being transmitted to the EC. The response is passed directly
back to the reader with no modification.

The character device will appear as /dev/wilco_telemN, where N
is some small non-negative integer, starting with 0. Only one
process may have the file descriptor open at a time. The calling
userspace program needs to keep the device file descriptor open
between the calls to write() and read() in order to preserve the
response. Up to 32 bytes will be available for reading.

For testing purposes, try requesting the EC's firmware build
date, by sending the WILCO_EC_TELEM_GET_VERSION command with
argument index=3. i.e. write [0x38, 0x00, 0x03]
to the device node. An ASCII string of the build date is
returned.

Signed-off-by: Nick Crews <ncrews@chromium.org>
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>

platform/chrome: wilco_ec: Remove 256 byte transfers

The 0xF6 command, intended to send and receive 256 byte payloads to
and from the EC, is not needed. The 0xF5 command for 32 byte
payloads is sufficient. This patch removes support for the 0xF6
command and 256 byte payloads.

Signed-off-by: Nick Crews <ncrews@chromium.org>
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>

platform/chrome: wilco_ec: Add Boot on AC support

Boot on AC is a policy which makes the device boot from S5 when AC
power is connected. This is useful for users who want to run their
device headless or with a dock.

Signed-off-by: Nick Crews <ncrews@chromium.org>
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>

platform/chrome: wilco_ec: Add RTC driver

This Embedded Controller has an internal RTC that is exposed
as a standard RTC class driver with read/write functionality.

The driver is added to the drivers/rtc/ so that the maintainer of that
directory will be able to comment on this change, as that maintainer is
the expert on this system. In addition, the driver code is called
indirectly after a corresponding device is registered from core.c,
as opposed to core.c registering the driver callbacks directly.

To test:
> hwclock --show --rtc /dev/rtc1
2007-12-31 16:01:20.460959-08:00
> hwclock --systohc --rtc /dev/rtc1
> hwclock --show --rtc /dev/rtc1
2018-11-29 17:08:00.780793-08:00

> hwclock --show --rtc /dev/rtc1
2007-12-31 16:01:20.460959-08:00
> hwclock --systohc --rtc /dev/rtc1
> hwclock --show --rtc /dev/rtc1
2018-11-29 17:08:00.780793-08:00

Signed-off-by: Duncan Laurie <dlaurie@google.com>
Signed-off-by: Nick Crews <ncrews@chromium.org>
Acked-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
[Fix the sparse warning: symbol 'wilco_ec_rtc_read/write' was not declared]
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>

platform/chrome: wilco_ec: Add support for raw commands in debugfs

Add a debugfs attribute that allows sending raw commands to the EC.
This is useful for development and debug but should not be enabled
in a production environment.

To test:
Get the EC firmware build date
First send the request command
> echo 00 f0 38 00 03 00 > raw
Then read the result. "12/21/18" is in the middle of the response
> cat raw
00 31 32 2f 32 31 2f 31 38 00 00 0f 01 00 01 00 .12/21/18.......

Get the EC firmware build date
First send the request command
> echo 00 f0 38 00 03 00 > raw
Then read the result. "12/21/18" is in the middle of the response
> cat raw
00 31 32 2f 32 31 2f 31 38 00 00 0f 01 00 01 00 .12/21/18.......

Signed-off-by: Duncan Laurie <dlaurie@google.com>
Signed-off-by: Nick Crews <ncrews@chromium.org>
[Fix off-by-one error in wilco_ec/debugfs.c]
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>

platform/chrome: Add new driver for Wilco EC

This EC is an incompatible variant of the typical Chrome OS embedded
controller. It uses the same low-level communication and a similar
protocol with some significant differences. The EC firmware does
not support the same mailbox commands so it is not registered as a
cros_ec device type. This commit exports the wilco_ec_mailbox()
function so that other modules can use it to communicate with the EC.

Signed-off-by: Duncan Laurie <dlaurie@google.com>
Signed-off-by: Nick Crews <ncrews@chromium.org>
[Fix the sparse warning: symbol 'wilco_ec_transfer' was not declared]
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
[Fix Kconfig dependencies for wilco_ec]
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>