leds: turris-omnia: Fix brightness setting and trigger activating

I have improperly refactored commits
4d5ed2621c24 ("leds: turris-omnia: Make set_brightness() more efficient")
and
aaf38273cf76 ("leds: turris-omnia: Support HW controlled mode via private trigger")
after Lee requested a change in API semantics of the new functions I
introduced in commit
28350bc0ac77 ("leds: turris-omnia: Do not use SMBUS calls").

Before the change, the function omnia_cmd_write_u8() returned 0 on
success, and afterwards it returned a positive value (number of bytes
written). The latter version was applied, but the following commits did
not properly account for this change.

This results in non-functional LED's .brightness_set_blocking() and
trigger's .activate() methods.

The main reasoning behind the semantics change was that read/write
methods should return the number of read/written bytes on success.
It was pointed to me [1] that this is not always true (for example the
regmap API does not do so), and since the driver never uses this number
of read/written bytes information, I decided to fix this issue by
changing the functions to the original semantics (return 0 on success).

[1] https://lore.kernel.org/linux-gpio/ZQnn+Gi0xVlsGCYA@smile.fi.intel.com/

Fixes: 28350bc0ac77 ("leds: turris-omnia: Do not use SMBUS calls")
Signed-off-by: Marek Behún <kabel@kernel.org>
Link: https://lore.kernel.org/r/20231016141538.30037-1-kabel@kernel.org
Signed-off-by: Lee Jones <lee@kernel.org>

leds: turris-omnia: Add support for enabling/disabling HW gamma correction

If the MCU on Turris Omnia is running newer firmware versions, the LED
controller supports RGB gamma correction (and enables it by default for
newer boards).

Determine whether the gamma correction setting feature is supported and
add the ability to set it via sysfs attribute file.

Signed-off-by: Marek Behún <kabel@kernel.org>
Link: https://lore.kernel.org/r/20230918161104.20860-5-kabel@kernel.org
Signed-off-by: Lee Jones <lee@kernel.org>

leds: turris-omnia: Support HW controlled mode via private trigger

Add support for enabling MCU controlled mode of the Turris Omnia LEDs
via a LED private trigger called "omnia-mcu". Recall that private LED
triggers will only be listed in the sysfs trigger file for LEDs that
support them (currently there is no user of this mechanism).

When in MCU controlled mode, the user can still set LED color, but the
blinking is done by MCU, which does different things for different LEDs:
- WAN LED is blinked according to the LED[0] pin of the WAN PHY
- LAN LEDs are blinked according to the LED[0] output of the
corresponding port of the LAN switch
- PCIe LEDs are blinked according to the logical OR of the MiniPCIe port
LED pins

In the future I want to make the netdev trigger to transparently offload
the blinking to the HW if user sets compatible settings for the netdev
trigger (for LEDs associated with network devices).
There was some work on this already, and hopefully we will be able to
complete it sometime, but for now there are still multiple blockers for
this, and even if there weren't, we still would not be able to configure
HW controlled mode for the LEDs associated with MiniPCIe ports.

In the meantime let's support HW controlled mode via the private LED
trigger mechanism. If, in the future, we manage to complete the netdev
trigger offloading, we can still keep this private trigger for backwards
compatibility, if needed.

We also set "omnia-mcu" to cdev->default_trigger, so that the MCU keeps
control until the user first wants to take over it. If a different
default trigger is specified in device-tree via the
'linux,default-trigger' property, LED class will overwrite
cdev->default_trigger, and so the DT property will be respected.

Signed-off-by: Marek Behún <kabel@kernel.org>
Link: https://lore.kernel.org/r/20230918161104.20860-4-kabel@kernel.org
Signed-off-by: Lee Jones <lee@kernel.org>

leds: turris-omnia: Make set_brightness() more efficient

Implement caching of the LED color and state values that are sent to MCU
in order to make the set_brightness() operation more efficient by
avoiding I2C transactions which are not needed.

On Turris Omnia's MCU, which acts as the RGB LED controller, each LED
has a RGB color, and a ON/OFF state, which are configurable via I2C
commands CMD_LED_COLOR and CMD_LED_STATE.

The CMD_LED_COLOR command sends 5 bytes and the CMD_LED_STATE command 2
bytes over the I2C bus, which operates at 100 kHz. With I2C overhead
this allows ~1670 color changing commands and ~3200 state changing
commands per second (or around 1000 color + state changes per second).
This may seem more than enough, but the issue is that the I2C bus is
shared with another peripheral, the MCU. The MCU exposes an interrupt
interface, and it can trigger hundreds of interrupts per second. Each
time, we need to read the interrupt state register over this I2C bus.
Whenever we are sending a LED color/state changing command, the
interrupt reading is waiting.

Currently, every time LED brightness or LED multi intensity is changed,
we send a CMD_LED_STATE command, and if the computed color (brightness
adjusted multi_intensity) is non-zero, we also send a CMD_LED_COLOR
command.

Consider for example the situation when we have a netdev trigger enabled
for a LED. The netdev trigger does not change the LED color, only the
brightness (either to 0 or to currently configured brightness), and so
there is no need to send the CMD_LED_COLOR command. But each change of
brightness to 0 sends one CMD_LED_STATE command, and each change of
brightness to max_brightness sends one CMD_LED_STATE command and one
CMD_LED_COLOR command:
set_brightness(0) -> CMD_LED_STATE
set_brightness(255) -> CMD_LED_STATE + CMD_LED_COLOR
(unnecessary)

We can avoid the unnecessary I2C transactions if we cache the values of
state and color that are sent to the controller. If the color does not
change from the one previously sent, there is no need to do the
CMD_LED_COLOR I2C transaction, and if the state does not change, there
is no need to do the CMD_LED_STATE transaction.

Because we need to make sure that our cached values are consistent with
the controller state, add explicit setting of the LED color to white at
probe time (this is the default setting when MCU resets, but does not
necessarily need to be the case, for example if U-Boot played with the
LED colors).

Signed-off-by: Marek Behún <kabel@kernel.org>
Link: https://lore.kernel.org/r/20230918161104.20860-3-kabel@kernel.org
Signed-off-by: Lee Jones <lee@kernel.org>

leds: turris-omnia: Do not use SMBUS calls

The leds-turris-omnia driver uses three function for I2C access:
- i2c_smbus_write_byte_data() and i2c_smbus_read_byte_data(), which
cause an emulated SMBUS transfer,
- i2c_master_send(), which causes an ordinary I2C transfer.

The Turris Omnia MCU LED controller is not semantically SMBUS, it
operates as a simple I2C bus. It does not implement any of the SMBUS
specific features, like PEC, or procedure calls, or anything. Moreover
the I2C controller driver also does not implement SMBUS, and so the
emulated SMBUS procedure from drivers/i2c/i2c-core-smbus.c is used for
the SMBUS calls, which gives an unnecessary overhead.

When I first wrote the driver, I was unaware of these facts, and I
simply used the first function that worked.

Drop the I2C SMBUS calls and instead use simple I2C transfers.

Fixes: 089381b27abe ("leds: initial support for Turris Omnia LEDs")
Signed-off-by: Marek Behún <kabel@kernel.org>
Link: https://lore.kernel.org/r/20230918161104.20860-2-kabel@kernel.org
Signed-off-by: Lee Jones <lee@kernel.org>

leds: turris-omnia: Drop unnecessary mutex locking

Do not lock driver mutex in the global LED panel brightness sysfs
accessors brightness_show() and brightness_store().

The mutex locking is unnecessary here. The I2C transfers are guarded by
I2C core locking mechanism, and the LED commands itself do not interfere
with other commands.

Fixes: 089381b27abe ("leds: initial support for Turris Omnia LEDs")
Signed-off-by: Marek Behún <kabel@kernel.org>
Reviewed-by: Lee Jones <lee@kernel.org>
Link: https://lore.kernel.org/r/20230802160748.11208-2-kabel@kernel.org
Signed-off-by: Lee Jones <lee@kernel.org>

leds: turris-omnia: Use sysfs_emit() instead of sprintf()

Use the dedicated sysfs_emit() function instead of sprintf() in sysfs
attribute accessor brightness_show().

Signed-off-by: Marek Behún <kabel@kernel.org>
Link: https://lore.kernel.org/r/20230802160748.11208-4-kabel@kernel.org
Signed-off-by: Lee Jones <lee@kernel.org>

leds: 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/20230517180559.166329-1-u.kleine-koenig@pengutronix.de
Signed-off-by: Lee Jones <lee@kernel.org>

leds: turris-omnia: 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: Marek Behún <kabel@kernel.org>
Signed-off-by: Lee Jones <lee@kernel.org>
Link: https://lore.kernel.org/r/20221118224540.619276-289-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>

leds: turris-omnia: convert to use dev_groups

The driver core supports the ability to handle the creation and removal
of device-specific sysfs files in a race-free manner. Take advantage of
that by converting this driver to use this by moving the sysfs
attributes into a group and assigning the dev_groups pointer to it.

Cc: Pavel Machek <pavel@ucw.cz>
Cc: linux-leds@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Reviewed-by: Marek Behún <kabel@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Pavel Machek <pavel@ucw.cz>

leds: turris-omnia: add missing MODULE_DEVICE_TABLE

This patch adds missing MODULE_DEVICE_TABLE definition which generates
correct modalias for automatic loading of this driver when it is built
as an external module.

Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Zou Wei <zou_wei@huawei.com>
Signed-off-by: Pavel Machek <pavel@ucw.cz>

treewide: change my e-mail address, fix my name

Change my e-mail address to kabel@kernel.org, and fix my name in
non-code parts (add diacritical mark).

Link: https://lkml.kernel.org/r/20210325171123.28093-2-kabel@kernel.org
Signed-off-by: Marek Behún <kabel@kernel.org>
Cc: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jassi Brar <jassisinghbrar@gmail.com>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

leds: turris-omnia: check for LED_COLOR_ID_RGB instead LED_COLOR_ID_MULTI

LED core does not allow LED_COLOR_ID_MULTI for now and instead for RGB
LEDs prefers LED_COLOR_ID_RGB.

Signed-off-by: Marek Behún <kabel@kernel.org>
Fixes: 77dce3a22e89 ("leds: disallow /sys/class/leds/*:multi:* for now")
Signed-off-by: Pavel Machek <pavel@ucw.cz>

leds: turris-omnia: fix checkpatch warning

Use kstrtoul instead of sscanf to satisfy checkpatch.

Signed-off-by: Marek Behún <kabel@kernel.org>
Signed-off-by: Pavel Machek <pavel@ucw.cz>

leds: turris-omnia: wrap to 80 columns

Although checkpatch changed the max-line-length default to 100 columns,
we still prefer 80 columns somewhere.

Signed-off-by: Marek Behún <kabel@kernel.org>
Signed-off-by: Pavel Machek <pavel@ucw.cz>

leds: turris-omnia: use constants instead of macros for color command

Use integer constants directly when building I2C messages for LED color
change command, instead of macros. The command is simple enough to
understand what is going on even without these names.

Signed-off-by: Marek Behún <kabel@kernel.org>
Signed-off-by: Pavel Machek <pavel@ucw.cz>

leds: parse linux,default-trigger DT property in LED core

Do the parsing of `linux,default-trigger` DT property to LED core.
Currently it is done in many different drivers and the code is repeated.

This patch removes the parsing from 23 drivers:
an30259a, aw2013, bcm6328, bcm6358, cr0014114, el15203000, gpio,
is31fl32xx, lm3532, lm36274, lm3692x, lm3697, lp50xx, lp8860, lt3593,
max77650, mt6323, ns2, pm8058, pwm, syscon, tlc591xx and turris-omnia.

There is one driver in drivers/input which parses this property on it's
own. I shall send a separate patch there after this is applied.

There are still 8 drivers that parse this property on their own because
they do not pass the led_init_data structure to the registering
function. I will try to refactor those in the future.

Signed-off-by: Marek Behún <marek.behun@nic.cz>
Signed-off-by: Pavel Machek <pavel@ucw.cz>

leds: various: fix OF node leaks

Fix OF node leaks by calling of_node_put in
for_each_available_child_of_node when the cycle breaks or returns.

Signed-off-by: Marek Behún <marek.behun@nic.cz>
Cc: Nikita Travkin <nikitos.tr@gmail.com>
Cc: Milo Kim <milo.kim@ti.com>
Cc: Dan Murphy <dmurphy@ti.com>
Signed-off-by: Pavel Machek <pavel@ucw.cz>
Not-for-stable: untested, theoretical, insignificant leaks

leds: various: use dev_of_node(dev) instead of dev->of_node

The dev_of_node function should be preferred.

Signed-off-by: Marek Behún <marek.behun@nic.cz>
Cc: Orson Zhai <orsonzhai@gmail.com>
Cc: Baolin Wang <baolin.wang7@gmail.com>
Cc: Chunyan Zhang <zhang.lyra@gmail.com>
Cc: Sean Wang <sean.wang@mediatek.com>
Cc: Matthias Brugger <matthias.bgg@gmail.com>
Cc: Riku Voipio <riku.voipio@iki.fi>
Signed-off-by: Pavel Machek <pavel@ucw.cz>

leds: initial support for Turris Omnia LEDs

This adds basic support for LEDs on the front side of CZ.NIC's Turris
Omnia router.

There are 12 RGB LEDs. The controller supports HW triggering mode for
the LEDs, but this driver does not support it yet, and sets all the LEDs
defined in device-tree into SW mode upon probe.

This driver uses the multicolor LED framework.

Signed-off-by: Marek Behún <marek.behun@nic.cz>
Reviewed-by: Dan Murphy <dmurphy@ti.com>
Signed-off-by: Pavel Machek <pavel@ucw.cz>