Input: ps2-gpio - 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/20230920125829.1478827-40-u.kleine-koenig@pengutronix.de
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

Input: move from strlcpy with unused retval to strscpy

Follow the advice of the below link and prefer 'strscpy' in this
subsystem. Conversion is 1:1 because the return value is not used.
Generated by a coccinelle script.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Link: https://lore.kernel.org/r/20220818210022.6865-1-wsa+renesas@sang-engineering.com
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

Input: ps2-gpio - enforce GPIOs flag open drain

The PS/2 bus defines the data and clock line be open drain, therefore
for both enforce the particular GPIO flags in the driver.

Without enforcing to flag at least the clock gpio as open drain we run
into the following warning:

WARNING: CPU: 1 PID: 40 at drivers/gpio/gpiolib.c:3175 gpiochip_enable_irq+0x54/0x90

gpiochip_enable_irq() warns on a GPIO being configured as output while
serving as IRQ source without being flagged as open drain.

Signed-off-by: Danilo Krummrich <danilokrummrich@dk-develop.de>
Link: https://lore.kernel.org/r/20220215180829.63543-4-danilokrummrich@dk-develop.de
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

Input: ps2-gpio - don't send rx data before the stop bit

Sending the data before processing the stop bit from the device already
saves the data of the current xfer in case the stop bit is missed.

However, when TX xfers are enabled this introduces a race condition when
a peripheral driver using the bus immediately requests a TX xfer from IRQ
context.

Therefore the data must be send after receiving the stop bit, although
it is possible the data is lost when missing the stop bit.

Signed-off-by: Danilo Krummrich <danilokrummrich@dk-develop.de>
Link: https://lore.kernel.org/r/20220215160208.34826-5-danilokrummrich@dk-develop.de
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

Input: ps2-gpio - remove tx timeout from ps2_gpio_irq_tx()

Actually, there's no extra clock pulse to wait for.

The assumption of an extra clock pulse was mistakenly derived from the
fact that by the time this driver was introduced the GPIO controller of
the test machine (bcm2835) generated spurious interrupts.

Since now spurious interrupts are handled properly this can and must be
removed in order to make TX xfers work properly.

While at it, remove duplicate gpiod_direction_input(). The data gpio
must already be configured to act as input when receiving the ACK bit.

This patch is tested with the original hardware (peripherals and board)
the driver was developed on.

Signed-off-by: Danilo Krummrich <danilokrummrich@dk-develop.de>
Link: https://lore.kernel.org/r/20220215160208.34826-4-danilokrummrich@dk-develop.de
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

Input: ps2-gpio - use ktime for IRQ timekeeping

Using jiffies for the IRQ timekeeping is not sufficient for two reasons:

(1) Usually jiffies have a resolution of 1ms to 10ms. The IRQ intervals
based on the clock frequency of PS2 protocol specification (10kHz -
16.7kHz) are between ~60us and 100us only. Therefore only those IRQ
intervals can be detected which are either at the end of a transfer
or are overly delayed. While this is sufficient in most cases, since
we have quite a lot of ways to detect faulty transfers, it can
produce false positives in rare cases: When the jiffies value
changes right between two interrupt that are in time, we wrongly
assume that we missed one or more clock cycles.

(2) Some gpio controllers (e.g. the one in the bcm283x chips) may generate
spurious IRQs when processing interrupts in the frequency given by PS2
devices.

Both issues can be fixed by using ktime resolution for IRQ timekeeping.

However, it is still possible to miss clock cycles without detecting
them. When the PS2 device generates the falling edge of the clock signal
we have between ~30us and 50us to sample the data line, because after
this time we reach the next rising edge at which the device changes the
data signal already. But, the only thing we can detect is whether the
IRQ interval is within the given period. Therefore it is possible to
have an IRQ latency greater than ~30us to 50us, sample the wrong bit on
the data line and still be on time with the next IRQ. However, this can
only happen when within a given transfer the IRQ latency increases
slowly.

___ ______ ______ ______ ___
\ / \ / \ / \ /
\ / \ / \ / \ /
\______/ \______/ \______/ \______/

|-----------------| |--------|
60us/100us 30us/50us

Signed-off-by: Danilo Krummrich <danilokrummrich@dk-develop.de>
Link: https://lore.kernel.org/r/20220215160208.34826-3-danilokrummrich@dk-develop.de
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

Input: ps2-gpio - refactor struct ps2_gpio_data

Refactor struct ps2_gpio_data in order to clearly separate RX and TX
state data.

This change intends to increase code readability and does not bring any
functional change.

Signed-off-by: Danilo Krummrich <danilokrummrich@dk-develop.de>
Link: https://lore.kernel.org/r/20220215160208.34826-2-danilokrummrich@dk-develop.de
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

Input: remove dev_err() usage after platform_get_irq()

We don't need dev_err() messages when platform_get_irq() fails now that
platform_get_irq() prints an error message itself when something goes
wrong. Let's remove these prints with a simple semantic patch.

// <smpl>
@@
expression ret;
struct platform_device *E;
@@

ret =
(
platform_get_irq(E, ...)
|
platform_get_irq_byname(E, ...)
);

if ( \( ret < 0 \| ret <= 0 \) )
{
(
-if (ret != -EPROBE_DEFER)
-{ ...
-dev_err(...);
-... }
|
...
-dev_err(...);
)
...
}
// </smpl>

While we're here, remove braces on if statements that only have one
statement (manually).

Signed-off-by: Stephen Boyd <swboyd@chromium.org>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500

Based on 2 normalized pattern(s):

this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license version 2 as
published by the free software foundation

this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license version 2 as
published by the free software foundation #

extracted by the scancode license scanner the SPDX license identifier

GPL-2.0-only

has been chosen to replace the boilerplate/reference in 4122 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Enrico Weigelt <info@metux.net>
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190604081206.933168790@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Input: ps2-gpio - flush TX work when closing port

To ensure that TX work is not running after serio port has been torn down,
let's flush it when closing the port.

Reported-by: Sven Van Asbroeck <thesven73@gmail.com>
Acked-by: Danilo Krummrich <danilokrummrich@dk-develop.de>
Reviewed-by: Sven Van Asbroeck <TheSven73@gmail.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

Input: ps2-gpio - actually abort probe when connected to sleeping GPIOs

We've been missing a goto to the unwind path...

Acked-by: Danilo Krummrich <danilokrummrich@dk-develop.de>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

Input: PS/2 gpio bit banging driver for serio bus

This driver provides PS/2 serio bus support by implementing bit banging
with the GPIO API. The GPIO pins, data and clock, can be configured with
a node in the device tree or by generic device properties (GDP).

Writing to a device is supported as well, though it is possible timings
can not be halt as they are tough and difficult to reach with bit banging.
Therefore it can be configured (also in DT and GDP) whether the serio
write function should be available for clients.

This driver is for development purposes and not recommended for productive
use. However, this driver can be useful e.g. when no USB port is available
or using old peripherals is desired as PS/2 controller chips getting rare.

This driver was tested on bcm2825 and on Kirin 960 and it worked well
together with the atkbd and psmouse driver.

Signed-off-by: Danilo Krummrich <danilokrummrich@dk-develop.de>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>