Reading current output value

[Yegor Yefremov <yegorslists@xxxxxxxxxxxxxx>]

On a am335x based board I have a GPIO pin that enables/disables power
of an external device (the bootloader sets this pin to output and 1,
and the kernel is instructed to not change it). Using kernel
5.19.0-rc2 and sysfs interface, I can read the current status as
follows:

echo 68 > /sys/class/gpio/export
cat /sys/class/gpio/gpio68/value

As a result, I read 1.

Using gpioget (libgpiod) v1.6.3, the line will be configured to
"input" and the value is set to 0:

# gpioget 2 4
0

So, how can I read the state without changing it? I am mostly
interested in using the kernel userspace API directly.

By the way, setting pin to 0 works but not to 1:

gpioset 2 4=0 - OK
gpioset 2 4=1 - no level change

sysfs works.

Regards,
Yegor