gpio: pcf857x: implement get_direction()

The GPIO core warns (and taints the kernel) when a gpiochip lacks
.get_direction() and a consumer queries a line's direction, for example
via /sys/kernel/debug/gpio. pcf857x provided direction_input/output but
no get_direction.

These quasi-bidirectional expanders cannot report direction in hardware,
and the 'out' software latch alone is ambiguous - a released (input)
line and an output driven high both read back as a set bit. Track the
direction explicitly in a 'dir' latch updated by the direction_input(),
direction_output() and set_multiple() paths, and return it from
get_direction(). Initialise it from the same reset state as 'out':
released lines are inputs, lines flagged in the power-on latch are
driven-low outputs.

Fixes: 15fae37d9f5f ("gpiolib: pcf857x i2c gpio expander support")
Signed-off-by: Tapio Reijonen <tapio.reijonen@vaisala.com>
Reviewed-by: Linus Walleij <linusw@kernel.org>
Link: https://patch.msgid.link/20260825-b4-gpio-pcf857x-get-direction-v1-1-de15996ae354@vaisala.com
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>

0 files changed, 0 insertions, 0 deletions