gpio: realtek: Add driver for Realtek DHC RTD1625 SoC

Add support for the GPIO controller found on Realtek DHC RTD1625 SoCs.

Unlike the existing Realtek GPIO driver (drivers/gpio/gpio-rtd.c),
which manages pins via shared bank registers, the RTD1625 introduces
a per-pin register architecture. Each GPIO line now has its own
dedicated 32-bit control register to manage configuration independently,
including direction, output value, input value, interrupt enable, and
debounce. Therefore, this distinct hardware design requires a separate
driver.

Additionally, the RTD1625 GPIO controller has a specific hardware quirk:
it fires both 'assert' and 'de-assert' interrupts simultaneously on any
edge toggle. To handle this, we utilize the polarity register to route
the requested edge (rising/falling) to the 'assert' IRQ line. The driver
then filters out the unwanted 'de-assert' interrupt in the IRQ handler
and pre-clears edge interrupts to prevent interrupt storms caused by
unhandled dropped interrupts.

Interrupt support is optional for this device, matching the dt-bindings.
If the interrupts property is not provided, the driver simply skips IRQ
initialization and operates purely as a basic GPIO controller.

Reviewed-by: Linus Walleij <linusw@kernel.org>
Signed-off-by: Tzuyi Chang <tychang@realtek.com>
Co-developed-by: Yu-Chun Lin <eleanor.lin@realtek.com>
Signed-off-by: Yu-Chun Lin <eleanor.lin@realtek.com>
Link: https://patch.msgid.link/20260622092335.1166876-4-eleanor.lin@realtek.com
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>

0 files changed, 0 insertions, 0 deletions