Configure GPIO on Rockchip: Pin Numbering, Device Tree and libgpiod

Rockchip pin names

Rockchip GPIOs are grouped into banks GPIO0 to GPIO4, each with 32 pins in four ports A–D of 8 pins. A schematic net like GPIO3_B5 means bank 3, port B, pin 5.

line offset in bank = port_index × 8 + pin      (A=0, B=1, C=2, D=3)
global GPIO number  = bank × 32 + line offset

GPIO3_B5 → offset 1×8+5 = 13 → global 3×32+13 = 109

Using a pin from user space (libgpiod)

sudo apt install -y gpiod
gpiodetect                       # gpiochip0..4 = banks GPIO0..GPIO4
gpioinfo gpiochip3               # shows line 13 and whether it's in use

# libgpiod v1 syntax
gpioset gpiochip3 13=1
gpioget gpiochip3 13

# libgpiod v2 syntax
gpioset -c gpiochip3 13=1

If gpioinfo shows the line as used by a kernel driver, or the pin is muxed to another function (UART, PWM…), you need a device-tree change first.

Describing GPIOs in the device tree

Use the Rockchip macros from dt-bindings/pinctrl/rockchip.h and dt-bindings/gpio/gpio.h. Here is an LED on GPIO3_B5 plus a button on GPIO0_C0:

/ {
    leds {
        compatible = "gpio-leds";
        pinctrl-names = "default";
        pinctrl-0 = <&status_led_pin>;

        status-led {
            gpios = <&gpio3 RK_PB5 GPIO_ACTIVE_HIGH>;
            linux,default-trigger = "heartbeat";
        };
    };
};

&pinctrl {
    leds {
        status_led_pin: status-led-pin {
            rockchip,pins = <3 RK_PB5 RK_FUNC_GPIO &pcfg_pull_none>;
        };
    };
};

Doing it as an overlay

Overlays keep one base DTB for every product variant:

/dts-v1/;
/plugin/;

#include <dt-bindings/gpio/gpio.h>
#include <dt-bindings/pinctrl/rockchip.h>

&{/} {
    my-leds {
        compatible = "gpio-leds";
        relay {
            gpios = <&gpio3 RK_PB5 GPIO_ACTIVE_HIGH>;
            default-state = "off";
        };
    };
};

# Preprocess (for #include) and compile
cpp -nostdinc -I include -undef -x assembler-with-cpp my.dts > my.pre.dts
dtc -@ -I dts -O dtb -o my.dtbo my.pre.dts

Load it via your image's mechanism: an fdtoverlays line in extlinux.conf, the vendor's overlay config file, or U-Boot's fdt apply.

Voltage domains matter

Each GPIO bank sits in an IO power domain powered at 1.8 V or 3.3 V (see the io-domains node and your schematic). Driving a 3.3 V peripheral from a 1.8 V domain, or the reverse, is a common bring-up mistake. Check before you wire.

Verify what the kernel got

sudo cat /sys/kernel/debug/pinctrl/pinctrl-rockchip-pinctrl/pinmux-pins | grep -i "gpio3"
dtc -I fs /proc/device-tree 2>/dev/null | less