Pin Definitions and Multiplexing Configuration

How is RK182X pin multiplexing configured?

Each RK182X pin supports multiple functions (GPIO, UART, SPI, I2C, MIPI, etc.), configured through the IOMUX controller.

Configuration methods

1. Device Tree — the recommended way
2. Direct register writes — for debugging

Device tree configuration example

&pinctrl {
    uart2_pins: uart2-pins {
        rockchip,pins =
            <1 RK_PB0 2 &pcfg_pull_up>,  /* UART2 TX, func 2 */
            <1 RK_PB1 2 &pcfg_pull_up>;  /* UART2 RX, func 2 */
    };

    i2c1_pins: i2c1-pins {
        rockchip,pins =
            <2 RK_PA0 1 &pcfg_pull_none>, /* SCL */
            <2 RK_PA1 1 &pcfg_pull_none>; /* SDA */
    };
};

&uart2 {
    pinctrl-names = "default";
    pinctrl-0 = <&uart2_pins>;
    status = "okay";
};

Pin function lookup

Bank	Pin	Default function	Multiplexed functions
GPIO0	PB0	GPIO	UART2_TX / SPI1_CLK / I2S_LRCK
GPIO0	PB1	GPIO	UART2_RX / SPI1_MISO / I2S_SCLK
GPIO1	PA0	GPIO	I2C1_SCL / UART0_TX
GPIO1	PA1	GPIO	I2C1_SDA / UART0_RX
GPIO2	PB3	GPIO	MIPI_DSI_D0_P
GPIO2	PB4	GPIO	MIPI_DSI_D0_N

For the complete pin multiplexing table, see the RK182X Datasheet (source: RK182X Datasheet V1.0, §PinMux)

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How do I control GPIO through sysfs?

# 1. Compute the GPIO number
# GPIO number = Bank × 32 + Pin
# GPIO0_B0 = 0 × 32 + 8 = 8

# 2. Export
echo 8 > /sys/class/gpio/export

# 3. Set the direction
echo out > /sys/class/gpio/gpio8/direction

# 4. Set the value
echo 1 > /sys/class/gpio/gpio8/value

# 5. Release
echo 8 > /sys/class/gpio/unexport

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Related documents

• Power Management — power specifications and consumption management
• Clock Tree — PLL and clock source configuration
• SDK Overview — overall architecture