Manual Pages  — FDT_PINCTRL

Pin multiplexing is a technology used to re-purpose a single physical connection (depending on chip packaging it may be pin, ball, or pad) by routing its signal to any one of several different SoC internal devices. For example, based on the actual device design, a single SoC chip pin might perform any of these roles: SPI clock, I2C data, GPIO pin, or PWM signal. Function selection is performed by the pinmux controller, a SoC hardware block which is usually controlled by a set of registers. Pinmux controller capabilities and register format depend on the actual hardware implementation.

pinctrl@7e220000 {
    compatible = "vndr,soc1715-pinctrl";
    reg = <0x7e220000 0x100>

    spi0_pins: spi0 {
        vndr,pins = <11 12>
        vndr,functions = <ALT0 ALT5>
    }

    i2c0_pins: i2c0 {
        ...
    }
}

backlight@7f000000 {
    compatible = "vndr,vndr-bl"
    reg = <0x7f000000 0x20>
    ...
    pinctrl-name = "active", "idle"
    pinctrl-0 = <&backlight_active_pins>
    pinctrl-1 = <&backlight_idle_pins>
}