FreeBSD/Linux Kernel Cross Reference
sys/contrib/device-tree/src/arm64/freescale/imx8mm-venice-gw72xx-0x-rs422.dts

     // SPDX-License-Identifier: (GPL-2.0+ OR MIT)
     /*
      * Copyright 2022 Gateworks Corporation
      *
      * GW72xx RS422 (RS485 full duplex):
      *  - GPIO1_0 rs485_term selects on-chip termination
      *  - GPIO4_0 rs485_en needs to be driven high (active)
      *  - GPIO4_2 rs485_hd needs to be driven low (in-active)
      *  - UART4_TX is DE for RS485 transmitter
     *  - RS485_EN needs to be pulled high
     *  - RS485_HALF needs to be low
     */
    
    #include <dt-bindings/gpio/gpio.h>
    
    #include "imx8mm-pinfunc.h"
    
    /dts-v1/;
    /plugin/;
    
    &{/} {
            compatible = "gw,imx8mm-gw72xx-0x";
    };
    
    &gpio4 {
            rs485_en {
                    gpio-hog;
                    gpios = <0 GPIO_ACTIVE_HIGH>;
                    output-high;
                    line-name = "rs485_en";
            };
    
            rs485_hd {
                    gpio-hog;
                    gpios = <2 GPIO_ACTIVE_HIGH>;
                    output-low;
                    line-name = "rs485_hd";
            };
    };
    
    &uart2 {
            pinctrl-names = "default";
            pinctrl-0 = <&pinctrl_uart2>;
            rts-gpios = <&gpio5 29 GPIO_ACTIVE_HIGH>;
            linux,rs485-enabled-at-boot-time;
            status = "okay";
    };
    
    &uart4 {
            status = "disabled";
    };
    
    &iomuxc {
            pinctrl_uart2: uart2grp {
                    fsl,pins = <
                            MX8MM_IOMUXC_UART2_RXD_UART2_DCE_RX     0x140
                            MX8MM_IOMUXC_UART2_TXD_UART2_DCE_TX     0x140
                            MX8MM_IOMUXC_UART4_TXD_GPIO5_IO29       0x140
                    >;
            };
    };

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