VAR-SOM-MX6 UART

VAR-SOM-MX6 - External UART

Test

By default, Variscite configured UART1, ttymxc2. to test:

Use minicom to connect.
Set the serial to ttymxc2
You can use a loopback or connect to anther computer

Example: configure UART4, ttymxc3

Edit arch/arm/boot/dts/imx6qdl-var-som.dtsi Look for:

/* ttymxc2 UART */
&uart3 {
                pinctrl-names = "default";
                pinctrl-0 = <&pinctrl_uart3_2>;
                fsl,uart-has-rtscts;
                status = "okay";
};

Duplicate it and change the name and the pinctrl name. For Example:

&uart4 {
                pinctrl-names = "default";
                pinctrl-0 = <&pinctrl_uart4_1>;
                fsl,uart-has-rtscts;
                status = "okay";
};

Now duplicate the pinctrl, copy :

                                /* Variscite Uart2 support */
                                pinctrl_uart3_2: uart3grp-2 {       /* RX/TX RTS/CTS */
                                                fsl,pins = <
                                                                MX6QDL_PAD_EIM_D25__UART3_RX_DATA     0x1b0b1
                                                                MX6QDL_PAD_EIM_D24__UART3_TX_DATA     0x1b0b1
                                                                MX6QDL_PAD_EIM_D23__UART3_CTS_B       0x1b0b1
                                                                MX6QDL_PAD_EIM_EB3__UART3_RTS_B       0x1b0b1
                                                >;
                                };

Into:

                                /* Variscite Uart3 support */
                                pinctrl_uart4_1: uart4grp-1 {       /* RX/TX RTS/CTS */
                                                fsl,pins = <
                                                                MX6QDL_PAD_KEY_COL0__UART4_RX_DATA    0x1b0b1
                                                                MX6QDL_PAD_KEY_COL0__UART4_TX_DATA    0x1b0b1
                                                                MX6QDL_PAD_CSI0_DAT16__UART4_RTS_B    0x1b0b1
                                                                MX6QDL_PAD_CSI0_DAT16__UART4_CTS_B    0x1b0b1
                                                >;

};

The pins are set arbitrary. You should set them based on your hardware design.