UART

Introduction

The serial port interface diagram is as follows.


DTS configuration

File path "kernel-5.10/arch/arm64/boot/dts/rockchip/roc-
rk3588-pc.dtsi"

   /* uart7 */
   &uart7 {
   	status = "okay";
   	pinctrl-0 = <&uart7m0_xfer>;
   };

After configuring the serial port, the hardware interface corresponds
to the node on the software as

   UART7: /dev/ttyS7

Send and receive verification

The easiest way is to short the UART7 TX RX pins, then use the command
to execute the command on the debug serial port or ADB

   busybox stty -echo -F /dev/ttyS7 # Turn off display back
   cat /dev/ttyS7 & # get /dev/ttyS7 input string in the background
   echo "firefly uart test..." > /dev/ttyS7 # Input string

The final debug serial terminal can receive the string "firefly uart
test..."