Zephyr UARTLITE Driver Support

This page gives an overview of the UARTLITE Zephyr driver which is available as part of the zephyr-amd repo.

HW Features

AXI UART Lite controller

Design Notes

N/A

Implementation

N/A

Features Supported

Polled Mode - UART Send/Receive
Interrupt Mode - UART Send/Receive
APIs supported and verified
- uart_poll_in - Read a character from the device for input
- uart_poll_out - Write a character to the device for output
- uart_configure - Set UART configuration
- uart_config_get - Get UART configuration
- uart_fifo_fill - Fill FIFO with data
- uart_fifo_read - Read data from FIFO

Missing Features

TBA

Known Issues

N/A

Limitations

N/A

Kernel Configuration

CONFIG_SERIAL=y
CONFIG_UART_INTERRUPT_DRIVEN=y

Device Tree

The uartlite device tree node:

uart0: serial@40600000 {
    compatible = "xlnx,xps-uartlite-1.00.a";
    reg = <0x40600000 0x1000>;
    interrupt-parent = <&axi_intc>;
    interrupts = <1 2>;
    clocks = <&clk100>;
    current-speed = <115200>;
};

Lopper support to generate UARTLITE node is added.

Driver Stack Size

uart_xlnx_uartlite.c (polled) - 0.4 KB
uart_xlnx_uartlite.c (interrupt) - 1.8 KB

Test Platform

zcu102 board

Test SoC Architecture

RPU - R5 core - Validated (zcu102)
APU - A53 core - Not tested
SMP - Switch - Not tested

Testing Sequence

Build zephyr application for the zcu102 board
- west build -p -b <board> <sample application path>
Run zephyr elf on board

Example Tests

Test Name	Example Source	Description
hello world	samples/hello_world/	Prints “Hello World” on uart console
uart_basic_api	tests/drivers/uart/uart_basic_api/	Performs Ztest which verifies basic uart driver APIs.

Code Coverage

With uart ztest, Code Coverage was 83%
- Code coverage report (download)

Performance Metric

NA

Mainline Status

The preceding features are mainlined as of 01-Oct-2024

Driver Source Path

drivers/serial/uart_xlnx_uartlite.c

Misra C Report

Per coding guidelines of zephyr (subset of Misra-C)
- Ref: https://docs.zephyrproject.org/latest/contribute/coding_guidelines/index.html#coding-guidelines

File	Required	Advisory
uart_xlnx_uartlite.c	49	24

Detailed Breakup

misra-c rule (zephyr guideline)	Severity	Actual File Violations	Kernel Utility Violations
Dir 4.6	Advisory	18	0
Dir 4.8	Advisory	0	10
Dir 4.9	Advisory	0	2
Rule 1.2	Advisory	1	11
Rule 2.7	Advisory	2	0
Rule 10.1	Required	16	1
Rule 10.3	Required	11	0
Rule 10.4	Required	13	0
Rule 11.9	Required	3	0
Rule 12.1	Advisory	1	0
Rule 12.2	Required	0	1
Rule 13.3	Advisory	2	0
Rule 13.5	Required	1	0
Rule 14.4	Required	5	0
Rule 20.7	Required	0	1
Rule 21.2	Required	0	3
Total violations		73	29