Zephyr AXI WDT Driver Support

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

HW Features

AXI Timebase Watchdog Timer
- Connects as a 32-bit slave on a AXI4-Lite interface
- Programmable watchdog timer width
- Watchdog timer with selectable timeout period and interrupt
- Configurable WDT enable: enable-after or enable-repeatedly
- One 32-bit free-running timebase counter with rollover interrupt-dual control register
- Configurable windowing mode with the following features:
  - Window Watchdog capability
  - Program Sequence Monitoring (PSM)
  - Second Sequence Timer (SST)
  - Fail counter (FC)

For more details refer: PG128-axi-timebase-wdt

Design Notes

N/A

Implementation

Zephyr AXI WDT Driver Implementation

Features Supported

Driver supports only timebase feature.

Missing Features

Window Watchdog Mode is not supported.
Second Sequence timer is not supported.
Program sequence monitor is not supported.
Fail counter (FC) is not supported.

Known Issues

N/A

Limitations

N/A

Kernel Configuration

CONFIG_WATCHDOG=y
CONFIG_WDT_XILINX_AXI=y
CONFIG_WDT_XILINX_AXI_HWINFO_API=y

Device Tree

clk100: clock {
    compatible = "fixed-clock";
    #clock-cells = <0>;
    clock-frequency = <100000000>;
};

axi_timebase_wdt_0: watchdog@41a00000 {
    compatible = "xlnx,axi-timebase-wdt-3.0" , "xlnx,xps-timebase-wdt-1.00.a";reg = <0x41a00000 0x10000>;
    clocks = <&clk100>;
    xlnx,wdt-enable-once = <0x1>;
    status = "okay";
    xlnx,wdt-interval = <0x1e>;
};

Driver Stack Size

TBA

Example Tests

Test Name

Example Source

Description

Watchdog Example

zephyr/samples/drivers/watchdog/

This example demonstrates how to use the watchdog driver API.

A typical use case for a watchdog is that the board is restarted in case some piece of code is kept in an infinite loop.

Code Coverage

TBA

Performance Metric

TBA

Mainline Status

https://github.com/zephyrproject-rtos/zephyr/blob/main/drivers/watchdog/wdt_xilinx_axi.c
The preceding features are mainlined as of 18-March-2025

Driver Source Path

drivers/watchdog/wdt_xilinx_axi.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

Misra-C Rule	Severity	Actual File Violations	Kernel Utility Violations
HIS_COMF		8	0
HIS_GOTO		4	0
HIS_RETURN		3	0
MISRA C-2012 Directive 4.6	Advisory	16	0
MISRA C-2012 Directive 4.8	Advisory	0	7
MISRA C-2012 Directive 4.9	Advisory	0	3
MISRA C-2012 Rule 1.2	Advisory	0	10
MISRA C-2012 Rule 10.1	Required	23	6
MISRA C-2012 Rule 10.3	Required	5	0
MISRA C-2012 Rule 10.4	Required	27	0
MISRA C-2012 Rule 11.5		11	0
MISRA C-2012 Rule 11.8	Required	0	6
MISRA C-2012 Rule 11.9	Required	4	0
MISRA C-2012 Rule 12.1	Advisory	10	0
MISRA C-2012 Rule 14.3	Required	4	0
MISRA C-2012 Rule 14.4	Required	3	0
MISRA C-2012 Rule 15.1		9	0
MISRA C-2012 Rule 15.4		0	3
MISRA C-2012 Rule 15.5		3	0
MISRA C-2012 Rule 2.4		3	0
MISRA C-2012 Rule 2.7	Advisory	1	0
MISRA C-2012 Rule 20.10		0	1
MISRA C-2012 Rule 20.12		0	3
MISRA C-2012 Rule 21.2		6	0
MISRA C-2012 Rule 5.8		3	0
MISRA C-2012 Rule 5.9		0	4
MISRA C-2012 Rule 8.13		0	3
MISRA C-2012 Rule 8.4		1	0
MISRA C-2012 Rule 8.6		0	1
MISRA C-2012 Rule 8.7		3	1
	Total violations	147	48