ZynqMP Linux Reset-controller Driver

Introduction

The ZynqMP reset-controller has the ability to reset lines connected to different blocks and peripheral in the Soc.

This page gives an overview of the ZynqMP reset-controller driver which is available as part of the ZynqMP Linux distribution.
Paths, files, links and documentation on this page are given relative to the Linux kernel source tree.

Below links provide the information about the reset-controller linux framework
http://elixir.free-electrons.com/linux/latest/source/Documentation/devicetree/bindings/reset/reset.txt
http://elixir.free-electrons.com/linux/latest/source/drivers/reset/core.c#L196


HW IP Features.

  • Ability to reset the lines connected to different blocks and peripheral in the Soc

Missing Features, Known Issues and Limitations

  • None

Kernel Configuration

Device Drivers --->[*] Reset Controller Support--->[*] Xilinx ZYNQMP Reset Controller Support



Devicetree

rst: reset-controller {
                compatible = "xlnx,zynqmp-reset";
                #reset-cells = <1>;
        };
 

Test procedure



The following commit will give you the better understanding and the exact use case of the reset controller.
https://github.com/Xilinx/linux-xlnx/commit/9b4eecd86677acf0d146fdab97dd5324e8f1b404
The Reset-controller driver itself will not initiate any IP reset request.
The Reset request always initiated by the consumer driver as shown in the above commit id

The below patch created only for testing purpose.
apply the patch 0001-Reset-Added-sysfs-entries-for-zynqmp-reset-controlle.patch
This patch has debug sysfs entry so that the reset controller driver can be tested from user space
1) echo reset_IP_num > /sys/class/reset-mgr/reset ----> It will reset the IP by providing the High to low signal.
2) echo reset_IP_num > /sys/class/reset-mgr/reset_assert ---> it will assert IP by providing the HIGH signal ( the relevant bit is set to High until it receives deassert signal).
3) echo reset_IP_num> /sys/class/reset-mgr/reset_deassert ---> it will deassert IP by providing the LOW signal

Reset_IP_num are available here:
https://github.com/Xilinx/linux-xlnx/blob/master/Documentation/devicetree/bindings/reset/zynqmp-reset.txt

Expected Output

$echo  reset_IP_num > /sys/class/reset-mgr/reset    ----> It will reset the IP by providing the  High  to low signal.
$echo reset_IP_num > /sys/class/reset-mgr/reset_assert  ---> it will assert IP by providing the HIGH signal ( the relevant bit is set to High until it receives deassert signal).
$echo reset_IP_num > /sys/class/reset-mgr/reset_deassert  ---> it will deassert IP by providing the LOW signal

Mainline Status

The current driver available in the Xilinx Linux git is in sync with the open-source 6.1 kernel driver except for the following:

Change Log

2024.1

Summary:

  • removed unneeded call to platform_set_drvdata()

Commits:

2023.2

  • None

2023.1

Summary:

  • Kernel version Upgrade to V6.1.

Commits:

2022.2

Summary:

  • Add support for Versal NET platform.

Commits:

2022.1

  • None

2021.2

Summary:

  • Fixed the argument data type.

  • replace spaces with tabs

Commits:

2021.1

Summary:

  • Added support for Versal platform.

Commits:

Related Links

https://github.com/Xilinx/linux-xlnx/blob/master/drivers/reset/reset-zynqmp.c




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