Table of Contents

Introduction

This page gives an overview of CSUDMA driver which is available as part of the Xilinx Vivado and Vitis distribution. CSUDMA provides an efficient data transfer mechanism between the PSS's Memory and the CSU Stream Peripherals.

On ZynqMP, the CSU_DMA is present inside CSU (Configuration Security Unit) module which is located within the Low-Power Subsystem (LPS) internal to the PS.

On Versal it is known as PMCDMA and present in PMC (used for Platform Management). CSUDMA is used interchangeably for PMCDMA in this documentation and driver unless specified.
CSU_DMA allows the CSU to move data efficiently between the memory (32 bit AXI interface) and the CSU stream peripherals (SHA, AES and PCAP) via Secure
Stream Switch (SSS). The CSU_DMA is a 2 channel simple DMA, allowing separate control of the SRC (read) channel and DST (write) channel. The DMA is effectively able to transfer data:

• From PS-side to the SSS-side (SRC DMA only)

• From SSS-side to the PS-side (DST DMA only)

• Simultaneous PS-side to SSS_side and SSS-side to the PS-side

For more information, please refer to CSUDMA chapter in ZynqMP TRM (UG1085) or PMCDMA chapter in Versal TRM (AM011).

Driver Sources

The source code for the driver is included with the Vitis Unified Software Platform installation, as well as being available in the Xilinx Github repository. 

The driver source code is organized into different folders.  The table below shows the csudma driver source organization. 

Note: AMD Xilinx embeddedsw build flow is changed from 2023.2 release to adapt to the new system device tree based flow. For further information, refer to the wiki page Porting embeddedsw components to system device tree (SDT) based flow - Xilinx Wiki - Confluence (atlassian.net).

The .yaml(in data folder) and CMakeLists.txt(in src folder) files are needed for the System Device Tree based flow. The Driver .tcl and .mdd files are for the older build flow which will be deprecated in the future.

Driver Implementation

For a full list of features supported by this IP, please refer to CSUDMA chapter in ZynqMP TRM (UG1085) or PMCDMA chapter in Versal TRM (AM011) for respective devices.

Features

Controller/Driver features supported

• Simple DMA, no scatter-gather

• Separate read channel (SRC) and write channel(DST) DMA

• Read channel fetches data from the PS-side(memory) and delivers it to the CSU secure stream switch (SSS) interface

• Write channel receives data from the CSU secure stream switch (SSS) interface and delivers it to the PS-side (memory).

• 32-bit AXI 3.0 interface on the PS-side

• Deep 128x32-bit data FIFOs for both the SRC and DST data paths

• PS-side AXI Issuing capability up to a maximum of 9 commands per channel, with programmable maximum

• Single thread (AXI-ID) operation for both read and write channels

• CSU_DMA operates synchronously in the “csu_main_clk” or PMC clock domain

• Target CSU_DMA frequency of 400MHz max

• DST DMA will only issue a write AXI command if the corresponding write data is available in the write data FIFO – Store and Forward.

• SRC DMA will only issue a read AXI command if there is enough space in the read data FIFO for the entire burst.

• DMA start address is 32-bit aligned

• DMA transfer length is in units of 4-byte words

• DMA can accept only 1 command per channel

• Timeout mechanisms for both SRC(read) and DST(write) channels

• Automatic hardware management of 4kbyte boundary crossing on the PS-side (AXI )

• Dedicated APB interface for CSU_DMA register access

• Always generates secure (AxPROT[1]=0) AXI commands

• DMA supports INCR and FIXED (keyhole) AXI burst-types

• Zero-ization of FIFOs for security purposes achieved via RAM MBIST

• Byte endianness option available for the SRC DMA

• Pseudo-CRC option available for the SRC DMA payload

Known Issues and Limitations

• None

Example Applications

CSUDMA driver supports a few basic polled and interrupt examples describing how its different features can be exercised. These example applications can be imported into the Vitis IDE from the Board Support Package  settings tab. 

Links to Examples

Examples Path:
https://github.com/Xilinx/embeddedsw/tree/master/XilinxProcessorIPLib/drivers/csudma/examples/

Example Application Usage

CSUDMA Selftest example

Basic CSUDMA selftest example to check sanity and use core APIs.

Expected Output

Successfully ran CSU_DMA Selftest Example

CSUDMA Polled example

Polled mode example demonstrating CSUDMA transfer via polling of busy state and local loopback.

Expected Output

Successfully ran CSU_DMA Polled Example

CSUDMA Interrupt example

Interrupt mode example demonstrating CSUDMA transfer via interrupts and local loopback.

Expected Output

Successfully ran CSU_DMA Interrupt Example

Example Design Architecture

NA

Performance

NA

Change Log

2023.2

https://github.com/Xilinx/embeddedsw/blob/xlnx_rel_v2023.2/doc/ChangeLog#L551

2023.1

https://github.com/Xilinx/embeddedsw/blob/xilinx_v2023.1/doc/ChangeLog#L66

2022.2

https://github.com/Xilinx/embeddedsw/blob/xilinx_v2022.2/doc/ChangeLog#L93

2022.1

https://github.com/Xilinx/embeddedsw/blob/xilinx_v2022.1/doc/ChangeLog#L235

2021.2

https://github.com/Xilinx/embeddedsw/blob/xlnx_rel_v2021.2/doc/ChangeLog#L201

2021.1

https://github.com/Xilinx/embeddedsw/commits/xilinx_v2021.1/XilinxProcessorIPLib/drivers/csudma

2020.2

https://github.com/Xilinx/embeddedsw/blob/release-2020.2/doc/ChangeLog#L444

2020.1

https://github.com/Xilinx/embeddedsw/blob/release-2020.1/doc/ChangeLog#L26

2019.2

https://github.com/Xilinx/embeddedsw/blob/release-2019.2/doc/ChangeLog#L32

2019.1

https://github.com/Xilinx/embeddedsw/blob/release-2019.1/doc/ChangeLog#L64

2018.3

https://github.com/Xilinx/embeddedsw/blob/release-2018.3/doc/ChangeLog#L412

2018.2

None

2018.1

https://github.com/Xilinx/embeddedsw/blob/release-2018.1/doc/ChangeLog#L278

Related Links

• http://www.wiki.xilinx.com/Baremetal+Drivers+and+Libraries