AXI DMA with Petalinux

Introduction

This repo contains the setup for implementing AXI DMA in Xilinx/AMD devices, for performing Memory Mapo MM2S and S2MM operations, using a User space mappable DMA Buffer u-dma-buf from https://github.com/ikwzm/udmabuf. An example design is also provided with a simple loopback setup.

Vivado Project

Petalinux Setup

Device Tree

The device tree described by the file <petalinux_project>/project-spec/meta-user/recipes-bsp/device-tree/files/system-user.dtsi must contain the following, for specifying the AXI DMA Buffers and DMA Controllers, settings for having a persistent filesystem in the SD card in an ext4 format, as well as some settings for disabling write protection of the SD (see note).

/include/ "system-conf.dtsi"
/ {
    chosen {
        bootargs = " earlycon console=ttyPS0,115200 clk_ignore_unused uio_pdrv_genirq.of_id=generic-uio root=/dev/mmcblk0p2 rootfstype=ext4 rw rootwait";
    };

    udmabuf@0x00 {
        compatible = "ikwzm,u-dma-buf";
        device-name = "udmabuf0";
        minor-number = <0>;
        size = <0x4000000>;
        sync-mode = <1>;
        sync-always;
    };

    udmabuf@0x01 {
        compatible = "ikwzm,u-dma-buf";
        device-name = "udmabuf1";
        minor-number = <1>;
        size = <0x4000000>;
        sync-mode = <1>;
        sync-always;
    };
};

&axi_dma_0{
    compatible = "generic-uio";
};

&axi_dma_1{
    compatible = "generic-uio";
};

&sdhci1 {
	no-1-8-v;
	disable-wp;
};

Note: The last node for the SD card was added for the RFSoC ZCU111 board, to avoid kernel panic at boot. Source: AMD/Xilinx Forum

Add the generated .xsa file generated from the Vivado project:

petalinux-config --get-hw-description=<xsa_file_path>

Build the Petalinux project

petalinux-build

Package the Petalinux project

petalinux-package --boot --fsbl images/linux/zynqmp_fsbl.elf --u-boot --force --fpga <bitstream_path> --output images/linux/BOOT.BIN

Loopback Example