Two non-blocking UARTs are connected to each other and through an AXI SmartConnect to XDMA PCIe. This is a test platform for UART over XDMA.
Refer to the innova2_flex_xcku15p_notes project's instructions on installing XDMA drivers and Loading a User Image to load the release bitstream into the Innova-2's FPGA Configuration Memory.
wget https://github.com/mwrnd/innova2_experiments/releases/download/v0.1-alpha/xdma_uart-to-uart_bitstream.zip
unzip -d . xdma_uart-to-uart_bitstream.zip
md5sum xdma_uart-to-uart_primary.bin xdma_uart-to-uart_secondary.bin
echo 4cab44d93b10960a7dd0ce653630d69b should be MD5 Checksum of xdma_uart-to-uart_primary.bin
echo 015c797003f4ddf770c6ea418bd22a18 should be MD5 Checksum of xdma_uart-to-uart_secondary.bin
xdma_tty_cuse.c bridges the AXI UARTs to the host's TTY subsystem. Compile then run with:
gcc xdma_tty_cuse.c `pkg-config fuse --cflags --libs` --std=gnu17 -g -Wall -latomic -o xdma_tty_cuse
sudo ./xdma_tty_cuse /dev/xdma0_c2h_0 /dev/xdma0_h2c_0 0x60100000 ttyCUSE0
In a second terminal, connect to the CUSE TTY device:
sudo gtkterm --port /dev/ttyCUSE0
In a third terminal, run a second instance of XDMA TTY CUSE TTY:
sudo ./xdma_tty_cuse /dev/xdma0_c2h_1 /dev/xdma0_h2c_1 0x60110000 ttyCUSE1
In a fourth terminal, connect to the second CUSE TTY device:
sudo gtkterm --port /dev/ttyCUSE1
Typing in one GTKTerm window should display the characters in the other window.
If you attempt to send a file, the TTY will lock up after sending about twice the number of characters that the RX and TX FIFOs hold.
001abcdefghijklmnopqrstuvwxyzA is 30 bytes while each FIFO has a 2^4=16-byte depth.
uart.c sends as much data as it can to the first AXI UART then reads as much data as it can from the second. Compile then run with:
gcc uart.c `pkg-config fuse --cflags --libs` --std=gnu17 -g -Wall -latomic -o uart
In a seperate terminal, test with:
sudo ./uart /dev/xdma0_c2h_0 /dev/xdma0_h2c_0 0x60100000 /dev/xdma0_c2h_1 /dev/xdma0_h2c_1 0x60110000
The software is able to fill the RX and TX FIFOs with 30 bytes (15 to each FIFO), and successfully read them back.
...
Wrote count = 30 bytes of data to XDMA0 : ABCDEFGHIJKLMNOPQRSTUVWXYZABCD
...
Read count = 30 bytes of data from XDMA1, readstring = ABCDEFGHIJKLMNOPQRSTUVWXYZABCD
...
Similarly with uartlite.c for the UARTlite interfaces:
gcc uartlite.c `pkg-config fuse --cflags --libs` --std=gnu17 -g -Wall -latomic -o uartlite
sudo ./uartlite /dev/xdma0_c2h_0 /dev/xdma0_h2c_0 0x60300000 /dev/xdma0_c2h_1 /dev/xdma0_h2c_1 0x60310000
The UARTlite software needs further debugging. Either delay after each byte sent or wait for the transmit FIFO to empty before sending another byte. Check for the various STATUS register errors.
...
Wrote count = 24 bytes of data to XDMA0 : ABCDEFGHIJKLMNOPQRSTUVWX
...
Read count = 17 bytes of data from XDMA1, readstring = AABCDEFGHIJKLMNOP
...
The de#cludes an Integrated Logic Analyzer (ILA) for the AXI interface of each UART.
On the computer hosting the Innova-2, enable JTAG Access:
sudo mst start
cd ~/Innova_2_Flex_Open_18_12/driver/
sudo ./make_device
cd ~
sudo insmod /usr/lib/modules/`uname -r`/updates/dkms/mlx5_fpga_tools.ko
sudo ~/Innova_2_Flex_Open_18_12/app/innova2_flex_app -v
Connect a Xilinx-Compatible 1.8V JTAG Adapter to the Innova-2 and run Vivado Hardware Manager. Add debug_nets.ltx to the Trigger Setup and capture AXI communication.
source xdma_uart-to-uart.tcl in Vivado.
- fpga-axi-uart.c is the RISC-V UART driver code from
vivado-risc-v - cusexmp.c CUSE example
- tty0tty is a Virtual TTY to TTY Bridge
- Linux Device Drivers 3rd Edition tiny_tty example
- CuseTTY is a Virtual TTY for ESP-Link and a great example of a TTY using CUSE