This is a quick guide how to program FPGA fabric on Microchip Polarfire, more specifically Beaglev-fire board.

Programming Link to heading

In 4, We need to get bitstream directory generated by gateware first. In this example, it’s called my_custom_fpga_design.

change-gateway Link to heading

So, what is there? We need to the bitstream and dtb overlay.

  • mpfs_bitstream.spi : spi bitstream
  • mpfs_dtbo.spi : overlay device tree

Then we call change-gateway script with my_custom_fpga_design to copy the files above.

sudo /usr/share/beagleboard/gateware/change-gateware.sh ./my_custom_fpga_design

if ! id | grep -q root; then
	echo "must be run as root"
	exit
fi

if [ -d $1 ]
then
    echo "Changing gateware."
    if [ -e $1/LinuxProgramming/mpfs_bitstream.spi ]
    then
        if [ -e $1/LinuxProgramming/mpfs_dtbo.spi ]
        then
            cp -v $1/LinuxProgramming/mpfs_dtbo.spi /lib/firmware/mpfs_dtbo.spi
            cp -v $1/LinuxProgramming/mpfs_bitstream.spi /lib/firmware/mpfs_bitstream.spi
            sync
            . /usr/share/microchip/gateware/update-gateware.sh
        else
            echo "No device tree overlay file found."
        fi
    else
        echo "No gateware file found."
    fi
else
    echo "No directory found for this requested gateware."
fi

update-gatewate Link to heading

Looking deeper into update-gatewate which uses mtd_debug5 to write mpfs_dtbo.spi.

The writing 1 to /sys/kernel/debug/fpga/microchip_exec_update to write the

If successful, the console should display some messages indicating that the bistream image has been transferred to the SPI flash and the bitstream address has been copied to the spi flash directory. For more information on the SPI flash memory layout please refer to the SPI Directory Layout section. Finally, the system controller reads the bitstream from the SPI flash to verify its content.

#!/bin/bash
echo "================================================================================"
echo "|                            FPGA Gateware Update                              |"
echo "|                                                                              |"
echo "|   Please ensure that the mpfs_bitstream.spi file containing the gateware     |"
echo "|   update has been copied to directory /lib/firmware.                         |"
echo "|                                                                              |"
echo "|                 !!! This will take a couple of minutes. !!!                  |"
echo "|                                                                              |"
echo "|               Give the system a few minutes to reboot itself                 |"
echo "|                        after Linux has shutdown.                             |"
echo "|                                                                              |"
echo "================================================================================"

if [ ! -f /lib/firmware/mpfs_bitstream.spi ] ; then
	echo "Missing: /lib/firmware/mpfs_bitstream.spi"
	exit 2
fi

#read -rsp $'Press any key to continue...\n' -n1 key

if [ ! -f /sys/kernel/debug/fpga/microchip_exec_update ] ; then
	/usr/bin/mount -t debugfs none /sys/kernel/debug
fi

# Trash exisitng device tree overlay in case the rest of the process fails:
/usr/sbin/mtd_debug erase /dev/mtd0 0x0 0x10000

# Write device tree overlay
dtbo_ls=$(ls -l /lib/firmware/mpfs_dtbo.spi)
dtbo_size=$(echo $dtbo_ls | cut -d " "  -f 5)

echo "Writing mpfs_dtbo.spi to /dev/mtd0"
/usr/sbin/mtd_debug write /dev/mtd0 0x400 $dtbo_size /lib/firmware/mpfs_dtbo.spi > /dev/zero

# Fake the presence of a golden image for now.
/usr/sbin/mtd_debug write /dev/mtd0 0 4 /dev/zero > /dev/zero

# Initiate FPGA update.
echo "Triggering FPGA Gateware Update (/sys/kernel/debug/fpga/microchip_exec_update)"
echo 1 > /sys/kernel/debug/fpga/microchip_exec_update

# Reboot Linux for the gateware update to take effect.
# FPGA reprogramming takes places between Linux shut-down and HSS restarting the board.
/usr/sbin/reboot