fclk_set

#!/bin/sh

set -e

write_to () {
    echo $2 | sudo tee $1 > /dev/null
}

set_rate () {
    c=fclk$1
    rate=$2

    d=$(readlink -f "/sys/class/xdevcfg/xdevcfg/device")

    [ -d $d/fclk/$c ] || write_to $d/fclk_export $c

    write_to $d/fclk/$c/enable 1
    write_to $d/fclk/$c/set_rate $rate

    echo "Set clock $c to " $(cat $d/fclk/$c/set_rate)
}

CLK=$1
FREQ=$2

if [ -z $CLK ] || [ -z $FREQ ]; then
   cat <<EOL
  Usage:  $0 clk freq
	clk  -- Which clock to change 0,1,2 or 3
	freq -- Desired frequency in Hz
EOL
    exit 1
fi

set_rate $CLK $FREQ

Not entirely related but our current system in development lacks xdevcfg drivers since we replaced it with fpga manager for programming fpga using device tree overlays. For setting clocks I patched fclk driver from staging to be able to set clocks as well. Patched file is available at: https://github.com/RedPitaya/linux-xlnx/blob/branch-redpitaya-v2017.1--rebase-xilinx-v2017.1/drivers/staging/fclk/xilinx_fclk.c
Any comments are welcome.