I am using Petalinux 2018.3 on a Zynq 7000 family device.
I see the following errors when I try to use flash_unlock
root@localhost:~# flash_unlock -i /dev/mtd0
flash_unlock: error!: could not check lock status device: /dev/mtd0
error 95 (Operation not supported)
I get a similar error for flash_lock and flash_unlock and if I specify "0 0" or "0 1" for offset and block count
flashcp and flash_erase seem to be working fine. Here's the version reported.
root@localhost:~# flash_unlock -V
flash_unlock (mtd-utils) 2.0.0