flash_unlock fails to unlock my m25p32 flash

[saeed bishara]

Hi,
    I'm using kernel based in version 2.6.26.5, and my board has a 4M
Flash ST-M25P32-VMF6P connected through spi.
    I have read access, and write access works when I do protect off
from uboot. but I can't do unlock from linux (flash_unlock fails on
-1 EOPNOTSUPP (Operation not supported)). the mtd-utils version is
20080508-1.

   Is this version of the kernel support unlocking? if yes, what does
my system missing?