bit 3 in efuse_rd_disable[3:0] is mapped to flash_crypt_config
        this bit is at position 19 in EFUSE_BLK0_RDATA0_REG

def get_flash_crypt_config(self):
        """ bit 3 in efuse_rd_disable[3:0] is mapped to flash_crypt_config
        this bit is at position 19 in EFUSE_BLK0_RDATA0_REG """
        word0 = self.read_efuse(0)
        rd_disable = (word0 >> 19) & 0x1

        if rd_disable == 0:
            """ we can read the flash_crypt_config efuse value
            so go & read it (EFUSE_BLK0_RDATA5_REG[31:28]) """
            word5 = self.read_efuse(5)
            word5 = (word5 >> 28) & 0xF
            return word5
        else:
            # if read of the efuse is disabled we assume it is set correctly
            return 0xF