nand_erase_op
status = nand_erase_op(chip, block);
EXPORT_SYMBOL_GPL(nand_erase_op);
ret = nand_erase_op(chip, (page & chip->pagemask) >>
ret = nand_erase_op(chip, eb);
int nand_erase_op(struct nand_chip *chip, unsigned int eraseblock);