struct nand_hw_control — Control structure for hardware controller (e.g ECC generator) shared among independent devices
struct nand_hw_control { spinlock_t lock; struct nand_chip * active; wait_queue_head_t wq; };
protection lock
the mtd device which holds the controller currently
wait queue to sleep on if a NAND operation is in progress used instead of the per chip wait queue when a hw controller is available