struct mtd_info

include/linux/mtd/mtd.h

struct mtd_info {

    u_char type;               //MTD 设备类型
    u_int32_t flags;           //MTD设备属性标志
    uint64_t size;              //标示了这个mtd设备的大小
    u_int32_t erasesize;       //MTD设备的擦除单元大小，对于NandFlash来说就是Block的大小
    u_int32_t writesize;        //MTD设备的读写单元大小，对于NandFlash来说就是page的大小
    u_int32_t oobsize;          //oob区域大小
    u_int32_t oobavail;         //有效的oob区域大小

    /* Kernel-only stuff starts here. */
    const char *name;         //
    int index;

    /* ecc layout structure pointer - read only ! */
    struct nand_ecclayout *ecclayout;

    /* Data for variable erase regions. If numeraseregions is zero,
     * it means that the whole device has erasesize as given above.
     */
    int numeraseregions;
    struct mtd_erase_region_info *eraseregions;

    /*
     * Erase is an asynchronous operation.  Device drivers are supposed
     * to call instr->callback() whenever the operation completes, even
     * if it completes with a failure.
     * Callers are supposed to pass a callback function and wait for it
     * to be called before writing to the block.
     */
    int (*erase) (struct mtd_info *mtd, struct erase_info *instr);

    /* This stuff for eXecute-In-Place */
    /* phys is optional and may be set to NULL */
    int (*point) (struct mtd_info *mtd, loff_t from, size_t len,
            size_t *retlen, void **virt, phys_addr_t *phys);

    /* We probably shouldn't allow XIP if the unpoint isn't a NULL */
    void (*unpoint) (struct mtd_info *mtd, loff_t from, size_t len);


    int (*read) (struct mtd_info *mtd, loff_t from, size_t len, size_t *retlen, u_char *buf);
    int (*write) (struct mtd_info *mtd, loff_t to, size_t len, size_t *retlen, const u_char *buf);

    /* In blackbox flight recorder like scenarios we want to make successful
       writes in interrupt context. panic_write() is only intended to be
       called when its known the kernel is about to panic and we need the
       write to succeed. Since the kernel is not going to be running for much
       longer, this function can break locks and delay to ensure the write
       succeeds (but not sleep). */

    int (*panic_write) (struct mtd_info *mtd, loff_t to, size_t len, size_t *retlen, const u_char *buf);

    int (*read_oob) (struct mtd_info *mtd, loff_t from,
             struct mtd_oob_ops *ops);
    int (*write_oob) (struct mtd_info *mtd, loff_t to,
             struct mtd_oob_ops *ops);

    /*
     * Methods to access the protection register area, present in some
     * flash devices. The user data is one time programmable but the
     * factory data is read only.
     */
    int (*get_fact_prot_info) (struct mtd_info *mtd, struct otp_info *buf, size_t len);
    int (*read_fact_prot_reg) (struct mtd_info *mtd, loff_t from, size_t len, size_t *retlen, u_char *buf);
    int (*get_user_prot_info) (struct mtd_info *mtd, struct otp_info *buf, size_t len);
    int (*read_user_prot_reg) (struct mtd_info *mtd, loff_t from, size_t len, size_t *retlen, u_char *buf);
    int (*write_user_prot_reg) (struct mtd_info *mtd, loff_t from, size_t len, size_t *retlen, u_char *buf);
    int (*lock_user_prot_reg) (struct mtd_info *mtd, loff_t from, size_t len);

/* XXX U-BOOT XXX */
#if 0
    /* kvec-based read/write methods.
       NB: The 'count' parameter is the number of _vectors_, each of
       which contains an (ofs, len) tuple.
    */
    int (*writev) (struct mtd_info *mtd, const struct kvec *vecs, unsigned long count, loff_t to, size_t *retlen);
#endif

    /* Sync */
    void (*sync) (struct mtd_info *mtd);

    /* Chip-supported device locking */
    int (*lock) (struct mtd_info *mtd, loff_t ofs, uint64_t len);
    int (*unlock) (struct mtd_info *mtd, loff_t ofs, uint64_t len);

    /* Bad block management functions */
    int (*block_isbad) (struct mtd_info *mtd, loff_t ofs);
    int (*block_markbad) (struct mtd_info *mtd, loff_t ofs);

/* XXX U-BOOT XXX */
#if 0
    struct notifier_block reboot_notifier;  /* default mode before reboot */
#endif

    /* ECC status information */
    struct mtd_ecc_stats ecc_stats;
    /* Subpage shift (NAND) */
    int subpage_sft;

    void *priv;

    struct module *owner;
    int usecount;

    /* If the driver is something smart, like UBI, it may need to maintain
     * its own reference counting. The below functions are only for driver.
     * The driver may register its callbacks. These callbacks are not
     * supposed to be called by MTD users */
    int (*get_device) (struct mtd_info *mtd);
    void (*put_device) (struct mtd_info *mtd);
};