Memory Technology Device DriversΒΆ

  • include/nuttx/mtd/mtd.h. All structures and APIs needed to work with MTD drivers are provided in this header file.

  • struct mtd_dev_s. Each MTD device driver must implement an instance of struct mtd_dev_s. That structure defines a call table with the following methods:

    Erase the specified erase blocks (units are erase blocks):

    Read/write from the specified read/write blocks:

    Some devices may support byte oriented reads (optional). Most MTD devices are inherently block oriented so byte-oriented accesses are not supported. It is recommended that low-level drivers not support read() if it requires buffering.

    Some devices may also support byte oriented writes (optional). Most MTD devices are inherently block oriented so byte-oriented accesses are not supported. It is recommended that low-level drivers not support read() if it requires buffering. This interface is only available if CONFIG_MTD_BYTE_WRITE is defined.

    Support other, less frequently used commands:

    • MTDIOC_GEOMETRY: Get MTD geometry

    • MTDIOC_XIPBASE:: Convert block to physical address for eXecute-In-Place

    • MTDIOC_BULKERASE: Erase the entire device

    is provided via a single ioctl method (see include/nuttx/fs/ioctl.h):

  • Binding MTD Drivers. MTD drivers are not normally directly accessed by user code, but are usually bound to another, higher level device driver. In general, the binding sequence is:

    1. Get an instance of struct mtd_dev_s from the hardware-specific MTD device driver, and

    2. Provide that instance to the initialization method of the higher level device driver.

  • Examples: drivers/mtd/m25px.c and drivers/mtd/ftl.c