46 lines
1.7 KiB
ReStructuredText
46 lines
1.7 KiB
ReStructuredText
================================
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Memory Technology Device Drivers
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================================
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- ``include/nuttx/mtd/mtd.h``. All structures and APIs needed
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to work with MTD drivers are provided in this header file.
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- ``struct mtd_dev_s``. Each MTD device driver must implement
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an instance of ``struct mtd_dev_s``. That structure defines a
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call table with the following methods:
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Erase the specified erase blocks (units are erase blocks):
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Read/write from the specified read/write blocks:
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Some devices may support byte oriented reads (optional). Most
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MTD devices are inherently block oriented so byte-oriented
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accesses are not supported. It is recommended that low-level
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drivers not support read() if it requires buffering.
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Some devices may also support byte oriented writes (optional).
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Most MTD devices are inherently block oriented so byte-oriented
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accesses are not supported. It is recommended that low-level
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drivers not support read() if it requires buffering. This
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interface is only available if ``CONFIG_MTD_BYTE_WRITE`` is
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defined.
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Support other, less frequently used commands:
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- ``MTDIOC_GEOMETRY``: Get MTD geometry
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- ``MTDIOC_BULKERASE``: Erase the entire device
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is provided via a single ``ioctl`` method (see
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``include/nuttx/fs/ioctl.h``):
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- **Binding MTD Drivers**. MTD drivers are not normally directly
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accessed by user code, but are usually bound to another, higher
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level device driver. In general, the binding sequence is:
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#. Get an instance of ``struct mtd_dev_s`` from the
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hardware-specific MTD device driver, and
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#. Provide that instance to the initialization method of the
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higher level device driver.
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- **Examples**: ``drivers/mtd/m25px.c`` and ``drivers/mtd/ftl.c``
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