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https://github.com/zephyrproject-rtos/zephyr
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d0d3c4a3a7
The documentation claims that Zephyr supports external file system implementations, and there's no reason not to do so. Rework the API to allow this. Note that the file system type cannot legally be an enum anymore, since we need to support file system types that don't have an identifier assigned in that enum. Rely on the implicit conversion of enum values to int to preserve backwards compatibility. Signed-off-by: Peter A. Bigot <pab@pabigot.com>
57 lines
1.7 KiB
ReStructuredText
57 lines
1.7 KiB
ReStructuredText
.. _file_system_api:
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File Systems
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############
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Zephyr RTOS Virtual Filesystem Switch (VFS) allows applications to mount multiple
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file systems at different mount points (e.g., ``/fatfs`` and ``/lfs``). The
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mount point data structure contains all the necessary information required
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to instantiate, mount, and operate on a file system. The File system Switch
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decouples the applications from directly accessing an individual file system's
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specific API or internal functions by introducing file system registration
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mechanisms.
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In Zephyr, any file system implementation or library can be plugged into or
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pulled out through a file system registration API. Each file system
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implementation must have a globally unique integer identifier; use
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:c:macro:`FS_TYPE_EXTERNAL_BASE` to avoid clashes with in-tree identifiers.
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.. code-block:: c
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int fs_register(int type, const struct fs_file_system_t *fs);
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int fs_unregister(int type, const struct fs_file_system_t *fs);
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Zephyr RTOS supports multiple instances of a file system by making use of
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the mount point as the disk volume name, which is used by the file system library
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while formatting or mounting a disk.
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A file system is declared as:
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.. code-block:: c
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static struct fs_mount_t mp = {
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.type = FS_FATFS,
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.mnt_point = FATFS_MNTP,
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.fs_data = &fat_fs,
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};
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where
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- ``FS_FATFS`` is the file system type like FATFS or LittleFS.
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- ``FATFS_MNTP`` is the mount point where the file system will be mounted.
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- ``fat_fs`` is the file system data which will be used by fs_mount() API.
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Sample
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******
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A sample of how the file system can be used is supplied in ``samples/subsys/fs``.
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API Reference
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*************
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.. doxygengroup:: file_system_api
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:project: Zephyr
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