Zephyr supports fatfs, nffs and fcb as storage layer. fatfs and nffs
are less suited for application in memory restricted IC's. fcb has a
smaller footprint but has a complex api.
The proposed module is a module with a even smaller footprint compared
to fcb and a simple interface for reading and writing entries. The
module provides wear levelling of flash. This allows the module to be
used not only to store configuration settings but to store device state
(e.g. state of a light switch over reboots) of a zephyr device.
Fixes buffer overflow by introducing maximum read length in nvs_read()
and nvs_read_hist().
Fixes nvs_write() not to reflash the same data. Allows the user to do
call nvs_write() for all defined entries without worries about flash
wear.
Fixes garbage collection error where wrong data could be copied.
Add nvs_delete() to allow deleting a stored entry. A deleted entry will
not be copied to a new flash sector
Include flash wear information in the README.md documentation
0/25 Update module after reviewers remarks, added documentation to
nvs.h, removed README.md by nvs.rst in doc/subsystems folder
04/26 Update module after reviewers remarks, updated nvs.rst, added more
documentation to samples/subsys/nvs/src/main.c, updated doxygen info
in nvs.h (hope this time it works).
04/26 Update subsystems.rst to include nvs.restart
04/27 Updated nvs.c and nvs.h to avoid a possible flash deletion loop
when the file system is full.
04/29 Updated nvs_write to detect and ignore deletes of non-existing
items
05/06 Update NVS module to return standard error codes, removed low
level API, added configuration options. NVS now uses the board dts to
determine the flash storage location (FLASH_AREA_STORAGE_OFFSET).
05/06 Update nvs.rst. Updated intendation and added intermediate
variables in nvs.c to make the code easier to read.
05/06 Update nvs.rst.
05/07 Update nvs.rst
05/08 Changed the API to a more standard file system API.
05/08 Removed cnt_max from nvs_read() as it is not used.
05/08 Removed #ifdef(CONFIG_NVS_LOG) from nvs_priv.h, now the module can
be build with debugging off.
05/09 Removed configuration options for SECTOR_SIZE, SECTOR_COUNT and
MAX_ELEM_SIZE. It is now easy to support multiple NVS filesystems on
one or multiple devices. Changed logging to support newlib systems.
Thanks to Olivier Martin for reporting and proposed changes.
Signed-off-by: Laczen JMS <laczenjms@gmail.com>
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