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https://github.com/zephyrproject-rtos/zephyr
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b9dead0a42
The nvs module has some disadvantages for larger block size. The data header and slot are taking up to much space. A rewrite is proposed that reduces the used storage space for systems with write block size > 4. The data storage in flash is now one unit consisting of: data_length, data_id, data and data_length again in a multiple of the write block size. The data_length at the end is used to validate the correctness of the flash write and also allows to travel backwards in the filesystem. As a comparison, on a system with block size 8 byte, a 32 bit values now fits 1 block including the metadata (length and id). This used to be 3 blocks. The data_length will occupy 1 byte if the data length is less than 128 byte, it will occupy 2 byte if the data length is 128 byte or more. The data length is limited to 16383 byte. Each write to flash is verified by a read back of the data. The read performance is improved because reading is done backwards so the latest items are found first. When the filesystem is locked it can be unlocked by calling reinit(), this will clear flash and setup everything for storage. add sample documentation - README.rst Update dtsi to include erase_block_size, use erase_block_size in sample Update prj.conf to include CONFIG_MPU_ALLOW_FLASH_WRITE Signed-off-by: Laczen JMS <laczenjms@gmail.com>
187 lines
4.9 KiB
C
187 lines
4.9 KiB
C
/* NVS: non volatile storage in flash
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*
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* Copyright (c) 2018 Laczen
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*
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* SPDX-License-Identifier: Apache-2.0
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*/
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#ifndef __NVS_H_
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#define __NVS_H_
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#ifdef __cplusplus
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extern "C" {
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#endif
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#include <sys/types.h>
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/**
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* @brief Non-volatile Storage
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* @defgroup nvs Non-volatile Storage
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* @{
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* @}
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*/
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/**
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* @brief Non-volatile Storage Data Structures
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* @defgroup nvs_data_structures Non-volatile Storage Data Structures
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* @ingroup nvs
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* @{
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*/
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/**
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* @brief Non-volatile Storage File system structure
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*
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* @param write_location Next write location
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* @param entry_location Start of the filesystem
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* @param offset File system offset in flash
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* @param sector_size File system is divided into sectors each sector should be
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* multiple of pagesize and also a power of 2
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* @param max_len Maximum size of storage items
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* @param sector_count Amount of sectors in the file systems
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* @param write_block_size Alignment size
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* @param locked State of the filesystem, locked = true means the filesystem is
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* read only
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* @param nvs_lock Mutex
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* @param flash_device Flash Device
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*/
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struct nvs_fs {
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off_t write_location; /* next write location */
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off_t entry_location; /* start of the filesystem */
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off_t offset; /* filesystem offset in flash */
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u16_t sector_size; /* filesystem is divided into sectors,
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* sector size should be multiple of pagesize
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* and a power of 2
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*/
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u16_t max_len; /* maximum size of stored item, set to sector_size/4 */
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u8_t sector_count; /* how many sectors in the filesystem */
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u8_t write_block_size; /* write block size for alignment */
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bool locked; /* the filesystem is locked after an error occurred
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* when it is locked it becomes a read-only filesystem
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* it can be unlocked by calling nvs_init again, this
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* will destroy all stored data
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*/
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struct k_mutex nvs_lock;
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struct device *flash_device;
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};
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/**
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* @}
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*/
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/**
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* @brief Non-volatile Storage APIs
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* @defgroup nvs_high_level_api Non-volatile Storage APIs
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* @ingroup nvs
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* @{
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*/
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/**
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* @brief nvs_init
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*
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* Initializes a NVS file system in flash.
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*
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* @param fs Pointer to file system
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* @param dev_name Pointer to flash device name
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* @retval 0 Success
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* @retval -ERRNO errno code if error
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*/
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int nvs_init(struct nvs_fs *fs, const char *dev_name);
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/**
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* @brief nvs_reinit
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*
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* Reinitializes a NVS file system in flash, if the filesystem is locked this
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* will erase the filesystem.
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*
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* @param fs Pointer to file system
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* @retval 0 Success
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* @retval -ERRNO errno code if error
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*/
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int nvs_reinit(struct nvs_fs *fs);
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/**
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* @brief nvs_clear
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*
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* Clears the NVS file system from flash.
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* @param fs Pointer to file system
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* @retval 0 Success
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* @retval -ERRNO errno code if error
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*/
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int nvs_clear(struct nvs_fs *fs);
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/**
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* @brief nvs_write
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*
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* Write an entry to the file system.
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*
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* @param fs Pointer to file system
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* @param id Id of the entry to be written
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* @param data Pointer to the data to be written
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* @param len Number of bytes to be written
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*
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* @return Number of bytes written. On success, it will be equal to the number
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* of bytes requested to be written. Any other value, indicates an error. Will
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* return -ERRNO code on error.
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*/
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ssize_t nvs_write(struct nvs_fs *fs, u16_t id, const void *data, size_t len);
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/**
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* @brief nvs_delete
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*
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* Delete an entry from the file system
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*
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* @param fs Pointer to file system
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* @param id Id of the entry to be deleted
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* @retval 0 Success
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* @retval -ERRNO errno code if error
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*/
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int nvs_delete(struct nvs_fs *fs, u16_t id);
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/**
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* @brief nvs_read
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*
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* Read an entry from the file system.
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*
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* @param fs Pointer to file system
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* @param id Id of the entry to be read
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* @param data Pointer to data buffer
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* @param len Number of bytes to be read
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*
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* @return Number of bytes read. On success, it will be equal to the number
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* of bytes requested to be read. Any other value, indicates an error. When
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* the number of bytes read is larger than the number of bytes requested to
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* read this indicates not all bytes were read, and more data is available.
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* Return -ERRNO code on error.
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*/
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ssize_t nvs_read(struct nvs_fs *fs, u16_t id, void *data, size_t len);
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/**
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* @brief nvs_read_hist
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*
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* Read a history entry from the file system.
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*
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* @param fs Pointer to file system
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* @param id Id of the entry to be read
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* @param data Pointer to data buffer
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* @param len Number of bytes to be read
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* @param cnt History counter: 0: latest entry, 1:one before latest ...
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*
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* @return Number of bytes read. On success, it will be equal to the number
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* of bytes requested to be read. Any other value, indicates an error. When
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* the number of bytes read is larger than the number of bytes requested to
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* read this indicates not all bytes were read, and more data is available.
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* Return -ERRNO code on error.
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*/
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ssize_t nvs_read_hist(struct nvs_fs *fs, u16_t id, void *data, size_t len,
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u16_t cnt);
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/**
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* @}
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*/
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#ifdef __cplusplus
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}
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#endif
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#endif /* __NVS_H_ */
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