This library is structured of both low-level and littlefs-level drivers. It is designed for systems using STM32 microcontrollers and is written on top of the STM32 HAL. It uses SPI interface to interract with serial flash memory.
These drivers provide the "bare-metal" access to the serial flash memory(reading ID, reading data, reading status registers, writing pages, erasing sectors, etc).
These drivers provide functions needed by littlefs filesystem to work: prog, erase, read and sync. Refer to the official littlefs Github if you want to learn more about littlefs itself: https://github.com/littlefs-project/littlefs .
The implementation of this library can be found here: https://github.com/filipembedded/stm32-nvs-demos. It features low-level demo and littlefs demo for w25q128 flash.