feat(fs): implement littlefs lfs.h driver support (#5562)

docs/libs/fs.rst

@@ -14,6 +14,7 @@ LVG has built in support for:
 - POSIX (Linux and Windows using POSIX function .e.g ``open``, ``read``)
 - WIN32 (Windows using Win32 API function .e.g ``CreateFileA``, ``ReadFile``)
 - MEMFS (read a file from a memory buffer)
+- LITTLEFS (a little fail-safe filesystem designed for microcontrollers)
 
 You still need to provide the drivers and libraries, this extension
 provides only the bridge between FATFS, STDIO, POSIX, WIN32 and LVGL.

docs/libs/index.rst

@@ -22,3 +22,4 @@
     rlottie
     ffmpeg
     rle
+    lfs

docs/libs/lfs.rst

@@ -0,0 +1,59 @@
+.. _lfs:
+
+==============
+littlefs
+==============
+
+littlefs is a little fail-safe filesystem designed for microcontrollers.
+
+Detailed introduction: https://github.com/littlefs-project/littlefs
+
+
+Usage
+-----
+
+Enable :c:macro:`LV_USE_FS_LITTLEFS` and define a :c:macro`LV_FS_LITTLEFS_LETTER` in ``lv_conf.h``.
+
+When enabled :c:macro:`lv_littlefs_set_handler` can be used to set up a mount point.
+
+Example
+-------
+
+.. code:: c
+    #include "lfs.h"
+
+    // configuration of the filesystem is provided by this struct
+    const struct lfs_config cfg = {
+        // block device operations
+        .read  = user_provided_block_device_read,
+        .prog  = user_provided_block_device_prog,
+        .erase = user_provided_block_device_erase,
+        .sync  = user_provided_block_device_sync,
+
+        // block device configuration
+        .read_size = 16,
+        .prog_size = 16,
+        .block_size = 4096,
+        .block_count = 128,
+        .cache_size = 16,
+        .lookahead_size = 16,
+        .block_cycles = 500,
+    };
+
+    // mount the filesystem
+    int err = lfs_mount(&lfs, &cfg);
+
+    // reformat if we can't mount the filesystem
+    // this should only happen on the first boot
+    if (err) {
+        lfs_format(&lfs, &cfg);
+        lfs_mount(&lfs, &cfg);
+    }
+
+    lv_littlefs_set_handler(&lfs);
+
+
+API
+---
+
+