fs: littlefs: add littlefs disk version selection

Add the ability to select littlefs disk version
to maintain backward compatibility
with existing littlefs
with the same major disk version.

Signed-off-by: Mikhail Siomin <victorovich.01@mail.ru>

dts/bindings/fs/zephyr,fstab,littlefs.yaml

@@ -76,3 +76,13 @@ properties:
       leveling.
 
       This corresponds to CONFIG_FS_LITTLEFS_BLOCK_CYCLES.
+
+  disk-version:
+    type: int
+    description: |
+      The littlefs disk version.
+
+      To maintain backward compatibility with existing littlefs
+      with the same major disk version.
+
+      The default version is LFS_DISK_VERSION.

include/zephyr/fs/littlefs.h

@@ -17,6 +17,22 @@
 extern "C" {
 #endif
 
+/**
+ * @brief Get the major part of the littlefs disk version
+ *
+ * @param disk_version The disk version of littlefs partition
+ * @return The major part of the littlefs disk version.
+ */
+#define FS_LITTLEFS_DISK_VERSION_MAJOR_GET(disk_version) FIELD_GET(GENMASK(31, 16), disk_version)
+
+/**
+ * @brief Get the minor part of the littlefs disk version
+ *
+ * @param disk_version The disk version of littlefs partition
+ * @return The minor part of the littlefs disk version.
+ */
+#define FS_LITTLEFS_DISK_VERSION_MINOR_GET(disk_version) FIELD_GET(GENMASK(15, 0), disk_version)
+
 /** @brief Filesystem info structure for LittleFS mount */
 struct fs_littlefs {
 	/* Defaulted in driver, customizable before mount. */

modules/littlefs/zephyr_lfs_config.h

@@ -43,6 +43,10 @@ extern "C"
 {
 #endif
 
+#ifdef CONFIG_FS_LITTLEFS_DISK_VERSION
+#define LFS_MULTIVERSION
+#endif
+
 /* Logging functions when using LittleFS with Zephyr. */
 #ifndef LFS_TRACE
 #ifdef LFS_YES_TRACE

subsys/fs/Kconfig.littlefs

@@ -118,4 +118,12 @@ config FS_LITTLEFS_BLK_DEV
 	  Enable this option to provide support for littlefs on the block
 	  devices (like for example SD card).
 
+config FS_LITTLEFS_DISK_VERSION
+	bool "Support for selecting littlefs disk version"
+	default y if $(dt_compat_any_has_prop,$(DT_COMPAT_ZEPHYR_FSTAB_LITTLEFS),disk-version)
+	help
+	  Enable this option to provide support for selecting littlefs disk version
+	  to maintain backward compatibility with existing littlefs
+	  with the same major disk version.
+
 endif # FILE_SYSTEM_LITTLEFS

subsys/fs/littlefs_fs.c

@@ -789,6 +789,14 @@ static int littlefs_init_cfg(struct fs_littlefs *fs, int flags)
 		lookahead_size = CONFIG_FS_LITTLEFS_LOOKAHEAD_SIZE;
 	}
 
+#ifdef CONFIG_FS_LITTLEFS_DISK_VERSION
+	uint32_t disk_version = lcp->disk_version;
+
+	if (disk_version == 0) {
+		disk_version = LFS_DISK_VERSION;
+	}
+#endif /* CONFIG_FS_LITTLEFS_DISK_VERSION */
+
 	/* No, you don't get to override this. */
 	lfs_size_t block_count = 0;
 
@@ -817,7 +825,7 @@ static int littlefs_init_cfg(struct fs_littlefs *fs, int flags)
 			dev->name,
 			(uint32_t)((struct flash_area *)fs->backend)->fa_off,
 			block_count, block_size, block_cycles);
-		LOG_INF("sizes: rd %u ; pr %u ; ca %u ; la %u",
+		LOG_INF("partition sizes: rd %u ; pr %u ; ca %u ; la %u",
 			read_size, prog_size, cache_size, lookahead_size);
 	}
 #endif /* CONFIG_FS_LITTLEFS_FMP_DEV */
@@ -862,7 +870,7 @@ static int littlefs_init_cfg(struct fs_littlefs *fs, int flags)
 
 		lcp->sync = lfs_api_sync_blk;
 
-		LOG_INF("sizes: rd %u ; pr %u ; ca %u ; la %u",
+		LOG_INF("partition sizes: rd %u ; pr %u ; ca %u ; la %u",
 			lcp->read_size, lcp->prog_size, lcp->cache_size,
 			lcp->lookahead_size);
 	} else {
@@ -882,6 +890,13 @@ static int littlefs_init_cfg(struct fs_littlefs *fs, int flags)
 		lcp->sync = lfs_api_sync;
 	}
 
+#ifdef CONFIG_FS_LITTLEFS_DISK_VERSION
+	lcp->disk_version = disk_version;
+	LOG_INF("partition disk version: %u.%u",
+		(uint32_t)FS_LITTLEFS_DISK_VERSION_MAJOR_GET(disk_version),
+		(uint32_t)FS_LITTLEFS_DISK_VERSION_MINOR_GET(disk_version));
+#endif /* CONFIG_FS_LITTLEFS_DISK_VERSION */
+
 	lcp->block_size = block_size;
 	lcp->block_count = block_count;
 	lcp->block_cycles = block_cycles;
@@ -1054,6 +1069,12 @@ static const struct fs_file_system_t littlefs_fs = {
 
 #define DT_DRV_COMPAT zephyr_fstab_littlefs
 #define FS_PARTITION(inst) DT_PHANDLE_BY_IDX(DT_DRV_INST(inst), partition, 0)
+#ifdef CONFIG_FS_LITTLEFS_DISK_VERSION
+#define FS_DISK_VERSION(inst) \
+	.disk_version = DT_INST_PROP_OR(inst, disk_version, LFS_DISK_VERSION),
+#else
+#define FS_DISK_VERSION(inst)
+#endif
 
 #define DEFINE_FS(inst) \
 static uint8_t __aligned(4) \
@@ -1081,6 +1102,7 @@ static struct fs_littlefs fs_data_##inst = { \
 		.read_buffer = read_buffer_##inst, \
 		.prog_buffer = prog_buffer_##inst, \
 		.lookahead_buffer = lookahead_buffer_##inst, \
+		FS_DISK_VERSION(inst) \
 	}, \
 }; \
 struct fs_mount_t FS_FSTAB_ENTRY(DT_DRV_INST(inst)) = { \