subsys/fs: add support for littlefs

littlefs is a fail-safe filesystem from ARM Mbed that has wear-leveling
capabilities.

Signed-off-by: Peter A. Bigot <[email protected]>
Signed-off-by: Jim Paris <[email protected]>

CODEOWNERS

@@ -337,6 +337,7 @@
 /subsys/fs/                               @nashif
 /subsys/fs/fcb/                           @nvlsianpu
 /subsys/fs/fuse_fs_access.c               @vanwinkeljan
+/subsys/fs/littlefs_fs.c                  @pabigot
 /subsys/fs/nvs/                           @Laczen
 /subsys/logging/                          @nordic-krch
 /subsys/mgmt/                             @carlescufi @nvlsianpu

include/fs/fs.h

@@ -48,6 +48,7 @@ enum fs_dir_entry_type {
 enum fs_type {
 	FS_FATFS = 0,
 	FS_NFFS,
+	FS_LITTLEFS,
 	FS_TYPE_END,
 };
 

include/fs/fs_interface.h

@@ -11,7 +11,7 @@
 extern "C" {
 #endif
 
-#ifdef CONFIG_FILE_SYSTEM_NFFS
+#if defined(CONFIG_FILE_SYSTEM_LITTLEFS) || defined(CONFIG_FILE_SYSTEM_NFFS)
 #define MAX_FILE_NAME 256
 #else /* FAT_FS */
 #define MAX_FILE_NAME 12 /* Uses 8.3 SFN */

include/fs/littlefs.h

@@ -0,0 +1,39 @@
+/*
+ * Copyright (c) 2019 Bolt Innovation Management, LLC
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#ifndef ZEPHYR_INCLUDE_FS_LITTLEFS_H_
+#define ZEPHYR_INCLUDE_FS_LITTLEFS_H_
+
+#include <zephyr/types.h>
+#include <kernel.h>
+#include <storage/flash_map.h>
+
+#include <lfs.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/** @brief Filesystem info structure for LittleFS mount */
+struct fs_littlefs {
+	/* These structures are filled automatically at mount. */
+	struct lfs lfs;
+	struct lfs_config cfg;
+	const struct flash_area *area;
+	struct k_mutex mutex;
+
+	/* Static buffers */
+	u8_t read_buffer[CONFIG_FS_LITTLEFS_CACHE_SIZE];
+	u8_t prog_buffer[CONFIG_FS_LITTLEFS_CACHE_SIZE];
+	/* Multiple of 8 bytes, but 4-byte aligned (littlefs #239) */
+	u32_t lookahead_buffer[CONFIG_FS_LITTLEFS_LOOKAHEAD_SIZE / sizeof(u32_t)];
+};
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* ZEPHYR_INCLUDE_FS_LITTLEFS_H_ */

subsys/fs/CMakeLists.txt

@@ -6,14 +6,16 @@ if(CONFIG_FILE_SYSTEM)
   zephyr_library()
   zephyr_library_include_directories(${CMAKE_CURRENT_SOURCE_DIR})
   zephyr_library_sources(fs.c fs_impl.c)
-  zephyr_library_sources_ifdef(CONFIG_FAT_FILESYSTEM_ELM fat_fs.c)
-  zephyr_library_sources_ifdef(CONFIG_FILE_SYSTEM_NFFS   nffs_fs.c)
-  zephyr_library_sources_ifdef(CONFIG_FILE_SYSTEM_SHELL  shell.c)
+  zephyr_library_sources_ifdef(CONFIG_FAT_FILESYSTEM_ELM   fat_fs.c)
+  zephyr_library_sources_ifdef(CONFIG_FILE_SYSTEM_LITTLEFS littlefs_fs.c)
+  zephyr_library_sources_ifdef(CONFIG_FILE_SYSTEM_NFFS     nffs_fs.c)
+  zephyr_library_sources_ifdef(CONFIG_FILE_SYSTEM_SHELL    shell.c)
 
   zephyr_library_link_libraries(FS)
 
-  target_link_libraries_ifdef(CONFIG_FAT_FILESYSTEM_ELM FS INTERFACE ELMFAT)
-  target_link_libraries_ifdef(CONFIG_FILE_SYSTEM_NFFS   FS INTERFACE NFFS)
+  target_link_libraries_ifdef(CONFIG_FAT_FILESYSTEM_ELM   FS INTERFACE ELMFAT)
+  target_link_libraries_ifdef(CONFIG_FILE_SYSTEM_LITTLEFS FS INTERFACE LITTLEFS)
+  target_link_libraries_ifdef(CONFIG_FILE_SYSTEM_NFFS     FS INTERFACE NFFS)
 endif()
 
 add_subdirectory_ifdef(CONFIG_FCB  ./fcb)

subsys/fs/Kconfig

@@ -39,6 +39,13 @@ config FILE_SYSTEM_NFFS
 	  Note: NFFS requires 1-byte unaligned access to flash thus it
 	  will not work on devices that support only aligned flash access.
 
+config FILE_SYSTEM_LITTLEFS
+	bool "LittleFS file system support"
+	depends on FLASH_MAP
+	depends on FLASH_PAGE_LAYOUT
+	help
+	  Enables LittleFS file system support.
+
 config FILE_SYSTEM_SHELL
 	bool "Enable file system shell"
 	depends on SHELL
@@ -121,6 +128,63 @@ config NFFS_FILESYSTEM_MAX_BLOCK_SIZE
 
 endmenu
 
+menu "LittleFS Settings"
+	visible if FILE_SYSTEM_LITTLEFS
+
+config FS_LITTLEFS_NUM_FILES
+	int "Maximum number of opened files"
+	default 4
+	help
+	  This is a global maximum across all mounted littlefs filesystems.
+
+config FS_LITTLEFS_NUM_DIRS
+	int "Maximum number of opened directories"
+	default 4
+	help
+	  This is a global maximum across all mounted littlefs filesystems.
+
+config FS_LITTLEFS_READ_SIZE
+	int "Minimum size of a block read"
+	default 16
+	help
+	  All read operations will be a multiple of this value.
+
+config FS_LITTLEFS_PROG_SIZE
+	int "Minimum size of a block program"
+	default 16
+	help
+	  All program operations will be a multiple of this value.
+
+config FS_LITTLEFS_CACHE_SIZE
+	int "Size of block caches in bytes"
+	default 64
+	help
+	  Each cache buffers a portion of a block in RAM.  The littlefs
+	  needs a read cache, a program cache, and one additional cache
+	  per file. Larger caches can improve performance by storing
+	  more data and reducing the number of disk accesses. Must be a
+	  multiple of the read and program sizes of the underlying flash
+	  device, and a factor of the block size.
+
+config FS_LITTLEFS_LOOKAHEAD_SIZE
+	int "Size of lookahead buffer in bytes"
+	default 32
+	help
+	  A larger lookahead buffer increases the number of blocks found
+	  during an allocation pass. The lookahead buffer is stored as a
+	  compact bitmap, so each byte of RAM can track 8 blocks. Must
+	  be a multiple of 8.
+
+config FS_LITTLEFS_BLOCK_CYCLES
+	int "Number of erase cycles before moving data to another block"
+	default 512
+	help
+	  For dynamic wear leveling, the number of erase cycles before data
+	  is moved to another block.  Set to a non-positive value to
+	  disable leveling.
+
+endmenu
+
 endif # FILE_SYSTEM
 
 source "subsys/fs/fcb/Kconfig"