littlefs 一个为微控制器设计的小故障安全文件系统，具有以下特点：
- 掉电恢复能力: 设计用于处理随机电源故障。所有文件操作都有很强的写时拷贝保证，如果断电，文件系统将恢复到上一次已知的良好状态。
- 动态磨损均衡: 设计考虑到闪存，并提供动态块磨损均衡。此外，littlefs可以检测坏块并在它们周围工作。
- 有限RAM/ROM: 被设计为使用少量内存。RAM的使用是严格限制的，这意味着RAM的使用不会随着文件系统的增长而改变。文件系统不包含无界递归，动态内存仅限于可静态提供的可配置缓冲区。
官方的详细介绍参照此链接（https://github.com/littlefs-project/littlefs/）
本试验目的主要适配littlefs MP135板子上上自带了512M 的DDR资源，我们修改链接脚本把最后的2M的资源分配给Littlefs 进行管理，little 需要使用堆资源同时把对资源也扩大点，链接脚本修改如下：
移植适配
littlefs 移植适配依赖物理层的配置结构体如下：
struct lfs_config {
// Opaque user provided context that can be used to pass
// information to the block device operations
void *context;
// Read a region in a block. Negative error codes are propagated
// to the user.
int (*read)(const struct lfs_config *c, lfs_block_t block,
lfs_off_t off, void *buffer, lfs_size_t size);
// Program a region in a block. The block must have previously
// been erased. Negative error codes are propagated to the user.
// May return LFS_ERR_CORRUPT if the block should be considered bad.
int (*prog)(const struct lfs_config *c, lfs_block_t block,
lfs_off_t off, const void *buffer, lfs_size_t size);
// Erase a block. A block must be erased before being programmed.
// The state of an erased block is undefined. Negative error codes
// are propagated to the user.
// May return LFS_ERR_CORRUPT if the block should be considered bad.
int (*erase)(const struct lfs_config *c, lfs_block_t block);
// Sync the state of the underlying block device. Negative error codes
// are propagated to the user.
int (*sync)(const struct lfs_config *c);
#ifdef LFS_THREADSAFE
// Lock the underlying block device. Negative error codes
// are propagated to the user.
int (*lock)(const struct lfs_config *c);
// Unlock the underlying block device. Negative error codes
// are propagated to the user.
int (*unlock)(const struct lfs_config *c);
#endif
// Minimum size of a block read in bytes. All read operations will be a
// multiple of this value.
lfs_size_t read_size;
// Minimum size of a block program in bytes. All program operations will be
// a multiple of this value.
lfs_size_t prog_size;
// Size of an erasable block in bytes. This does not impact ram consumption
// and may be larger than the physical erase size. However, non-inlined
// files take up at minimum one block. Must be a multiple of the read and
// program sizes.
lfs_size_t block_size;
// Number of erasable blocks on the device.
lfs_size_t block_count;
// Number of erase cycles before littlefs evicts metadata logs and moves
// the metadata to another block. Suggested values are in the
// range 100-1000, with large values having better performance at the cost
// of less consistent wear distribution.
//
// Set to -1 to disable block-level wear-leveling.
int32_t block_cycles;
// Size of block caches in bytes. 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, and a factor of the block size.
lfs_size_t cache_size;
// Size of the lookahead buffer in bytes. 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.
lfs_size_t lookahead_size;
// Optional statically allocated read buffer. Must be cache_size.
// By default lfs_malloc is used to allocate this buffer.
void *read_buffer;
// Optional statically allocated program buffer. Must be cache_size.
// By default lfs_malloc is used to allocate this buffer.
void *prog_buffer;
// Optional statically allocated lookahead buffer. Must be lookahead_size
// and aligned to a 32-bit boundary. By default lfs_malloc is used to
// allocate this buffer.
void *lookahead_buffer;
// Optional upper limit on length of file names in bytes. No downside for
// larger names except the size of the info struct which is controlled by
// the LFS_NAME_MAX define. Defaults to LFS_NAME_MAX when zero. Stored in
// superblock and must be respected by other littlefs drivers.
lfs_size_t name_max;
// Optional upper limit on files in bytes. No downside for larger files
// but must be <= LFS_FILE_MAX. Defaults to LFS_FILE_MAX when zero. Stored
// in superblock and must be respected by other littlefs drivers.
lfs_size_t file_max;
// Optional upper limit on custom attributes in bytes. No downside for
// larger attributes size but must be <= LFS_ATTR_MAX. Defaults to
// LFS_ATTR_MAX when zero.
lfs_size_t attr_max;
// Optional upper limit on total space given to metadata pairs in bytes. On
// devices with large blocks (e.g. 128kB) setting this to a low size (2-8kB)
// can help bound the metadata compaction time. Must be <= block_size.
// Defaults to block_size when zero.
lfs_size_t metadata_max;
};
主要包含物理层设备的读写/擦除最小编程块属性配置，本地使用ddr模拟flash，最小擦除的sector 配置为4096字节，最小读写操作1字节，我们按照littlefs 依赖的配置结构实现对应的而函数。
int lfs_mflash_read(const struct lfs_config *lfsc, lfs_block_t block, lfs_off_t off, void *buffer, lfs_size_t size)
{
struct lfs_mflash_ctx *ctx;
uint32_t flash_addr;
assert(lfsc);
ctx = (struct lfs_mflash_ctx *)lfsc->context;
assert(ctx);
flash_addr = ctx->start_addr + block * lfsc->block_size + off;
for(lfs_size_t i=0; i < size; i++)
{
((int8_t *)buffer)[i] = *((volatile int8_t*)flash_addr);
flash_addr++;
}
return LFS_ERR_OK;
}
int lfs_mflash_prog(
const struct lfs_config *lfsc, lfs_block_t block, lfs_off_t off, const void *buffer, lfs_size_t size)
{
struct lfs_mflash_ctx *ctx;
uint32_t flash_addr;
assert(lfsc);
ctx = (struct lfs_mflash_ctx *)lfsc->context;
assert(ctx);
flash_addr = ctx->start_addr + block * lfsc->block_size + off;
memcpy(((void*)flash_addr),buffer,size);
return LFS_ERR_OK;
}
int lfs_mflash_erase(const struct lfs_config *lfsc, lfs_block_t block)
{
uint32_t page_addr;
struct lfs_mflash_ctx *ctx;
ctx = (struct lfs_mflash_ctx *)lfsc->context;
page_addr = ctx->start_addr + block * lfsc->block_size;
memset(((void *)page_addr),0xff,4096);
return LFS_ERR_OK;
}
对应配置如下：
测试验证
我们基于https://shequ.stmicroelectronics.cn/forum.php?mod=viewthread&tid=642247&page=1&extra=#pid2647582 shell 基础上添加测试命令来验证littlefs 功能,测试命令代码如下：
#include "lfs_ddr.h"
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <string.h>
#include "littleshell.h"
#define SHELL_Printf printf
#define PRINTF printf
/*******************************************************************************
* Variables
******************************************************************************/
lfs_t lfs;
struct lfs_config cfg;
int lfs_mounted;
static unsigned int format(char argc, char **argv)
{
int res;
if (lfs_mounted)
{
SHELL_Printf("LFS is mounted, please unmount it first.\r\n");
return 1;
}
if (argc != 2 || strcmp(argv[1], "yes"))
{
SHELL_Printf("Are you sure? Please issue command \"format yes\" to proceed.\r\n");
return 1;
}
res = lfs_format(&lfs, &cfg);
if (res)
{
PRINTF("\rError formatting LFS: %d\r\n", res);
}
return 1;
}
LTSH_FUNCTION_EXPORT(format,"lfs format api");
static unsigned int mount(char argc, char **argv)
{
int res;
if (lfs_mounted)
{
SHELL_Printf("LFS already mounted\r\n");
return 1;
}
res = lfs_mount(&lfs, &cfg);
if (res)
{
PRINTF("\rError mounting LFS\r\n");
}
else
{
lfs_mounted = 1;
}
return 1;
}
LTSH_FUNCTION_EXPORT(mount,"lfs mount api");
static unsigned int unmount(char argc, char **argv)
{
int res;
if (!lfs_mounted)
{
SHELL_Printf("LFS not mounted\r\n");
return 1;
}
res = lfs_unmount(&lfs);
if (res)
{
PRINTF("\rError unmounting LFS: %i\r\n", res);
}
lfs_mounted = 0;
return 1;
}
LTSH_FUNCTION_EXPORT(unmount,"lfs unmount api");
static unsigned int cd(char argc, char **argv)
{
SHELL_Printf(
"There is no concept of current directory in this example.\r\nPlease always specify the full path.\r\n");
return 1;
}
LTSH_FUNCTION_EXPORT(cd,"lfs cd api");
static unsigned int lls(char argc, char **argv)
{
int res;
char *path;
lfs_dir_t dir;
struct lfs_info info;
int files;
int dirs;
if (!lfs_mounted)
{
SHELL_Printf("LFS not mounted\r\n");
return 1;
}
if (argc > 2)
{
SHELL_Printf("Invalid number of parameters\r\n");
return 1;
}
if (argc < 2)
{
path = "/";
}
else
{
path = argv[1];
}
/* open the directory */
res = lfs_dir_open(&lfs, &dir, path);
if (res)
{
PRINTF("\rError opening directory: %i\r\n", res);
return 1;
}
PRINTF(" Directory of %s\r\n", path);
files = 0;
dirs = 0;
/* iterate until end of directory */
while ((res = lfs_dir_read(&lfs, &dir, &info)) != 0)
{
if (res < 0)
{
/* break the loop in case of an error */
PRINTF("\rError reading directory: %i\r\n", res);
break;
}
if (info.type == LFS_TYPE_REG)
{
SHELL_Printf("%8d %s\r\n", info.size, info.name);
files++;
}
else if (info.type == LFS_TYPE_DIR)
{
SHELL_Printf("% DIR %s\r\n", info.name);
dirs++;
}
else
{
SHELL_Printf("%???\r\n");
}
}
res = lfs_dir_close(&lfs, &dir);
if (res)
{
PRINTF("\rError closing directory: %i\r\n", res);
return 1;
}
PRINTF(" %d File(s), %d Dir(s)\r\n", files, dirs);
return 1;
}
LTSH_FUNCTION_EXPORT(lls,"lfs ls api");
static unsigned int rm(int32_t argc, char **argv)
{
int res;
if (!lfs_mounted)
{
SHELL_Printf("LFS not mounted\r\n");
return 1;
}
res = lfs_remove(&lfs, argv[1]);
if (res)
{
PRINTF("\rError while removing: %i\r\n", res);
}
return 1;
}
LTSH_FUNCTION_EXPORT(rm,"lfs rm api");
static unsigned int lmkdir(char argc, char **argv)
{
int res;
if (!lfs_mounted)
{
SHELL_Printf("LFS not mounted\r\n");
return 1;
}
res = lfs_mkdir(&lfs, argv[1]);
if (res)
{
PRINTF("\rError creating directory: %i\r\n", res);
}
return 1;
}
LTSH_FUNCTION_EXPORT(lmkdir,"lfs mkdir api");
static unsigned int write(char argc, char **argv)
{
int res;
lfs_file_t file;
if (!lfs_mounted)
{
SHELL_Printf("LFS not mounted\r\n");
return 1;
}
res = lfs_file_open(&lfs, &file, argv[1], LFS_O_WRONLY | LFS_O_APPEND | LFS_O_CREAT);
if (res)
{
PRINTF("\rError opening file: %i\r\n", res);
return 1;
}
res = lfs_file_write(&lfs, &file, argv[2], strlen(argv[2]));
if (res > 0)
res = lfs_file_write(&lfs, &file, "\r\n", 2);
if (res < 0)
{
PRINTF("\rError writing file: %i\r\n", res);
}
res = lfs_file_close(&lfs, &file);
if (res)
{
PRINTF("\rError closing file: %i\r\n", res);
}
return 1;
}
LTSH_FUNCTION_EXPORT(write,"lfs write api");
static unsigned int cat(char argc, char **argv)
{
int res;
lfs_file_t file;
uint8_t buf[16+1];
if (!lfs_mounted)
{
SHELL_Printf("LFS not mounted\r\n");
return 1;
}
res = lfs_file_open(&lfs, &file, argv[1], LFS_O_RDONLY);
if (res)
{
PRINTF("\rError opening file: %i\r\n", res);
return 1;
}
do
{
res = lfs_file_read(&lfs, &file, buf, sizeof(buf));
if (res < 0)
{
PRINTF("\rError reading file: %i\r\n", res);
break;
}
if(res > 0)
{
buf[res] = '\0';
PRINTF("%s",(char *)buf);
}
} while (res);
res = lfs_file_close(&lfs, &file);
if (res)
{
PRINTF("\rError closing file: %i\r\n", res);
}
return 1;
}
LTSH_FUNCTION_EXPORT(cat,"lfs cat api");
static unsigned int lfsinit(char argc, char **argv)
{
lfs_get_default_config(&cfg);
return 1;
}
LTSH_FUNCTION_EXPORT(lfsinit,"lfs init api");
static unsigned int df(char argc, char **argv)
{
printf("used block %d\r\n",lfs_fs_size(&lfs));
return 1;
}
LTSH_FUNCTION_EXPORT(df,"lfs init api");
void getcwd(char * buff, int len)
{
if(lfs_mounted)
{
buff[0] = '/';
buff[1] = ' ';
buff[2] = '\0';
}
}
void fs_init(void)
{
int res;
lfs_get_default_config(&cfg);
res = lfs_mount(&lfs, &cfg);
if (res)
{
PRINTF("\rError mounting LFS\r\n");
res = lfs_format(&lfs, &cfg);
if (res)
{
PRINTF("\rError formatting LFS: %d\r\n", res);
}
else
{
res = lfs_mount(&lfs, &cfg);
if(res)
PRINTF("\rError mounting LFS\r\n");
}
}
else
{
lfs_mounted = 1;
}
};
代码对应完后工程下整体的littlefs 相关代码如下：
将测试程序下载到板子中运行，执行测试命令格式化文件系统，mount操作创建文件夹及文件的写入后回读验证都是ok 的，基于DDR的littlefs适配基本已经完成。
代码路径：
[https://gitee.com/andeyqi/stm32-mp135/tree/master/STM32Cube_FW_MP13_V1.0.0/Projects/STM32MP135C-DK/Examples/UART/UART_Receive_Transmit_Console
.png)
andey
发布时间：2024-1-31 11:10
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