if(start_up_called)

return 0;

start_up_called = 1;

yaffs_devconfig(YAFFSFS_MNT_POINT, YAFFSFS_START_BLOCK, YAFFSFS_END_BLOCK);

/* Call the OS initialisation (eg. set up lock semaphore */

yaffsfs_OSInitialisation();

return 0;

}

其中yaffs_devconfig(YAFFSFS_MNT_POINT, YAFFSFS_START_BLOCK, YAFFSFS_END_BLOCK)，的参数是宏，如下：

#define YAFFSFS_MNT_POINT "/nand"

#define YAFFSFS_OFFSET (2*SIZE_1M) /* YAFFS2 file system start offset address */

#define YAFFSFS_SIZE (10*SIZE_1M) /* YAFFS2 file system size */

#define YAFFSFS_START_BLOCK ( YAFFSFS_OFFSET/NF_BLOCK_SIZE )

#define K9F2G08_BLOCK_SIZE 0x20000 /* Nandflash block size: 128K */

#define NF_BLOCK_SIZE K9F2G08_BLOCK_SIZE

#define YAFFSFS_END_BLOCK ( YAFFSFS_START_BLOCK+(YAFFSFS_SIZE/NF_BLOCK_SIZE) )

yaffs_devconfig（）函数的代码如下：

位置：yaffs2/yaffs2/yaffscfg2k.c

int yaffs_devconfig(char *_mp, int start_block, int end_block)

{

struct yaffs_dev *dev = NULL;

char *mp = NULL;

dev = malloc(sizeof(*dev));

mp = strdup(_mp);

if (!dev || !mp)

{

/* Alloc error */

printf("Failed to allocate memory\n");

return -1;

}

/* Seems sane, so configure */

memset(dev, 0, sizeof(*dev));

dev->param.name = mp;

dev->param.is_yaffs2 = 1;

dev->param.total_bytes_per_chunk = NF_PAGE_SIZE;

dev->param.spare_bytes_per_chunk = NF_SPARE_SIZE;

dev->param.chunks_per_block = NF_BLOCK_SIZE / NF_PAGE_SIZE;

dev->param.start_block = start_block;

dev->param.end_block = end_block;

dev->param.n_reserved_blocks = 8;

dev->param.inband_tags = 0;

dev->param.use_nand_ecc = 0;

dev->param.no_tags_ecc = 0;

dev->param.n_caches=0;

dev->param.empty_lost_n_found = 1;

dev->param.skip_checkpt_rd = 0;

dev->param.skip_checkpt_wr = 0;

dev->param.refresh_period = 1000;

dev->param.initialise_flash_fn = ynf_init;

dev->param.erase_fn = ynf_erase_block;

dev->param.write_chunk_tags_fn = ynf_write_chunk_tags;

dev->param.read_chunk_tags_fn = ynf_read_chunk_tags;

dev->param.bad_block_fn = ynf_mark_block_bad;

dev->param.query_block_fn = ynf_query_block;

dev->driver_context = NULL;

yaffs_add_device(dev);

printf("Configures yaffs mount %s: start block %d, end block %d %s\n",

mp, start_block, end_block, dev->param.inband_tags "using inband tags" : "");

return 0;

}

其中主要是有一个重要的数据结构体struct yaffs_dev，如下

代码清单 struct yaffs_dev结构体

struct yaffs_dev {

struct yaffs_param param;

/* Context storage. Holds extra OS specific data for this device */



void *os_context;

void *driver_context;

struct list_head dev_list;



/* Runtime parameters. Set up by YAFFS. */

int data_bytes_per_chunk;

/* Non-wide tnode stuff */

u16 chunk_grp_bits; /* Number of bits that need to be resolved if

* the tnodes are not wide enough.

*/

u16 chunk_grp_size; /* == 2^^chunk_grp_bits */



/* Stuff to support wide tnodes */

u32 tnode_width;

u32 tnode_mask;

u32 tnode_size;



/* Stuff for figuring out file offset to chunk conversions */

u32 chunk_shift; /* Shift value */

u32 chunk_div; /* Divisor after shifting: 1 for 2^n sizes */

u32 chunk_mask; /* Mask to use for power-of-2 case */