uboot烧写yaffs2过程中，如何写入oob数据的

int nand_write_opts(nand_info_t *meminfo, 
 const nand_write_options_t *opts) 
{ 
... 
memcpy(data_buf, buffer, readlen); 
buffer += readlen; 
 
if (opts->writeoob) { 
/* read OOB data from input memory block, exit on failure */ 
memcpy(oob_buf, buffer, meminfo->oobsize); 
         
buffer += meminfo->oobsize; 
 
/* write OOB data first, as ecc will be placed in there*/ 
result = meminfo->write_oob(meminfo, 
  mtdoffset, 
  meminfo->oobsize, 
  &written, 
  (unsigned char *) 
  &oob_buf); 
... 
} 
 
result = meminfo->write(meminfo, 
  mtdoffset, 
  meminfo->oobblock, 
  &written, 
  (unsigned char *) &data_buf);

static int nand_write (struct mtd_info *mtd, loff_t to, 
 size_t len, size_t * retlen, const u_char * buf) 
{ 
return (nand_write_ecc (mtd, to, len, retlen, buf, NULL, NULL)); 
} 
 
static int nand_write_ecc (struct mtd_info *mtd, loff_t to, size_t len, 
 size_t * retlen, const u_char * buf, 
 u_char * eccbuf, struct nand_oobinfo *oobsel) 
{ 
... 
 oobbuf = nand_prepare_oobbuf (mtd, eccbuf, oobsel, autoplace, numpages); 
 while (written < len) { 
  this->data_poi = (u_char*) &buf[written]; 
 
  ret = nand_write_page (mtd, this, page, &oobbuf[oob], 
    oobsel, (--numpages > 0)); 
... 
} 
... 
}

if (opts->writeyaffs) 
{ 
/* read page data from input memory buffer */ 
memcpy(data_buf, buffer, readlen); 
buffer += readlen; 
/* read OOB data from input memory block, exit on failure */ 
memcpy(oob_buf, buffer, meminfo->oobsize); 
buffer += meminfo->oobsize; 
 
result = meminfo->write_ecc(meminfo, 
  mtdoffset, 
  meminfo->oobblock, 
  &written, 
  (unsigned char *) &data_buf, 
  (unsigned char *)&oob_buf, 
  NULL); 
 
if (result != 0) { 
  printf("writing NAND page at offset 0x%lx failed\n", 
   mtdoffset); 
  goto restoreoob; 
} 
imglen -= meminfo->oobsize; 
imglen -= readlen; 
} else {...}