分类： LINUX
2009-03-25 16:29:52
Arm-linux东东之5: nand_get_flash_type
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/* Read manufacturer and device IDs */
*maf_id = chip->read_byte(mtd);
dev_id = chip->read_byte(mtd);
/* Try again to make sure, as some systems the bus-hold or other
* interface concerns can cause random data which looks like a
* possibly credible NAND flash to appear. If the two results do
* not match, ignore the device completely.
*/
chip->cmdfunc(mtd, NAND_CMD_READID, 0x00, -1);
/* Read manufacturer and device IDs */
tmp_manf = chip->read_byte(mtd);
tmp_id = chip->read_byte(mtd);
if (tmp_manf != *maf_id || tmp_id != dev_id) {
printk(KERN_INFO "%s: second ID read did not match "
"%02x,%02x against %02x,%02x\n", __func__,
*maf_id, dev_id, tmp_manf, tmp_id);
return ERR_PTR(-ENODEV);
}
命令发完了就可以读了.然后再发一次同样的命令.如果两次获得的ID不同就说明出错了.没用的NAND.
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/* Lookup the flash id */
for (i = 0; nand_flash_ids[i].name != NULL; i++) {
if (dev_id == nand_flash_ids[i].id) {
type = &nand_flash_ids[i];
break;
}
}
if (!type)
return ERR_PTR(-ENODEV);
if (!mtd->name)
mtd->name = type->name;
chip->chipsize = type->chipsize << 20;
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Nand_flash_id就是这些:
struct nand_flash_dev nand_flash_ids[] = {
…………………
{"NAND 64MiB 1,8V 8-bit", 0x36, 512, 64, 0x4000, 0},
{"NAND 64MiB 3,3V 8-bit", 0x76, 512, 64, 0x4000, 0},
{"NAND 64MiB 1,8V 16-bit", 0x46, 512, 64, 0x4000, NAND_BUSWIDTH_16},
{"NAND 64MiB 3,3V 16-bit", 0x56, 512, 64, 0x4000, NAND_BUSWIDTH_16},
{"NAND 128MiB 1,8V 8-bit", 0x78, 512, 128, 0x4000, 0},
{"NAND 128MiB 1,8V 8-bit", 0x39, 512, 128, 0x4000, 0},
{"NAND 128MiB 3,3V 8-bit", 0x79, 512, 128, 0x4000, 0},
{"NAND 128MiB 1,8V 16-bit", 0x72, 512, 128, 0x4000, NAND_BUSWIDTH_16},
{"NAND 128MiB 1,8V 16-bit", 0x49, 512, 128, 0x4000, NAND_BUSWIDTH_16},
{"NAND 128MiB 3,3V 16-bit", 0x74, 512, 128, 0x4000, NAND_BUSWIDTH_16},
{"NAND 128MiB 3,3V 16-bit", 0x59, 512, 128, 0x4000, NAND_BUSWIDTH_16},
/*
* Renesas AND 1 Gigabit. Those chips do not support extended id and
* have a strange page/block layout ! The chosen minimum erasesize is
* 4 * 2 * 2048 = 16384 Byte, as those chips have an array of 4 page
* planes 1 block = 2 pages, but due to plane arrangement the blocks
* 0-3 consists of page 0 + 4,1 + 5, 2 + 6, 3 + 7 Anyway JFFS2 would
* increase the eraseblock size so we chose a combined one which can be
* erased in one go There are more speed improvements for reads and
* writes possible, but not implemented now
*/
{"AND 128MiB 3,3V 8-bit", 0x01, 2048, 128, 0x4000,
NAND_IS_AND | NAND_NO_AUTOINCR |NAND_NO_READRDY | NAND_4PAGE_ARRAY |
BBT_AUTO_REFRESH
},
{NULL,}
};
每一种类NAND在这里都有个表.如果在这里找不到属于你NAND的表就game over了
struct nand_flash_dev {
char *name;
int id;
unsigned long pagesize;
unsigned long chipsize;
unsigned long erasesize;
unsigned long options;
};来看一下上面这个结构体.pagesize 就是一页的大小.一般就是512.注意呀不是528.chipsize就是容量.64M的就是64.erasesize就是咱们前面说的块大小.NAND是以块为erase单位的.
Options 就是一些宏的组合.
{"AND 128MiB 3,3V 8-bit", 0x01, 2048, 128, 0x4000,
NAND_IS_AND | NAND_NO_AUTOINCR |NAND_NO_READRDY | NAND_4PAGE_ARRAY |
BBT_AUTO_REFRESH
},
看到这个比较变态的NAND没有??属于options的宏都用上了.这里不说这个NAND,因为主流不是它.
chip->chipsize = type->chipsize << 20;
这句计算容量.1<<20就是1M.64<<20就是64M.
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f (!type->pagesize) {
int extid;
/* The 3rd id byte holds MLC / multichip data */
chip->cellinfo = chip->read_byte(mtd);
/* The 4th id byte is the important one */
extid = chip->read_byte(mtd);
/* Calc pagesize */
mtd->writesize = 1024 << (extid & 0x3);
extid >>= 2;
/* Calc oobsize */
mtd->oobsize = (8 << (extid & 0x01)) * (mtd->writesize >> 9);
extid >>= 2;
/* Calc blocksize. Blocksize is multiples of 64KiB */
mtd->erasesize = (64 * 1024) << (extid & 0x03);
extid >>= 2;
/* Get buswidth information */
busw = (extid & 0x01) ? NAND_BUSWIDTH_16 : 0;
} else {
/*
* Old devices have chip data hardcoded in the device id table
*/
mtd->erasesize = type->erasesize;
mtd->writesize = type->pagesize;
mtd->oobsize = mtd->writesize / 32;
busw = type->options & NAND_BUSWIDTH_16;
}
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Pagesize我们是有的.所以跳到else来了.
来说下这个:
mtd->oobsize = mtd->writesize / 32;
512/32就是16.就是上面说的C区.
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for (maf_idx = 0; nand_manuf_ids[maf_idx].id != 0x0; maf_idx++) {
if (nand_manuf_ids[maf_idx].id == *maf_id)
break;
}
…struct nand_manufacturers nand_manuf_ids[] = {
{NAND_MFR_TOSHIBA, "Toshiba"},
{NAND_MFR_SAMSUNG, "Samsung"},
{NAND_MFR_FUJITSU, "Fujitsu"},
{NAND_MFR_NATIONAL, "National"},
{NAND_MFR_RENESAS, "Renesas"},
{NAND_MFR_STMICRO, "ST Micro"},
{NAND_MFR_HYNIX, "Hynix"},
{NAND_MFR_MICRON, "Micron"},
{NAND_MFR_AMD, "AMD"},
{0x0, "Unknown"}
};…………..
这个没有问题.就是找厂商吗!!!!
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if (busw != (chip->options & NAND_BUSWIDTH_16)) {
printk(KERN_INFO "NAND device: Manufacturer ID:"
" 0x%02x, Chip ID: 0x%02x (%s %s)\n", *maf_id,
dev_id, nand_manuf_ids[maf_idx].name, mtd->name);
printk(KERN_WARNING "NAND bus width %d instead %d bit\n",
(chip->options & NAND_BUSWIDTH_16) ? 16 : 8,
busw ? 16 : 8);
return ERR_PTR(-EINVAL);
}
/* Calculate the address shift from the page size */
chip->page_shift = ffs(mtd->writesize) - 1;
/* Convert chipsize to number of pages per chip -1. */
chip->pagemask = (chip->chipsize >> chip->page_shift) - 1;
chip->bbt_erase_shift = chip->phys_erase_shift =
ffs(mtd->erasesize) - 1;
chip->chip_shift = ffs(chip->chipsize) - 1;
/* Set the bad block position */
chip->badblockpos = mtd->writesize > 512 ?
NAND_LARGE_BADBLOCK_POS : NAND_SMALL_BADBLOCK_POS;
/* Get chip options, preserve non chip based options */
chip->options &= ~NAND_CHIPOPTIONS_MSK;
chip->options |= type->options & NAND_CHIPOPTIONS_MSK;
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Busw是传进来的参数.如果传进来的参数与表中的不一致就出错.
chip->page_shift = ffs(mtd->writesize) - 1;
后面会看到当给定一个32的地址.add>>chip->page_shift.因为NAND是页寻址的.512的页就是右移9位. Pagemask就是用来限制地址高位.64M的就只用17位有效地址所以高于17就mask了.chip_shift是用于多NAND中的.其他的我们用到的时候再说.好吧!!
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if (*maf_id != NAND_MFR_SAMSUNG && !type->pagesize)
chip->options &= ~NAND_SAMSUNG_LP_OPTIONS;
/* Check for AND chips with 4 page planes */
if (chip->options & NAND_4PAGE_ARRAY)
chip->erase_cmd = multi_erase_cmd;
else
chip->erase_cmd = single_erase_cmd;
/* Do not replace user supplied command function ! */
if (mtd->writesize > 512 && chip->cmdfunc == nand_command)
chip->cmdfunc = nand_command_lp;
printk(KERN_INFO "NAND device: Manufacturer ID:"
" 0x%02x, Chip ID: 0x%02x (%s %s)\n", *maf_id, dev_id,
nand_manuf_ids[maf_idx].name, type->name);
return type;
}
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我们的erase_cmd是等于single_erase_cmd的;
好nand_get_flash_type就这样完了.
回到nand_scan_ident中来.
……………….
if (IS_ERR(type)) {
printk(KERN_WARNING "No NAND device found!!!\n");
chip->select_chip(mtd, -1);
return PTR_ERR(type);
}
/* Check for a chip array */
for (i = 1; i < maxchips; i++) {
chip->select_chip(mtd, i);
/* Send the command for reading device ID */
chip->cmdfunc(mtd, NAND_CMD_READID, 0x00, -1);
/* Read manufacturer and device IDs */
if (nand_maf_id != chip->read_byte(mtd) ||
type->id != chip->read_byte(mtd))
break;
}
if (i > 1)
printk(KERN_INFO "%d NAND chips detected\n", i);
/* Store the number of chips and calc total size for mtd */
chip->numchips = i;
mtd->size = i * chip->chipsize;
return 0;
}
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这里呀maxchips是为1的.那个for不会执行的.不过多于一块的NAND也容易搞懂.
又回到了s3c24xx_nand_probe中了.
………………………………..
if (nmtd->scan_res == 0) {
s3c2410_nand_update_chip(info, nmtd);
nand_scan_tail(&nmtd->mtd);
s3c2410_nand_add_partition(info, nmtd, sets);
}
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只余三个函数了.不过千万不要小看这三个函数.个个都他妈的难.
