/*
* drivers/mtd/nand_bbt.c
*
* Overview:
* Bad block table support for the NAND driver
*
* Copyright © 2004 Thomas Gleixner (tglx@linutronix.de)
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* Description:
*
* When nand_scan_bbt is called, then it tries to find the bad block table
* depending on the options in the BBT descriptor(s). If no flash based BBT
* (NAND_BBT_USE_FLASH) is specified then the device is scanned for factory
* marked good / bad blocks. This information is used to create a memory BBT.
* Once a new bad block is discovered then the "factory" information is updated
* on the device.
* If a flash based BBT is specified then the function first tries to find the
* BBT on flash. If a BBT is found then the contents are read and the memory
* based BBT is created. If a mirrored BBT is selected then the mirror is
* searched too and the versions are compared. If the mirror has a greater
* version number, then the mirror BBT is used to build the memory based BBT.
* If the tables are not versioned, then we "or" the bad block information.
* If one of the BBTs is out of date or does not exist it is (re)created.
* If no BBT exists at all then the device is scanned for factory marked
* good / bad blocks and the bad block tables are created.
*
* For manufacturer created BBTs like the one found on M-SYS DOC devices
* the BBT is searched and read but never created
*
* The auto generated bad block table is located in the last good blocks
* of the device. The table is mirrored, so it can be updated eventually.
* The table is marked in the OOB area with an ident pattern and a version
* number which indicates which of both tables is more up to date. If the NAND
* controller needs the complete OOB area for the ECC information then the
* option NAND_BBT_NO_OOB should be used (along with NAND_BBT_USE_FLASH, of
* course): it moves the ident pattern and the version byte into the data area
* and the OOB area will remain untouched.
*
* The table uses 2 bits per block
* 11b: block is good
* 00b: block is factory marked bad
* 01b, 10b: block is marked bad due to wear
*
* The memory bad block table uses the following scheme:
* 00b: block is good
* 01b: block is marked bad due to wear
* 10b: block is reserved (to protect the bbt area)
* 11b: block is factory marked bad
*
* Multichip devices like DOC store the bad block info per floor.
*
* Following assumptions are made:
* - bbts start at a page boundary, if autolocated on a block boundary
* - the space necessary for a bbt in FLASH does not exceed a block boundary
*
*/
#include <linux/slab.h>
#include <linux/types.h>
#include <linux/mtd/mtd.h>
#include <linux/mtd/bbm.h>
#include <linux/mtd/nand.h>
#include <linux/mtd/nand_ecc.h>
#include <linux/bitops.h>
#include <linux/delay.h>
#include <linux/vmalloc.h>
#include <linux/export.h>
#include <linux/string.h>
#define BBT_BLOCK_GOOD 0x00
#define BBT_BLOCK_WORN 0x01
#define BBT_BLOCK_RESERVED 0x02
#define BBT_BLOCK_FACTORY_BAD 0x03
#define BBT_ENTRY_MASK 0x03
#define BBT_ENTRY_SHIFT 2
static int nand_update_bbt(struct mtd_info *mtd, loff_t offs);
static inline uint8_t bbt_get_entry(struct nand_chip *chip, int block)
{
uint8_t entry = chip->bbt[block >> BBT_ENTRY_SHIFT];
entry >>= (block & BBT_ENTRY_MASK) * 2;
return entry & BBT_ENTRY_MASK;
}
static inline void bbt_mark_entry(struct nand_chip *chip, int block,
uint8_t mark)
{
uint8_t msk = (mark & BBT_ENTRY_MASK) << ((block & BBT_ENTRY_MASK) * 2);
chip->bbt[block >> BBT_ENTRY_SHIFT] |= msk;
}
static int check_pattern_no_oob(uint8_t *buf, struct nand_bbt_descr *td)
{
if (memcmp(buf, td->pattern, td->len))
return -1;
return 0;
}
/**
* check_pattern - [GENERIC] check if a pattern is in the buffer
* @buf: the buffer to search
* @len: the length of buffer to search
* @paglen: the pagelength
* @td: search pattern descriptor
*
* Check for a pattern at the given place. Used to search bad block tables and
* good / bad block identifiers.
*/
static int check_pattern(uint8_t *buf, int len, int paglen, struct nand_bbt_descr *td)
{
if (td->options & NAND_BBT_NO_OOB)
return check_pattern_no_oob(buf, td);
/* Compare the pattern */
if (memcmp(buf + paglen + td->offs, td->pattern, td->len))
return -1;
return 0;
}
/**
* check_short_pattern - [GENERIC] check if a pattern is in the buffer
* @buf: the buffer to search
* @td: search pattern descriptor
*
* Check for a pattern at the given place. Used to search bad block tables and
* good / bad block identifiers. Same as check_pattern, but no optional empty
* check.
*/
static int check_short_pattern(uint8_t *buf, struct nand_bbt_descr *td)
{
/* Compare the pattern */
if (memcmp(buf + td->offs, td->pattern, td->len))
return -1;
return 0;
}
/**
* add_marker_len - compute the length of the marker in data area
* @td: BBT descriptor used for computation
*
* The length will be 0 if the marker is located in OOB area.
*/
static u32 add_marker_len(struct nand_bbt_descr *td)
{
u32 len;
if (!(td->options & NAND_BBT_NO_OOB))
return 0;
len = td->len;
if (td->options & NAND_BBT_VERSION)
len++;
return len;
}
/**
* read_bbt - [GENERIC] Read the bad block table starting from page
* @mtd: MTD device structure
* @buf: temporary buffer
* @page: the starting page
* @num: the number of bbt descriptors to read
* @td: the bbt describtion table
* @offs: block number offset in the table
*
* Read the bad block table starting from page.
*/
static int read_bbt(struct mtd_info *mtd, uint8_t *buf, int page, int num,
struct nand_bbt_descr *td, int offs)
{
int res, ret = 0, i, j, act = 0;
struct nand_chip *this = mtd->priv;
size_t retlen, len, totlen;
loff_t from;
int bits = td->options & NAND_BBT_NRBITS_MSK;
uint8_t msk = (uint8_t)((1 << bits) - 1);
u32 marker_len;
int reserved_block_code = td->reserved_block_code;
totlen = (num * bits) >> 3;
marker_len = add_marker_len(td);
from = ((loff_t)page) << this->page_shift;
while (totlen) {
len = min(totlen, (size_t)(1 << this->bbt_erase_shift));
if (marker_len) {
/*
* In case the BBT marker is not in the OOB area it
* will be just in the first page.
*/
len -= marker_len;
from += marker_len;
marker_len = 0;
}
res = mtd_read(mtd, from, len, &retlen, buf);
if (res < 0) {
if (mtd_is_eccerr(res)) {
pr_info("nand_bbt: ECC error in BBT at 0x%012llx\n",
from & ~mtd->writesize);
return res;
} else if (mtd_is_bitflip(res)) {
pr_info("nand_bbt: corrected error in BBT at 0x%012llx\n",
from & ~mtd->writesize);
ret = res;
} else {
pr_info("nand_bbt: error reading BBT\n");
return res;
}
}
/* Analyse data */
for (i = 0; i < len; i++) {
uint8_t dat = buf[i];
for (j = 0; j < 8; j += bits, act++) {
uint8_t tmp = (dat >> j) & msk;
if (tmp == msk)
continue;
if (reserved_block_code && (tmp == reserved_block_code)) {
pr_info("nand_read_bbt: reserved block at 0x%012llx\n",
(loff_t)(offs + act) <<
this->bbt_erase_shift);
bbt_mark_entry(this, offs + act,
BBT_BLOCK_RESERVED);
mtd->ecc_stats.bbtblocks++;
continue;
}
/*
* Leave it for now, if it's matured we can
* move this message to pr_debug.
*/
pr_info("nand_read_bbt: bad block at 0x%012llx\n",
(loff_t)(offs + act) <<
this->bbt_erase_shift);
/* Factory marked bad or worn out? */
if (tmp == 0)
bbt_mark_entry(this, offs + act,
BBT_BLOCK_FACTORY_BAD);
else
bbt_mark_entry(this, offs + act,
BBT_BLOCK_WORN);
mtd->ecc_stats.badblocks++;
}
}
totlen -= len;
from += len;
}
return ret;
}
/**
* read_abs_bbt - [GENERIC] Read the bad block table starting at a given page
* @mtd: MTD device structure
* @buf: temporary buffer
*
