/*
* linux/drivers/mtd/onenand/onenand_bbt.c
*
* Bad Block Table support for the OneNAND driver
*
* Copyright(c) 2005 Samsung Electronics
* Kyungmin Park <kyungmin.park@samsung.com>
*
* Derived from nand_bbt.c
*
* TODO:
* Split BBT core and chip specific BBT.
*/
#include <linux/slab.h>
#include <linux/mtd/mtd.h>
#include <linux/mtd/onenand.h>
#include <linux/mtd/compatmac.h>
/**
* check_short_pattern - [GENERIC] check if a pattern is in the buffer
* @param buf the buffer to search
* @param len the length of buffer to search
* @param paglen the pagelength
* @param 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 and the pattern is expected to start
* at offset 0.
*
*/
static int check_short_pattern(uint8_t *buf, int len, int paglen, struct nand_bbt_descr *td)
{
int i;
uint8_t *p = buf;
/* Compare the pattern */
for (i = 0; i < td->len; i++) {
if (p[i] != td->pattern[i])
return -1;
}
return 0;
}
/**
* create_bbt - [GENERIC] Create a bad block table by scanning the device
* @param mtd MTD device structure
* @param buf temporary buffer
* @param bd descriptor for the good/bad block search pattern
* @param chip create the table for a specific chip, -1 read all chips.
* Applies only if NAND_BBT_PERCHIP option is set
*
* Create a bad block table by scanning the device
* for the given good/bad block identify pattern
*/
static int create_bbt(struct mtd_info *mtd, uint8_t *buf, struct nand_bbt_descr *bd, int chip)
{
struct onenand_chip *this = mtd->priv;
struct bbm_info *bbm = this->bbm;
int i, j, numblocks, len, scanlen;
int startblock;
loff_t from;
size_t readlen, ooblen;
printk(KERN_INFO "Scanning device for bad blocks\n");
len = 1;
/* We need only read few bytes from the OOB area */
scanlen = ooblen = 0;
readlen = bd->len;
/* chip == -1 case only */
/* Note that numblocks is 2 * (real numblocks) here;
* see i += 2 below as it makses shifting and masking less painful
*/
numblocks = mtd->size >> (bbm->bbt_erase_shift - 1);
startblock = 0;
from = 0;
for (i = startblock; i < numblocks; ) {
int ret;
for (j = 0; j < len; j++) {
size_t retlen;
/* No need to read pages fully,
* just read required OOB bytes */
ret = mtd->read_oob(mtd, from + j * mtd->oobblock + bd->offs,
readlen, &retlen, &buf[0]);
if (ret)
return ret;
if (check_short_pattern(&buf[j * scanlen], scanlen, mtd->oobblock, bd)) {
bbm->bbt[i >> 3] |= 0x03 << (i & 0x6);
printk(KERN_WARNING "Bad eraseblock %d at 0x%08x\n",
i >> 1, (unsigned int) from);
break;
}
}
i += 2;
from += (1 << bbm->bbt_erase_shift);
}
return 0;
}
/**
* onenand_memory_bbt - [GENERIC] create a memory based bad block table
* @param mtd MTD device structure
* @param bd descriptor for the good/bad block search pattern
*
* The function creates a memory based bbt by scanning the device
* for manufacturer / software marked good / bad blocks
*/
static inline int onenand_memory_bbt (struct mtd_info *mtd, struct nand_bbt_descr *bd)
{
struct onenand_chip *this = mtd->priv;
bd->options &= ~NAND_BBT_SCANEMPTY;
return create_bbt(mtd, this->page_buf, bd, -1);
}
/**
* onenand_isbad_bbt - [OneNAND Interface] Check if a block is bad
* @param mtd MTD device structure
* @param offs offset in the device
* @param allowbbt allow access to bad block table region
*/
static int onenand_isbad_bbt(struct mtd_info *mtd, loff_t offs, int allowbbt)
{
struct onenand_chip *this = mtd->priv;
struct bbm_info *bbm = this->bbm;
int block;
uint8_t res;
/* Get block number * 2 */
block = (int) (offs >> (bbm->bbt_erase_shift - 1));
res = (bbm->bbt[block >> 3] >> (block & 0x06)) & 0x03;
DEBUG(MTD_DEBUG_LEVEL2, "onenand_isbad_bbt: bbt info for offs 0x%08x: (block %d) 0x%02x\n",
(unsigned int) offs, block >> 1, res);
switch ((int) res) {
case 0x00: return 0;
case 0x01: return 1;
case 0x02: return allowbbt ? 0 : 1;
}
return 1;
}
/**
* onenand_scan_bbt - [OneNAND Interface] scan, find, read and maybe create bad block table(s)
* @param mtd MTD device structure
* @param bd descriptor for the good/bad block search pattern
*
* The function checks, if a bad block table(s) is/are already
* available. If not it scans the device for manufacturer
* marked good / bad blocks and writes the bad block table(s) to
* the selected place.
*
* The bad block table memory is allocated here. It must be freed
* by calling the onenand_free_bbt function.
*
*/
int onenand_scan_bbt(struct mtd_info *mtd, struct nand_bbt_descr *bd)
{
struct onenand_chip *this = mtd->priv;
struct bbm_info *bbm = this->bbm;
int len, ret = 0;
len = mtd->size >> (this->erase_shift + 2);
/* Allocate memory (2bit per block) */
bbm->bbt = kmalloc(len, GFP_KERNEL);
if (!bbm->bbt) {
printk(KERN_ERR "onenand_scan_bbt: Out of memory\n");
return -ENOMEM;
}
/* Clear the memory bad block table */
memset(bbm->bbt, 0x00, len);
/* Set the bad block position */
bbm->badblockpos = ONENAND_BADBLOCK_POS;
/* Set erase shift */
bbm->bbt_erase_shift = this->erase_shift;
if (!bbm->isbad_bbt)
bbm->isbad_bbt = onenand_isbad_bbt;
/* Scan the device to build a memory based bad block table */
if ((ret = onenand_memory_bbt(mtd, bd))) {
printk(KERN_ERR "onenand_scan_bbt: Can't scan flash and build the RAM-based BBT\n");
kfree(bbm->bbt);
bbm->bbt = NULL;
}
return ret;
}
/*
* Define some generic bad / good block scan pattern which are used
* while scanning a device for factory marked good / bad blocks.
*/
static uint8_t scan_ff_pattern[] = { 0xff, 0xff };
static struct nand_bbt_descr largepage_memorybased = {
.options = 0,
.offs = 0,
.len = 2,
.pattern = scan_ff_pattern,
};
/**
* onenand_default_bbt - [OneNAND Interface] Select a default bad block table for the device
* @param mtd MTD device structure
*
* This function selects the default bad block table
* support for the device and calls the onenand_scan_bbt function
*/
int onenand_default_bbt(struct mtd_info *mtd)
{
struct onenand_chip *this = mtd->priv;
struct bbm_info *bbm;
this->bbm = kmalloc(sizeof(struct bbm_info), GFP_KERNEL);
if (!this->bbm)
return -ENOMEM;
bbm = this->bbm;
memset(bbm, 0, sizeof(struct bbm_info));
/* 1KB page has same configuration as 2KB page */
if (!bbm->badblock_pattern)
bbm->badblock_pattern = &largepage_memorybased;
return onenand_scan_bbt(mtd, bbm->badblock_pattern);
}
EXPORT_SYMBOL(onenand_scan_bbt);
EXPORT_SYMBOL(onenand_default_bbt);
