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![Thomas Gleixner](/assets/img/avatar_default.png)
Hopefully the last iteration on this! The handling of out of band data on NAND was accompanied by tons of fruitless discussions and halfarsed patches to make it work for a particular problem. Sufficiently annoyed by I all those "I know it better" mails and the resonable amount of discarded "it solves my problem" patches, I finally decided to go for the big rework. After removing the _ecc variants of mtd read/write functions the solution to satisfy the various requirements was to refactor the read/write _oob functions in mtd. The major change is that read/write_oob now takes a pointer to an operation descriptor structure "struct mtd_oob_ops".instead of having a function with at least seven arguments. read/write_oob which should probably renamed to a more descriptive name, can do the following tasks: - read/write out of band data - read/write data content and out of band data - read/write raw data content and out of band data (ecc disabled) struct mtd_oob_ops has a mode field, which determines the oob handling mode. Aside of the MTD_OOB_RAW mode, which is intended to be especially for diagnostic purposes and some internal functions e.g. bad block table creation, the other two modes are for mtd clients: MTD_OOB_PLACE puts/gets the given oob data exactly to/from the place which is described by the ooboffs and ooblen fields of the mtd_oob_ops strcuture. It's up to the caller to make sure that the byte positions are not used by the ECC placement algorithms. MTD_OOB_AUTO puts/gets the given oob data automaticaly to/from the places in the out of band area which are described by the oobfree tuples in the ecclayout data structre which is associated to the devicee. The decision whether data plus oob or oob only handling is done depends on the setting of the datbuf member of the data structure. When datbuf == NULL then the internal read/write_oob functions are selected, otherwise the read/write data routines are invoked. Tested on a few platforms with all variants. Please be aware of possible regressions for your particular device / application scenario Disclaimer: Any whining will be ignored from those who just contributed "hot air blurb" and never sat down to tackle the underlying problem of the mess in the NAND driver grown over time and the big chunk of work to fix up the existing users. The problem was not the holiness of the existing MTD interfaces. The problems was the lack of time to go for the big overhaul. It's easy to add more mess to the existing one, but it takes alot of effort to go for a real solution. Improvements and bugfixes are welcome! Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
249 lines
6.7 KiB
C
249 lines
6.7 KiB
C
/*
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* linux/drivers/mtd/onenand/onenand_bbt.c
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*
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* Bad Block Table support for the OneNAND driver
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*
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* Copyright(c) 2005 Samsung Electronics
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* Kyungmin Park <kyungmin.park@samsung.com>
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*
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* Derived from nand_bbt.c
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*
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* TODO:
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* Split BBT core and chip specific BBT.
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*/
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#include <linux/slab.h>
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#include <linux/mtd/mtd.h>
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#include <linux/mtd/onenand.h>
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#include <linux/mtd/compatmac.h>
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extern int onenand_do_read_oob(struct mtd_info *mtd, loff_t from, size_t len,
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size_t *retlen, u_char *buf);
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/**
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* check_short_pattern - [GENERIC] check if a pattern is in the buffer
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* @param buf the buffer to search
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* @param len the length of buffer to search
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* @param paglen the pagelength
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* @param td search pattern descriptor
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*
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* Check for a pattern at the given place. Used to search bad block
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* tables and good / bad block identifiers. Same as check_pattern, but
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* no optional empty check and the pattern is expected to start
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* at offset 0.
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*
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*/
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static int check_short_pattern(uint8_t *buf, int len, int paglen, struct nand_bbt_descr *td)
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{
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int i;
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uint8_t *p = buf;
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/* Compare the pattern */
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for (i = 0; i < td->len; i++) {
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if (p[i] != td->pattern[i])
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return -1;
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}
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return 0;
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}
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/**
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* create_bbt - [GENERIC] Create a bad block table by scanning the device
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* @param mtd MTD device structure
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* @param buf temporary buffer
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* @param bd descriptor for the good/bad block search pattern
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* @param chip create the table for a specific chip, -1 read all chips.
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* Applies only if NAND_BBT_PERCHIP option is set
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*
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* Create a bad block table by scanning the device
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* for the given good/bad block identify pattern
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*/
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static int create_bbt(struct mtd_info *mtd, uint8_t *buf, struct nand_bbt_descr *bd, int chip)
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{
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struct onenand_chip *this = mtd->priv;
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struct bbm_info *bbm = this->bbm;
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int i, j, numblocks, len, scanlen;
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int startblock;
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loff_t from;
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size_t readlen, ooblen;
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printk(KERN_INFO "Scanning device for bad blocks\n");
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len = 1;
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/* We need only read few bytes from the OOB area */
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scanlen = ooblen = 0;
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readlen = bd->len;
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/* chip == -1 case only */
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/* Note that numblocks is 2 * (real numblocks) here;
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* see i += 2 below as it makses shifting and masking less painful
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*/
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numblocks = mtd->size >> (bbm->bbt_erase_shift - 1);
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startblock = 0;
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from = 0;
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for (i = startblock; i < numblocks; ) {
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int ret;
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for (j = 0; j < len; j++) {
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size_t retlen;
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/* No need to read pages fully,
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* just read required OOB bytes */
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ret = onenand_do_read_oob(mtd, from + j * mtd->writesize + bd->offs,
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readlen, &retlen, &buf[0]);
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if (ret)
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return ret;
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if (check_short_pattern(&buf[j * scanlen], scanlen, mtd->writesize, bd)) {
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bbm->bbt[i >> 3] |= 0x03 << (i & 0x6);
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printk(KERN_WARNING "Bad eraseblock %d at 0x%08x\n",
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i >> 1, (unsigned int) from);
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break;
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}
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}
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i += 2;
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from += (1 << bbm->bbt_erase_shift);
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}
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return 0;
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}
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/**
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* onenand_memory_bbt - [GENERIC] create a memory based bad block table
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* @param mtd MTD device structure
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* @param bd descriptor for the good/bad block search pattern
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*
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* The function creates a memory based bbt by scanning the device
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* for manufacturer / software marked good / bad blocks
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*/
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static inline int onenand_memory_bbt (struct mtd_info *mtd, struct nand_bbt_descr *bd)
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{
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struct onenand_chip *this = mtd->priv;
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bd->options &= ~NAND_BBT_SCANEMPTY;
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return create_bbt(mtd, this->page_buf, bd, -1);
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}
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/**
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* onenand_isbad_bbt - [OneNAND Interface] Check if a block is bad
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* @param mtd MTD device structure
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* @param offs offset in the device
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* @param allowbbt allow access to bad block table region
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*/
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static int onenand_isbad_bbt(struct mtd_info *mtd, loff_t offs, int allowbbt)
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{
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struct onenand_chip *this = mtd->priv;
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struct bbm_info *bbm = this->bbm;
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int block;
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uint8_t res;
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/* Get block number * 2 */
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block = (int) (offs >> (bbm->bbt_erase_shift - 1));
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res = (bbm->bbt[block >> 3] >> (block & 0x06)) & 0x03;
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DEBUG(MTD_DEBUG_LEVEL2, "onenand_isbad_bbt: bbt info for offs 0x%08x: (block %d) 0x%02x\n",
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(unsigned int) offs, block >> 1, res);
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switch ((int) res) {
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case 0x00: return 0;
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case 0x01: return 1;
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case 0x02: return allowbbt ? 0 : 1;
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}
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return 1;
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}
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/**
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* onenand_scan_bbt - [OneNAND Interface] scan, find, read and maybe create bad block table(s)
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* @param mtd MTD device structure
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* @param bd descriptor for the good/bad block search pattern
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*
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* The function checks, if a bad block table(s) is/are already
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* available. If not it scans the device for manufacturer
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* marked good / bad blocks and writes the bad block table(s) to
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* the selected place.
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*
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* The bad block table memory is allocated here. It must be freed
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* by calling the onenand_free_bbt function.
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*
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*/
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int onenand_scan_bbt(struct mtd_info *mtd, struct nand_bbt_descr *bd)
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{
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struct onenand_chip *this = mtd->priv;
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struct bbm_info *bbm = this->bbm;
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int len, ret = 0;
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len = mtd->size >> (this->erase_shift + 2);
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/* Allocate memory (2bit per block) */
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bbm->bbt = kmalloc(len, GFP_KERNEL);
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if (!bbm->bbt) {
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printk(KERN_ERR "onenand_scan_bbt: Out of memory\n");
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return -ENOMEM;
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}
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/* Clear the memory bad block table */
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memset(bbm->bbt, 0x00, len);
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/* Set the bad block position */
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bbm->badblockpos = ONENAND_BADBLOCK_POS;
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/* Set erase shift */
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bbm->bbt_erase_shift = this->erase_shift;
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if (!bbm->isbad_bbt)
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bbm->isbad_bbt = onenand_isbad_bbt;
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/* Scan the device to build a memory based bad block table */
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if ((ret = onenand_memory_bbt(mtd, bd))) {
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printk(KERN_ERR "onenand_scan_bbt: Can't scan flash and build the RAM-based BBT\n");
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kfree(bbm->bbt);
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bbm->bbt = NULL;
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}
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return ret;
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}
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/*
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* Define some generic bad / good block scan pattern which are used
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* while scanning a device for factory marked good / bad blocks.
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*/
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static uint8_t scan_ff_pattern[] = { 0xff, 0xff };
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static struct nand_bbt_descr largepage_memorybased = {
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.options = 0,
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.offs = 0,
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.len = 2,
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.pattern = scan_ff_pattern,
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};
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/**
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* onenand_default_bbt - [OneNAND Interface] Select a default bad block table for the device
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* @param mtd MTD device structure
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*
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* This function selects the default bad block table
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* support for the device and calls the onenand_scan_bbt function
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*/
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int onenand_default_bbt(struct mtd_info *mtd)
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{
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struct onenand_chip *this = mtd->priv;
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struct bbm_info *bbm;
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this->bbm = kmalloc(sizeof(struct bbm_info), GFP_KERNEL);
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if (!this->bbm)
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return -ENOMEM;
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bbm = this->bbm;
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memset(bbm, 0, sizeof(struct bbm_info));
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/* 1KB page has same configuration as 2KB page */
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if (!bbm->badblock_pattern)
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bbm->badblock_pattern = &largepage_memorybased;
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return onenand_scan_bbt(mtd, bbm->badblock_pattern);
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}
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EXPORT_SYMBOL(onenand_scan_bbt);
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EXPORT_SYMBOL(onenand_default_bbt);
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