From 837a6ba4f3b6d23026674e6af6b6849a4634fff9 Mon Sep 17 00:00:00 2001 From: "Gupta, Pekon" Date: Fri, 15 Mar 2013 17:55:53 +0530 Subject: mtd: nand: subpage write support for hardware based ECC schemes This patch adds support for subpage (partial-page) writes when using hardware based ECC schemes. Advantages: (1) reduces storage overhead when using file-systems like UBIFS, which store LEB header at page-size granularity. (2) allows independent subpage writes, thereby increasing NAND storage efficiency for non-page aligned data. + updated cafe_nand and lpc32xx_mlc NAND drivers for change in chip->write_page interface. Signed-off-by: Gupta, Pekon Signed-off-by: Artem Bityutskiy Signed-off-by: David Woodhouse --- drivers/mtd/nand/cafe_nand.c | 4 +- drivers/mtd/nand/lpc32xx_mlc.c | 4 +- drivers/mtd/nand/nand_base.c | 99 ++++++++++++++++++++++++++++++++++++------ 3 files changed, 90 insertions(+), 17 deletions(-) (limited to 'drivers/mtd') diff --git a/drivers/mtd/nand/cafe_nand.c b/drivers/mtd/nand/cafe_nand.c index a01ccb970102..c34985a55101 100644 --- a/drivers/mtd/nand/cafe_nand.c +++ b/drivers/mtd/nand/cafe_nand.c @@ -530,8 +530,8 @@ static int cafe_nand_write_page_lowlevel(struct mtd_info *mtd, } static int cafe_nand_write_page(struct mtd_info *mtd, struct nand_chip *chip, - const uint8_t *buf, int oob_required, int page, - int cached, int raw) + uint32_t offset, int data_len, const uint8_t *buf, + int oob_required, int page, int cached, int raw) { int status; diff --git a/drivers/mtd/nand/lpc32xx_mlc.c b/drivers/mtd/nand/lpc32xx_mlc.c index 0ca22ae9135c..a94facb46e5c 100644 --- a/drivers/mtd/nand/lpc32xx_mlc.c +++ b/drivers/mtd/nand/lpc32xx_mlc.c @@ -540,8 +540,8 @@ static int lpc32xx_write_page_lowlevel(struct mtd_info *mtd, } static int lpc32xx_write_page(struct mtd_info *mtd, struct nand_chip *chip, - const uint8_t *buf, int oob_required, int page, - int cached, int raw) + uint32_t offset, int data_len, const uint8_t *buf, + int oob_required, int page, int cached, int raw) { int res; diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c index ae9790b659b1..dfcd0a565c5b 100644 --- a/drivers/mtd/nand/nand_base.c +++ b/drivers/mtd/nand/nand_base.c @@ -1110,7 +1110,7 @@ static int nand_read_page_swecc(struct mtd_info *mtd, struct nand_chip *chip, } /** - * nand_read_subpage - [REPLACEABLE] software ECC based sub-page read function + * nand_read_subpage - [REPLACEABLE] ECC based sub-page read function * @mtd: mtd info structure * @chip: nand chip info structure * @data_offs: offset of requested data within the page @@ -1978,6 +1978,67 @@ static int nand_write_page_hwecc(struct mtd_info *mtd, struct nand_chip *chip, return 0; } + +/** + * nand_write_subpage_hwecc - [REPLACABLE] hardware ECC based subpage write + * @mtd: mtd info structure + * @chip: nand chip info structure + * @column: column address of subpage within the page + * @data_len: data length + * @oob_required: must write chip->oob_poi to OOB + */ +static int nand_write_subpage_hwecc(struct mtd_info *mtd, + struct nand_chip *chip, uint32_t offset, + uint32_t data_len, const uint8_t *data_buf, + int oob_required) +{ + uint8_t *oob_buf = chip->oob_poi; + uint8_t *ecc_calc = chip->buffers->ecccalc; + int ecc_size = chip->ecc.size; + int ecc_bytes = chip->ecc.bytes; + int ecc_steps = chip->ecc.steps; + uint32_t *eccpos = chip->ecc.layout->eccpos; + uint32_t start_step = offset / ecc_size; + uint32_t end_step = (offset + data_len - 1) / ecc_size; + int oob_bytes = mtd->oobsize / ecc_steps; + int step, i; + + for (step = 0; step < ecc_steps; step++) { + /* configure controller for WRITE access */ + chip->ecc.hwctl(mtd, NAND_ECC_WRITE); + + /* write data (untouched subpages already masked by 0xFF) */ + chip->write_buf(mtd, data_buf, ecc_size); + + /* mask ECC of un-touched subpages by padding 0xFF */ + if ((step < start_step) || (step > end_step)) + memset(ecc_calc, 0xff, ecc_bytes); + else + chip->ecc.calculate(mtd, data_buf, ecc_calc); + + /* mask OOB of un-touched subpages by padding 0xFF */ + /* if oob_required, preserve OOB metadata of written subpage */ + if (!oob_required || (step < start_step) || (step > end_step)) + memset(oob_buf, 0xff, oob_bytes); + + data_buf += ecc_size; + ecc_calc += ecc_bytes; + oob_buf += oob_bytes; + } + + /* copy calculated ECC for whole page to chip->buffer->oob */ + /* this include masked-value(0xFF) for unwritten subpages */ + ecc_calc = chip->buffers->ecccalc; + for (i = 0; i < chip->ecc.total; i++) + chip->oob_poi[eccpos[i]] = ecc_calc[i]; + + /* write OOB buffer to NAND device */ + chip->write_buf(mtd, chip->oob_poi, mtd->oobsize); + + return 0; +} + + /** * nand_write_page_syndrome - [REPLACEABLE] hardware ECC syndrome based page write * @mtd: mtd info structure @@ -2030,6 +2091,8 @@ static int nand_write_page_syndrome(struct mtd_info *mtd, * nand_write_page - [REPLACEABLE] write one page * @mtd: MTD device structure * @chip: NAND chip descriptor + * @offset: address offset within the page + * @data_len: length of actual data to be written * @buf: the data to write * @oob_required: must write chip->oob_poi to OOB * @page: page number to write @@ -2037,15 +2100,25 @@ static int nand_write_page_syndrome(struct mtd_info *mtd, * @raw: use _raw version of write_page */ static int nand_write_page(struct mtd_info *mtd, struct nand_chip *chip, - const uint8_t *buf, int oob_required, int page, - int cached, int raw) + uint32_t offset, int data_len, const uint8_t *buf, + int oob_required, int page, int cached, int raw) { - int status; + int status, subpage; + + if (!(chip->options & NAND_NO_SUBPAGE_WRITE) && + chip->ecc.write_subpage) + subpage = offset || (data_len < mtd->writesize); + else + subpage = 0; chip->cmdfunc(mtd, NAND_CMD_SEQIN, 0x00, page); if (unlikely(raw)) - status = chip->ecc.write_page_raw(mtd, chip, buf, oob_required); + status = chip->ecc.write_page_raw(mtd, chip, buf, + oob_required); + else if (subpage) + status = chip->ecc.write_subpage(mtd, chip, offset, data_len, + buf, oob_required); else status = chip->ecc.write_page(mtd, chip, buf, oob_required); @@ -2159,7 +2232,7 @@ static int nand_do_write_ops(struct mtd_info *mtd, loff_t to, uint8_t *oob = ops->oobbuf; uint8_t *buf = ops->datbuf; - int ret, subpage; + int ret; int oob_required = oob ? 1 : 0; ops->retlen = 0; @@ -2174,10 +2247,6 @@ static int nand_do_write_ops(struct mtd_info *mtd, loff_t to, } column = to & (mtd->writesize - 1); - subpage = column || (writelen & (mtd->writesize - 1)); - - if (subpage && oob) - return -EINVAL; chipnr = (int)(to >> chip->chip_shift); chip->select_chip(mtd, chipnr); @@ -2226,9 +2295,9 @@ static int nand_do_write_ops(struct mtd_info *mtd, loff_t to, /* We still need to erase leftover OOB data */ memset(chip->oob_poi, 0xff, mtd->oobsize); } - - ret = chip->write_page(mtd, chip, wbuf, oob_required, page, - cached, (ops->mode == MTD_OPS_RAW)); + ret = chip->write_page(mtd, chip, column, bytes, wbuf, + oob_required, page, cached, + (ops->mode == MTD_OPS_RAW)); if (ret) break; @@ -3414,6 +3483,10 @@ int nand_scan_tail(struct mtd_info *mtd) chip->ecc.read_oob = nand_read_oob_std; if (!chip->ecc.write_oob) chip->ecc.write_oob = nand_write_oob_std; + if (!chip->ecc.read_subpage) + chip->ecc.read_subpage = nand_read_subpage; + if (!chip->ecc.write_subpage) + chip->ecc.write_subpage = nand_write_subpage_hwecc; case NAND_ECC_HW_SYNDROME: if ((!chip->ecc.calculate || !chip->ecc.correct || -- cgit v1.2.3