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| author | Miquel Raynal <miquel.raynal@bootlin.com> | 2020-05-19 10:45:45 +0300 |
|---|---|---|
| committer | Miquel Raynal <miquel.raynal@bootlin.com> | 2020-05-24 23:34:55 +0300 |
| commit | d7904619ea0636411f40fb1f34057288c0783ecf (patch) | |
| tree | 4f60bc86a5fee1ebabd8c2d0eb3c2ddcb60d5d05 | |
| parent | 0651ed5082bc5af45be9f79cabcbc32c1cf4e599 (diff) | |
| download | linux-d7904619ea0636411f40fb1f34057288c0783ecf.tar.xz | |
mtd: rawnand: Add nand_extract_bits()
There are cases where ECC bytes are not byte-aligned. Indeed, BCH
implies using a number of ECC bits, which are not always a multiple of
8. We then need a helper like nand_extract_bits() to extract these
syndromes from a buffer.
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Link: https://lore.kernel.org/linux-mtd/20200519074549.23673-5-miquel.raynal@bootlin.com
| -rw-r--r-- | drivers/mtd/nand/raw/nand_base.c | 44 | ||||
| -rw-r--r-- | include/linux/mtd/rawnand.h | 4 |
2 files changed, 48 insertions, 0 deletions
diff --git a/drivers/mtd/nand/raw/nand_base.c b/drivers/mtd/nand/raw/nand_base.c index 475647ea6948..6a6a0a36b3fd 100644 --- a/drivers/mtd/nand/raw/nand_base.c +++ b/drivers/mtd/nand/raw/nand_base.c @@ -275,6 +275,50 @@ static int check_offs_len(struct nand_chip *chip, loff_t ofs, uint64_t len) } /** + * nand_extract_bits - Copy unaligned bits from one buffer to another one + * @dst: destination buffer + * @dst_off: bit offset at which the writing starts + * @src: source buffer + * @src_off: bit offset at which the reading starts + * @nbits: number of bits to copy from @src to @dst + * + * Copy bits from one memory region to another (overlap authorized). + */ +void nand_extract_bits(u8 *dst, unsigned int dst_off, const u8 *src, + unsigned int src_off, unsigned int nbits) +{ + unsigned int tmp, n; + + dst += dst_off / 8; + dst_off %= 8; + src += src_off / 8; + src_off %= 8; + + while (nbits) { + n = min3(8 - dst_off, 8 - src_off, nbits); + + tmp = (*src >> src_off) & GENMASK(n - 1, 0); + *dst &= ~GENMASK(n - 1 + dst_off, dst_off); + *dst |= tmp << dst_off; + + dst_off += n; + if (dst_off >= 8) { + dst++; + dst_off -= 8; + } + + src_off += n; + if (src_off >= 8) { + src++; + src_off -= 8; + } + + nbits -= n; + } +} +EXPORT_SYMBOL_GPL(nand_extract_bits); + +/** * nand_select_target() - Select a NAND target (A.K.A. die) * @chip: NAND chip object * @cs: the CS line to select. Note that this CS id is always from the chip diff --git a/include/linux/mtd/rawnand.h b/include/linux/mtd/rawnand.h index a3bac8824937..2804c13e5662 100644 --- a/include/linux/mtd/rawnand.h +++ b/include/linux/mtd/rawnand.h @@ -1414,6 +1414,10 @@ int nand_gpio_waitrdy(struct nand_chip *chip, struct gpio_desc *gpiod, void nand_select_target(struct nand_chip *chip, unsigned int cs); void nand_deselect_target(struct nand_chip *chip); +/* Bitops */ +void nand_extract_bits(u8 *dst, unsigned int dst_off, const u8 *src, + unsigned int src_off, unsigned int nbits); + /** * nand_get_data_buf() - Get the internal page buffer * @chip: NAND chip object |