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mtd: mxc_nand: cleanup copy_spare function

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To give people without the reference manual at hand a chance to
understand how spare area is handled in the i.MX nand controller,
improve commenting, naming of variables and coding style.

No functional change intended.

Reviewed-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
[baruch: declare oob_chunk_size; update comments; reword commit log]
Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>
This commit is contained in:
Uwe Kleine-König 2015-05-13 11:17:36 +03:00 committed by Brian Norris
parent bcb83a19d3
commit 35d5d20efa
1 changed files with 29 additions and 13 deletions
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42
drivers/mtd/nand/mxc_nand.c
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@ -807,32 +807,48 @@ static void mxc_nand_select_chip_v2(struct mtd_info *mtd, int chip)
}
/*
* Function to transfer data to/from spare area.
* The controller splits a page into data chunks of 512 bytes + partial oob.
* There are writesize / 512 such chunks, the size of the partial oob parts is
* oobsize / #chunks rounded down to a multiple of 2. The last oob chunk then
* contains additionally the byte lost by rounding (if any).
* This function handles the needed shuffling between host->data_buf (which
* holds a page in natural order, i.e. writesize bytes data + oobsize bytes
* spare) and the NFC buffer.
*/
static void copy_spare(struct mtd_info *mtd, bool bfrom)
{
struct nand_chip *this = mtd->priv;
struct mxc_nand_host *host = this->priv;
u16 i, j;
u16 n = mtd->writesize >> 9;
u16 i, oob_chunk_size;
u16 num_chunks = mtd->writesize / 512;
u8 *d = host->data_buf + mtd->writesize;
u8 __iomem *s = host->spare0;
u16 t = host->devtype_data->spare_len;
u16 sparebuf_size = host->devtype_data->spare_len;
j = (mtd->oobsize / n >> 1) << 1;
/* size of oob chunk for all but possibly the last one */
oob_chunk_size = (mtd->oobsize / num_chunks) & ~1;
if (bfrom) {
for (i = 0; i < n - 1; i++)
memcpy32_fromio(d + i * j, s + i * t, j);
for (i = 0; i < num_chunks - 1; i++)
memcpy32_fromio(d + i * oob_chunk_size,
s + i * sparebuf_size,
oob_chunk_size);
/* the last section */
memcpy32_fromio(d + i * j, s + i * t, mtd->oobsize - i * j);
/* the last chunk */
memcpy32_fromio(d + i * oob_chunk_size,
s + i * sparebuf_size,
mtd->oobsize - i * oob_chunk_size);
} else {
for (i = 0; i < n - 1; i++)
memcpy32_toio(&s[i * t], &d[i * j], j);
for (i = 0; i < num_chunks - 1; i++)
memcpy32_toio(&s[i * sparebuf_size],
&d[i * oob_chunk_size],
oob_chunk_size);
/* the last section */
memcpy32_toio(&s[i * t], &d[i * j], mtd->oobsize - i * j);
/* the last chunk */
memcpy32_toio(&s[oob_chunk_size * sparebuf_size],
&d[i * oob_chunk_size],
mtd->oobsize - i * oob_chunk_size);
}
}