[PATCH 07/16] mtd: nand: sunxi: implement ->read_subpage()

Boris Brezillon
2016-03-07T16:20:41Z

Being able to read subpages can greatly improve read performances if the
MTD user is only interested in a small section of a NAND page.
This is particularly true with large pages (>= 8k).

Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
---
drivers/mtd/nand/sunxi_nand.c | 36 ++++++++++++++++++++++++++++++++++++
1 file changed, 36 insertions(+)

diff --git a/drivers/mtd/nand/sunxi_nand.c b/drivers/mtd/nand/sunxi_nand.c
index 8977a5f..df73e55 100644
--- a/drivers/mtd/nand/sunxi_nand.c
+++ b/drivers/mtd/nand/sunxi_nand.c
@@ -974,6 +974,39 @@ static int sunxi_nfc_hw_ecc_read_page(struct mtd_info *mtd,
return max_bitflips;
}

+static int sunxi_nfc_hw_ecc_read_subpage(struct mtd_info *mtd,
+ struct nand_chip *chip,
+ u32 data_offs, u32 readlen,
+ u8 *bufpoi, int page)
+{
+ struct nand_ecc_ctrl *ecc = &chip->ecc;
+ int ret, i, cur_off = 0;
+ unsigned int max_bitflips = 0;
+
+ sunxi_nfc_hw_ecc_enable(mtd);
+
+ chip->cmdfunc(mtd, NAND_CMD_READ0, 0, page);
+ for (i = data_offs / ecc->size;
+ i < DIV_ROUND_UP(data_offs + readlen, ecc->size); i++) {
+ int data_off = i * ecc->size;
+ int oob_off = i * (ecc->bytes + 4);
+ u8 *data = bufpoi + data_off;
+ u8 *oob = chip->oob_poi + oob_off;
+
+ ret = sunxi_nfc_hw_ecc_read_chunk(mtd, data, data_off,
+ oob,
+ oob_off + mtd->writesize,
+ &cur_off, &max_bitflips,
+ !i, page);
+ if (ret < 0)
+ return ret;
+ }
+
+ sunxi_nfc_hw_ecc_disable(mtd);
+
+ return max_bitflips;
+}
+
static int sunxi_nfc_hw_ecc_write_page(struct mtd_info *mtd,
struct nand_chip *chip,
const uint8_t *buf, int oob_required,
@@ -1384,6 +1417,7 @@ static int sunxi_nand_hw_ecc_ctrl_init(struct mtd_info *mtd,
ecc->write_page = sunxi_nfc_hw_ecc_write_page;
ecc->read_oob_raw = nand_read_oob_std;
ecc->write_oob_raw = nand_write_oob_std;
+ ecc->read_subpage = sunxi_nfc_hw_ecc_read_subpage;
layout = ecc->layout;
nsectors = mtd->writesize / ecc->size;

@@ -1630,6 +1664,8 @@ static int sunxi_nand_chip_init(struct device *dev, struct sunxi_nfc *nfc,
if (nand->options & NAND_NEED_SCRAMBLING)
nand->options |= NAND_NO_SUBPAGE_WRITE;

+ nand->options |= NAND_SUBPAGE_READ;
+
ret = sunxi_nand_chip_init_timings(chip, np);
if (ret) {
dev_err(dev, "could not configure chip timings: %d\n", ret);
--
2.1.4