[MTD] NAND: add subpage write support
Many SLC NANDs support up to 4 writes at one NAND page. Add support
of this feature.
Signed-off-by: Artem Bityutskiy <dedekind@infradead.org>
diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
index 5dcb2e0..eed3271 100644
--- a/drivers/mtd/nand/nand_base.c
+++ b/drivers/mtd/nand/nand_base.c
@@ -1590,7 +1590,7 @@
return NULL;
}
-#define NOTALIGNED(x) (x & (mtd->writesize-1)) != 0
+#define NOTALIGNED(x) (x & (chip->subpagesize - 1)) != 0
/**
* nand_do_write_ops - [Internal] NAND write with ECC
@@ -1603,15 +1603,16 @@
static int nand_do_write_ops(struct mtd_info *mtd, loff_t to,
struct mtd_oob_ops *ops)
{
- int chipnr, realpage, page, blockmask;
+ int chipnr, realpage, page, blockmask, column;
struct nand_chip *chip = mtd->priv;
uint32_t writelen = ops->len;
uint8_t *oob = ops->oobbuf;
uint8_t *buf = ops->datbuf;
- int bytes = mtd->writesize;
- int ret;
+ int ret, subpage;
ops->retlen = 0;
+ if (!writelen)
+ return 0;
/* reject writes, which are not page aligned */
if (NOTALIGNED(to) || NOTALIGNED(ops->len)) {
@@ -1620,8 +1621,11 @@
return -EINVAL;
}
- if (!writelen)
- return 0;
+ 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);
@@ -1644,12 +1648,24 @@
memset(chip->oob_poi, 0xff, mtd->oobsize);
while(1) {
+ int bytes = mtd->writesize;
int cached = writelen > bytes && page != blockmask;
+ uint8_t *wbuf = buf;
+
+ /* Partial page write ? */
+ if (unlikely(column || writelen < (mtd->writesize - 1))) {
+ cached = 0;
+ bytes = min_t(int, bytes - column, (int) writelen);
+ chip->pagebuf = -1;
+ memset(chip->buffers->databuf, 0xff, mtd->writesize);
+ memcpy(&chip->buffers->databuf[column], buf, bytes);
+ wbuf = chip->buffers->databuf;
+ }
if (unlikely(oob))
oob = nand_fill_oob(chip, oob, ops);
- ret = chip->write_page(mtd, chip, buf, page, cached,
+ ret = chip->write_page(mtd, chip, wbuf, page, cached,
(ops->mode == MTD_OOB_RAW));
if (ret)
break;
@@ -1658,6 +1674,7 @@
if (!writelen)
break;
+ column = 0;
buf += bytes;
realpage++;
@@ -2201,8 +2218,8 @@
/* Newer devices have all the information in additional id bytes */
if (!type->pagesize) {
int extid;
- /* The 3rd id byte contains non relevant data ATM */
- extid = chip->read_byte(mtd);
+ /* The 3rd id byte holds MLC / multichip data */
+ chip->cellinfo = chip->read_byte(mtd);
/* The 4th id byte is the important one */
extid = chip->read_byte(mtd);
/* Calc pagesize */
@@ -2482,6 +2499,24 @@
}
chip->ecc.total = chip->ecc.steps * chip->ecc.bytes;
+ /*
+ * Allow subpage writes up to ecc.steps. Not possible for MLC
+ * FLASH.
+ */
+ if (!(chip->options & NAND_NO_SUBPAGE_WRITE) &&
+ !(chip->cellinfo & NAND_CI_CELLTYPE_MSK)) {
+ switch(chip->ecc.steps) {
+ case 2:
+ mtd->subpage_sft = 1;
+ break;
+ case 4:
+ case 8:
+ mtd->subpage_sft = 2;
+ break;
+ }
+ }
+ chip->subpagesize = mtd->writesize >> mtd->subpage_sft;
+
/* Initialize state */
chip->state = FL_READY;