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[MTD] OneNAND: Implement read-while-load 

Read-while-load enables higher performance read operations.

Signed-off-by: Adrian Hunter <ext-adrian.hunter@nokia.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
This commit is contained in:
Adrian Hunter 2007-01-04 09:51:26 +02:00 committed by Artem Bityutskiy
parent 2fd32d4af8
commit a8de85d557
2 changed files with 40 additions and 29 deletions
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68
drivers/mtd/onenand/onenand_base.c
View File

@ -727,40 +727,47 @@ static int onenand_read(struct mtd_info *mtd, loff_t from, size_t len,
/* TODO handling oob */
stats = mtd->ecc_stats;
while (read < len) {
cond_resched();
thislen = min_t(int, mtd->writesize, len - read);
/* Read-while-load method */
column = from & (mtd->writesize - 1);
if (column + thislen > mtd->writesize)
thislen = mtd->writesize - column;
/* Do first load to bufferRAM */
if (read < len) {
if (!onenand_check_bufferram(mtd, from)) {
this->command(mtd, ONENAND_CMD_READ, from, mtd->writesize);
ret = this->wait(mtd, FL_READING);
onenand_update_bufferram(mtd, from, !ret);
}
}
if (!onenand_check_bufferram(mtd, from)) {
this->command(mtd, ONENAND_CMD_READ, from, mtd->writesize);
thislen = min_t(int, mtd->writesize, len - read);
column = from & (mtd->writesize - 1);
if (column + thislen > mtd->writesize)
thislen = mtd->writesize - column;
ret = this->wait(mtd, FL_READING);
/* First copy data and check return value for ECC handling */
onenand_update_bufferram(mtd, from, !ret);
}
while (!ret) {
/* If there is more to load then start next load */
from += thislen;
if (read + thislen < len) {
this->command(mtd, ONENAND_CMD_READ, from, mtd->writesize);
ONENAND_SET_PREV_BUFFERRAM(this);
}
/* While load is going, read from last bufferRAM */
this->read_bufferram(mtd, ONENAND_DATARAM, buf, column, thislen);
/* See if we are done */
read += thislen;
if (read == len)
break;
/* Set up for next read from bufferRAM */
ONENAND_SET_NEXT_BUFFERRAM(this);
buf += thislen;
thislen = min_t(int, mtd->writesize, len - read);
column = 0;
cond_resched();
/* Now wait for load */
ret = this->wait(mtd, FL_READING);
onenand_update_bufferram(mtd, from, !ret);
}
this->read_bufferram(mtd, ONENAND_DATARAM, buf, column, thislen);
if (ret) {
DEBUG(MTD_DEBUG_LEVEL0, "onenand_read: read failed = %d\n", ret);
goto out;
}
read += thislen;
if (read == len)
break;
from += thislen;
buf += thislen;
}
out:
/* Deselect and wake up anyone waiting on the device */
onenand_release_device(mtd);
@ -774,6 +781,9 @@ out:
if (mtd->ecc_stats.failed - stats.failed)
return -EBADMSG;
if (ret)
return ret;
return mtd->ecc_stats.corrected - stats.corrected ? -EUCLEAN : 0;
}

1
include/linux/mtd/onenand.h
View File

@ -143,6 +143,7 @@ struct onenand_chip {
#define ONENAND_CURRENT_BUFFERRAM(this) (this->bufferram_index)
#define ONENAND_NEXT_BUFFERRAM(this) (this->bufferram_index ^ 1)
#define ONENAND_SET_NEXT_BUFFERRAM(this) (this->bufferram_index ^= 1)
#define ONENAND_SET_PREV_BUFFERRAM(this) (this->bufferram_index ^= 1)
#define ONENAND_GET_SYS_CFG1(this) \
(this->read_word(this->base + ONENAND_REG_SYS_CFG1))