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mtd: nand: Add support to use nand_base poi databuf as bounce buffer

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nand_base can be passed a kmap()'d buffers from highmem by
filesystems like jffs2. This results in failure to map the
physical address of the DMA buffer on various contoller
driver on different platforms. This change adds a chip option
to use preallocated databuf as bounce buffers used in
nand_do_read_ops() and nand_do_write_ops().
This allows for specific nand controller driver to set this
option as needed.

Signed-off-by: Kamal Dasu <kdasu.kdev@gmail.com>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>
This commit is contained in:
Kamal Dasu 2014-05-01 20:51:19 -04:00 committed by Brian Norris
parent 6e5221558d
commit 66507c7bc8
2 changed files with 36 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

37
drivers/mtd/nand/nand_base.c
View File

@ -37,6 +37,7 @@
#include <linux/err.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/mm.h>
#include <linux/types.h>
#include <linux/mtd/mtd.h>
#include <linux/mtd/nand.h>
@ -1500,6 +1501,7 @@ static int nand_do_read_ops(struct mtd_info *mtd, loff_t from,
mtd->oobavail : mtd->oobsize;
uint8_t *bufpoi, *oob, *buf;
int use_bufpoi;
unsigned int max_bitflips = 0;
int retry_mode = 0;
bool ecc_fail = false;
@ -1522,9 +1524,20 @@ static int nand_do_read_ops(struct mtd_info *mtd, loff_t from,
bytes = min(mtd->writesize - col, readlen);
aligned = (bytes == mtd->writesize);
if (!aligned)
use_bufpoi = 1;
else if (chip->options & NAND_USE_BOUNCE_BUFFER)
use_bufpoi = !virt_addr_valid(buf);
else
use_bufpoi = 0;
/* Is the current page in the buffer? */
if (realpage != chip->pagebuf || oob) {
bufpoi = aligned ? buf : chip->buffers->databuf;
bufpoi = use_bufpoi ? chip->buffers->databuf : buf;
if (use_bufpoi && aligned)
pr_debug("%s: using read bounce buffer for buf@%p\n",
__func__, buf);
read_retry:
chip->cmdfunc(mtd, NAND_CMD_READ0, 0x00, page);
@ -1546,7 +1559,7 @@ read_retry:
ret = chip->ecc.read_page(mtd, chip, bufpoi,
oob_required, page);
if (ret < 0) {
if (!aligned)
if (use_bufpoi)
/* Invalidate page cache */
chip->pagebuf = -1;
break;
@ -1555,7 +1568,7 @@ read_retry:
max_bitflips = max_t(unsigned int, max_bitflips, ret);
/* Transfer not aligned data */
if (!aligned) {
if (use_bufpoi) {
if (!NAND_HAS_SUBPAGE_READ(chip) && !oob &&
!(mtd->ecc_stats.failed - ecc_failures) &&
(ops->mode != MTD_OPS_RAW)) {
@ -2375,11 +2388,23 @@ static int nand_do_write_ops(struct mtd_info *mtd, loff_t to,
int bytes = mtd->writesize;
int cached = writelen > bytes && page != blockmask;
uint8_t *wbuf = buf;
int use_bufpoi;
int part_pagewr = (column || writelen < (mtd->writesize - 1));
/* Partial page write? */
if (unlikely(column || writelen < (mtd->writesize - 1))) {
if (part_pagewr)
use_bufpoi = 1;
else if (chip->options & NAND_USE_BOUNCE_BUFFER)
use_bufpoi = !virt_addr_valid(buf);
else
use_bufpoi = 0;
/* Partial page write?, or need to use bounce buffer */
if (use_bufpoi) {
pr_debug("%s: using write bounce buffer for buf@%p\n",
__func__, buf);
cached = 0;
bytes = min_t(int, bytes - column, (int) writelen);
if (part_pagewr)
bytes = min_t(int, bytes - column, writelen);
chip->pagebuf = -1;
memset(chip->buffers->databuf, 0xff, mtd->writesize);
memcpy(&chip->buffers->databuf[column], buf, bytes);

5
include/linux/mtd/nand.h
View File

@ -175,6 +175,11 @@ typedef enum {
#define NAND_OWN_BUFFERS 0x00020000
/* Chip may not exist, so silence any errors in scan */
#define NAND_SCAN_SILENT_NODEV 0x00040000
/*
* This option could be defined by controller drivers to protect against
* kmap'ed, vmalloc'ed highmem buffers being passed from upper layers
*/
#define NAND_USE_BOUNCE_BUFFER 0x00080000
/*
* Autodetect nand buswidth with readid/onfi.
* This suppose the driver will configure the hardware in 8 bits mode