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Commit 66507c7b authored by Kamal Dasu's avatar Kamal Dasu Committed by Brian Norris
Browse files

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



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: default avatarKamal Dasu <kdasu.kdev@gmail.com>
Signed-off-by: default avatarBrian Norris <computersforpeace@gmail.com>
parent 6e522155

drivers/mtd/nand/nand_base.c

+31 −6
Original line number Diff line number Diff line
@@ -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));



		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? */

		if (unlikely(column || writelen < (mtd->writesize - 1))) {

		/* 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);

include/linux/mtd/nand.h

+5 −0
Original line number Diff line number Diff line
@@ -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