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Commit c46f6483 authored by Brian Norris's avatar Brian Norris Committed by Artem Bityutskiy
Browse files

mtd: support reading OOB without ECC 



This fixes issues with `nanddump -n' and the MEMREADOOB[64] ioctls on
hardware that performs error correction when reading only OOB data. A
driver for such hardware needs to know when we're doing a RAW vs. a
normal write, but mtd_do_read_oob does not pass such information to the
lower layers (e.g., NAND). We should pass MTD_OOB_RAW or MTD_OOB_PLACE
based on the MTD file mode.

For now, most drivers can get away with just setting:

  chip->ecc.read_oob_raw = chip->ecc.read_oob

This is done by default; but for systems that behave as described above,
you must supply your own replacement function.

This was tested with nandsim as well as on actual SLC NAND.

Signed-off-by: default avatarBrian Norris <computersforpeace@gmail.com>
Cc: Jim Quinlan <jim2101024@gmail.com>
Signed-off-by: default avatarArtem Bityutskiy <artem.bityutskiy@intel.com>
parent e9195edc

drivers/mtd/mtdchar.c

+8 −6
Original line number Diff line number Diff line
@@ -435,9 +435,11 @@ static int mtd_do_writeoob(struct file *file, struct mtd_info *mtd, 
	return ret;

}



static int mtd_do_readoob(struct mtd_info *mtd, uint64_t start,

	uint32_t length, void __user *ptr, uint32_t __user *retp)

static int mtd_do_readoob(struct file *file, struct mtd_info *mtd,

	uint64_t start, uint32_t length, void __user *ptr,

	uint32_t __user *retp)

{

	struct mtd_file_info *mfi = file->private_data;

	struct mtd_oob_ops ops;

	int ret = 0;
@@ -455,7 +457,7 @@ static int mtd_do_readoob(struct mtd_info *mtd, uint64_t start, 
	ops.ooblen = length;

	ops.ooboffs = start & (mtd->writesize - 1);

	ops.datbuf = NULL;

	ops.mode = MTD_OOB_PLACE;

	ops.mode = (mfi->mode == MTD_MODE_RAW) ? MTD_OOB_RAW : MTD_OOB_PLACE;



	if (ops.ooboffs && ops.ooblen > (mtd->oobsize - ops.ooboffs))

		return -EINVAL;
@@ -716,7 +718,7 @@ static int mtd_ioctl(struct file *file, u_int cmd, u_long arg) 
		if (copy_from_user(&buf, argp, sizeof(buf)))

			ret = -EFAULT;

		else

			ret = mtd_do_readoob(mtd, buf.start, buf.length,

			ret = mtd_do_readoob(file, mtd, buf.start, buf.length,

				buf.ptr, &buf_user->start);

		break;

	}
@@ -743,7 +745,7 @@ static int mtd_ioctl(struct file *file, u_int cmd, u_long arg) 
		if (copy_from_user(&buf, argp, sizeof(buf)))

			ret = -EFAULT;

		else

			ret = mtd_do_readoob(mtd, buf.start, buf.length,

			ret = mtd_do_readoob(file, mtd, buf.start, buf.length,

				(void __user *)(uintptr_t)buf.usr_ptr,

				&buf_user->length);

		break;
@@ -1029,7 +1031,7 @@ static long mtd_compat_ioctl(struct file *file, unsigned int cmd, 
		if (copy_from_user(&buf, argp, sizeof(buf)))

			ret = -EFAULT;

		else

			ret = mtd_do_readoob(mtd, buf.start,

			ret = mtd_do_readoob(file, mtd, buf.start,

				buf.length, compat_ptr(buf.ptr),

				&buf_user->start);

		break;

drivers/mtd/nand/nand_base.c

+6 −1
Original line number Diff line number Diff line
@@ -1787,6 +1787,9 @@ static int nand_do_read_oob(struct mtd_info *mtd, loff_t from, 
	page = realpage & chip->pagemask;



	while (1) {

		if (ops->mode == MTD_OOB_RAW)

			sndcmd = chip->ecc.read_oob_raw(mtd, chip, page, sndcmd);

		else

			sndcmd = chip->ecc.read_oob(mtd, chip, page, sndcmd);



		len = min(len, readlen);
@@ -3385,6 +3388,8 @@ int nand_scan_tail(struct mtd_info *mtd) 
	}



	/* For many systems, the standard OOB write also works for raw */

	if (!chip->ecc.read_oob_raw)

		chip->ecc.read_oob_raw = chip->ecc.read_oob;

	if (!chip->ecc.write_oob_raw)

		chip->ecc.write_oob_raw = chip->ecc.write_oob;

include/linux/mtd/nand.h

+3 −0
Original line number Diff line number Diff line
@@ -341,6 +341,7 @@ struct nand_hw_control { 
 * @write_page:	function to write a page according to the ECC generator

 *		requirements.

 * @write_oob_raw:	function to write chip OOB data without ECC

 * @read_oob_raw:	function to read chip OOB data without ECC

 * @read_oob:	function to read chip OOB data

 * @write_oob:	function to write chip OOB data

 */
@@ -371,6 +372,8 @@ struct nand_ecc_ctrl { 
			const uint8_t *buf);

	int (*write_oob_raw)(struct mtd_info *mtd, struct nand_chip *chip,

			int page);

	int (*read_oob_raw)(struct mtd_info *mtd, struct nand_chip *chip,

			int page, int sndcmd);

	int (*read_oob)(struct mtd_info *mtd, struct nand_chip *chip, int page,

			int sndcmd);

	int (*write_oob)(struct mtd_info *mtd, struct nand_chip *chip,