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: Brian Norris <computersforpeace@gmail.com>
Cc: Jim Quinlan <jim2101024@gmail.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@intel.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/include/linux/mtd/nand.h b/include/linux/mtd/nand.h
index c7113a9cd66d..0b3d464cba13 100644
--- a/include/linux/mtd/nand.h
+++ b/include/linux/mtd/nand.h
@@ -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,