mtd: nand: add software BCH ECC support

This patch adds software BCH ECC support to mtd, in order to handle recent
NAND device ecc requirements (4 bits or more).

It does so by adding a new ecc mode (NAND_ECC_SOFT_BCH) for use by board
drivers, and a new Kconfig option to enable BCH support. It relies on the
generic BCH library introduced in a previous patch.

When a board driver uses mode NAND_ECC_SOFT_BCH, it should also set fields
chip->ecc.size and chip->ecc.bytes to select BCH ecc data size and required
error correction capability. See nand_bch_init() documentation for details.

It has been tested on the following platforms using mtd-utils, UBI and
UBIFS: x86 (with nandsim), arm926ejs.

Signed-off-by: Ivan Djelic <ivan.djelic@parrot.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/include/linux/mtd/nand.h b/include/linux/mtd/nand.h
index 1f489b247a29..ae67ef56a8f5 100644
--- a/include/linux/mtd/nand.h
+++ b/include/linux/mtd/nand.h
@@ -140,6 +140,7 @@ typedef enum {
         NAND_ECC_HW,
         NAND_ECC_HW_SYNDROME,
         NAND_ECC_HW_OOB_FIRST,
+        NAND_ECC_SOFT_BCH,
 } nand_ecc_modes_t;
 
 /*
@@ -339,6 +340,7 @@ struct nand_hw_control {
  * @prepad:     padding information for syndrome based ecc generators
  * @postpad:    padding information for syndrome based ecc generators
  * @layout:     ECC layout control struct pointer
+ * @priv:       pointer to private ecc control data
  * @hwctl:      function to control hardware ecc generator. Must only
  *              be provided if an hardware ECC is available
  * @calculate:  function for ecc calculation or readback from ecc hardware
@@ -362,6 +364,7 @@ struct nand_ecc_ctrl {
         int prepad;
         int postpad;
         struct nand_ecclayout   *layout;
+        void *priv;
         void (*hwctl)(struct mtd_info *mtd, int mode);
         int (*calculate)(struct mtd_info *mtd, const uint8_t *dat,
                         uint8_t *ecc_code);