mtd: nand: add new enum for storing ECC algorithm

Our nand_ecc_modes_t is already a bit abused by value NAND_ECC_SOFT_BCH.
This enum should store ECC mode only and putting algorithm details there
is a bad idea. It would result in too many values impossible to support
in a sane way.

To solve this problem let's add a new enum. We'll have to modify all
drivers to set it properly but once it's done it'll be possible to drop
NAND_ECC_SOFT_BCH. That will result in a cleaner design and more
possibilities like setting ECC algorithm for hardware ECC mode.

Signed-off-by: Rafał Miłecki <zajec5@gmail.com>
Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>

include/linux/mtd/nand.h

@@ -119,6 +119,12 @@ typedef enum {
 	NAND_ECC_SOFT_BCH,
 } nand_ecc_modes_t;
 
+enum nand_ecc_algo {
+	NAND_ECC_UNKNOWN,
+	NAND_ECC_HAMMING,
+	NAND_ECC_BCH,
+};
+
 /*
  * Constants for Hardware ECC
  */
@@ -458,6 +464,7 @@ struct nand_hw_control {
 /**
  * struct nand_ecc_ctrl - Control structure for ECC
  * @mode:	ECC mode
+ * @algo:	ECC algorithm
  * @steps:	number of ECC steps per page
  * @size:	data bytes per ECC step
  * @bytes:	ECC bytes per step
@@ -508,6 +515,7 @@ struct nand_hw_control {
  */
 struct nand_ecc_ctrl {
 	nand_ecc_modes_t mode;
+	enum nand_ecc_algo algo;
 	int steps;
 	int size;
 	int bytes;