mtd: nand: omap: add CONFIG_NAND_OMAP_ECCSCHEME for selection of ecc-scheme

This patch adds new CONFIG_NAND_OMAP_ECCSCHEME, replacing other distributed
CONFIG_xx used for selecting NAND ecc-schemes.
This patch aims at solving following issues.

1) Currently ecc-scheme is tied to SoC platform, which prevents user to select
   other ecc-schemes also supported in hardware. like;
 - most of OMAP3 SoC platforms use only 1-bit Hamming ecc-scheme, inspite
   the fact that they can use higher ecc-schemes like 8-bit ecc-schemes with
   software based error detection (OMAP_ECC_BCH4_CODE_HW_DETECTION_SW).
 - most of AM33xx SoC plaforms use 8-bit BCH ecc-scheme for now, but hardware
   supports BCH16 ecc-scheme also.

2) Different platforms use different CONFIG_xx to select ecc-schemes, which
   adds confusion for user while migrating platforms.
 - *CONFIG_NAND_OMAP_ELM* which enables ELM hardware engine, selects only
    8-bit BCH ecc-scheme with h/w based error-correction (OMAP_ECC_BCH8_CODE_HW)
    whereas ELM hardware engine supports other ecc-schemes also like; BCH4,
    and BCH16 (in future).
 - *CONFIG_NAND_OMAP_BCH8* selects 8-bit BCH ecc-scheme with s/w based error
    correction (OMAP_ECC_BCH8_CODE_HW_DETECTION_SW).
 - *CONFIG_SPL_NAND_SOFTECC* selects 1-bit Hamming ecc-scheme using s/w library

Thus adding new *CONFIG_NAND_OMAP_ECCSCHEME* de-couples ecc-scheme dependency
on SoC platform and NAND driver. And user can select ecc-scheme independently
foreach board.
However, selection some hardware based ecc-schemes (OMAP_ECC_BCHx_CODE_HW) still
depends on presence of ELM hardware engine on SoC. (Refer doc/README.nand)

Signed-off-by: Pekon Gupta <pekon@ti.com>

doc/README.nand

@@ -208,6 +208,29 @@ Platform specific options
 	detection. However ECC calculation on such plaforms would still be
 	done by GPMC controller.
 
+   CONFIG_NAND_OMAP_ECCSCHEME
+	On OMAP platforms, this CONFIG specifies NAND ECC scheme.
+	It can take following values:
+	OMAP_ECC_HAM1_CODE_SW
+		1-bit Hamming code using software lib.
+		(for legacy devices only)
+	OMAP_ECC_HAM1_CODE_HW
+		1-bit Hamming code using GPMC hardware.
+		(for legacy devices only)
+	OMAP_ECC_BCH4_CODE_HW_DETECTION_SW
+		4-bit BCH code (unsupported)
+	OMAP_ECC_BCH4_CODE_HW
+		4-bit BCH code (unsupported)
+	OMAP_ECC_BCH8_CODE_HW_DETECTION_SW
+		8-bit BCH code with
+		- ecc calculation using GPMC hardware engine,
+		- error detection using software library.
+		- requires CONFIG_BCH to enable software BCH library
+		(For legacy device which do not have ELM h/w engine)
+	OMAP_ECC_BCH8_CODE_HW
+		8-bit BCH code with
+		- ecc calculation using GPMC hardware engine,
+		- error detection using ELM hardware engine.
 
 NOTE:
 =====

doc/README.omap3

@@ -161,8 +161,7 @@ BCH8
 
 To enable hardware assisted BCH8 (8-bit BCH [Bose, Chaudhuri, Hocquenghem]) on
 OMAP3 devices we can use the BCH library in lib/bch.c. To do so add CONFIG_BCH
-to enable the library and CONFIG_NAND_OMAP_BCH8 to to enable hardware assisted
-syndrom generation to your board config.
+and set CONFIG_NAND_OMAP_ECCSCHEME=5 (refer README.nand) for selecting BCH8_SW.
 The NAND OOB layout is the same as in linux kernel, if the linux kernel BCH8
 implementation for OMAP3 works for you so the u-boot version should also.
 When you require the SPL to read with BCH8 there are two more configs to

drivers/mtd/nand/omap_gpmc.c

@@ -1004,18 +1004,13 @@ int board_nand_init(struct nand_chip *nand)
 	nand->ecc.layout = &omap_ecclayout;
 
 	/* select ECC scheme */
-#if defined(CONFIG_NAND_OMAP_ELM)
-	err = omap_select_ecc_scheme(nand, OMAP_ECC_BCH8_CODE_HW,
+#if defined(CONFIG_NAND_OMAP_ECCSCHEME)
+	err = omap_select_ecc_scheme(nand, CONFIG_NAND_OMAP_ECCSCHEME,
 			CONFIG_SYS_NAND_PAGE_SIZE, CONFIG_SYS_NAND_OOBSIZE);
-#elif defined(CONFIG_NAND_OMAP_BCH8)
-	err = omap_select_ecc_scheme(nand, OMAP_ECC_BCH8_CODE_HW_DETECTION_SW,
-			CONFIG_SYS_NAND_PAGE_SIZE, CONFIG_SYS_NAND_OOBSIZE);
-#elif !defined(CONFIG_SPL_BUILD) || defined(CONFIG_SPL_NAND_SOFTECC)
+#else
+	/* pagesize and oobsize are not required to configure sw ecc-scheme */
 	err = omap_select_ecc_scheme(nand, OMAP_ECC_HAM1_CODE_SW,
 			0, 0);
-#else
-	err = omap_select_ecc_scheme(nand, OMAP_ECC_HAM1_CODE_HW,
-			CONFIG_SYS_NAND_PAGE_SIZE, CONFIG_SYS_NAND_OOBSIZE);
 #endif
 	if (err)
 		return err;

include/configs/am335x_evm.h

@@ -240,7 +240,8 @@
 
 #define CONFIG_SYS_NAND_ECCSIZE		512
 #define CONFIG_SYS_NAND_ECCBYTES	14
-
+#define CONFIG_SYS_NAND_ONFI_DETECTION
+#define CONFIG_NAND_OMAP_ECCSCHEME	OMAP_ECC_BCH8_CODE_HW
 #define CONFIG_SYS_NAND_U_BOOT_START	CONFIG_SYS_TEXT_BASE
 #define CONFIG_SYS_NAND_U_BOOT_OFFS	0x80000
 #endif

include/configs/am335x_igep0033.h

@@ -264,6 +264,7 @@
 
 #define CONFIG_SYS_NAND_ECCSIZE		512
 #define CONFIG_SYS_NAND_ECCBYTES	14
+#define CONFIG_NAND_OMAP_ECCSCHEME	OMAP_ECC_BCH8_CODE_HW
 
 #define	CONFIG_SYS_NAND_U_BOOT_START	CONFIG_SYS_TEXT_BASE
 

include/configs/am3517_crane.h

@@ -340,6 +340,7 @@
 						10, 11, 12, 13}
 #define CONFIG_SYS_NAND_ECCSIZE		512
 #define CONFIG_SYS_NAND_ECCBYTES	3
+#define CONFIG_NAND_OMAP_ECCSCHEME	OMAP_ECC_HAM1_CODE_HW
 #define CONFIG_SYS_NAND_U_BOOT_START	CONFIG_SYS_TEXT_BASE
 #define CONFIG_SYS_NAND_U_BOOT_OFFS	0x80000
 

include/configs/am3517_evm.h

@@ -334,6 +334,7 @@
 						10, 11, 12, 13}
 #define CONFIG_SYS_NAND_ECCSIZE		512
 #define CONFIG_SYS_NAND_ECCBYTES	3
+#define CONFIG_NAND_OMAP_ECCSCHEME	OMAP_ECC_HAM1_CODE_HW
 #define CONFIG_SYS_NAND_U_BOOT_START	CONFIG_SYS_TEXT_BASE
 #define CONFIG_SYS_NAND_U_BOOT_OFFS	0x80000
 

include/configs/devkit8000.h

@@ -327,6 +327,7 @@
 
 #define CONFIG_SYS_NAND_ECCSIZE		512
 #define CONFIG_SYS_NAND_ECCBYTES	3
+#define CONFIG_NAND_OMAP_ECCSCHEME	OMAP_ECC_HAM1_CODE_HW
 
 #define CONFIG_SYS_NAND_U_BOOT_START   CONFIG_SYS_TEXT_BASE
 

include/configs/mcx.h

@@ -353,7 +353,6 @@
 #define CONFIG_SPL_FRAMEWORK
 #define CONFIG_SPL_BOARD_INIT
 #define CONFIG_SPL_NAND_SIMPLE
-#define CONFIG_SPL_NAND_SOFTECC
 
 #define CONFIG_SPL_LIBCOMMON_SUPPORT
 #define CONFIG_SPL_LIBDISK_SUPPORT
@@ -395,6 +394,7 @@
 					 56, 57, 58, 59, 60, 61, 62, 63}
 #define CONFIG_SYS_NAND_ECCSIZE		256
 #define CONFIG_SYS_NAND_ECCBYTES	3
+#define CONFIG_NAND_OMAP_ECCSCHEME	OMAP_ECC_HAM1_CODE_SW
 
 #define CONFIG_SYS_NAND_U_BOOT_START   CONFIG_SYS_TEXT_BASE
 

include/configs/omap3_beagle.h

@@ -432,6 +432,7 @@
 						10, 11, 12, 13}
 #define CONFIG_SYS_NAND_ECCSIZE		512
 #define CONFIG_SYS_NAND_ECCBYTES	3
+#define CONFIG_NAND_OMAP_ECCSCHEME	OMAP_ECC_HAM1_CODE_HW
 #define CONFIG_SYS_NAND_U_BOOT_START	CONFIG_SYS_TEXT_BASE
 #define CONFIG_SYS_NAND_U_BOOT_OFFS	0x80000
 

include/configs/omap3_evm.h

@@ -107,6 +107,7 @@
 						10, 11, 12, 13}
 #define CONFIG_SYS_NAND_ECCSIZE		512
 #define CONFIG_SYS_NAND_ECCBYTES	3
+#define CONFIG_NAND_OMAP_ECCSCHEME	OMAP_ECC_HAM1_CODE_HW
 #define CONFIG_SYS_NAND_U_BOOT_START   CONFIG_SYS_TEXT_BASE
 #define CONFIG_SYS_NAND_U_BOOT_OFFS	0x80000
 

include/configs/omap3_evm_quick_nand.h

@@ -86,6 +86,7 @@
 						10, 11, 12, 13}
 #define CONFIG_SYS_NAND_ECCSIZE		512
 #define CONFIG_SYS_NAND_ECCBYTES	3
+#define CONFIG_NAND_OMAP_ECCSCHEME	OMAP_ECC_HAM1_CODE_HW
 #define CONFIG_SYS_NAND_U_BOOT_START   CONFIG_SYS_TEXT_BASE
 #define CONFIG_SYS_NAND_U_BOOT_OFFS	0x80000
 

include/configs/omap3_igep00x0.h

@@ -362,6 +362,7 @@
 						10, 11, 12, 13}
 #define CONFIG_SYS_NAND_ECCSIZE		512
 #define CONFIG_SYS_NAND_ECCBYTES	3
+#define CONFIG_NAND_OMAP_ECCSCHEME	OMAP_ECC_HAM1_CODE_HW
 #define CONFIG_SYS_NAND_U_BOOT_START	CONFIG_SYS_TEXT_BASE
 #define CONFIG_SYS_NAND_U_BOOT_OFFS	0x80000
 #endif

include/configs/omap3_overo.h

@@ -325,6 +325,7 @@
 						10, 11, 12, 13}
 #define CONFIG_SYS_NAND_ECCSIZE		512
 #define CONFIG_SYS_NAND_ECCBYTES	3
+#define CONFIG_NAND_OMAP_ECCSCHEME	OMAP_ECC_HAM1_CODE_HW
 #define CONFIG_SYS_NAND_U_BOOT_START	CONFIG_SYS_TEXT_BASE
 #define CONFIG_SYS_NAND_U_BOOT_OFFS	0x80000
 

include/configs/siemens-am33x-common.h

@@ -196,6 +196,7 @@
 
 #define CONFIG_SYS_NAND_ECCSIZE		512
 #define CONFIG_SYS_NAND_ECCBYTES	14
+#define CONFIG_NAND_OMAP_ECCSCHEME	OMAP_ECC_BCH8_CODE_HW
 
 #define CONFIG_SYS_NAND_ECCSTEPS	4
 #define	CONFIG_SYS_NAND_ECCTOTAL	(CONFIG_SYS_NAND_ECCBYTES * \

include/configs/tam3517-common.h

@@ -225,7 +225,6 @@
 #define CONFIG_SPL_BOARD_INIT
 #define CONFIG_SPL_CONSOLE
 #define CONFIG_SPL_NAND_SIMPLE
-#define CONFIG_SPL_NAND_SOFTECC
 #define CONFIG_SPL_NAND_WORKSPACE	0x8f07f000 /* below BSS */
 
 #define CONFIG_SPL_LIBCOMMON_SUPPORT
@@ -262,6 +261,7 @@
 					 56, 57, 58, 59, 60, 61, 62, 63}
 #define CONFIG_SYS_NAND_ECCSIZE		256
 #define CONFIG_SYS_NAND_ECCBYTES	3
+#define CONFIG_NAND_OMAP_ECCSCHEME	OMAP_ECC_HAM1_CODE_SW
 
 #define CONFIG_SYS_NAND_U_BOOT_START	CONFIG_SYS_TEXT_BASE
 

include/configs/tricorder.h

@@ -138,7 +138,6 @@
 
 #define CONFIG_SYS_MAX_NAND_DEVICE	1		/* Max number of NAND */
 							/* devices */
-#define CONFIG_NAND_OMAP_BCH8
 #define CONFIG_BCH
 #define CONFIG_SYS_NAND_MAX_OOBFREE	2
 #define CONFIG_SYS_NAND_MAX_ECCPOS	56
@@ -376,6 +375,7 @@
 
 #define CONFIG_SYS_NAND_ECCSIZE		512
 #define CONFIG_SYS_NAND_ECCBYTES	13
+#define CONFIG_NAND_OMAP_ECCSCHEME	OMAP_ECC_BCH8_CODE_HW_DETECTION_SW
 
 #define CONFIG_SYS_NAND_U_BOOT_START	CONFIG_SYS_TEXT_BASE