Configuration Options:
+ CONFIG_SYS_NAND_U_BOOT_OFFS
+ NAND Offset from where SPL will read u-boot image. This is the starting
+ address of u-boot MTD partition in NAND.
+
CONFIG_CMD_NAND
Enables NAND support and commmands.
CONFIG_SYS_MAX_NAND_DEVICE
The maximum number of NAND devices you want to support.
+ CONFIG_SYS_NAND_MAX_ECCPOS
+ If specified, overrides the maximum number of ECC bytes
+ supported. Useful for reducing image size, especially with SPL.
+ This must be at least 48 if nand_base.c is used.
+
+ CONFIG_SYS_NAND_MAX_OOBFREE
+ If specified, overrides the maximum number of free OOB regions
+ supported. Useful for reducing image size, especially with SPL.
+ This must be at least 2 if nand_base.c is used.
+
CONFIG_SYS_NAND_MAX_CHIPS
The maximum number of NAND chips per device to be supported.
Please convert your driver even if you don't need the extra
flexibility, so that one day we can eliminate the old mechanism.
+
+ CONFIG_SYS_NAND_ONFI_DETECTION
+ Enables detection of ONFI compliant devices during probe.
+ And fetching device parameters flashed on device, by parsing
+ ONFI parameter page.
+
+ CONFIG_BCH
+ Enables software based BCH ECC algorithm present in lib/bch.c
+ This is used by SoC platforms which do not have built-in ELM
+ hardware engine required for BCH ECC correction.
+
+ CONFIG_SYS_NAND_BUSWIDTH_16BIT
+ Indicates that NAND device has 16-bit wide data-bus. In absence of this
+ config, bus-width of NAND device is assumed to be either 8-bit and later
+ determined by reading ONFI params.
+ Above config is useful when NAND device's bus-width information cannot
+ be determined from on-chip ONFI params, like in following scenarios:
+ - SPL boot does not support reading of ONFI parameters. This is done to
+ keep SPL code foot-print small.
+ - In current U-Boot flow using nand_init(), driver initialization
+ happens in board_nand_init() which is called before any device probe
+ (nand_scan_ident + nand_scan_tail), thus device's ONFI parameters are
+ not available while configuring controller. So a static CONFIG_NAND_xx
+ is needed to know the device's bus-width in advance.
+ Some drivers using above config are:
+ drivers/mtd/nand/mxc_nand.c
+ drivers/mtd/nand/ndfc.c
+ drivers/mtd/nand/omap_gpmc.c
+
+
+Platform specific options
+=========================
+ CONFIG_NAND_OMAP_GPMC
+ Enables omap_gpmc.c driver for OMAPx and AMxxxx platforms.
+ GPMC controller is used for parallel NAND flash devices, and can
+ do ECC calculation (not ECC error detection) for HAM1, BCH4, BCH8
+ and BCH16 ECC algorithms.
+
+ CONFIG_NAND_OMAP_ELM
+ Enables omap_elm.c driver for OMAPx and AMxxxx platforms.
+ ELM controller is used for ECC error detection (not ECC calculation)
+ of BCH4, BCH8 and BCH16 ECC algorithms.
+ Some legacy platforms like OMAP3xx do not have in-built ELM h/w engine,
+ thus such SoC platforms need to depend on software library for ECC error
+ detection. However ECC calculation on such plaforms would still be
+ done by GPMC controller.
+
+ CONFIG_SPL_NAND_AM33XX_BCH
+ Enables SPL-NAND driver (am335x_spl_bch.c) which supports ELM based
+ hardware ECC correction. This is useful for platforms which have ELM
+ hardware engine and use NAND boot mode.
+ Some legacy platforms like OMAP3xx do not have in-built ELM h/w engine,
+ so those platforms should use CONFIG_SPL_NAND_SIMPLE for enabling
+ SPL-NAND driver with software ECC correction support.
+
+ 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.
+ OMAP_ECC_BCH16_CODE_HW
+ 16-bit BCH code with
+ - ecc calculation using GPMC hardware engine,
+ - error detection using ELM hardware engine.
+
+ How to select ECC scheme on OMAP and AMxx platforms ?
+ -----------------------------------------------------
+ Though higher ECC schemes have more capability to detect and correct
+ bit-flips, but still selection of ECC scheme is dependent on following
+ - hardware engines present in SoC.
+ Some legacy OMAP SoC do not have ELM h/w engine thus such
+ SoC cannot support BCHx_HW ECC schemes.
+ - size of OOB/Spare region
+ With higher ECC schemes, more OOB/Spare area is required to
+ store ECC. So choice of ECC scheme is limited by NAND oobsize.
+
+ In general following expression can help:
+ NAND_OOBSIZE >= 2 + (NAND_PAGESIZE / 512) * ECC_BYTES
+ where
+ NAND_OOBSIZE = number of bytes available in
+ OOB/spare area per NAND page.
+ NAND_PAGESIZE = bytes in main-area of NAND page.
+ ECC_BYTES = number of ECC bytes generated to
+ protect 512 bytes of data, which is:
+ 3 for HAM1_xx ecc schemes
+ 7 for BCH4_xx ecc schemes
+ 14 for BCH8_xx ecc schemes
+ 26 for BCH16_xx ecc schemes
+
+ example to check for BCH16 on 2K page NAND
+ NAND_PAGESIZE = 2048
+ NAND_OOBSIZE = 64
+ 2 + (2048 / 512) * 26 = 106 > NAND_OOBSIZE
+ Thus BCH16 cannot be supported on 2K page NAND.
+
+ However, for 4K pagesize NAND
+ NAND_PAGESIZE = 4096
+ NAND_OOBSIZE = 64
+ ECC_BYTES = 26
+ 2 + (4096 / 512) * 26 = 210 < NAND_OOBSIZE
+ Thus BCH16 can be supported on 4K page NAND.
+
+
NOTE:
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projects / karo-tx-uboot.git / blobdiff