+ CONFIG_SYS_NAND_SELF_INIT
+ Traditionally, glue code in drivers/mtd/nand/nand.c has driven
+ the initialization process -- it provides the mtd and nand
+ structs, calls a board init function for a specific device,
+ calls nand_scan(), and registers with mtd.
+
+ This arrangement does not provide drivers with the flexibility to
+ run code between nand_scan_ident() and nand_scan_tail(), or other
+ deviations from the "normal" flow.
+
+ If a board defines CONFIG_SYS_NAND_SELF_INIT, drivers/mtd/nand/nand.c
+ will make one call to board_nand_init(), with no arguments. That
+ function is responsible for calling a driver init function for
+ each NAND device on the board, that performs all initialization
+ tasks except setting mtd->name, and registering with the rest of
+ U-Boot. Those last tasks are accomplished by calling nand_register()
+ on the new mtd device.
+
+ Example of new init to be added to the end of an existing driver
+ init:
+
+ /*
+ * devnum is the device number to be used in nand commands
+ * and in mtd->name. Must be less than
+ * CONFIG_SYS_NAND_MAX_DEVICE.
+ */
+ mtd = &nand_info[devnum];
+
+ /* chip is struct nand_chip, and is now provided by the driver. */
+ mtd->priv = &chip;
+
+ /*
+ * Fill in appropriate values if this driver uses these fields,
+ * or uses the standard read_byte/write_buf/etc. functions from
+ * nand_base.c that use these fields.
+ */
+ chip.IO_ADDR_R = ...;
+ chip.IO_ADDR_W = ...;
+
+ if (nand_scan_ident(mtd, CONFIG_SYS_MAX_NAND_CHIPS, NULL))
+ error out
+
+ /*
+ * Insert here any code you wish to run after the chip has been
+ * identified, but before any other I/O is done.
+ */
+
+ if (nand_scan_tail(mtd))
+ error out
+
+ if (nand_register(devnum))
+ error out
+
+ In addition to providing more flexibility to the driver, it reduces
+ the difference between a U-Boot driver and its Linux counterpart.
+ nand_init() is now reduced to calling board_nand_init() once, and
+ printing a size summary. This should also make it easier to
+ transition to delayed NAND initialization.
+
+ 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.
+
+
+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.
+
+
+ CONFIG_NAND_OMAP_GPMC_PREFETCH
+ On OMAP platforms that use the GPMC controller
+ (CONFIG_NAND_OMAP_GPMC_PREFETCH), this options enables the code that
+ uses the prefetch mode to speed up read operations.
projects / karo-tx-uboot.git / blobdiff