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- How to enable PMECC(Programmable Multibit ECC) for nand on Atmel SoCs
- -----------------------------------------------------------
- 2012-08-22 Josh Wu <josh.wu@atmel.com>
- The Programmable Multibit ECC (PMECC) controller is a programmable binary
- BCH(Bose, Chaudhuri and Hocquenghem) encoder and decoder. This controller
- can be used to support both SLC and MLC NAND Flash devices. It supports to
- generate ECC to correct 2, 4, 8, 12 or 24 bits of error per sector (512 or
- 1024 bytes) of data.
- Following Atmel AT91 products support PMECC.
- - AT91SAM9X25, X35, G25, G15, G35 (tested)
- - AT91SAM9N12 (not tested, Should work)
- As soon as your nand flash software ECC works, you can enable PMECC.
- To use PMECC in this driver, the user needs to set:
- 1. the PMECC correction error bits capability: CONFIG_PMECC_CAP.
- It can be 2, 4, 8, 12 or 24.
- 2. The PMECC sector size: CONFIG_PMECC_SECTOR_SIZE.
- It only can be 512 or 1024.
- Take 'configs/at91sam9x5ek_nandflash_defconfig' as an example, the board
- configuration file has the following entries:
- CONFIG_PMECC_CAP=2
- CONFIG_PMECC_SECTOR_SIZE=512
- CONFIG_SPL_GENERATE_ATMEL_PMECC_HEADER=y
- How to enable PMECC header for direct programmable boot.bin
- -----------------------------------------------------------
- 2014-05-19 Andreas Bießmann <andreas@biessmann.org>
- The usual way to program SPL into NAND flash is to use the SAM-BA Atmel tool.
- This however is often not usable when doing field updates. To be able to
- program a SPL binary into NAND flash we need to add the PMECC header to the
- binary before. Chapter '12.4.4.1 NAND Flash Boot: NAND Flash Detection' in
- sama5d3 SoC spec (as of 03. April 2014) defines how this PMECC header has to
- look like. In order to do so we have a new image type added to mkimage to
- generate this PMECC header and integrated this into the build process of SPL.
- To enable the generation of atmel PMECC header for SPL one needs to define
- CONFIG_SPL_GENERATE_ATMEL_PMECC_HEADER. The required parameters are taken from
- board configuration and compiled into the host tools atmel_pmecc_params. This
- tool will be called in build process to parametrize mkimage for atmelimage
- type. The mkimage tool has intentionally _not_ compiled in those parameters.
- The mkimage image type atmelimage also set the 6'th interrupt vector to the
- correct value. This feature can also be used to setup a boot.bin for MMC boot.
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