1How to enable PMECC(Programmable Multibit ECC) for nand on Atmel SoCs 2----------------------------------------------------------- 32012-08-22 Josh Wu <josh.wu@atmel.com> 4 5The Programmable Multibit ECC (PMECC) controller is a programmable binary 6BCH(Bose, Chaudhuri and Hocquenghem) encoder and decoder. This controller 7can be used to support both SLC and MLC NAND Flash devices. It supports to 8generate ECC to correct 2, 4, 8, 12 or 24 bits of error per sector (512 or 91024 bytes) of data. 10 11Following Atmel AT91 products support PMECC. 12- AT91SAM9X25, X35, G25, G15, G35 (tested) 13- AT91SAM9N12 (not tested, Should work) 14 15As soon as your nand flash software ECC works, you can enable PMECC. 16 17To use PMECC in this driver, the user needs to set: 18 1. the PMECC correction error bits capability: CONFIG_PMECC_CAP. 19 It can be 2, 4, 8, 12 or 24. 20 2. The PMECC sector size: CONFIG_PMECC_SECTOR_SIZE. 21 It only can be 512 or 1024. 22 23Take 'configs/at91sam9x5ek_nandflash_defconfig' as an example, the board 24configuration file has the following entries: 25 26 CONFIG_PMECC_CAP=2 27 CONFIG_PMECC_SECTOR_SIZE=512 28 CONFIG_SPL_GENERATE_ATMEL_PMECC_HEADER=y 29 30How to enable PMECC header for direct programmable boot.bin 31----------------------------------------------------------- 322014-05-19 Andreas Bießmann <andreas@biessmann.org> 33 34The usual way to program SPL into NAND flash is to use the SAM-BA Atmel tool. 35This however is often not usable when doing field updates. To be able to 36program a SPL binary into NAND flash we need to add the PMECC header to the 37binary before. Chapter '12.4.4.1 NAND Flash Boot: NAND Flash Detection' in 38sama5d3 SoC spec (as of 03. April 2014) defines how this PMECC header has to 39look like. In order to do so we have a new image type added to mkimage to 40generate this PMECC header and integrated this into the build process of SPL. 41 42To enable the generation of atmel PMECC header for SPL one needs to define 43CONFIG_SPL_GENERATE_ATMEL_PMECC_HEADER. The required parameters are taken from 44board configuration and compiled into the host tools atmel_pmecc_params. This 45tool will be called in build process to parametrize mkimage for atmelimage 46type. The mkimage tool has intentionally _not_ compiled in those parameters. 47 48The mkimage image type atmelimage also set the 6'th interrupt vector to the 49correct value. This feature can also be used to setup a boot.bin for MMC boot. 50