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 AT91SAM9X5EK as an example, the board definition file likes: 24 25/* PMECC & PMERRLOC */ 26#define CONFIG_ATMEL_NAND_HWECC 1 27#define CONFIG_ATMEL_NAND_HW_PMECC 1 28#define CONFIG_PMECC_CAP 2 29#define CONFIG_PMECC_SECTOR_SIZE 512 30 31How to enable PMECC header for direct programmable boot.bin 32----------------------------------------------------------- 332014-05-19 Andreas Bießmann <andreas.devel@googlemail.com> 34 35The usual way to program SPL into NAND flash is to use the SAM-BA Atmel tool. 36This however is often not usable when doing field updates. To be able to 37program a SPL binary into NAND flash we need to add the PMECC header to the 38binary before. Chapter '12.4.4.1 NAND Flash Boot: NAND Flash Detection' in 39sama5d3 SoC spec (as of 03. April 2014) defines how this PMECC header has to 40look like. In order to do so we have a new image type added to mkimage to 41generate this PMECC header and integrated this into the build process of SPL. 42 43To enable the generation of atmel PMECC header for SPL one need to define 44CONFIG_SPL_GENERATE_ATMEL_PMECC_HEADER. The required parameters are taken from 45board configuration and compiled into the host tools atmel_pmecc_params. This 46tool will be called in build process to parametrize mkimage for atmelimage 47type. The mkimage tool has intentionally _not_ compiled in those parameters. 48 49The mkimage image type atmelimage also set the 6'th interrupt vector to the 50correct value. This feature can also be used to setup a boot.bin for MMC boot. 51