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Wu, Joshbdfd59a2012-08-23 00:05:36 +00001How to enable PMECC(Programmable Multibit ECC) for nand on Atmel SoCs
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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.
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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.
Wu, Joshbdfd59a2012-08-23 00:05:36 +000022
Derald D. Woods49ad4022018-12-15 01:36:46 -060023Take 'configs/at91sam9x5ek_nandflash_defconfig' as an example, the board
24configuration file has the following entries:
Wu, Joshbdfd59a2012-08-23 00:05:36 +000025
Derald D. Woods49ad4022018-12-15 01:36:46 -060026 CONFIG_PMECC_CAP=2
27 CONFIG_PMECC_SECTOR_SIZE=512
28 CONFIG_SPL_GENERATE_ATMEL_PMECC_HEADER=y
Andreas Bießmann5c390a52014-05-19 14:23:40 +020029
30How to enable PMECC header for direct programmable boot.bin
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Andreas Bießmann09c2b8f2016-05-01 03:46:16 +0200322014-05-19 Andreas Bießmann <andreas@biessmann.org>
Andreas Bießmann5c390a52014-05-19 14:23:40 +020033
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
Derald D. Woods49ad4022018-12-15 01:36:46 -060042To enable the generation of atmel PMECC header for SPL one needs to define
Andreas Bießmann5c390a52014-05-19 14:23:40 +020043CONFIG_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.