| 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 AT91SAM9X5EK as an example, the board definition file likes: |
| |
| /* PMECC & PMERRLOC */ |
| #define CONFIG_ATMEL_NAND_HWECC 1 |
| #define CONFIG_ATMEL_NAND_HW_PMECC 1 |
| #define CONFIG_PMECC_CAP 2 |
| #define CONFIG_PMECC_SECTOR_SIZE 512 |