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Diffstat (limited to 'roms/u-boot/doc/README.cfi')
-rw-r--r-- | roms/u-boot/doc/README.cfi | 63 |
1 files changed, 63 insertions, 0 deletions
diff --git a/roms/u-boot/doc/README.cfi b/roms/u-boot/doc/README.cfi new file mode 100644 index 000000000..ad5285081 --- /dev/null +++ b/roms/u-boot/doc/README.cfi @@ -0,0 +1,63 @@ +The common CFI driver provides this weak default implementation for +flash_cmd_reset(): + +static void __flash_cmd_reset(flash_info_t *info) +{ + /* + * We do not yet know what kind of commandset to use, so we issue + * the reset command in both Intel and AMD variants, in the hope + * that AMD flash roms ignore the Intel command. + */ + flash_write_cmd(info, 0, 0, AMD_CMD_RESET); + udelay(1); + flash_write_cmd(info, 0, 0, FLASH_CMD_RESET); +} +void flash_cmd_reset(flash_info_t *info) + __attribute__((weak,alias("__flash_cmd_reset"))); + +Some flash chips seem to have trouble with this reset sequence. +In this case, board-specific code can override this weak default +version with a board-specific function. + +At the time of writing, there are two boards that define their own +routine for this. + +First, the digsy_mtc board equipped with the M29W128GH from Numonyx +needs this version to function properly: + +void flash_cmd_reset(flash_info_t *info) +{ + flash_write_cmd(info, 0, 0, AMD_CMD_RESET); +} + +In addition, the t3corp board defines the routine thusly: + +void flash_cmd_reset(flash_info_t *info) +{ + /* + * FLASH at address CONFIG_SYS_FLASH_BASE is a Spansion chip and + * needs the Spansion type reset commands. The other flash chip + * is located behind a FPGA (Xilinx DS617) and needs the Intel type + * reset command. + */ + if (info->start[0] == CONFIG_SYS_FLASH_BASE) + flash_write_cmd(info, 0, 0, AMD_CMD_RESET); + else + flash_write_cmd(info, 0, 0, FLASH_CMD_RESET); +} + +see also: +http://www.mail-archive.com/u-boot@lists.denx.de/msg24368.html + + +Config Option + + CONFIG_SYS_MAX_FLASH_SECT: Number of sectors available on Flash device + + CONFIG_SYS_FLASH_CFI_WIDTH: Data-width of the flash device + + CONFIG_CMD_FLASH: Enables Flash command library + + CONFIG_FLASH_CFI_DRIVER: Enables CFI Flash driver + + CONFIG_FLASH_CFI_MTD: Enables MTD frame work for NOR Flash devices |