doc/README.cfi

   1 The common CFI driver provides this weak default implementation for
   2 flash_cmd_reset():
   3
   4 static void __flash_cmd_reset(flash_info_t *info)
   5 {
   6         /*
   7          * We do not yet know what kind of commandset to use, so we issue
   8          * the reset command in both Intel and AMD variants, in the hope
   9          * that AMD flash roms ignore the Intel command.
  10          */
  11         flash_write_cmd(info, 0, 0, AMD_CMD_RESET);
  12         udelay(1);
  13         flash_write_cmd(info, 0, 0, FLASH_CMD_RESET);
  14 }
  15 void flash_cmd_reset(flash_info_t *info)
  16         __attribute__((weak,alias("__flash_cmd_reset")));
  17
  18 Some flash chips seem to have trouble with this reset sequence.
  19 In this case, board-specific code can override this weak default
  20 version with a board-specific function.
  21
  22 At the time of writing, there are two boards that define their own
  23 routine for this.
  24
  25 First, the digsy_mtc board equipped with the M29W128GH from Numonyx
  26 needs this version to function properly:
  27
  28 void flash_cmd_reset(flash_info_t *info)
  29 {
  30         flash_write_cmd(info, 0, 0, AMD_CMD_RESET);
  31 }
  32
  33 In addition, the t3corp board defines the routine thusly:
  34
  35 void flash_cmd_reset(flash_info_t *info)
  36 {
  37         /*
  38          * FLASH at address CONFIG_SYS_FLASH_BASE is a Spansion chip and
  39          * needs the Spansion type reset commands. The other flash chip
  40          * is located behind a FPGA (Xilinx DS617) and needs the Intel type
  41          * reset command.
  42          */
  43         if (info->start[0] == CONFIG_SYS_FLASH_BASE)
  44                 flash_write_cmd(info, 0, 0, AMD_CMD_RESET);
  45         else
  46                 flash_write_cmd(info, 0, 0, FLASH_CMD_RESET);
  47 }
  48
  49 see also:
  50 http://www.mail-archive.com/u-boot@lists.denx.de/msg24368.html
  51
  52
  53 Config Option
  54
  55   CONFIG_SYS_MAX_FLASH_SECT: Number of sectors available on Flash device
  56
  57   CONFIG_SYS_FLASH_CFI_WIDTH: Data-width of the flash device
  58
  59   CONFIG_CMD_FLASH: Enables Flash command library
  60
  61   CONFIG_FLASH_CFI_DRIVER: Enables CFI Flash driver
  62
  63   CONFIG_FLASH_CFI_MTD: Enables MTD frame work for NOR Flash devices