Configuring the Flash driver (MTD)

The ST Linux rel. 2.0 provides, for each supported platform, a default kernel configuration file, which guarantee a proper Flash device setup. Assuming a standard STM platform the user is not required to take any specific action. However, since the MTD configuration in ST Linux Rel. 2.0 leads some minor differences with the previous release (1.0), and to make the task as easiest as possible, below is reported a quick list of all the actions required to properly configure the MTD.

Enter the `Device Driver' and `Memory Technology Devices (MTD)' submenus and enables:

• The MTD itself (CONFIG_MTD).
• Support for FLASH partitioning and partitioning stile are recommended:
  • `MTD partitioning support' (CONFIG_MTD_PARTITIONS)
  • the `Command line partition table parsing' provides an easy and flexible way to partition the Flash.
• Both access type: `Direct char device access' (CONFIG_MTD_CHAR) and `Caching block device access' (CONFIG_MTD_BLOCK) have to be enabled to allow respectively a direct FLASH access (read, write and erase) and the JFFS or JFFS2 to be used.
• Choose the `RAM/ROM/Flash chip driver' you will be using. This is dictated by which devices are present on the target board. There are two aspects to this:
  1. How MTD should probe for Flash chips: so far the ST Linux Rel. 2 supports STM platforms equipped by FLASH devices which accept the detection via Common Flash Interface (CFI) (CONFIG_MTD_CFI)
  2. Which command set should be used to program the devices. This is largely based on which company manufactured the Flash, so either 'Support for Intel/Sharp flash chips' (CONFIG_MTD_CFI_INTELEXT) (which supports CFI command set 0001) or 'Support for AMD/Fujitsu flash chips' (CONFIG_MTD_CFI_AMDSTD) (which supports CFI command set 0002) needs to be selected.
• Enable the `Flash chip driver advanced configuration options' and disable 'Support 1-chip flash interleave' (CONFIG_MTD_CFI_I1) if your platform has two or more Flash chips (example: Espresso). It must be ON in case of only one Flash chip is present.
• The last setting concerns the chip mapping. All the ST evaluation boards supported by ST Linux Rel. 2 share a common mapping driver: `CFI Flash device mapped on STMicroelectronics ST40 boards' (CONFIG_MTD_STBOARDS). Flash on STEM are no longer supported nor tested.

For an exhaustive explanation of the MTD technology please refer the Getting Started MTD chapter.