On 04/11/2013 12:20 PM, Marek Vasut wrote:
Dear Mike Dunn,
A quick overview of u-boot implementation on the treo 680...
The treo 680 has a Diskonchip G4 nand flash chip. This device has a 2k region that maps to the system bus at the reset vector in a NOR-like fashion so that it can be used as the boot device. The phone is shipped with this 2k region configured as write-protected (can't be modified) and programmed with an initial program loader (IPL). At power-up, this IPL loads the contents of two flash blocks to SDRAM and jumps to it. The capacity of the two blocks is not large enough to hold all of u-boot, so a u-boot SPL is used. To conserve flash space, these two blocks and the necessary number of subsequent blocks are programmed with a concatenated spl + u-boot image. That way, the IPL will also load a portion of u-boot proper, and when the spl runs, it relocates the portion of u-boot that the IPL has already loaded, and then resumes loading the remaining part of u-boot before jumping to it.
The default_environment is used (CONFIG_ENV_IS_NOWHERE) because I didn't think that having a writable environment was worth the cost of a flash block, although adding it would be straightforward. I abuse the CONFIG_EXTRA_ENV_SETTINGS option to specify the usbtty for the console (CONFIG_SYS_CONSOLE_IS_IN_ENV).
Support for the LCD is included, but currently it is only useful for displaying the u-boot splash screen. But if u-boot is built without the usbtty console, it does display the auto-boot progress nicely.
Signed-off-by: Mike Dunn mikedunn@newsguy.com
I think the tool shall really go as a separate patch. Besides, can the tool not be implemented as a part of u-boot's mkimage infrastructure?
OK, I can make the flash_u-boot utility (which writes u-boot to the flash boot blocks) a separate patch.
As for making it part of mkimage... I didn't really consider that because based on my (limited) knowledge, I figured they are unrelated. As I understand it, mkimage creates an OS image file that u-boot can parse and load. flash_u-boot is a utility that performs the task of writing u-boot itself to flash.
I figured that mine was a special case, since u-boot must be written in a special format (redundant pages) and in a special manner (alternate 4k regions skipped), with the flash device in a special mode, and so it can not be done in the normal manner; e.g., 'nandwrite' from mtd-utils, or its u-boot 'nand write' equivalent, even if you first ran the u-boot image through a separate utility that simply converted the format of the image.
Hope that makes sense. Any insight appreciated. I'll take a look at what's in the tools directory.
Thanks Marek, Mike