[U-Boot-Users] CFI support for flash with hardware write-protect.

We have a built a custom board with onboard flash and using CFI. Our design supports a jumper that enables hardware write-protection on the flash, but u-boot will not come up with the jumper installed. It fails due to code in drivers/cfi_flash.c that must write a command word to detect the flash configuration.
Is there an elegant way to override the CFI discovery process, prefilling flash_info[] with the details of our flash hardware? Our board will boot if we hardcode our flash settings and bypass auto-detection, but I was wondering if somebody has a patch to cfi_flash.c to do it through configuration parameters.
In case you are wondering, we cannot use software write-protect because our equipment must conform with a security directive from the U.S. Department of Defense, paraphrased: "There shall be no user-modifiable, non-removable, persistent storage." The onboard flash cannot be removed from the unit, and therefore may not be allowed to be written by an operator (e.g., by stopping in u-boot). Forcing somebody to disassemble the unit to switch a jumper is apparently acceptable to the security guys.
Thanks,
Ed Jubenville

Hi Ed,
On Friday 29 June 2007, Edward Jubenville wrote:
We have a built a custom board with onboard flash and using CFI. Our design supports a jumper that enables hardware write-protection on the flash, but u-boot will not come up with the jumper installed. It fails due to code in drivers/cfi_flash.c that must write a command word to detect the flash configuration.
Is there an elegant way to override the CFI discovery process, prefilling flash_info[] with the details of our flash hardware?
No, there is no elegant method for this right now. But I'm wondering why your board crashes upon writes. You seem to have disabled writes in the chip selects, correct? Why did you have to do this?
Best regards, Stefan
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participants (2)
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Edward Jubenville
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Stefan Roese