[flashrom] Programming N25Q256 ?

[David Hendricks]

On Wed, Mar 30, 2016 at 3:14 PM, Steve Miller <stevem at tanisys.com> wrote:

> Hi,
>
>
>
> I have the code built and running on a Raspberry PI.  Unfortunately, the
> target part I am trying to program is a Micron N25Q256.  I don’t see that
> part in the list.   When I execute the program with –VV   it seems to scan
> lots of devices.  I see activity on CLK, CS, MOSI with an oscilloscope.
> But MISO remains logic low.   When the program terminates,  it just tells
> me No EEPROM/Flash device found.
>
>
>
> Stupid Noob Questions:
>
> 1.        Is the static level on MISO to be expected?  Or should it at
> least toggle?
>
You should definitely see some activity on MISO. Flashrom sends
identification instructions (RDID, REMS, etc) to the chip and the chip
should respond with its JEDEC-assigned manufacturer ID and vendor-specific
device info.

That said, the N25Q256 is not currently added in upstream flashrom. There
is limited support in the Chromium branch, though.

> 2.        Is there any hope with this device?    Can I perhaps force it
> to think the chip is smaller?
>
Yep, that's what we currently do in the Chromium branch*. The chip uses
24-bit addresses unless either a bit in a nonvolatile config register is
set or alternate instructions which accept 32-bit addresses are used.

*Full 4-byte address support should be ready soon, I just need to find a
few spare cycles to finish up what I have written...

-- 
David Hendricks (dhendrix)
Systems Software Engineer, Google Inc.
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