[flashrom] [PATCH] 4 byte address mode for Macronix MX25L25735F

[Tim Chick]

Hi David,

There was a mistake in the logic, which I have corrected.

I was also asked by someone else on the list if it worked with the MX25L25635F, which is 32Mbytes, but uses 3-byte addressing by default.

So I made the attached changes, which switch the chip to 4-byte mode. It also has some dedicated 4-byte commands, and a BAR register, but it seemed easiest to just use what I had tested for the MX25L25735F. I can’t actually test the MX25L25635F though, as I don’t have one.

Thanks,
Tim


From: David Hendricks [mailto:dhendrix at google.com]
Sent: 04 April 2016 23:21
To: Tim Chick
Cc: flashrom at flashrom.org
Subject: Re: [flashrom] [PATCH] 4 byte address mode for Macronix MX25L25735F

On Thu, Mar 31, 2016 at 8:21 AM, Tim Chick <Tim.Chick at mediatek.com<mailto:Tim.Chick at mediatek.com>> wrote:
Hi List,

Flashrom would not detect this chip. When the definition was added, everything failed as the chip only supports 4 byte address operation.

Interesting - I didn't know such chips existed. The ones I've used have backwards-compatible commands that support 3-byte addresses. FYI - Some other high-capacity chips have 4-byte address enable bit in a config register that will make the usual read/write/erase instructions accept 4 byte addresses. And yet other large chips have alternative instructions that function the same but only accept a 4-byte address.

The attached patch adds 4 byte address support for 4 byte only chips, as determined by the JEDEC flash parameter table, and support for this chip specifically.

I’ve only allowed it to work with the SPI_CONTROLLER_FT2232 controller, as that is the only one I have to test.

I’ve also only ported spi_block_erase_20 – the other block erase functions will fail.

Please let me know what you think!

Good stuff! FWIW, I have a work-in-progress patch on chromium.org<http://chromium.org> (https://chromium-review.googlesource.com/#/c/323359/) for the other types of high-capacity flash chips. I've tested on a Spansion S25FS256 using linux_spi and ft2232. It needs a lot of clean-up, but might be of help. Most of the changes were to convert read/write/erase functions to use allocated buffers whose length depends on whether we're using a 3- or 4-byte address.

I'll borrow some ideas from your patch as well to support the "4-byte address only" chips.

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