Message-ID: <87eehj3nd5.fsf@figgyc.uk>
Date:   Sat, 13 Feb 2021 17:10:14 +0000
From:   George Brooke <figgyc@...gyc.uk>
To:     Tudor.Ambarus@...rochip.com
Cc:     miquel.raynal@...tlin.com, richard@....at, vigneshr@...com,
        linux-kernel@...r.kernel.org, linux-mtd@...ts.infradead.org
Subject: Re: [PATCH] mtd: spi-nor: boya: add support for boya by25q128as

Hello Tudor,

Tudor.Ambarus@...rochip.com writes:

> Hi, George,
>
> On 2/7/21 2:30 PM, George Brooke wrote:
>> EXTERNAL EMAIL: Do not click links or open attachments unless 
>> you know the content is safe
>>
>> Adds support for the Boya Microelectronics BY25Q128AS 128 Mbit 
>> flash.
>> I tested this on the Creality WB-01 embedded device which uses 
>> this,
>> although that was with OpenWrt which is still using 5.4 so I 
>> had to
>> do a bit of porting work. Don't see how that would make much of 
>> a
>> difference though.
>>
>> Signed-off-by: George Brooke <figgyc@...gyc.uk>
>> ---
>>  drivers/mtd/spi-nor/Makefile |  1 +
>>  drivers/mtd/spi-nor/boya.c   | 23 +++++++++++++++++++++++
>>  drivers/mtd/spi-nor/core.c   |  1 +
>>  drivers/mtd/spi-nor/core.h   |  1 +
>>  4 files changed, 26 insertions(+)
>>  create mode 100644 drivers/mtd/spi-nor/boya.c
>>
>> diff --git a/drivers/mtd/spi-nor/Makefile 
>> b/drivers/mtd/spi-nor/Makefile
>> index 653923896205..7d1551fbfbaa 100644
>> --- a/drivers/mtd/spi-nor/Makefile
>> +++ b/drivers/mtd/spi-nor/Makefile
>> @@ -2,6 +2,7 @@
>>
>>  spi-nor-objs                   := core.o sfdp.o
>>  spi-nor-objs                   += atmel.o
>> +spi-nor-objs                   += boya.o
>>  spi-nor-objs                   += catalyst.o
>>  spi-nor-objs                   += eon.o
>>  spi-nor-objs                   += esmt.o
>> diff --git a/drivers/mtd/spi-nor/boya.c 
>> b/drivers/mtd/spi-nor/boya.c
>> new file mode 100644
>> index 000000000000..014b0087048a
>> --- /dev/null
>> +++ b/drivers/mtd/spi-nor/boya.c
>> @@ -0,0 +1,23 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * Copyright (C) 2005, Intec Automation Inc.
>> + * Copyright (C) 2014, Freescale Semiconductor, Inc.
>> + */
>> +
>> +#include <linux/mtd/spi-nor.h>
>> +
>> +#include "core.h"
>> +
>> +static const struct flash_info boya_parts[] = {
>> +       /* Boya */
>> +       { "by25q128as", INFO(0x684018, 0, 64 * 1024, 256,
>
> The manufacturer’s identification code is defined by one or more
> eight (8) bit fields each consisting of seven (7) data bits plus 
> one (1)
> odd parity bit. It is a single field limiting the possible 
> number of
> vendors to 126. To expand the maximum number of identification 
> codes a
> continuation scheme has been defined.
>
> According to JEP106BA, the manufacturer ID for Boya should be 
> preceded by
> eight continuation codes. So I would expect the manufacturer ID 
> for this
> flash to be: 0x7f, 0x7f, 0x7f, 0x7f, 0x7f, 0x7f, 0x7f, 0x7f, 
> 0x68.
>
> Without the continuation codes, we will have collisions between
> manufacturer IDs, Convex Computer being an example.
>
> I see that the datasheet [1] for this flash doesn't specify 
> anything
> about the continuation codes, so I suspect that Boya just got it 
> wrong.

It appears you are right. I thought it would be the best idea to 
actually
interact with the flash chip and read its responses, so I found a 
tool
called spincl [2] to send some commands to it with a Raspberry Pi:

$ spincl -ib -m0 -c0 -s0 -p0 6 0x90
0x00 0x00 0x00 0x00 0x68 0x17
$ spincl -ib -m0 -c0 -s0 -p0 4 0x9F
0x00 0x68 0x40 0x18
and indeed there doesn't seem to be any continuation codes.

> We'll have to check other datasheets from Boya and see if they 
> got
> their manufacturer ID wrong for all their flashes. We'll have to 
> add

The BY25Q64AS [3] appears to be described similarly.

> some fixup mechanism for the manufacturers ID handling, in order 
> to
> avoid collisions with other manufacturers IDs.

I looked into this a bit more, and what I'm realising is that I'm 
not sure if
there even is any mechanism to deliver the continuation codes 
within the
base SPI-NOR standard? Take esmt.c: the f25l32qa has a device id 
0x8c4116.
JEP106BA attribytes 8c to Monolithic Memories in the first bank, 
while
Elite Flash Storage (presumably an alias of ESMT) should be 
identifying
as 0x7f, 0x7f, 0x7f, 0x8c. Its datasheet [4] appears to be equally 
sparse on
detail. To my untrained eye, this seems to be the exact same 
situation we
find ourselves in here. (You probably know a lot more about this 
then I do -
if I'm wrong do point it out!)

That said I can't seem to find any formalised definition of what 
the 0x90
"manufacturer and device ID" command is actually supposed to do in 
the case of
a manufacturer ID that isn't in the first bank. Likewise with 0x9f 
"JEDEC ID".
Do you know of any flashes made by companies not in the first bank 
that
identify themselves correctly?

As far as I can tell the only proper method available is in SFDP, 
where the
Parameter ID of a vendor specific table would be the bank number 
in the MSB
and the actual manufacturer code in the LSB. However, this is a 
very
over-engineered solution, wouldn't work on devices with no vendor 
specific
tables, and in this case, I couldn't even get the SFDP table to 
read out of
the by25q128as at all:
$ spincl -ib -m0 -c0 -s0 -p0 32 0x5A
0x00 0x00 0x00 0x00 0x00 0xff 0xff 0xff 0xff 0xff 0xff 0xff 0xff 
0xff 0xff ...
(This may very well be a peculiarity of the way I'm accessing it, 
but in any
case I don't think this fix would be a very good idea.)

I'm not sure what would actually make a good fixup in this 
scenario. We'd need
something that could differentiate a Boya chip from any other 
hypothetical
0x68 manufacturer flash.
Maybe even the missing SFDP output would make a good detection 
routine, but
that would need testing with a better SPI inspection method and 
across multiple
flash chips because I doubt that's intentional - surely if SFDP 
didn't work it
would just not be described in the datasheet. Probably better to 
think of
something other than that though.

Thanks,
figgyc

[2] https://github.com/CrosseyeJack/spincl
[3] 
https://datasheet.lcsc.com/szlcsc/1904091402_BOYAMICRO-BY25Q64ASSIG_C383793.pdf
[4] 
https://www.esmt.com.tw/upload/pdf/ESMT/datasheets/F25L32QA.pdf

>
> Cheers,
> ta
>
> [1] 
> https://datasheet.lcsc.com/szlcsc/1904091402_BOYAMICRO-BY25Q128ASSIG_C383794.pdf
>
>> +                       SECT_4K | SPI_NOR_DUAL_READ | 
>> SPI_NOR_QUAD_READ |
>> +                       SPI_NOR_HAS_LOCK | SPI_NOR_HAS_TB)
>> +       },
>> +};
>> +
>> +const struct spi_nor_manufacturer spi_nor_boya = {
>> +       .name = "boya",
>> +       .parts = boya_parts,
>> +       .nparts = ARRAY_SIZE(boya_parts),
>> +};
>> diff --git a/drivers/mtd/spi-nor/core.c 
>> b/drivers/mtd/spi-nor/core.c
>> index 20df44b753da..4d0d003e9c3f 100644
>> --- a/drivers/mtd/spi-nor/core.c
>> +++ b/drivers/mtd/spi-nor/core.c
>> @@ -2160,6 +2160,7 @@ int spi_nor_sr2_bit7_quad_enable(struct 
>> spi_nor *nor)
>>
>>  static const struct spi_nor_manufacturer *manufacturers[] = {
>>         &spi_nor_atmel,
>> +       &spi_nor_boya,
>>         &spi_nor_catalyst,
>>         &spi_nor_eon,
>>         &spi_nor_esmt,
>> diff --git a/drivers/mtd/spi-nor/core.h 
>> b/drivers/mtd/spi-nor/core.h
>> index d631ee299de3..d5ed5217228b 100644
>> --- a/drivers/mtd/spi-nor/core.h
>> +++ b/drivers/mtd/spi-nor/core.h
>> @@ -409,6 +409,7 @@ struct spi_nor_manufacturer {
>>
>>  /* Manufacturer drivers. */
>>  extern const struct spi_nor_manufacturer spi_nor_atmel;
>> +extern const struct spi_nor_manufacturer spi_nor_boya;
>>  extern const struct spi_nor_manufacturer spi_nor_catalyst;
>>  extern const struct spi_nor_manufacturer spi_nor_eon;
>>  extern const struct spi_nor_manufacturer spi_nor_esmt;
>> --
>> 2.30.0
>>

Powered by blists - more mailing lists