Re: [Qemu-devel] SPI EEPROM device model

[Peter Crosthwaite]

On Mon, Nov 30, 2015 at 12:53 AM, Krzeminski, Marcin (Nokia -
PL/Wroclaw)  wrote:
> Hello,
>
> I need to write some SPI eeprom device model (probably AT25128B or AT93C56).
> I can not see any such device in qemu, but this time I want to ask before I 
> start to implement,
> if something that can speed up work is already present somewhere ?
> Maybe do you have some preferences which eeprom device is better to have in 
> qemu?
>

So some of those EEPROM devices are nearly identical to M25P80 in
functionality, the main difference being that individual cells can be
programmed from 0 back to 1. A quick look at a AT25128B datasheet
looks like this may be the case. Read and write instructions as the
same encoding as M25P80.

Search m25p80 for WR_1, which is a flag you can set that allows write
of 1 to individual bits. I think can become a feature of M25P80 (more
table entries) if the basic instructions are just an M25P80 subset.

HTH

Regards,
Peter

> Regards,
> Marcin

Re: [Qemu-devel] SPI EEPROM device model

[Krzeminski, Marcin (Nokia - PL/Wroclaw)]

> -Original Message-
> From: EXT Peter Crosthwaite [mailto:crosthwaitepe...@gmail.com]
> Sent: Monday, November 30, 2015 7:45 PM
> To: Krzeminski, Marcin (Nokia - PL/Wroclaw)
> Cc: qemu-devel@nongnu.org
> Subject: Re: SPI EEPROM device model
> 
> On Mon, Nov 30, 2015 at 12:53 AM, Krzeminski, Marcin (Nokia -
> PL/Wroclaw)  wrote:
> > Hello,
> >
> > I need to write some SPI eeprom device model (probably AT25128B or
> AT93C56).
> > I can not see any such device in qemu, but this time I want to ask
> > before I start to implement, if something that can speed up work is already
> present somewhere ?
> > Maybe do you have some preferences which eeprom device is better to
> have in qemu?
> >
> 
> So some of those EEPROM devices are nearly identical to M25P80 in
> functionality, the main difference being that individual cells can be
> programmed from 0 back to 1. A quick look at a AT25128B datasheet looks
> like this may be the case. Read and write instructions as the same encoding
> as M25P80.
> 
> Search m25p80 for WR_1, which is a flag you can set that allows write of 1 to
> individual bits. I think can become a feature of M25P80 (more table entries) 
> if
> the basic instructions are just an M25P80 subset.
> 
The goal of my question was to be sure that there is no such device model 
implemented somewhere.
I target to extend M25P80 with some eeprom device, will see if this make sense.

Thanks,
Marcin

> HTH
> 
> Regards,
> Peter
> 
> > Regards,
> > Marcin

Re: [Qemu-devel] SPI EEPROM device model

[Peter Crosthwaite]

On Mon, Nov 30, 2015 at 11:43 AM, Krzeminski, Marcin (Nokia -
PL/Wroclaw)  wrote:
>
>
>> -Original Message-
>> From: EXT Peter Crosthwaite [mailto:crosthwaitepe...@gmail.com]
>> Sent: Monday, November 30, 2015 7:45 PM
>> To: Krzeminski, Marcin (Nokia - PL/Wroclaw)
>> Cc: qemu-devel@nongnu.org
>> Subject: Re: SPI EEPROM device model
>>
>> On Mon, Nov 30, 2015 at 12:53 AM, Krzeminski, Marcin (Nokia -
>> PL/Wroclaw)  wrote:
>> > Hello,
>> >
>> > I need to write some SPI eeprom device model (probably AT25128B or
>> AT93C56).
>> > I can not see any such device in qemu, but this time I want to ask
>> > before I start to implement, if something that can speed up work is already
>> present somewhere ?
>> > Maybe do you have some preferences which eeprom device is better to
>> have in qemu?
>> >
>>
>> So some of those EEPROM devices are nearly identical to M25P80 in
>> functionality, the main difference being that individual cells can be
>> programmed from 0 back to 1. A quick look at a AT25128B datasheet looks
>> like this may be the case. Read and write instructions as the same encoding
>> as M25P80.
>>
>> Search m25p80 for WR_1, which is a flag you can set that allows write of 1 to
>> individual bits. I think can become a feature of M25P80 (more table entries) 
>> if
>> the basic instructions are just an M25P80 subset.
>>
> The goal of my question was to be sure that there is no such device model 
> implemented somewhere.
> I target to extend M25P80 with some eeprom device, will see if this make 
> sense.
>

Ok not that I know of beyond the WR_1 support. When I did this, it was
as simple as a table entry with WR_1 to at least be good enough for
the task at hand.

Regards,
Peter

> Thanks,
> Marcin
>
>> HTH
>>
>> Regards,
>> Peter
>>
>> > Regards,
>> > Marcin

[Qemu-devel] SPI EEPROM device model

[Krzeminski, Marcin (Nokia - PL/Wroclaw)]

Hello,

I need to write some SPI eeprom device model (probably AT25128B or AT93C56).
I can not see any such device in qemu, but this time I want to ask before I 
start to implement,
if something that can speed up work is already present somewhere ?
Maybe do you have some preferences which eeprom device is better to have in 
qemu?

Regards,
Marcin