mtd: looking for serial flash storage

mtd: looking for serial flash storage

[Brendan J Simon]

I'm looking for flash storage to put Linux and a root filesystem on.  My 
embedded system is tiny (credit card size) so space is an issue.  I can 
not easily use a DiskOnChip as there are only 12 address lines from the 
CPU board connector available to me.  I am investigating serial flash 
devices.  Are there any that MTD or Linux supports ???

I know about the Atmel data flash devices.  Are they supported by Linux 
or MTD ???

I am interested in investigating the chipsets that the key ring type USB 
hard drives use.  Does anyone know what chipsets these are ?  Does MTD 
or Linux support them ???

Thanks for any advise, suggestion or pointers,
Brendan Simon.

Re: mtd: looking for serial flash storage

[David Woodhouse]

brendan.simon@bigpond.com said:
>  I can  not easily use a DiskOnChip as there are only 12 address lines
> from the  CPU board connector available to me.  I am investigating
> serial flash  devices.  Are there any that MTD or Linux supports ???

You don't need 12 address lines for a DiskOnChip, do you? 

> I know about the Atmel data flash devices.  Are they supported by
> Linux  or MTD ???

I'm not sure what devices you're referring to - do you have a reference?

> I am interested in investigating the chipsets that the key ring type
> USB  hard drives use.  Does anyone know what chipsets these are ?
> Does MTD  or Linux support them ???

The flash in those devices is generally just standard NAND flash, which is 
supported by Linux. I have no idea about the microcontrollers which are 
used to do the translation layer and emulate a hard drive.

--
dwmw2

RE: mtd: looking for serial flash storage

[Hamish Guthrie (Mail Lists)]

You need 13 address lines for a DoC (A0..A12).

There are drivers in Linux 2.4.x for Disk-on-Key (The M-Systems USB devices)


Hamish

> -----Original Message-----
> From: linux-mtd-admin@lists.infradead.org
> [mailto:linux-mtd-admin@lists.infradead.org]On Behalf Of David Woodhouse
> Sent: Monday, October 08, 2001 11:38 AM
> To: brendan.simon@bigpond.com
> Cc: mtd
> Subject: Re: mtd: looking for serial flash storage
>
>
>
> brendan.simon@bigpond.com said:
> >  I can  not easily use a DiskOnChip as there are only 12 address lines
> > from the  CPU board connector available to me.  I am investigating
> > serial flash  devices.  Are there any that MTD or Linux supports ???
>
> You don't need 12 address lines for a DiskOnChip, do you?
>
> > I know about the Atmel data flash devices.  Are they supported by
> > Linux  or MTD ???
>
> I'm not sure what devices you're referring to - do you have a reference?
>
> > I am interested in investigating the chipsets that the key ring type
> > USB  hard drives use.  Does anyone know what chipsets these are ?
> > Does MTD  or Linux support them ???
>
> The flash in those devices is generally just standard NAND flash,
> which is
> supported by Linux. I have no idea about the microcontrollers which are
> used to do the translation layer and emulate a hard drive.
>
> --
> dwmw2
>
>
>
> ______________________________________________________
> Linux MTD discussion mailing list
> http://lists.infradead.org/mailman/listinfo/linux-mtd/

Re: mtd: looking for serial flash storage

[David Woodhouse]

hamishl@dplanet.ch said:
> You need 13 address lines for a DoC (A0..A12). 

That's only for backwards-compatibility with the DiskOnChip1000 sockets.

You should be able to omit half of them - just make sure you have A11 and
A12 connected, and also the bottom six lines. 

Take a look at the addresses in include/linux/mtd/doc2000.h and observe 
that we never address the chip such that (addr & 0x7c0). So you can just 
tie those address lines (A6-A10) low from the DiskOnChip. Connect your 
CPU's A6 and A7 to the DiskOnChip's A11 and A12, and make your ReadDOC_ and 
WriteDOC_ macros use (adr & 0x3f | ((adr |0x1800)>>4) as the offset they 
use.

If you want to boot from it, then use a DiskOnChip Millennium where you can 
change its firmware to deal with this setup, and wire as many of the extra 
address lines as you can so you can use as much of the IPL SRAM as possible. 
If you're only missing one address line, you should be able to see the 
whole of the IPL SRAM without problems too - wire up A0-A9 normally, and 
A10,A11 to the DiskOnChip's A11,12. 


--
dwmw2

Re: mtd: looking for serial flash storage

[Brendan J Simon]

David Woodhouse wrote:

>hamishl@dplanet.ch said:
>
>>You need 13 address lines for a DoC (A0..A12). 
>>
>
>That's only for backwards-compatibility with the DiskOnChip1000 sockets.
>
>You should be able to omit half of them - just make sure you have A11 and
>A12 connected, and also the bottom six lines. 
>
>Take a look at the addresses in include/linux/mtd/doc2000.h and observe 
>that we never address the chip such that (addr & 0x7c0). So you can just 
>tie those address lines (A6-A10) low from the DiskOnChip. Connect your 
>CPU's A6 and A7 to the DiskOnChip's A11 and A12, and make your ReadDOC_ and 
>WriteDOC_ macros use (adr & 0x3f | ((adr |0x1800)>>4) as the offset they 
>use.
>
>If you want to boot from it, then use a DiskOnChip Millennium where you can 
>change its firmware to deal with this setup, and wire as many of the extra 
>address lines as you can so you can use as much of the IPL SRAM as possible. 
>If you're only missing one address line, you should be able to see the 
>whole of the IPL SRAM without problems too - wire up A0-A9 normally, and 
>A10,A11 to the DiskOnChip's A11,12. 
>
This is fantastic news.  I assumed that if the DOC had those address 
lines then it would need all of them.

Is this information true for the 16MB TSOP-I DOC2000 and also the 32MB 
TSOP-I DOC Millenium Plus ???  Aparently they are pin compatible and can 
be used as a drop in replacement for each other.

Thanks,
Brendan Simon.

Re: mtd: looking for serial flash storage

[David Woodhouse]

brendan.simon@bigpond.com said:
> This is fantastic news.  I assumed that if the DOC had those address
> lines then it would need all of them.

They're there for compatibility. M-Systems make sure that you can drop the 
newer devices into the same hole on your board as the older devices. If you 
skimp on the address lines because you happen to know one of their devices 
doesn't need them, don't sulk if the next one doesn't work :)

> Is this information true for the 16MB TSOP-I DOC2000 and also the 32MB
>  TSOP-I DOC Millenium Plus ???  Aparently they are pin compatible and
> can  be used as a drop in replacement for each other. 

It should be true for the DOC2000. The Millennium Plus is a different beast 
entirely, and isn't supported - we only support the Millennium. In this 
context, 'pin-compatible and can be used as a drop in replacement' means 
solely that it doesn't need more than the 13 address lines and 8 data lines 
which were specified for all the DiskOnChip family. 

I doubt the Millennium Plus actually needs the A10 line either, but it's all
academic because we can't drive it anyway - we don't have any specs for it.

--
dwmw2