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RE: Flash infrastructure rework


Hi,

This is really great to hear.
Vivek, please let me know if I can be to any help for you (testing,
porting, .cdl-files, etc., etc.)
I'm really looking out for CFI support. The chip-mess I know :-|

Best regards,
David Marqvar

-----Original Message-----
From: Vivek Kumar [mailto:vivek@employees.org] 
Sent: 6. august 2004 19:19
To: David Marqvar (DAM); Andrew Lunn
Cc: ecos-discuss@ecos.sourceware.org; Vivek.Kumar@zeevo.com
Subject: Re: [ECOS] Flash infrastructure rework

Hi,

The exact cfi specs can be downloaded from www.jedec.com (registration
is probably required). AMD and Intel would cover all bases. SST has its
own extensions (so does Mitsubishi) but they are almost similar to the
AMD type.

The implementation is really simple, but the the real pain was  to take
care of is the 'diversions' which the vendors take and not tell you.

The things I remember offhand are

-	SST flash lists its sectors twice, so if you add all of them up 
	you get double the flash size.
-	SST also needs some extended commands to enter the CFI mode.
-	AMD extensions V1.1 and below do not tell whether its a top boot

	flash or a bottom boot and the sectors are sometime stored as 
	smallest first or the largest first. We had to read the Flash ID

	to determine what to do with the sectors.
 
and on and on and on 


At one point we were thinking why the hell did we try cfi? But having
one that I can say for sure its really good we did that. Marketing now
does not now come to me every other day asking if I can add driver
support for xxx flash, which most of the time meant reading the spec
adding another table and testing it. Whew..

-Vivek

http://www.vivekkumar.net

> -----Original Message-----
> From: David Marqvar (DAM) [mailto:DAM@tt.dk]
> Sent: Friday, August 06, 2004 6:45 AM
> To: Andrew Lunn
> Cc: ecos-discuss@ecos.sourceware.org
> Subject: RE: [ECOS] Flash infrastructure rework
> 
> 
> Sounds great.
> 
> I've been wanting to make a general flash driver based on CFI which 
> would support the two main programming algorithm's around: Intel
> (Strata) and AMD (don't know if it's really these companies that 
> invented the algorithm, anyway I think you know what I mean). Is SST 
> yet another programming algorithm or == ADM?
> 
> Though CFI I can read the physical layout of the flash and the 
> programming algorithm to use.
> This way the flash-driver could be generel, not limited to one or more

> certian devices.
> 
> Do you see any show-stoppers for creating such driver?
> 
> /David
> 
> -----Original Message-----
> From: ecos-discuss-owner@ecos.sourceware.org
> [mailto:ecos-discuss-owner@ecos.sourceware.org] On Behalf Of Andrew 
> Lunn
> Sent: 6. august 2004 15:23
> To: eCos Disuss
> Subject: Re: [ECOS] Flash infrastructure rework
> 
> > I put the code on a branch so that a few people can test it and so 
> > we get a better idea how stable the code is with hardware i don't 
> > have access to.
> 
> This is what i decided to do. In cvs there is now a branch called 
> flash_v2. If you checkout/update to that branch you will get my new 
> flash code. There is also new generic drivers for SST and Strata. 
> Since so many targets use strata i did not want to modify them all to 
> use the new driver. So the strata driver is a new packets along side 
> the old one. For the SST driver i have modified all targets that use 
> it. That was easier since only the e7t and the aim711 use this driver.
> 
> I've attached a hardware dependent driver for our platform which makes

> use of the sst and strata device. This could be used as an example as 
> to how to modify the hardware dependent part of a flash driver to use 
> the new code.
> 
> One thing to watch out for is that the hardware dependent driver has 
> to go into libextras.a. If you forget this the driver will be thrown 
> away at link time...
> 
> And lastly a warning to testers.... There could be bugs which destroy 
> your boot loader etc. Make sure you can restore the device with jtag 
> before playing with this code.
> 
>         Thanks
>                 Andrew
> 
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