[U-Boot] Question regarding FPGA firmware load in u-boot

[André Schwarz]

Dieter,

On Mon, 2009-06-22 at 08:19 +0200, Dieter Kiermaier wrote:
> André,
> 
> > Dieter,
> >
> > On Fri, 2009-06-19 at 17:46 +0200, Dieter Kiermaier wrote:
> > > Hello List,
> > >
> > > I want to boot a (Lattice) FPGA from u-boot by using Slave Serial
> > > configuration on a Marvell Kirkwood device.
> >
> > Should be no problem as long as you'll have access to GPIO.
> 
> I'm working on it :)
> But more likely I would have the SPI controller to do the serializing of the 
> bitstream. But maybe this would be the second step.

Bitbanging is not critical and works pretty fast.
You definitely have to control maximum frequency and observe errors
during load. If you'll use SPI make sure to disconnect the bus from the
FPGA and keep the config pins in a sane state.

> >
> > > As seen there is an (Xilinx and Altera) FPGA loader driver allready
> > > available in u-boot.
> > > Please can somebody explain how I have to provide a FPGA bitstream
> > > image to u-boot?
> >
> > The easiest way is to reserve some unused flash sectors and use the
> > first sector's start adress as arg for "fpga load".
> >
> 
> I assume this will only work with NOR flash, right?

I'm using NOR flash, but it will work with any adressable memory.

> If I'm using NAND flash I have to copy the image to ram first?

yes.

> 
> > > It seems I have to create a image with mkimage?

you can store e.g. fpga.bin as a single file inside jffs, read it and
load your fpga. 

> >
> > no - Lattice specififc bitstream can be stored in raw format.
> > mkimage may be useful for update, but personally I prefer update via
> > dedicated linux mtd partition.
> >
> > > This image have to be loaded into ram and the address has to be provided
> > > to the load command?
> >
> > Usually an FPGA is *very* board specific. I'd suggest to use flash and
> > create a corresponding mtd partition for linux, i.e. make it
> > maintainable.
> >

> Seems to be a good way.

yes - but not for jffs2 on NAND. You can use a plain binary file
instead.

> Is there a cmd in u-boot to read a file from a jffs2 filesystem inside a nand 
> flash partition?

Have a look at the end of common/cmd_jffs2.c : fsload is the one for
you.

> 
> > > Is there a maintainer for the FPGA code inside u-boot?
> > > I'm willing to contribute some extensions for Lattice FPGAs if I'm
> > > successful!
> >
> > excellent - all you'll need is the Lattice specific bit toggle sequence.
> >
> > submitting a proper patch will surely do.
> >
> I'm trying to get an idea what place is the best to integrate the lattice 
> architecture in to the fpga framework.
> If I have any further questions - can I ask you again?

of course, but since I'm a PowerPC user I can't tell anything specific
to ARM ...


Cheers,

André
> 
> >
> > Regards,
> >
> > André
> 
> Many thanks for helping,
> Dieter

> >
> > > Thanks to all,
> > > Dieter
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MATRIX VISION GmbH, Talstraße 16, DE-71570 Oppenweiler
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