Re: [microblaze-uclinux] Storage Device Driver Development

[John Williams <jwilliams@xxxxxxxxxxxxxx>]

Hi Rudi,

Rudolf Usselmann wrote:

> On Tue, 2005-05-10 at 07:27 +0100, Aurash wrote:
> 
>>I have a driver (block) which works with MMC card, in a Microblaze 
>>sytem, conected on opb with the opb_spi core, The card can be mounted as 
>>a dos (FAT) drive and it performs read write.
>>Aurash
> 
> Our IP Core does all the low level protocols in Hardware. The
> cards come up as memory mapped. It will automatically select
> the highest supported protocol, up to 8 bit for the new MMC
> cards. I have written a boot loader based on the xilinx fat
> fs libraries - basically just writing a read_sector function
> and than opening a file using the xilinx library and copying
> the file to SDRAM and executing it. Very trivial.

There are two approaches I would consider here - the first is to take an 
existing MMC driver and port it into uClinux and across to your 
hardware.  This would use the native MMC command set, and is probably 
the most portable.  I know of at least two - there is one in the ARM 
linux tree, and another in celinux.

The 2nd approach is to use the MTD driver/device layer, which could make 
use of your memory mapped IO capability.  For example, the Disk-on-Chip 
(DOC) devices are supported in this manner.

Of course, cost and time are always factors, but you want to be careful 
of the quick hack - time saved now may cost you later.

Cheers,

John




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