[U-Boot] [ANNOUNCE] DATAFLASH DRIVER

[Ulf Samuelsson]

ons 2009-01-07 klockan 21:56 +0100 skrev Jean-Christophe
PLAGNIOL-VILLARD:
> Hi,
> 
> 	The AT91 arch use a at45 driver design to be show as a parallel flash
> 	but it's a spi flash.
> 
> 	Haavard add a new spi flash framework which support the dataflash
> 	so the current driver is mark as *depracated* and plan to be remove

There is very limited support for the flash in the new spi driver.
so most things you would like to do with a flash is not supported

I would like to have capabilities to

1) print contents of the dataflash
2) compare contents of the dataflash with SDRAM.
3) Automatically add a CRC when the dataflash is written
	based on an environment variable "crc-check"
4) Verify that the CRC is correct.
5) high granularity read/writes
	The dataflash can easily support byte write.
6) Support partitions for 
	bootstrap
	environemnt
	u-boot
	kernel
	filesystem
   in the boot dataflash.
   additional dataflash should have other partitions.
7) protection of partitions.

I have my own patches for the memory commands
to enable most of this but adding that to the
cmd_mem driver was not accepted.
At that time it was promised that the new driver
will not limit the functionality, and would
only remove the use of direct addressing to the dataflash.

The whole storage concept is really not working
when storage becomes larger than the SDRAM.

How do you download an 128 MB image over the network
to a machine with 64 MB SDRAM. - Major pain...
You need to be able to TFTP to flash directly
if you want to have an easy user interface.

That is likely to require another way of handling storage.
and parameter parsing so you can do
tftp mmc0:kernel linux-2.6.28
or
tftp df3:fs rootfs.arm.ext2

The tftp can then write incoming packets to a caching driver
and will delay fetching new packets when waiting for flash
writes  to complete. Whn your storage is handled
by a DMA controller, you should be able to implement
this nicely.



> 	New board and cpu must use the new framework
> 
> 	Only justify exception will be ack
> 
> 	The actual only exception will the at91rm9200ek and bug fix
> 
> Best Regards,
> J.
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