[U-Boot-Users] nand flash controller on 440ep/epx

[Stefan Roese <sr@denx.de>]

On Monday 09 October 2006 16:15, Jeff Mann wrote:
> That would work. Is simple, and would work for initialization. It would
> involve using a proper mask for nand_baseaddr[..] when setting the
> location of the nand read/write/control registers to ignore the CS data.

OK.

> Nand_init(...) calls nand_init_chip(...) which then calls
> board_nand_init(...)
> I think the most appropriate place to select the proper Chip select is
> in the board_nand_init() function.

No. It should be a function called from the following functions:
- board_nand_init()
- do_nand() (in the "device" part)

Something like:

void nand_select_chip(struct nand_chip *nand)
{
	int cs = nand->IO_ADDR_R & 0x3
	...
}

This should do it. Or did I miss something?

> This function is only passed an 
> address of the chip nand_chip struct address. So I still think that an
> entry in the nand_chip struct should be used for tracking the chip
> select to keep the chip select code out of nand.c and keep the code as
> simple as possible.

Hmmm. Is something missing in my example above?

> So, I like the
> #define CFG_NAND_BASE_LIST	{ CFG_NAND_BASE + 1, CFG_NAND_BASE + 2 }
>
> configuration method, but I still think that the struct nand_chip needs
> a chip select variable.

Please explain why.

> Do we assume the use of the nand flash controller on PPC 440 EP, Epx,
> GP, and GPx processors by default (unless still using the legacy drivers
> like the bamboo board)?

For now yes. It's very unlikely that a board with a PPC with an embedded NAND 
controller like 440EP/GR/EPx/GRx will implement a NAND interface in a 
different way. If such a board will appear we can still add some 
configuration method for this.

Best regards,
Stefan