NAND driver

Mark Underwood basicmark at
Tue Feb 26 04:04:27 EST 2008

--- Mark Underwood <basicmark at> wrote:

> I’m writing a NAND driver for an ASIC. The NAND controller has been designed to handle page read
> &
> writes with little SW intervention using interrupts or DMA, so I plan to implement the
> write_page_raw & read_page_raw functions.
> However, looking through nand_base.c it looks like not all NAND access go through these
> functions
> so to start with I have implemented the cmd_ctrl function & supplied the IO_ADDR_R & IO_ADDR_W
> address with the thinking that these would be a fall back when the access doesn't go through the
> raw functions.
> Unfortunately it seems the single write functionality of the controller is broken. The page 
> read
> & write functionality only allow me to work in 512byte blocks so I can't write OOB that way. Can
> you confirm that there are cases where OOB is written separately and if so do you have any
> suggestions for getting around this problem?
> Many thanks,
> Mark

I forgot to say that I'm working on a kernel.

After some pondering I managed to implement the single write functionality by abusing the command
fifo and playing with GPIO pins.

Looking through nand_base.c I notice that although I can pass in *_page_raw operations in the
nand_chip structure they are not used in the *_page_swecc functions but instead they call the
internal *_page_raw functions directly. I propose just to replace the direct calls with indirect
ones (via the function pointers in the nand_chip structure). Does this proposal sound OK?


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