Abstractation

Abstractation

[Kári Davíðsson]

Hi,

I need to add a cfi_cmdset_0003 to support a Intel chip that we have in
our boards.

Why does I as the cmdset writer have to know all this stuff about the
buswith,
number of chips etc?

Me as a cmdset writer should only be conserned with implementing the
cmdset which is
only affecting one chip at a time, no matter how many there might be on
the bus.

What I am trying to say why is the layering not something like:

--------------------
| Kernel interface |
| has notation of  |
| read / write     |   Sees flash as linear buffer
| to/from linear   |
| buffers (buf)    |  
--------------------
          |
          |
          |
-----------------------  Sees flash as collection of linear sectors
| Mtd knows  the      |  that might be distributed over many flash chips
| mapping from        |
| buffer range to     |
| individual flash    |
| chips/sectors       |
| i.e. where          |
| buf[x] is physically|
-----------------------
          |
          |
          |
--------------------
| cmdset            | sees only one flash chip.
| knows how to write| it knows how to erase sectors, write to them,
read,
| to chip at given  | at word level
| offset for given  |
| chip              |
---------------------

Any way,

Just a thought.

K.D.


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Re: Abstractation

[David Woodhouse]

kd@flaga.is said:
>  I need to add a cfi_cmdset_0003 to support a Intel chip that we have
> in our boards.

You'll probably find it works if you just hack cfi_probe to invoke 
cfi_cmdset_0001 instead. See the list archives - this came up quite 
recently.

> Why does I as the cmdset writer have to know all this stuff about the
> buswith, number of chips etc?

You need to handle multiple chips interleaved on a wide bus anyway. 

Numchips isn't too difficult and by doing it at the command set level we 
eliminate the need for external wrapper functions which make multiple calls 
to the single-chip version of the access function.

--
dwmw2




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Re: Abstractation

[Florian Schirmer / TayTron]

Hi,

> I need to add a cfi_cmdset_0003 to support a Intel chip that we have in
> our boards.

I posted a hack for this some days ago. Just set P_ID to 1 (instead of 3)
right after it was filled and everythings works fine with the cmdset_0001
module.

Hope that helps,
    Florian Schirmer



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