MTD support for 8x16 devices

Alice Hennessy ahennessy at
Thu Aug 31 21:05:10 EDT 2000

David Woodhouse wrote:

> ahennessy at said:
> >  Has any of this already been checked in recently?  And what is the
> > procedure?
> Stéphane already pointed you at the latest CVS. If you want write access,
> let me have a SSH public key and a sample of your work :)

Ok, I will do that.  I also just found out  that I need to subscribe to the
mtd-cvs list to follow what is being checked in?

> Can you confirm the mapping of the flash chips - you've got two interleaved
> 16-bit devices ('2_by_16') but you can only actually access them a byte at
> a time? What is the CPU? What happens if you _do_ try to read a whole word
> instead of only a byte?

One product has two interleaved 16 devices and is recognized as such by
cfi_probe_new_chip() and can be read as a whole word.

The other product has a single strata chip (8x16 variety) set in byte mode so
the bus width is 1.  The cfi ident info is requested at address 0xaa and read
starting at 0x20 so this is new code that I've added.   I'll  merge my code to
make use of the new define CFI_DEVICETYPE_X8 which I'm assuming was added for
this purpose?

The CPU is  PPC405GP.

> ahennessy at said:
> >  I'm also thinking about different ways for the partition sizes to be
> > set outside of physmap.c.   - any opinions?   Perhaps board specifics
> > should be contained in a header file and be set via menuconfig or
> > command line or ?
> I think it's probably best to keep it in a header file or in physmap.c
> itself. The driver can default to no partitioning, and we can set up some
> #defines at the beginning which allow people to change it as they see fit.


> ahennessy at said:
> > 4.   I need to implement a char device where the customer wants to
> > write to the flash and have all the erase details handle by the
> > driver.  They want to simply do a dd into the device.
> No. Erase is a single ioctl() call, or a single invocation of the
> 'eraseall' utility. The customer is wrong. :)

Sooo,  I need to do the extra logic outside the driver level. ;)

> --
> dwmw2
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