64 bit bus access on a customed MPC8245 board

[Eric W. Biederman]

Shawn Jin <shawnxtech at yahoo.com> writes:

> Hi,
> 
> I'm working on a customed MPC8245 board with flash
> chip Am29LV320 and trying to enable MTD driver
> support.

The MPC8245 is an embedded ppc processor.
?? 

I looked and I can't find documentation for that chip.
Is it an atmel one?

Chips with similar part numbers are 8 bit flash.  Atmel
does make a few 16bit flash parts.  And I don't know
if Atmel does cfi?  You may need jedec_probe.
 
> The configuration is 32 bit bus width in each chip
> with 2 chips interleaved. So CONFIG_MTD_CFI_B8 and
> CONFIG_MTD_CFI_I2 are defined.

Ok so you have configured it for 2 8bit chips that are
interleaved to form a 16bit path.

> MPC8245 requires the following memory mapping:
> bank 0: 0xFF800000 - 0xFFFFFFFF
> bank 1: 0xFF000000 - 0xFF7FFFFF
> 
> I noticed that FPU must be enabled for 64-bit
> read/write from/to flash.

But that is not even interesting if you are only 16bits wide.

> I use read64() and write64() functions in the
> attachment, which are copied from sbc8240.c. However
> no chip can be found. Any suggestions? Thank you very
> much.

I suggest you focus on read16()/write16().

Eric