Re: A2232 driver question

[<gri...@ps...>]

> In that driver, I access the 64kB of the ZorroII board directly and I
> wonder if this
> is clean; that means if it at least does not only work under m68k but
> also under
> APUS/PPC.

Most of the drivers for the m68k will 'just work' on APUS as well. Nothing
special required. Only when you start doing memory mapping/protection
tricks (usually DMA engines and such) are there some differences.

The only thing that sometimes has to be added are some [rw]mb() calls
because the PPC chip will re-order reads and writes to optimise it's
I/O. This can cause problems when talking to peripheral chips, 
because they may need a certain specific order in which things are
written to their registers. (eg. address register first, then data)

Adding mb() around these specific I/O routines makes sure that the
PPC doesn't start to re-order the writes. Look at 'drivers/scsi/a3000.c'
for an obvious example.

							Bye, Arno.

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