In article <440CFA76.1070500@tadpole.com>
garrett_damore@tadpole.com wrote:

>     2) use a separate bus space.  I don't know of any existing examples
> outside of my AR5212 com driver.  In this case I had to implement a
> pretty hefty amount of bus space logic *in com_arbus.c".  This seems
> ugly and unwieldy.

Well, how about com_dio.c and com_frodo.c in arch/hp300/dev/ ?

> My proposal is to *change* com so that instead of using fixed offsets,
> it uses a register look up table.  E.g.
> 
> bus_offset_t   sc_regoffs[NCOM_PORTS];
> 
> #define   GETREG(x)   bus_space_read_1(bst, bsh, sc_regoffs[x])
> 
> Then the various attachment points can populate these registers as they
> see fit.

IMHO, if address mapping (sparse address etc.) is bus specific
it should be handled by bus_space. On the other hand, if the
(unusual) mapping is the device specific, it should be handled
by each driver.
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Izumi Tsutsui