Re: [PATCH] i2c/busses: Add i2c-icy for I2C on m68k/Amiga

Geert Uytterhoeven
2019-08-13T06:53:14Z

Hi Max,

On Tue, Aug 13, 2019 at 12:21 AM Max Staudt <max@enpas.org> wrote:
> On 08/12/2019 11:37 AM, Geert Uytterhoeven wrote:
> >> + iowrite8(val, address);
> >
> > As this is on a Zorro bus, z_writeb()?
>
> I forgot to ask about this.
>
> What is the reasoning behind having a separate z_writeb() for Zorro?
> As far as I can see in arch/m68k/include/asm this maps 1:1 to a direct memory access, and it prohibits cross-arch code as in i2c-elektor.

write*() and friends are intended for PCI, and thus little endian, while
the Zorro bus is big endian. For byte accesses this doesn't matter,
obviously.

Note that this predates iowrite*(), which does have *be variants.
If you want to add compile-testing to your driver, using iowrite*() is fine.

Gr{oetje,eeting}s,

Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds